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140 Cards in this Set
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In a 99mTc-MDP bone scan, a 60-year-old with prostate CA with increased PSA demonstrates a single post rib lesion. Most likely diagnosis?
• Mets • Fracture • Osteomyelitis |
• False – met is not the correct answer.
only 15% of pts w/ proven mets have a single lesion (most common in the spine); exception: sternum in breast ca [Mettler, p. 291] Of 93 pts with solitary rib hot spot, 11.8% malignant , 88.2% benign -Clinical Significance of Solitary Rib Hot Spots on Bone scan in Patients with Extraskeletal Cancer…Clinical Nuc Medicine Aug 200. (note this was not limited to prostate ca pts) |
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Captopril renal study shows prolonged enhancement except
• Renal artery stenosis • Right vein thrombosis • ATN • Chronic atrophic pyelonephritis • High grade hydronephrosis |
Answer D, Chronic Atrophic pyelonephritis
• RAS does show prolonged enhancement • Renal vein thrombosis does with 131I OIH • ATN-? Note that ATN causes a persistent nephrogram with MAG3 without captopril, so ? it should do the same with captopril [this would make D the best answer] • Chronic atrophic pyelonephritis does with 131I OIH Prolonged enhancement i.e. a positive study for hemodynamically sig RAS; also seen with: dehydration hypotension urinary obstruction [Nuc Requisites, p.3 40] Emedicine.com topic 600 lists false-positives with 131I-OIH [?NOT MAG3]: chronic pyelo, renal outlet obstruction, r. vein thrombosis, perirenal abscess or hematoma , compression of renal hilum |
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All the following are absolute indications to decrease the dose of perfusion agent for a V/Q scan except ?
• PAH • Left-to-right shunt • h/o PE • Pediatric patient • Pneumonectomy |
Answer B. Left to right shunt is fine, right to left you use decreased particles.
• If recalled incorrectly prior PE is next best. • Indications to reduce the number of particles in Tc 99m MAA for perfusion scanning include children under approximately 8 years (number of alveoli and arteries are not at adult level until this time), diseases with pulmonary blood flow compromise (pulmonary hypertension, cor pulmonale), and right to left heart shunt (particles go to brain, liver, etc.). • Prior PE and pneumonectomy are not specifically mentioned, but logic would include these in diseases with pulmonary blood flow abnormalities. Left to right shunt would make no difference since IV injection of particles goes to right heart first. If the question is misremembered (choice was actually right to left shunt), I cannot find any specific reference calling for reduced particles in post op patients. • Source: Henkin Nuclear Medicine vol 2 p. 1368-9. • PAH gives reversal of perfusion gradient with flow to the upper lung zones, possibly even segmental defects in the bases [Mettler, p. 231] • If the question is about V/Q scanning, 99mTc-MAA goes to systemic circulation with right-to-left shunts • With chronic PE, defects can persist |
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Which of the following is the most common of unilateral lung perfusion on a 99mTc-MAA study?
• Swyer James • Mucus plug • PTE • Bronchial CA • Pulmonary artery atresia |
Bronchial ca probably correct
• . • . • PTE – lobar or whole-lung perfusion defects are unusual presentations for PE. Other possibilities include hilar masses, mediastinal fibrosis, & hypoplastic pulm. artery. [Mettler, p. 217] • bronchial ca- probably correct; • pulm artery hypoplasia or aplasia less common |
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FDG Pet; what is false-
• a) staging of non small cell is never better with FDG than with CT • b) it is less accurate for small cell than non-small cell • c) granulomas can give false postives • d) lesions smaller than 1 cm can give a falsely low SUV • e) SUV > 2.5 highly suspicious for malignancy (except in the liver) |
• Ans. A. Non-small cell staging with PET is superior to CT staging.
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In the chest, which of the following is not an indication for FDG PET?
• Breast mets • Small cell lung CA • Esophageal CA |
b. Small cell lung ca
Indications include: Non-small cell lung ca Breast, colorectal, lymphoma Esophageal head&neck ca thyroid [specific situation] melanoma single pulmonary nodule myocardial viability |
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Hot nodule in thyroid
• Greater than 5% chance cancer • Multinodular goiter • Autonomous adenoma • Uptake >40% at 24 hours • RAIU will be >40% |
c. Autonomous adenoma
• F; hot nodule <1% malignant • F; multiple mostly nonfunctioning nodules in MNG • T • F; uptake >40% a/w Graves |
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Which is false in parathyroid sestamibi scan?
• Fast washout causes false negative • Thyroid cancer can cause false positive • Used intraoperatively • Size related to detection • sestamibi works on the principle that parathyroid is hypervascular |
Answer E. works on principle of delayed washout of partathyroid
• T “some adenomas demonstrate sufficiently rapid…clearance that they are not detectable at 2 hrs.” Nuc Requ p385 • T This happens with pertech/thallium subtraction imaging. UCLA NM mediabook states metastatic thyroid ca is a cause of false positives w/ sestamibi • T gamma probe is used; minimally invasive radioguided parathyroidectomy (MIRP ) Effect of Minimally Invasive Radioguided Parathyroidectomy Annals of Surgery. 231(5):732-742, May 2000 • T False-negative findings include parathyroid lesions, which are too small to be detected . Emedicine topic 525 and UCLA NM mediabook online |
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Follicular thyroid CA s/p resection with increased thyroglobulin levels. The patient has a negative I131 whole body scan. What should be next?
• FDG PET • Surgery • Repeat 131I treatment • Repeat 131I scan |
a. PET
Medicare covers the use of FDG PET for thyroid cancer only for restaging of recurrent or residual thyroid cancers of follicular cell origin that have been previously treated by thyroidectomy and radioiodine ablation and have a serum thyroglobulin >10ng/ml and negative 131I whole body scan performed. . need an imaging study (ideally) before repeat therapy. Dr. Tiu says they used to just give another therapeutic dose of I 131, but in the new age of PET scans, need to do PET to see if there are any abnormalities. c. NCI says 131I: Studies have shown that a postoperative course of therapeutic (ablative) doses of 131I results in a decreased recurrence rate among high-risk patients with papillary and follicular carcinomas (However for stage III & IV they list: >131I ablation following total thyroidectomy if the tumor demonstrates uptake of this isotope. >External-beam irradiation if 131I uptake is minimal) |
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What will cause your LVEF in MUGA to increase?
• a) including spleen in background counts • b) including field outside patient in background counts • c) including diaphragm in background counts • d) including the rt atrium in both diastole and systole • e) including rt atrium in systole |
• Ans: A. Remember the formula: LVEF= [(ED-B)-(ES-B)]/(ED-B) which is equivalent to: (ED-ES)/(ED-Background). The spleen has very high counts. (So does the right atrium, but it is so small it really doesn’t affect the counts).
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Which is false about difference b/w Thallium and Sestamibi?
• a) sestamibi will redistribute • b) sestamibi passively taken up by mitochondria |
• Ans: A. Sestamibi does not redistribute, this is a property of thallium
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Regarding gastric emptying studies, which is true?
• a) solids more sensitive than liquids. • b) liquids more sensitive than solids |
Ans: A. solids more sensitive (Repeat).
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What is absolute an contraindication to administration of adenosine?
• third degree heart block • CABG • asthma |
Ans: A. 3rd degree heart block. Contraindications to adenosine myocardial perfusion imaging:
• a. Severe bronchospastic pulmonary disease • b. Hypotension • c. Recent Ml (within 6 weeks) or CVA - relative contraindication, requires consultation with nuclear medicine staff • d. Sick sinus syndrome • e. Second or 3rd degree AV block • f. Severe CHF • g. Low left ventricular ejection fraction • h. Theophylline containing preparations within 48 hours of scheduled exam • i. Caffeine-containing products within 6 hours of scheduled exam • j. Oral dipyridamole within 48 hours of scheduled exam • k. Inability to give informed consent • l. Inability to lie still for imaging |
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Which of following does not uptake octreotide?
• renal cell carcinoma • pheochromocytoma • medullary carcinoma thyroid • carcinoid • Neuroblastoma • Small cell ca of lung • Meningioma • Lymphoma • Breast ca • Islet cell tumor • Merkel cell tumor • Hormonaly active pituitary adenoma |
• Ans: A. RCC does not uptake (Nuc Med Reqs).
• NM imaging pg 323 |
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what is a characteristic of hemangioma?
• a) increased uptake on delayed Tc99m sulfur colloid scan • b) hyperechoic with increased acoustic enhancement • c) hyperechoic peripherally with hypoechoic center is a variant presentation |
Ans: C. This is an atypical appearance of hemangiomas that is only rarely seen in metastatic disease (pg 54 Ultrasound Case Review). Increased uptake is seen on delayed Tc99m RBC scan. The typical ultrasound appearance is hyperechoic WITHOUT increased acoustic enhancement (it can happen, but it is not typical). Answer A is wrong, b/c Tc99m RBC scan is used.
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Gallium vs. Indium, what is Indium better for?
• a) disc infection • b) otitis media • c) acute inflammatory bowel disease • d) splenic abscess |
• Ans: C. Acute inflammatory bowel disease. (Repeat).
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Which test and result go together?
• a) intrinsic: integral function • b) extrinsic: collimator malfunction • c) Center of rotation: spatial axis • d) • e) Line bar: linearity |
: B. Measures of performance of a scintillation scanner with the collimator attached are called system or extrinsic measurements (Bushberg pg 678).
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Tibial stress fractures- what is most characteristic for them on 3 phase bone scan?
• a) normal on first two, hot on delayed • b) hot on all three • c) hot, hot, then slightly decreased uptake on delayed • d) cold on all three |
Hot on all 3 if acute, hot on delayed if chronic. Note difference between shin splints and fracture
Ans. B (but A can be seen!). A is true if chronic, but B can be true if acute. However, the best and more traditional answer is ?. N.B., this is similar to: Shin splints- normal on flow and blood pool, increased activity on delayed in long linear distr at least along 1/3rd of length in postmed tibial cortex at insertion of soleus Stress fracture: stress fractures are more focal, and not in the postmed tibial cortex (classic for shin splints). |
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What happens to DISIDA in liver?
• a) passive uptake by hepatocytes, conjugated • b) active uptake by RES, conjugated • c) active uptake by hepatocytes, excreted unchanged |
Ans: C. DISIDA competes for uptake by the liver, but is not conjugated by the hepatocytes.
• Nm imaging pg 275 |
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Xenon vs. Tc99m DTPA. DTPA does all of the following except:
• a) more dose to lungs • b) easier for patient • c) no need for special back ventilation room • d) stays in lungs longer • e) shorter half life |
Ans: A. 30 mCi of Tc99m DTPA in 3 ml Saline delivers 100K counts in 2 minutes on a standard gamma camera with low energy collimation. The typical radiation exposure to the lungs is 100 mrads. This is less than the several hundred millirad exposure from a typical Xe133 rebreathing ventilation exam.
Additionally, Xe has a longer half-life (5.3days), and is retained longer (esp in COPD/asthma), without washing out |
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FDG Pet and seizure what is false?
• a) 90% sensitivity for diagnosing seizure focus ictally • b) if basal ganglia hypometabolic next to hypermetabolic seizure focus, then more likely to get more seizures after surgery • c) the brighter the uptake, the better the outcome after resection • d) Seizure foci demonstarte-hyperperf and hypermetabolism during seizures and hypo and hypo in interictal period • e) PET with FDG for metabolism and HMPAO or ED for perfusion |
Ans. ? (A is correct- Nuc Med Requisites states that PET has >90% sensitivity for dx seizure ictally)
• D is correct |
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• All of the following are true regarding PET scan in the interictal period except:
• A. Has a 90% sensitivity in localizing seizure focus • B. Greater asymmetry in temporal lobes better postoperative outcome • C. If basal ganglia have low activity, then that indicates poorer postoperative outcome • D. Low signal in seizure focus • E. Common in frontal and temporal lobe |
• PET scanning in the ictal period can have >90% sensitivity, but all sources cite between 65 and 75% sensitivity for interictal studies making this the likely answer.
• PET scanning is of utility for both temporal and frontal lobe seizures, and seizure foci are hypometabolic in the interictal phase (low signal). Note they have increased activity with ictal studies. • I found an article suggesting that the more focal, clear asymmetry in mesial temporal lesions yields more successful surgeries. Neurology, Vol 44, Issue 12 2331-2336. • Another article talks about low activity in the basal ganglia being more common with global seizures so these patients would be less likely to respond to surgeries. Annals of Nuclear Medicine Vol. 18, No. 7, 579–584, 2004 • Answer: A |
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Repeat about patient contamination with some type of nuclear medicine agent- what do you do?
• a) address the patient’s medical concerns • b) clear the area and get nuclear medicine consult before touching patient • c) decontaminate patient before treating |
• Ans. A. Address the medical concerns.
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• Captopril is given to a patient with right renal artery stenosis prior to a 99mTc-DTPA renogram. Which of the following findings is most likely?
a. Normal b. Increased uptake right kidney c. Decreased uptake right kidney |
• C. Decreased uptake right kidney. Seen with DPTA secondary to decreased cortical uptake 2nd to perfusion
• If mag3 would have increased retention aka increased uptake 2nd to decreased washout. |
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• A 7 months pregnant patient with history of breast CA now has bone pain in the femur. Which is true regarding NM bone scan.
a. should not be done because of the risk to the fetus. b. should not be done because she is already known to have breast CA. c. should be done. d. |
• C. Should be done
• Risk of radiation to a third trimester fetus is less than risk of untreated metastases in the mother. |
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• When labeling RBC’s with 99mTc for a tagged red cell study, where does the Technetium bind?
a. alpha hemoblobin subunit b. beta hemoglobin subunit c. membrane d. cytoplasmic structure |
• B. beta hemoglobin subunit
• straight from ’95 exam. |
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• Regarding the “stripe sign” in a V/Q scan:
a. Indicates a peripheral perfusion defect b. Cannot be interpreted in the presence of small bilateral pleural effusions c. Commonly seen in patients with COPD d. Indicates decreased perfusion in the periphery of the pleura |
• C. Commonly seen in patients with COPD
• The stripe sign consists of a thin line or stripe of activity representing perfused lung tissue between a perfusion defect and the adjacent pleural surface. Perfusion defects with a stripe sign are very unlikely to represent PE based on the assumption that non-pleural-based lesions are not emboli. A stripe sign is frequently seen with COPD and indicates a low probability defect. Source: Mettler 4th ed. p.215, 235** This question had been a source of some debate when answering old recalls. On the ’03 test, choice ‘D’ definitely said decreased pleural perfusion, making it even clearer that ‘C’ was the best answer ** |
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• A young woman has a history of sore throat for 2 months. Her T4 is elevated, but RAIU is only 1%. Likely cause?
a. Hashimoto’s b. subacute thyroiditis c. Plummer’s d. Grave’s disease |
• B. subacute thyroiditis.seen on ’00 exam. Nothing about a “recent CT scan” in this year’s question.
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• Which of the following is the best test for assessing myocardial viability?
a. 99mTc-Sestamibi planar b. 201Thallium c. 99mTc-Sestamibi gated SPECT d. FDG-PET e. MUGA |
• I think PET.
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On a 99mTc-HMPAO cerebral perfusion study, crossed diaschisis in the cerebellar area is associated with what?
• a) acute cerebral infarct • b) grand mal seizure • c) decreased cerebral blood flow reserve • d) TIA • e) tumor |
• “Crossed cerebellar diaschisis refers to hypometabolism in a cerebellar hemisphere contralateral to a cerebral hemispheric lesion. The location of the lesion is a critical factor in producing this effect as lesions located in the motor cortex, anterior corona radiata, and thalamus produce the most marked suppression of the contralateral cerebellar cortical metabolism.”—M. Roarke, MD et al of Mallinckrodt @ gamma.wustl.edu.
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Concerning FDG PET, which of the following statements is true?
a. May proceed in pt. with hyperglycemia if injected immediately after AM Insulin b. Image 15-30 min. after injection c. Have pt. rest quietly for 1 hr. post-injection before imaging d. Load pt. with glucose to saturate heart activity |
C. Have pt. rest quietly for 1 hr. post-injection before imaging
• “Within an hour of injection, most of the FDG has left the blood, and, in tissues with little glucose-6-phosphatase such as the brain, most of the radioactive signal is present as FDG-6-phosphate. Using rate constants derived for normal brain, it has been demonstrated that the total radioactivity measured > 45 minutes after injection is linearly related to the cerebral metabolic rate of glucose use (CMRglu). This allows qualitative FDG imaging to be done relatively simply. Frequent collection of arterial or “arterialized” venous blood and serial PET images over the 45 minutes of tracer uptake can be eliminated, and fasting patients can be allowed to relax quietly between the injection of FDG and imaging.”—Taveras , 3:28. |
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On a HIDA scan in a patient with cholecystitis, there is elevated uptake around the gallbladder. This is due to which of the following?
• a) increased uptake in the gallbladder wall • b) increased uptake in inflamed liver tissue • c) bile leak |
B. Inflamed liver tissue
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Which of the following is true about Sincalide?
• a) Gallbladder EF is proportional to the infusion rate • b) Gallbladder EF is measured 10 minutes after injection • c) it is the synthetic C-terminal octapeptide of CCK • d) it is used to differentiate between neonatal hepatitis and biliary atresia |
C. C-terminal octapeptide of cholecystekinin
• “Kinevac (Sincalide for Injection) is a cholecystopancreatic-gastrointestinal hormone peptide for parenteral administration. The agent is a synthetically-prepared C-terminal octapeptide of cholecystokinin.”—www.rxlist.com |
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Which is least likely to show uptake on bone scan?
• Osteopoikilosis • Fibrous Dysplasia • Osteoid Osteoma • Osteomyelitis • Paget’s Disease |
• osteopoikolosis
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For which of the following conditions does 111Indium labeled leukocytes not have an advantage over 67Ga?
a. Inflammatory bowel disease b. Discitis c. Abdominal abscess d. Infection in an artificial hip |
B. Discitis
In-111 has low sensitivity for spine infections (appear photopenic, False Neg. 10-40%), and “67Ga may be preferred”. Sources: Mettler 4th p. 397-398; Nuc. Req. p. 171. |
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Regarding 123I for thyroid imaging:
a. kV of primary photons is inferior to those of 131i b. Cost is prohibitive for most clinical applications c. Administered IV d. Useful for workup of discordant nodule |
Cost prohibitive, costs twice as much as I-131
• “The physiologic standard radionuclide for thyroid imaging is 123I. Its 13.3 hour half-life and 159-keV principal photon allow good imaging with a modest patient radiation exposure.” • “In the past, 131I was widely used. It is no longer used for imaging because of its unacceptable dosimetry.” • “A comparison of dosimetry of these available isotopes at the administered doses used clinically demonstrates an excessive radiation burden from 131I” |
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• Which tumor is least prominent on FDG-PET?
• Bronchoalveolar • Melanoma • Breast • Prostate • Lymphoma |
This is single best answer.
• Ans---Prostate Bronchoalveolar is another good answer. Prostate is better since prostate carcinoma not only is low metabolic it lives behind the bladder that is full of activity. • By critical assessment of large number of clinical investigations, the cost-effectiveness of FDG PET scans has been confirmed in the following cases: differential diagnosis of solitary pulmonary nodule, diagnosis, staging and restaging of non-small cell lung cancer, colorectal cancer, malignant lymphomas, malignant melanoma, esophageal neoplasms and cancers of the head and neck. The role of this method in breast cancer is currently under intensive investigation but the FDA currently only approved PET for follow-up of treated breast cancer, not for initial diagnosis or staging. |
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• Which statement regarding FDG PET is false?
• a) Tb shows increased uptake • b) sarcoid shows increased uptake • c) fungal infection shows increased uptake • d) malignant nodes are “hot” in 60 or 80% • e) small cell carcinoma is “hot” |
• Which statement regarding FDG PET is false?
• a) Tb shows increased uptake • b) sarcoid shows increased uptake • c) fungal infection shows increased uptake • d) malignant nodes are “hot” in 60 or 80% • e) small cell carcinoma is “hot” • Answer: E. Small cell ca. is cold |
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• Which of the following is true regarding gastric emptying studies?
a. solid meals are more sensitive for early emptying delays b. t1/2 for solid meal is 20 minutes c. liquid meals show linear emptying d. anterior and posterior images are essential for obtaining accurate results e. results are not reproducible |
• A. Solid meals are more sensitive for early emptying delays“…the solid phase is more sensitive than the liquid phase for delayed gastric emptying…” [Mettler 4th p. 278].
• t1/2 for solid emptying is given as 90 min. (range 45 to 110 min); for liquids, it is 40 min. (range 12 to 65 min.) [Mettler 4th p. 278]Liquid meals show exponential emptying; it is solid meals that show nearly linear emptying (after a short lag phase). [Requ 2nd p. 273]The NM Reqisites, 2nd. Ed., does describe a “geometric mean” method for data acquisition as being the gold standard; however, it is certainly not essential, as a single-camera technique is listed in the next paragraph (p. 277).Both Mettler and The Requisites describe sticking to a standardized protocol (which may vary between labs) as key for accurate (reproducible) results. Also, a prior year’s recall phrased this choice as “It cannot be used to follow patients with gastroparesis because of poor Reproducibility”, which is clearly False. |
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• Why is PET used for esophageal cancer?
a. To evaluate for local invasion b. To evaluate size of primary tumor c. provides better information for distant mets than CT |
• C. Provides better information for distant mets than CT
• PET is approved for diagnosis, staging, and re-staging of esophageal CA. One reference had this to say: “Flanagan et al. also showed that PET is more sensitive than CT for revealing regional and distant metastases (3). These investigators considered PET as a cost-effective imaging procedure that may decrease the number of unnecessary surgeries by identifying patients who have unresectable disease.” http://brighamrad.harvard.edu/Cases/jpnm/hcache/1096/full.html |
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• Molybdenum breakthrough is a concern because:
a. Beta emitter b. 60 hour half life c. pyogenic d. Photon energy is high e. interferes with 99mTc localization |
• A. Beta emitter
• b-decay is the primary mechanism for Molybdenum breakdown. These particles impart radioactivity within the body without any clinical benefit. [recall b-particles have a quality factor of 2 = twice as damaging as an equal energy photon] T1/2 = 2.8 days; USP contamination limit: 0.15 mCi per mCi 99mTc when administeredThe high energy gamma rays (740, 780) are very penetrating and cannot be efficiently detected by scintillation cameras. Although they are used for measuring contamination, they contribute little to image noise.Sources: Dähnert 4th p. 1067; Nuc Req. 2nd p. 53. |
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• Which of the following is false, regarding myocardial perfusion imaging?
a. timing of imaging is more important with thallium than with sestamibi b. thallium has a higher extraction than sestamibi c. sestamibi uptake is by active transport d. imaging for myocardial infarction may done up to six hours post onset of symptoms e. sestamibi does not redistribute |
• C. Sestamibi uptake is by active transport
• Sestamibi = Cardiolyte = hexakis 2-methoxyisobutyl isonitrile; diffuses passively out of the blood, localizes in mitochondria on the basis of negative electrical potential. Nuc Req. 2nd p. 67 • Recall that Thallium undergoes “redistribution”, which is one reason timing is very important (peak myocardial uptake at 10-20 min). On the other hand, the clearance T1/2 of sestamibi is ~ 5 hrs., and it undergoes essentially no redistribution. • Thallium is approximately 88% extracted in the 1st-pass (“90% in 90 seconds”) • Almost all patients with myocardial infarction injected within 6 hrs. after the onset of chest pain demonstrate perfusion defects Mettler 4th p. 161. |
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• The main reason PET is used in non small cell carcinoma:
a. avoid unnecessary surgery b. evaluate local extent of tumor |
• A. avoid unnecessary surgery
• An on-line article by Lederman had this to say: ”It is estimated that in early stage lung cancer, that PET scan shows unsuspected metastases in about 10% of patients… [and] In 100 patients with Stage III disease, 24 (24%) had metastases… “ ”…Our data suggests that PET may have an even greater impact on patient selection for radical radiation [rather] than on selection for surgery” http://www.siuh.edu/radoncology/otarticle50.html |
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• Which is true regarding breast imaging with 99mTc MIBI ?
a. if a lesion is only seen on MIBI imaging, MIBI guided biopsy should be performed b. has been proven to be an effective screening exam c. increased activity may be seen in hyperplasia |
• C. increased activity may be seen in hyperplasia
• False-positive results are generally related to fibroadenomas, fibrocystic change, or inflammation but have also been reported in benign conditions that confer a higher risk for developing carcinoma, including epithelial hyperplasia and sclerosing adenosis.Potential uses for 99mTc sestamibi imaging in the setting of suspected or diagnosed breast cancer include (1) selection of mammographic abnormalities for biopsy; (2) evaluation of palpable masses without discernible mammographic abnormalities, especially in patients with dense breasts, (3) detection of recurrence after lumpectomy, (4) detection of regional lymph node metastases, and (5) evaluation of patients with breast implants. Source: Mettler 4th p. 377.MIBI breast imaging has no role in screening; MIBI-guided biopsy equipment is currently under development (unproven). MIBI breast imaging is said to have an overall sensitivity of 85% and specificity of 81%. [* mammography sensitivity usually 85-90%] Source: Nuc. Req. 2nd p. 205 |
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• Which is true regarding the standardized uptake value (SUV) in PET imaging?
a. widely accepted to be accurate for malignancy b. is most accurate for lesions less than 1 cm c. an SUV of 1.5 or greater is characteristic of cancer d. is equal to the activity of the lesion divided by the dose per body weight e. SUV is measured approximately 3 hours after injection |
• D. is equal to the activity of the lesion divided by the dose per body weight By definition: SUV = normalized target-to-background measure to allow comparison within and between different patients and diseases. SUV = FDGregion / (FDGdose / WT) [Dähnert 5th p. 1072]While the SUV is useful, there is a wide overlap between benign and malignant conditions: blood pool 1.5-2.0; liver 2.5; renal cortex 3.5; malignancies 2-20.The spatial resolution of PET is 4-7mm, so it will be less accurate for lesions smaller than 1 cm.Typical PET imaging time is 50-70 min. after administration (recall the T½ of FDG is 110 min, and even shorter for other PET agents)
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• Which of the following is least likely to cause hot nodules on 99mTc-sulfur colloid imaging?
a. IVC thrombosis b. Budd-Chiari c. Portal vein thrombosis d. Focal nodular hyperplasia (FNH) e. Regenerating nodules |
• C. Portal vein thrombosis
• Portal vein thrombosis (portal HTN) will cause shunting of colloid-laden blood away from the liver, making it relatively photopenic [see Nuc. Req 2nd Fig. 10-40 for a great image of this] • Budd-Chiari syndrome [liver venous outflow obstruction] causes increased uptake in the caudate lobe; • IVC thrombosis (leg injection) and SVC thrombosis / syndrome (arm injection) cause focal increased uptake, as also do FNH and cirrhosis with a regenerating nodule. [sources: Mettler 4th p. 241, Nuc. Req. 2nd p. 258] |
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• Which of the following metabolic disorders will cause increased false negatives on PET imaging?
a. hyponatremia b. hyperkalemia c. hypoglycemia d. hyperglycemia e. hyperparathyroidism |
• C. Hyperglycemia Serum glucose competes with FDG for entry into tumor cells. Therefore, patients are typically required to fast for 4-18 hrs. before the exam, as FDG tumor uptake is diminished by an elevated serum glucose level. Source: Dähnert 5th p. 1072
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• For which of the following is Indium-111 WBC imagining preferred over Gallium-67?
a. splenic abscess b. lung infection c. spinal osteomyelitis d. active phase of inflammatory bowel disease e. discitis |
• D. Active phase of inflammatory bowel diseaseThis is clearly the best answer—Ga-67 is normally cleared through the GI tract, which complicates imaging of this area (esp. at 24-48hrs.). On the other hand, any activity of In-111 labeled leukocytes in the GI / GU tract is abnormal. IBD is specifically listed as a use of In-111 WBC’s. [source: Dahnert 5th p. 1078]Optimal uses:
Ga-67: chest (interstitial pneumonia, opportunistic infection, sarcoid, drug toxicity); bone: osteomyelitis; lymphoma, melanoma In-111 WBC: most all infections, except splenic abscess (high normal uptake in spleen); IBD; graft / prosthesis infections; however, In-111 has low sensitivity for spine infections (appear photopenic, False Neg. 10-40%), and “67Ga may be preferred”. Sources: Mettler 4th p. 397-398; Nuc. Req. p. 171. |
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• On 99mTc-MDP bone imaging for mets, which of the following is true?
a. most mets are in appendicular skeleton b. most mets are in axial skeleton c. equally distributed between axial and appendicular skeleton d. most mets in the distal extremeties |
• B. Most mets are in the axial skeleton
• “In normal adults the red marrow is distributed to the bones of the axial skeleton, including the cranium, and the proximal portions of the femurs and humerus. Over 90% of skeletal metastatic lesions from most epithelial tumors are found in this distribution…” Nuc. Req. 2nd p. 116 • In multifocal metastatic disease, the regional distribution of lesions for common bone-seeking primary tumors is as follows: thorax and ribs, 37%; spine, 26%; pelvis, 16%; limbs, 15%; and skull, 6%. Mettler 4th p. 293Axial > appendicular skeleton (dependent on distribution of bone marrow); vertebrae, ribs, pelvis involved in 80%. Dähnert 5th p. 118 |
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• Which of the following is true about MUGA?
a. wide histogram is compatible with a regular heart rate b. if diastolic region of interest (ROI) is too large the ejection fraction will be underestimated c. most ROI’s are manually drawn d. background counts account for approximately 30% of total counts |
• D. Background counts account for approximately 30% of total counts
• Normal background counts vary 30-60% end diastolic activity (Dähnert 5th p. 1101 notes “high background activity” as a CON of MUGA).Note that EF = (EDC – ESC) / (EDC – Background) [EDC = end diastolic count, ESC = end systolic count] Therefore, high EDC (from too large diastolic ROI) will overestimate EF, not underestimate.A regular HR should have a nearly contant beat length, which will give a narrow histogram.Most ROI’s are computer drawn (possibly manually reviewed) Sources: Nuc. Req. 2nd p. 97-102; Mettler 4th p. 164-169 |
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• PET is not typically used for which of the following?
a. cardiac viability b. cardiac coronary artery perfusion c. assessment of distant esophageal cancer metastases D. assessment of the solitary pulmonary nodule E. assessment of colon cancer metastases for localization |
• B. cardiac coronary artery perfusion
• Although PET can be used for myocardial perfusion (e.g., 13N ammonia or 82Rb), SPECT Sestamibi or 201Tl are much more common. Among other issues, the T½ of 13N is 10 min., and 82Rb, 76 sec.!However, assessment of cardiac viability is a practical (and approved) role of FDG. Hypoperfused (but viable) myocardium can switch from fatty acid to glucose metabolism, possibly making it brighter than normal on FDG PET. The hallmark finding of “hibernating” myocardium is an area that is “cold” on perfusion but bright on FDG PET. Scar does not take up FDG. Source: Nuc. Req. 2nd p. 90-92. |
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• Diamox is used to evaluate which of the following in SPECT imaging of the brain?
a. Alzheimer’s b. Cerebrovascular reserve c. seizures |
• B. Cerebrovascular reserve
• The distribution of 99mTc-HMPAO is proportional to cerebral blood flow. Normally, the administration of Diamox [or CO2] causes a fourfold increase in blood flow (recall Diamox = acetazolamide = carbonic anhydrase inhibtor). However, regions of the brain without a reserve are already maximally dilated, and therefore will show a regional perfusion defect when compared with the baseline study. [Nuc. Req. 2nd p. 310]Alzheimer’s: classically bilateral posterior temporal and parietal hypoperfusion on SPECTSeizures: hypoperfusion interictally, hyperperfusion ictally. [p. 313] |
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• Which of the following is the most typical for renal artery stenosis in a MAG-3 captopril study?
a. prolonged cortical retention b. decreased arterial upstroke c. decreased cortical retention d. delayed nephrogram |
• A. prolonged cortical retention.99mTc-Mercaptylacetyltriglycine (MAG3) is nearly a pure tubular agent (less than 3% filtered in glomerulus). It is usually taken up normally even when renal artery stenosis is present (* it is a glomerular agent such as DTPA that shows decreased uptake).Administration of captopril (an ACE inhibitor) will inhibit vasoconstriction of the efferent arteriole, and thus the kidney’s ability to compensate & maintain GFR in renal artery hypertension. This decreased GFR on the affected side will result in delayed washout [prolonged retention] of the radiopharmaceutical.
[Nuc. Req. 2nd p. 339] |
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• Which of the following should be used to obtain the best resolution for evaluating a child with AVN of the hip with 99mTc-MDP?
a. SPECT b. electronic magnifier with planar imaging c. diverging collimator with planar imaging d. converging collimator with planar imaging e. Pinhole collimator with planar imaging |
• E. Pinhole collimator with planar imaging“The usual procedure [for evaluation of the femoral head] is to compare the normal with the suspected abnormal side. For these studies, a pinhole collimator should be used to provide the high-quality detail needed for accurate diagnosis.” Mettler 4th p. 314.Pinhole collimators offer high resolution (via magnification) at the expense of sensitivity. They potentially offer higher resolution than the intrinsic resolution of the gamma camera. Converging collimators can also magnify an image, but at the expense of image distortion. Diverging collimators shrink an image. Nuc. Req. 2nd p. 22.SPECT typically increases contrast. [Nuc. Req. 2nd p. 113]
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• A 99mTc-DISIDA biliary scan in a child shows multiple photopenic areas initially which do not fill in on delayed images. Most likely diagnosis:
a. Caroli’s disease b. focal nodular hyperplasia c. biliary atresia d. polycystic liver disease |
• D. Polycystic liver disease
• “Liver scintigraphy often shows areas of photopenia with normal excretion of the radionuclide into the GI tract” Ped. Req. 2nd p. 129 • Caroli’s – Normal early activity, accumulation on delayed images Mettler 4th p. 276 (Fig. 10-36) • FNH – prompt uptake, delayed clearance Nuc. Req. 2nd p. 246 • Biliary atresia – does not visualize in the SB by 30 min. and disappears from the liver by 6 hrs. Ped. Req. 2nd p. 128 |
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• Which is true regarding lymphoscintigraphy for melanoma?
a. pathology of sentinel node predicts pathology of lymph node basin b. often cant complete because of technical difficulty c. skip lesions cause false negatives d. draining anatomy corresponds to classic anatomy |
• A. pathology of sentinel node predicts pathology of lymph node basin
• Recent studies have shown that sentinel lymph node biopsy is an accurate alternative to routine nodal dissection. Many consider it the standard of care. Negative biopsy does not require further surgery and are at low risk. • Studies have shown an orderly progression of lymph node tumor spread [i.e., implies no “skip” lesions]. The newest development in the nuclear technique is to use an intraoperative gamma probe detector that provides accurate localization at the time of surgery. • Lymphatic drainage is unpredictable, particularly in the head and neck. Source: Nuc. Req. 2nd p. 226. |
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• A patient has prostate cancer, a PSA of 40 and a hot lesion in the lumbar spine on bone scintigraphy. What is the most appropriate next step?
a. increase stage b. recommend correlation with lumbar x-rays c. MRI (with prostate coil) d. PET e. U/S guided prostate biopsy |
• B. Recommend correlation with lumbar X-rays
• Prostate cancer with a PSA of 40 is certainly likely to metastasize. However, only about 15% of patients with proven metastases have a single lesion [with the spine being the most common location]. Given this, it is worth correlating with plain radiographs to exclude benign disease (e.g., injury / fracture or infection). Mettler 4th p. 291 • If the PSA is < 10 ng/mL, the likelihood of bone mets. Is < 1%. PET is not sensitive for Prostate CA. Nuc. Req. 2nd p. 122. |
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• What findings are typical for shin splints on Tc-99m-MDP triple phase scan?
a. Hot on all three phases b. Hot on flow and blood pool images/ cold on delayed images c. Hot on flow image/ cold on blood pool and delayed d. Cold on flow and blood pool images/ hot on delayed images |
• D. Cold on flow and blood pool images / hot on delayed images Shin splints refers to soreness along the posterior / posteromedial tibial cortex of the Tibia; typically bilateral, though not necessarily symmetrical. Characteristic findings on 99mTc-MDP scintigraphy are normal flow and blood-pool images, but linear longitudinal uptake on delayed images. They are thought to be the result of traction periostitis. Dähnert 5th p. 158, Nuc. Req. 2nd p. 130. A stress fracture will show focal uptake that is hot on all three phases. Nuc. Req. 2nd p. 131.
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• Diagram of RIAU vs. time. 5 simple curves corresponding to letters with 4 and 24 hrs labelled. Which one is wrong?
4 hours 24 hours a. moderate hyperthyroid high higher b. hypothyroid low low • c. euthyroid low higher • d. marked hyperthyroid very high lower e. subacute thyroiditis (DeQuervan’s) high low |
• E. Subacute thyroiditis (DeQuervan’s)
• The description for uptake in this entity (high at 4 hrs., then low) is not correct. Subacute thyroiditis (also called granulomatous thyroiditis) is probably viral in etiology. The patient will clinically be hyperthyroid, as well as have elevated T4 lab values. However, RAIU will be abnormally low, possibly increased uptake late. Nuc. Req. 2nd p. 376. • Hyperthyroid - Moderate: elevated at 4 hrs. (> 12%) and at 24 hrs (> 30-35%) - Marked: “…in some patients with florid hyperthyroidism, the uptake peaks before 24 hrs. and the measurement at 24 hrs. is misleadingly low.” Nuc. Req. 2nd p. 378. • Hypothyroid: low RAIU due to decreased functioning of the gland. Normally should be at least 10% uptake by 24 hrs. Primary hypothyroidism occurs when the gland does not respond to TSH; secondary hypothyroidism is due to lack of TSH (e.g., a pituitary abnormality). Mettler 4th p. 108. • Euthyroid (normal): < 25% at 4 hrs., < 35% at 24 hrs.* Note that any number of drugs, renal failure, enzyme defects, etc. can affect RAIU. See Mettler 4th p. 109 Tab. 7-3 for a breakdown. |
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• For a Xe ventilation study, which is true?
a. Xe gas leakage during study is treated same as precautions for patient after the study is over b. Xe single dose leakage requires evacuation of NM department c. CO2 scrubber needed in rebreather d. Tight fit of rebreather mask necessary to prevent leak, and room contamination e. The central bronchi get a higher dose |
Incomplete Recall **Emergency Procedure for Xenon-133
Remove people from room immediately. Block off room location to inhibit any through traffic. Notify Chief Nuclear Medicine Technologist or designee immediately. Enter the room after 45min with a GM probe and survey the room. If readings are less than 0.05 mR/hr release the room. If not repeat after 45min. (UCSF Office of Environmental and Health Safety)The exact answer is unclear, given the choices recalled. However, it shouldn’t be necessary to evacuate the entire NM department as Xenon-133 is used in a negative-pressure room. • Xe-133 requires a negative pressure room and a dedicated Xe trap or exhaust vent. The insert also states that the lungs get the highest absorbed dose compared to any other organ system |
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• In a patient with thyroid cancer, which is true?
a. FDG-PET may detect mets not seen with 131I b. mets not seen with 131I are untreatable c. positive on TCO4, treat d. negative on 131I, cannot treat |
• A. FDG-PET may detect mets not seen with 131I Medullary and anaplastic thyroid carcinoma do not concentrate 131I and are therefore not detectable by thyroid scanning. Follicular, mixed papillary-follicular, and a high percentage of papillary carcinomas concentrate sufficient 131I to be demonstrated. Maisey p. 204 “…more aggressive tumors which often do not accumulate radioiodine accumulate FDG. FDG-PET may be of greatest utility in locating tumor foci in patients with rising serum thyroglobulin levels and normal 131I scans.”
PET has a reported sensitivity of 69-94% and a specificity of 42-95%. (Aunt Minnie.com, search PET medullary thyroid cancer article #54629)Identifying non-iodine avid tumors may be important, as they may be treated by surgery if localized or external beam radiation.Hot lesions on 99mTc-TCO4 must be followed up with 131I imaging. |
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• Renal Captopril MAG-3 scan and what you see with Fibromuscular Dysplasia?
a. Decreased cortical excretion b. Decreased uptake c. Increased uptake d. Delayed nephrogram |
• A. Decreased cortical excretion** This appears to be a spin on the renal artery stenosis question **99mTc-Mercaptylacetyltriglycine (MAG3) is nearly a pure tubular agent (less than 3% filtered in glomerulus). It is usually taken up normally even when renal artery stenosis is present (* it is a glomerular agent such as DTPA that shows decreased uptake).Administration of captopril (an ACE inhibitor) will inhibit vasoconstriction of the efferent arteriole, and thus the kidney’s ability to compensate & maintain GFR in renal artery hypertension. This decreased GFR on the affected side will result in delayed washout [prolonged retention] of the radiopharmaceutical.
[Nuc. Req. 2nd p. 339] |
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• Which is best to detect radiation changes (scar) versus recurrent brain glioma?
a. HMPAO b. CT with contrast c. SPECT d. FDG-PET e. thallium |
• D. FDG-PET Monitoring brain tumor treatment using PET is quite commonly performed if there is a difficult diagnostic question after treatment. A decline in FDG uptake in a tumor at several weeks to months after the conclusion of therapy suggests a good response of the tumor to treatment. By contrast, increased FDG uptake versus the basal level, or persistent FDG uptake, would strongly suggest residual tumor being present despite treatment. Maisey p. 180
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• Persistently increased MAG3 activity is seen with each except:
a. ATN b. RAS premedicated with captopril c. hypotension d. acute pyelonephritis e. renal vein thrombosis |
• D. acute pyelonephritis Acute pyelonephritis causes decreased renal perfusion (Mettler 4th p. 344, Fig. 12-6) case at http://www.uhrad.com/spectarc/nucs007.htm
• Renal vein thrombosis: there may be decreased perfusion and delayed and diminished accumulation and excretion of 99mTc-MAG3 by an enlarged, engorged kidney. Mettler 4th p. 343. View a case at http://gamma.wustl.edu/rs024rs287.gif • In general, anything that decreases GFR will cause persistent activity of MAG3. This is because it’s extracted in the renal tubules (97%) and washed out by GFR: - RAS with captopril (* see related question from ’02) - Hypotension (decreases renal blood flow and therefore GFR) • ATN: Progressive parenchymal accumulation of 99mTc-MAG3 (Dähnert 5th p. 908; Mettler 4th p. 345). Scan findings in renal dysfunction (Palmer, 262) • Cause Sz Perfusion Uptake(1-2m) Uptake(30m) • Prerenal nl nl nl increased • Obstructed lg ? decreased decreased • Vascular nl(acute)decreased decreased decreased sm(chronic) • Parench. nl(acute)reduced reduced reduced sm(chronic) • ATN nl nl reduced reduce/increase*(*reduced glomerular agents, increased tubular) |
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• Regarding thyroid disease, which of the following is false?
a. A higher dose is used to treat Plummer’s than Graves b. There is a higher incidence of hypothyroidism after treating Plummer’s than Graves d. Either disease can present with an autonomous nodule e. Either disease can be multinodular |
• B. There is a higher incidence of hypothyroidism after treating Plummer’s than Graves’
• Hyperthyroidism related to toxic nodular goiter (Plummer’s disease) is particularly resistant to radioactive iodine therapy and frequently requires doses 2 to 3 times larger than those applicable in diffuse toxic goiter (Graves’ disease). Large multinodular goiters may require doses in excess of 30 mCi and multiple treatments may be needed. “In our experience, … a one-time orally administered activity of 10-15 mCi is all that is needed to treat 90-95% of patients with Graves’ disease successfully, and 25 mCi cures about 80-90% of patients with a toxic nodular goiter.” Source: Mettler 4th ed. p.122-123 |
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• Regarding Alzheimer’s disease, which of the following is most commonly seen on Tc99m-HMPAO?
a. Decreased perfusion in the temporal and parietal lobes b. Decreased perfusion in the frontal lobes c. Increased perfusion in the parietal lobes d. Increased perfusion in the basal ganglia |
• A. Decreased perfusion in the temporal and parietal lobes
• The most common and highly suggestive finding of Alzheimer’s disease on SPECT brain perfusion images using Tc99m-HMPAO or Tc99m-EDC is symmetric bilateral posterior temporal and parietal perfusion defects (posterior association cortex), with a positive predictive value of more than 80%. Source: Mettler 4th ed. p.93 |
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• A patient undergoing cardiac stress testing with dipyridamole develops severe chest pain. The most appropriate next step is:
a. Stop the test and administer aminophylline b. Stop the test and wait until symptoms resolve c. Administer nitroglycerine d. Continue the test with administration of propranolol |
• A. Stop the test and administer aminophylline
• Incidence of Dipyridamole-induced side effects observed in 4000 patients: chest pain/angina 20-25%, dizziness/headache 10-15%, ECG abnormalities 5-10%, flushing/warmth <5%, Nausea/abd pain <5%, SOB/wheezing <5%.About 25% of the patients experience some side effects after the administration of dipyridamole. If sever complications occur (such as severe bronchospasm, ischemia, induced hypotension, or conduction abnormalities), administer aminophylline. This indirectly blocks the action of dipyridamole by blocking the action of adenosine. Monitoring should be continued for 3-5 minutes after administration of aminophylline. This is necessary because aminophylline has a shorter biologic half-life than dipyridamole and the side effects of dipyridamole may recur as the counteracting effects of aminophylline diminish. Source: The Mayo Clinic Manual of Nuc Med. p.175 |
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• An octreotide scan is good for all of the following except:
a. Neuroblastoma b. Pheochromocytoma c. Adrenal Adenoma d. Medullary thyroid CA |
• C. Adrenal Adenoma
• In other years (1998, 2000), adrenal adenoma was not a choice. In those years the correct answer (NOT detected by octeotide scan) was Renal Cell Carcinoma. For most neuorendocrine tumors, such as gastinoma and carcinoid, sensitivity of octreotide scan (same as In-111 Pentreotide scan) is very high. Two exceptions are insulinoma and medullary carcinoma of the thyroid with only 50% sensitivity. The sensitivity for pheochromocytoma and neuroblastoma is high (approx. 90%), similar to I-131 MIBG imaging. • Octreotide scan is not used for adrenal adenoma. Adrenocortical scintigraphy is performed with NP-59. Source: Nuc Requisites 2nd ed. p.225, 381 |
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• Concerning left ventricular scintigraphy, which of the following is false?
a. Dyskinesis is seen in a left ventricular aneurysm b. Hypokinesis may be seen in an ischemic region c. Hypokinesis is seen with dilated cardiomyopathy d. Hypokinesis is seen in IHSS |
• D. Hypokinesis is seen in IHSS
• Idiopathic Hypertrophic Subaortic Stenosis (IHSS) is a subset of hypertrophic cardiomyopathy. Hypertrophic cardiomyopathy typically presents with a normal or elevated LVEF and hyperdynamic systolic function. Dilated cardiomyopathy presents with 4-chamber dilatation and diffuse hypokinesis, with a reduced LVEF. Ischemic cardiomyopathy is suspected when there is a focal left ventricular wall motion abnormality and relative preservation of right ventricular function. Focal dyskinesia is seen with a left ventricular aneurysm. Source: Mettler 4th ed. p.166, 178; Dahnert 5th ed. p.621 |
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• How does HIDA get into cells?
a. Active transport b. Passive diffusion c. Phagocytosis d. Sequestration |
• A. Active transport
• A number of IDA analogs are available. These radiopharmaceuticals are rapidly removed from the circulation by active transport into the hepatocytes and secreted into the bile canaliculi and then into the biliary radicles, bile duct, gallbladder and small intestine. Source: Mettler 4th ed. p.261 |
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• A young patient has a liver lesion with a central scar. The lesion is cold on sulfur colloid. Which of the following is most likely?
a. Fibrolamellar HCC b. FNH c. Hepatoma d. Adenoma e. Hemangioblastoma |
• A. Fibrolamellar HCC
• Fibrolamellar HCC is an uncommon variant of HCC. Affected patients are mostly in the 2nd or 3rd decade. Pathologically, it is a large well-circumscribed lobulated nonencapsulated strikingly desmoplastic tumor with calcifications and a fibrous scar. It demonstrates a photopenic defect on sulfur colloid scan. • FNH is a benign lesion also containing a central scar. Peak age is in 3rd-4th decade. It can demonstrate normal (50-70%), increased (7-10%) or cold (30-50%) uptake on sulfur colloid scan. However, only increased uptake is (almost) pathognomic for FNH. • Hepatomas and adenomas do not have central scars. Source: Dahnert 5th ed. p.703, 715 |
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• V/Q scan and CXR demonstrate a triple match in the upper and middle lobes. For PE, this is consistent with:
a. Very low probability b. High probability c. Intermediate probability d. Low probability |
• D. Low probability
• Matching ventilation-perfusion defects corresponding to chest radiographic opacities isolated to the upper and middle lung zones imply a low probability of PE, whereas similar findings in the lower lung zones represent an intermediate probability for PE. There appears to be no differences in the prevalence of PE among various sizes of triple matches. Source: Mettler 4th ed. p.217 |
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• A patient has a nuclear medicine test to evaluate RAS. Captopril is given to:
a. Block renin production b. Block conversion of angiotensinogen to angiotensin I c. Block conversion of angiotensin I to angiotensin II d. Affect efferent arteriole |
• C. Block conversion of angiotensin I to angiotensin II
• The renin-angiotensin system is the major factor controlling aldosterone secretion. The juxtaglomerular cells of the kidney secrete renin in response to a decrease in circulating volume and/or a reduction in renal perfusion pressure. Renin cleaves angiotensinogen (synthesized by the liver) to angiotensin I. Angiotensin I is rapidly converted to angiotensin II by ACE in the lungs and other tissues. Angiotensin I has no biological activity, but angiotensin II is a potent vasopressor and also acts to stimulate aldosterone activity. Captopril is an ACE inhibitor and therefore blocks conversion of angiotensin I to angiotensin II. Source: Cecil Essentials of Medicine 4th ed. p.497; see also Mettler p. 351 |
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• According to the Nuclear Regulatory Commission, the administered dose of a radiopharmaceutical should be within what percentage of the prescribed dose?
a. 5% b. 10% c. 1% d. 20% |
• B. 10%The NRC requires that radiopharmaceutical activity be assayed to an accuracy of +10% of the prescribed dose before patient administration.
Source: Mettler 4th ed. p.412 |
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• A patient has a Sestamibi cardiac study that shows a fixed defect. There is uptake on F18-FDG. The most likely cause is:
a. Stunned myocardium b. Scar c. Hibernating myocardium |
• C. Hibernating myocardium
• Hibernating myocardium is the result of severe coronary artery stenoses or partially reopened occlusions producing chronic hypoperfusion and ischemia. These areas present as segments of decreased perfusion and absent or diminished contractility, even when the patient is in a resting state. Because the myocardium is ischemic, but still viable there will be F18-FDG uptake. • Stunned myocardium is a more acute ischemic injury secondary to acute coronary artery occlusion that has reopened before significant myocardial infarction can occur. This shows areas of normal or near-normal perfusion but with absent or diminished contractility. Scar shows a fixed defect without F18-FDG uptake. Source: Mettler 4th ed. p.160, 184, 186 |
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• Which of the following is not an indication for FDG PET?
a. Staging lung cancer b. Differentiating brain abscess from GBM c. Evaluating for recurrence of colorectal cancer d. Finding a seizure focus in epileptics e. Assessing myocardial viability |
• B. Differentiating brain abscess from GBM
• Indications for FDG PET include staging lung cancer, evaluating for recurrence of colorectal cancer, finding a seizure focus and assessing myocardial viability. FDG PET is also used to differentiate residual brain tumor from necrosis. FDG PET shows uptake in areas of inflammation/infection such as an abscess as well as tumor. Therefore, it cannot be used to differentiate brain abscess from GBM. Source: Mettler 4th ed. p.183, Dahnert 5th ed. p.1072 |
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• Regarding a sulfur colloid scan for GI bleeding, which of the following is true?
a. Best test to evaluate upper GI bleed b. Can be used for 24-hour delayed images c. Requires tagging of RBC’s d. More sensitive than angiography |
• D. More sensitive than angiography
• Two most common nuclear medicine techniques for localizing GI bleeding are 99mTc RBC study and 99mTc sulfur colloid study. Both are significantly more sensitive than angiography for the detection of lower GI bleeding. Bleeding rates on the order of 0.2 mL/min are detected (angiography >1.0 mL/min). Background activity in the upper GI tract decreases the diagnostic efficacy of these techniques. 99m Tc RBC studies require tagging of RBC’s and can be used for 24-hour delayed images. There is rapid blood clearance of sulfur colloid. Source: Mettler 4th ed. p.257 |
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• Regarding the “stripe sign” in a V/Q scan:
a. Indicates a peripheral perfusion defect b. Cannot be interpreted in the presence of small bilateral pleural effusions c. Commonly seen in patients with COPD d. Indicates evidence of perfusion in the periphery of the pleura |
• C. Commonly seen in patients with COPD
• The stripe sign consists of a thin line or stripe of activity representing perfused lung tissue between a perfusion defect and the adjacent pleural surface. Perfusion defects with a stripe sign are very unlikely to represent PE based on the assumption that non-pleural-based lesions are not emboli. A stripe sign is frequently seen with COPD and indicates a low probability defect. Source: Mettler 4th ed. p.215, 235*The last choice (d) appears tricky, but this same question was recalled on the 1995 test. Note that the visceral pleura lining the lung has a dual blood supply (pulmonary and bronchial arteries). Therefore, if the “stripe sign” represented pleural perfusion, it would also be seen with a PE (and have no value). Therefore, ‘D’ is most likely false—pleural perfusion is not visible on a V-Q scan. (http://www.wikipedia.org/wiki/Pleural_cavity) |
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• An HMPAO diamox perfusion scan is used to (or increases sensitivity for):
a. Evaluate perfusion reserve b. Assess an old CVA c. Evaluate Parkinson’s disease d. |
• A. Evaluate perfusion reserve
• The distribution of Tc99m-HMPAO is proportional to cerebral blood flow. Normally, the administration of Diamox causes a fourfold increase in blood flow (Diamox = acetazolamide = carbonic anhydrase inhibitor). However, regions of the brain without a reserve are already maximally dilated, and therefore will show a regional perfusion defect when compared with the baseline study. Source: Nuc Requisites 2nd ed. p.310 |
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• On a V/Q scan, 70% of perfusion goes to the right lung. Which of the following would be least likely to cause this?
a. Large left effusion b. Mucus plug in the left mainstem bronchus c. Left pulmonary artery hypoplasia d. Right Blalock-Taussig shunt e. Radiopharmaceutical given with patient in a left lateral decubitus position • Modfied Blalock-Taussig shunt |
• E. Radiopharmeceutical given with patient in a left lateral decubitus positionA decubitus or oblique patient position can markedly affect the distribution of ventilation and perfusion. If the injection for perfusion scintigraphy… is performed in the decubitus or oblique position, mismatched patterns can result. But since PBF is gravity dependent, this would cause flow to the left lung.
see http://www.snm.org/pdf/lung2.pdf ; Freundlich 2nd p. 11 • Unilateral lung perfusion- “SAFE POEM”: Dähnert 5th p. 1092 Swyer-James, Agenesis, Fibrosis (mediastinal), Effusion, Pneumonectomy/PTX, Obstruction, Embolus, Mucus plugA large pleural effusion causes increased attenuation of photons, especially on the supine view (layering posteriorly). This can cause an apparent marked asymmetry of activity (perfusion). NM Req. 2nd p. 160 & Fig 7-15Mucus plugging of the left mainstem brochus would cause hypoxia & reflex vasoconstriction throughout the left lung. The abnormality would be matched w/ the ventilation scan. NM Req. 2nd Box 7-9Pulmonary hypoplasia causes unilateral decreased flow. B&H p. 559.A Blalock-Taussig (BT) shunt is a subclavian to pulmonary artery anastomosis used in Tetrology of Fallot (TOF) patients; the side opposite the aortic arch is typically used (e.g., normal left arch right subclavian/PA anastamosis). In any case, both TOF and the BT shunt cause asymmetric pulmonary blood flow. Also remember that although 95% of 99mTc-MAA is extracted on the 1st-pass through the lung, a functioning BT shunt presumably has a large VSD (also part of TOF), allowing initial bypassing of the pulmonary capillary bed. [ B&H p. 559, 1141, Dähnert 5th p. 572] |
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• DMSA or glucoheptonate is most commonly used for:
a. Wilm’s tumor b. Acute pyelonephritis c. Acute tubular necrosis |
• B. Acute pyelonephritis
• 99m Tc-DMSA and 99m Tc glucoheptonate are renal cortical agents. Per Mettler, “Radionuclide renal cortical imaging is a highly sensitive technique for diagnosis of renal parenchymal infection and should be considered the imaging procedure of choice for the diagnosis of acute pyelonephritis in children.”Acute tubular necrosis is evaluated with Tc99m MAG3.Wilm’s tumor may show uptake on a delayed Gallium scan. Source: Mettler 4th ed. p.343, 355; Dähnert 5th ed. p.1077 |
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• Which of the following is most likely sensitive for gastrinoma?
a. CT b. MRI c. Octreotide scan d. US e. Angiography |
• C. Octreotide scan
• (Note: all 3 references cited must be compared to come to the right conclusion.)A gastrinoma is considered an APUDoma which are imaged with sensitivities approaching 80-100% on Octreotide scan. Per Dähnert, the “sensitivity of preoperative localization” (I am equating this to sensitivity) are as follows: US 25%, CT 35%, MRI 20%, Angiography 68-70%. Source: Mettler 4th ed. p.379; Nuc Req |
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• Which radiopharmaceutical is most sensitive for demonstrating myocardial viability?
a. FDG PET b. 201Tl c. 99m Tc Sestamibi d. stress echo |
• A. FDG PET
• Dähnert says, “ FDG may provide best assessment” for myocardial viability. Source: Dähnert 5th ed. p.1098 “Of the methods available for identifying hibernation which include 99mTc sestamibi SPECT flow studies, thallium rest/reinjection studies and stress echo, PET flow/metabolism studies are generally regarded as the gold standard” Maisey p. 301. |
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• Regarding the sentinel lymph node in breast cancer, which of the following is true?
a. The sentinel node is the first node to receive regional lymphatic flow from the tumor site b. Identification of a sentinel node indicates the presence of tumor spread c. Identification of a sentinel node does not alter therapy d. |
• A. The sentinel node is the first node to receive regional lymphatic flow from the tumor siteThe sentinel node is the first node to receive regional lymphatic flow from the tumor site and a reliable biopsy indicator of the presence or absence of metastatic tumor in a lymph node group.
Source: Mettler 4th ed. p.384; also NM Req 2nd p. 226. |
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• Regarding PET scanning versus SPECT:
a. PET uses isotopes of equal energy as the 511keV photons in SPECT scanning b. Dual head SPECT scanners for coincidence scanning can be done with software modifications c. A Dual head SPECT camera can perform as well as PET by using high energy collimators d. PET requires an onsite cyclotron |
• B. Dual head SPECT scanners for coincidence scanning can be done with software modifications.PET is based on annihilation coincidence detection, which detects the two 511-keV photons that are emitted 180o apart when a positron undergoes annihilation by combining with electrons. It requires at least 2 detectors on opposite sides of the subject. PET can be performed with a dedicated PET scanner (full ring or partial rotating ring with 100-200 detector pairs), a SPECT camera with a high-energy collimator, or a SPECT camera with coincidence counting.SPECT uses single photon radionuclides that are produced by beta neg decay and electron capture, such as Tc-99m, Ga-67, In-111, I-131, etc. In simplest form, SPECT is performed with a single gamma (Anger) camera detector head and parallel hole or hybrid collimator fitted to a rotating gantry. Systems with multiple camera heads are now becoming more common. In PET scanning, sensitivity and resolution (3-7mm), as well as cost, are highest with a dedicated PET scanner. A dual-headed SPECT camera can be combined with coincidence counting software to perform PET scanning. These are of medium sensitivity and resolution. Alternatively, a cheaper method of modifying a SPECT camera is to use a high-energy collimator with either a single- or a multiple-headed rotating detector. The 511-keV photon is imaged w/o coincident counting, and the relative sens and resolution is low. Reference: Mettler
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• What is true regarding cardiac imaging with 18F-FDG?
a. Lower dose is needed for PET than for coincidence imaging b. PET requires a thicker NaI crystal c. PET requires an on-site cyclotron |
• B. PET requires a thicker NaI crystal
• PET: advantages: better spatial resolution than SPECT, better quantitation, availability of tracers that map myocardial physiology; provides assessment of myocardial perfusion or metabolism. BUT, advantages are generally not thought to justify the enormous cost of PET. If a SPECT camera is used for PET imaging, the high energy photons renders the standard 3/8-in NaI crystal inefficient. Thus, methods have been developed to use thicker NaI crystals without much loss of spatial resolution when using lower energy radionuclides. Reference: Mettler |
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• Regarding 99mTc Sestamibi, which of the following is true?
a. Pulmonary activity on stress imaging indicates left ventricular failure b. Can distinguish acute versus chronic infarct c. Enters cell mitochondria independent of the Na/K pump d. Can use to detect hibernating myocardium e. Imaging can be done in a single injection |
• C. Enters cell mitochondria independent of the Na/K pump
• Sestamibi (Cardiolite) is a cationic isonitrile that is extracted by the myocardium with a first pass efficiency of 60% and with lengthy myocardial retention through binding with cytoplasmic mitochondria. It enters the myocyte by passive diffusion and binds with the mitochondria by active transport. • Thallium is the agent that utilizes the Na/K pump. Unlike thallium, it lacks redistribution and it requires TWO separate injections for stress and rest conditions. Activity is seen primarily in the heart and liver, but renal, bladder, bowel and skeletal activity are also present. • Lung activity IS an indicator of LV dysfunction with THALLIUM, not for sestamibi. • Chronic or acute infarct is a scar and appears the same however hibernating myocardium can be confused with a fixed defect. 30-60% of “fixed” defects on a 3 to 4 hour delayed image actually represents viable myocardium rather than post-infarction scarring. In patients with severe coronary artery stenosis, these defects remain poorly perfused at rest with loss of functional wall motion but it is still viable, otherwise known as hibernating myocardium. Although sestamibi demonstrates an abnormal scan with hibernating myocardium, it is Thallium (by additional injection) that can DIAGNOSE hibernating myocardium. (Essentials of Nuclear Medicine Imaging 4th edition pgs.151-3, 378) • The extraction fraction in the coronary circulation is less than teboroxime or Tl-201. At rest flows, the extraction is 1/2 of Tl-201. The maximum extraction decreases with increasing flow. Sestamibi underestimates flow at very high flows and overestimates at low flows. Uptake in the myocardium is rapid but is somewhat obscured by activity in the lung and liver in the time immediately after injection. Clearance t 1/2 of tc-sestamibi is excess of 5 hours. Progressive clearance by lung and liver over 60-120 minutes improves imaging of heart. There is minimal recirculation or redistributions after initial uptake. Requisites p.67 |
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• Regarding MUGA:
a. Area of photopenia surrounding the heart indicates pericardial effusion. b. Over subtraction of background causes falsely elevated LVEF c. Right ventricle EF equals left ventricle EF in a normal individual d. |
• B. Over subtraction of background causes falsely elevated LVEF Using the formula LVEF=(ED-ES)/(ED-background), answer B is correct. The EF of the RV is 35-40% and the EF for the LV is 50-55%.
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• A worker sustains multiple trauma in a Nuclear Power Plant accident. In the ER, what do you do first?
a. Assess the amount of contamination b. Assess the medical needs of the patient c. Decontaminate him d. Find source of contamination |
• B. Assess the medical needs of the patient Life-saving efforts and vital first aid have priority over contamination concerns. I.e., decontamination will do the patient little good if they’re dead.
- however, you may want to “isolate” them as much as possible to protect other patients.Nucs M & G, p. 458. |
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• What is NOT an advantage of using Tc-99 aerosol instead of 133-Xe in ventilation scanning?
a. Multiple projections can be obtained to correlate with perfusion images b. Requires less patient cooperation c. Post perfusion ventilation acquisition results in less radiation d. Better containment of radionuclide released into the clinical setting e. Can do even if patient is on ventilator |
• C. Post perfusion ventilation acquisition results in less radiation
• Both MAA and DTPA aerosols are labeled with Tc-99m, therefore, need to adjust the doses of each to prevent interference on sequential imaging- would have to increase the dose of the second agent. see Mettler 4th p. 194.Tc-99m aerosols have several advantages- map the distribution of aerated lung volume without much pt. cooperation, Tc is readily available, has an ideal energy (140 keV), can be delivered at pt’s bedside and there is no need for special exhaust systems or traps. The disadvantage is the wastage involved during administration –end up delivering 1-2 mCi when using 30mCi in the nebulizer. (Nuclear Medicine- M&G) • Xenon 133: m/c ventilation agent. Physical T1/2 of 5.2d, biologic T1/2 < 1min. Less than 15% of inhaled gas absorbed by body, soluble in fat and localizes to liver and fatty tissue. Requires pt cooperation. 3 phases to study: 1) 1ST breath/wash-in (15-20 sec): exhale fully and hold max inspiration 2) Equilibrium (3-5 min): 2 sequential 90 sec images during nl breathing 3) Washout: 3 sequential 45 sec post images, LPO, RPO, and final post imageTc99m: Large amt of radioactivity (25-75mCi/1110-1850 MBq) placed in nebulizer (only 5-10% of activity reaches lungs) with patient breathing for 3-5 min. Pulmonary clearance > 1hr (faster in smokers, IPF, and ARDS), which allows for multiple projection images. Uses only 20% of activity used for perfusion study, thus can follow with perfusion imaging, or can give reduced dose (1mCi) of MAA to do perfusion study first. Requisites.p.146-150 |
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• What is essential for the use of MAG-3 lasix renal scintigraphy to differentiate functional versus anatomic obstruction?
a. Absence of stone b. Increased CR c. Preserved renal function d. Dehydration prior to study e. New onset obstruction |
• C. preserved renal function
• Renal function is necessary for the test to be performed. The reason is not the use of MAG-3, since this is cleared by tubular secretion, and is not GFR dependent, but Lasix does depend on preserved renal function. |
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• What would be the expected finding in a captopril Tech 99m MAG3 renal scan in a patient with a right sided renal artery stenosis?
a. increased uptake in the left kidney b. increased uptake in the right kidney c. decreased uptake in the left kidney d. decreased uptake in the right kidney e. no uptake in the right kidney |
If dpta, cortical agent, decreased uptake on diseased side.
• B. increased uptake in the right kidney • 99mTc-Mercaptylacetyltriglycine (MAG3) is nearly a pure tubular agent (less than 3% filtered in glomerulus). It is usually taken up normally even when renal artery stenosis is present (* it is a glomerular agent such as DTPA that shows decreased uptake).Administration of captopril (an ACE inhibitor) will inhibit vasoconstriction of the efferent arteriole, and thus the kidney’s ability to compensate & maintain GFR in renal artery hypertension. This decreased GFR on the affected side will result in delayed washout [prolonged retention] of the radiopharmaceutical. Nuc. Req. 2nd p. 339 |
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• Where does captopril act?
a. inhibits release of rennin b. blocks angiotensinogen conversion to angiotensin 1 c. blocks angiotensin 1 conversion to angiotensin 2 d. inhibits renin directly |
• C. blocks Ang I conversion to Ang II Causes vasoconstriction of efferent arteriole
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• Which is most likely to give increased activity on bone scan?
a. Hepatic mets b. Amyloidosis c. Acute hepatitis d. Hepatic necrosis |
• A. Hepatic mets
• By virtue of being the most common of all these entities which cause increased uptake, mets is correct. The most common cause overall is poorly prepared radiopharmecuetical. This was not a choice. C and D cause diffuse uptake. D is uncommon. see Mettler 4th Table 11-5 p. 299. |
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• On bone scan, which lesion is most characteristic of vertebral metastatic disease?
a. focal increased uptake in vertebral body. b. focal increased uptake in vertebral body and lamina. c. focal increased uptake in vertebral body and pedicle. d. increased uptake spanning 2 adjacent vertebrae. |
• C. Focal increased uptake in vertebral body and pedicle
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• Which of the following does not take up MIBG?
a. Pheochromocytoma b. Aldosterone secreting adenoma c. Neuroblastoma d. Islet cell tumor. |
• B. Aldosterone secreting adenoma
• MIBG is a guanethidine analog similar to norepinephrine. It is taken up by chromaffin cells and useful for imaging pheochromocytoma and neuroblastoma (90% sens and specificity). Also localizes in other neuroendocrine tumors like carcinoid, medullary thyroid Ca and paraganglioma. Islet cell tumors arise derivatives of APUD cell line (embryonic neuroectoderm).I-131 metaiodobenzylguanidine (MIBG) Indications-- Apudomas = tumors of neural crest origin (C cells of thyroid, melanocytes of skin, chromaffin cells of adrenal medulla, pancreatic cells, Kulchitsky cells), which share the presence of neurosecretory granules capable of accumulating I-131 MIBG. 1. Pheochromocytoma (80-90% sensitivity, > 90% specificity) 2. Neuroblastoma, carcinoid, medullary thyroid carcinoma, etc. Danhertt 5th ed p.1116 |
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• Indium-111 is preferred to Gallium-67 for which of the following?
a. acute osteomyelitis b. vertebral osteomyelitis c. suspected pulmonary inflammation d. fever of unknown origin e. intraabdominal abscess |
• E. Intraabdominal abscess
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• Indium-111 WBC examination is preferable over 67Ga for which process?
a. PCP b. Splenic abcess c. IBD flareup d. Spinal osteomyelitis e. Discitis |
• C. IBD flare-up
• This is clearly the best answer—Ga-67 is normally cleared through the GI tract, which complicates imaging of this area (esp. at 24-48hrs.). On the other hand, any activity of In-111 labeled leukocytes in the GI / GU tract is abnormal. IBD is specifically listed as a use of In-111 WBC’s. [source: Dahnert 5th p. 1078]Optimal uses: Ga-67: chest (interstitial pneumonia, opportunistic infection, sarcoid, drug toxicity); bone: osteomyelitis; lymphoma, melanoma In-111 WBC: most all infections, except splenic abscess (high normal uptake in spleen); IBD; graft / prosthesis infections; however, In-111 has low sensitivity for spine infections (appear photopenic, False Neg. 10-40%), and “67Ga may be preferred”.Sources: Mettler 4th p. 397-398; Nuc. Req. p. 171. |
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• Which of the following items can be used to evaluate uniformity in nuclear medicine Gamma cameras?
a. Cesium 137 b. Cobalt 60 c. Technetium 99m and bar phantom d. Point source of technetium 99m e. Cobalt 57 |
• E. Cobalt 57.
• Field uniformity is tested by using a 57Co solid plastic sheet source. The whole point of testing for field uniformity is to see if the gamma camera can produce a uniform image from the entire crystal surface. Mettler 4th p. 40. • 99mTc can be used to evaluate gamma camera uniformity, however, a point source of 99mTc is not what is used. Rather, a plastic tank of 99mTc dissolved in liquid is used.But, Cobalt 60 and Cesium 137 are for therapy and QC respectively. (Answers A and B are wrong), and bar phantoms are used for spatial resolution (Answer C is wrong). M&G p. 40. |
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• Which is false regarding bone scan?
a. can assess the viability of cortical bone graft b. disphosphonate treatment can increase uptake c. there is generalized increase in uptake in mastocytosis d. maximum activity seen in fracture occurs between 2 to 5 weeks e. this is the right answer but we don't rememeber it |
• A. True. positive bone scan <1 wk viable bone. But, positive scan >1wk laying down new bone, so this is meaningless for graft viability (Resnick).
• B. False. recent diphosphonate decreases uptake (M&G p. 12). Diphosphonates, in general, decrease bone turnover. • C. True. mastocytosis is in the ddx for dense bones. • D. False. acute phase is 3-4 weeks, generalized diffuse uptake; subacute phase is 2-3 months, local intense uptake, healing phase is >3 months, gradual decline. (M&G) |
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• Which of the following is not a cause of diffuse uptake of technetium-99m MDP in the bones with no appreciable uptake in the kidneys?
a. hypoparathyroidism b. aggressive osteoporosis c. diffuse osteoblastic bony metastases d. hyperthyroidism e. chronic renal disease |
Some recall choice as hyperparathyroidism , osteomalacia not superscan?
• A. Hypoparathyroidism • Superscan can be seen in all the other choices as well as osteomalacia.Review of Superscan from Dahnert.5th ed p.1081 A. Metabolic 1. Renal osteodystrophy 2. Osteomalacia: randomly distributed focal sites of intense activity = Looser zones = pseudofractures = Milkman fractures (most characteristic) 3. Hyperparathyroidism: focal intense uptake corresponds to site of brown tumors 4. Hyperthyroidism: rate of bone resorption more increased than rate of formation (= decrease in bone mass); hypercalcemia (occasionally); elevated alkaline phosphatase NOT visible on radiographs, susceptible to fractures B. Widespread bone lesions 1. Diffuse skeletal metastases (most frequent) from breast, lung, prostate, bladder, lymphoma 2. Myelofibrosis / myelosclerosis 3. Aplastic anemia, leukemia 4. Waldenstrom macroglobulinemia 5. Systemic mastocytosis 6. Widespread Paget disease: diffusely increased activity in bones: particularly prominent in axial skeleton, calvarium, mandible, costochondral junctions (= "rosary beading"), sternum, (= "tie sternum"), long bones; increased metaphyseal + periarticular activity; increased bone-to-soft-tissue ratio; "absent kidney sign" = little / no activity in kidneys; femoral cortices become visible |
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• What is the finding of a "shin splint" on bone scan?.
a. hot on flow and blood pool phase with no activity on delayed phase. b. normal on flow and blood pool phase with increased uptake on delayed c. stress fracture d. |
• B. Normal on flow and blood pool phase with increased uptake on delayed phase.
• Shin splints refers to soreness along the posterior / posteromedial tibial cortex of the Tibia; typically bilateral, though not necessarily symmetrical. Characteristic findings on 99mTc-MDP scintigraphy are normal flow and blood-pool images, but linear longitudinal uptake on delayed images. They are thought to be the result of traction periostitis. Dähnert 5th p. 158, Nuc. Req. 2nd p. 130.A stress fracture will show focal uptake that is hot on all three phases. Nuc. Req. 2nd p. 131. |
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• A 7 months pregnant patient with history of breast CA now has bone pain in the femur. Which is true regarding NM bone scan.
a. should not be done because of the risk to the fetus. b. should not be done because she is already known to have breast CA. c. should be done. d. |
• C. Should be done Risk of radiation to a third trimester fetus is less than risk of untreated metastases in the mother.
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• Regarding I-131 therapy, which is false?
a. > 200 mCi can result in pulmonary fibrosis in the setting of pulmonary metastases b. can occasionally give > 30 mCi as outpatient c. risk of leukemia increases if there are more than 2 treatments greater than 100 mCi d. therapy may be indicated after negative I-131 scan with elevated thyroglobulin level |
• B. can occasionally give > 30 mCi as outpatient
• This appears to be the best answer given. But… Mettler p. 124-125 has this to say: ”According to prior Nuclear Regulatory Commission (NRC) regulations, any patient with 131I activity in excess of 29.9 mCi needed to be hospitalized. This is still true in some agreement states. Newer NRC regulations permit release based on (1) administered activity (33 mCi for 131I), (2) measured dose rate < 7 mrem / h, or (3) patient-specific dose calculations…”About 1% of patients with pulmonary metastases may develop pulmonary fibrosis after high-dose therapy. Although controversial, some studies do suggest an increased incidence of leukemia post-131I therapy. In the rare case where the surgeon has actually removed all the normal thyroid tissue and in which the whole-body scan is negative, high-dose therapy can be used with some modifications. |
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• Regarding technetium-99m-labeling of red blood cells:
a. in order to do in vivo labeling, 0.5-1.0 mg of stannous ion is injected intravenously b. some other choices |
• A. in order to do in vivo labeling, 0.5-1.0mg of stannous ion is injected intravenously
• In vivo RBC labeling does involve I.V. injection of stannous ion (3 cc of stannous from the standard kit), and for a 70kg avg adult (10mcg/kg) the dose =700mcg=0.7mg. Requisites p. 282 |
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• What is the advantage of the sulfur colloid bleeding scan over a tagged RBC study?
a. Faster preparation time b. Greater sensitivity than angiography c. Increased sensitivity for upper GI bleeds d. Allows delayed imaging e. Better for intermittent bleeds |
• A. faster preparation timeTc-99m SC: injected with rapid extraction by liver, spleen and BM (T1/2 of 3 min, mostly cleared from vascular system by 15 min). During ACTIVE bleeding, tracer extravasates at bleeding site with each recirculation, resulting in high target-to-background due to constant extravasation with simultaneous clearance. ACTIVE bleeding is detected in first 5-10 min, with bleeding site a focal area of tracer that increases in intensity and MOVES thru GI tract during the course of the study. Time required: 20 min.Tagged RBC: can detect INTERMITTENT bleeds since site can be detected over longer time, dependent only on T1/2 of Tc-99m and stability of radiolabel. Longer prep time since labeling with Tc-99m sodium pertechnetate is required (20 min). In vivo and in vitro methods of labeling can be used. Sequential images acquired for 90 min. If neg, repeat 30 min acquisitions at 2-4 hrs and whenever active bleeding suspected up to 24 hrs. May also show sites that are not actively bleeding and define vascular structures. ACTIVE bleeding must be intraluminal, increase over time, and move thru GI tract. Very sensitive for lower GI bleed. Upper GI bleeds are more difficult to diagnose, glucagon may be helpful. Can detect rates as low as 0.1 mL/min; only 2-3 mL blood necessary for detection. Large multicenter study showed sens 93%, spec 95% (much higher than for Tc-99m SC). False positives due to misinterpretation of nl variants and other pitfalls, such as bladder or ectopic kidney, free tracer, or misinterpretation of delayed images. Requisites p.280-281
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• Concerning HIDA scanning, which is true?
a. Taken up by hepatic adenoma b. Conjugated by hepatocytes c. Visualization in small bowel differentiates between bilary atresia and neonatal hepatitis d. Phenobarbital will decrease uptake e. Biliary obstruction will show vicarious excretion into small bowel |
• C. visualization in small bowel differentiates between biliary atresia and neonatal hepatitis
• Often no uptake with a hepatic adenoma (AuntMinnie.com). Visualization in bowel does differentiate between biliary atresia and neonatal hepatitis but in the absence of visualization of the biliary tree atresia may not be successfully differentiated from severe hepatocellular disease. • It is taken up into hepatocytes and secreted into the bile, unlike bilirubin it is not conjugated. • Phenobarbital stimulates hepatic excretion (so presumably increases uptake). IDA is excreted in the bile with minimal in the kidneys. If the bile duct is obstructed there is no way to reach the bowel. You will get a liver scan sign. Nucs; M & G. pp. 260-274.Normal study: immediate and sequential images every 5 min. see liver size, shape, and lesions with biliary excretion beginning in about 10 min, should see GB in 30 min (up to 60 min is nl) Biliary to bowel transit should also occur in 60 min, but 10-20% nls will have delayed biliary-to-bowel due to physiologic “hypertonic” sphincter of Oddi. Can give CCK to differentiate bet this and partial obstruction.Can pretreat with phenobarb to rev up liver excretory enzymes and should see transit by 24 hrs. Requisites p.243 |
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• Which of the following agents will cause decreased secretion and increased uptake during a Meckel’s scan?
a. Pentagastrin b. Phenobarbital c. Cimetidine d. glucagon |
• C. Cimetidine
• [best answer based on phrasing of question & comparison with other recalls]Cimetidine – Histamine H2 receptor antagonist: blocks secrection/outflow. More intense and prolonged uptake.Pentagastrin – Stimulates uptake into gastric cells. Increases rapidity, duration, and intensity of uptake. [improves detection, but not by blocking outflow]Glucagon – antiperistaltic effect prevents washout. [Nuc Req p. 289, B&H p. 1201, 1285; Dähnert 5th p. 845.] |
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• Regarding gastric emptying studies, which is true?
a. Solid phase is more sensitive for early gastroparesis than liquid phase b. Liquid phase is linear c. Anterior and posterior images are essential to calculate the geometric mean d. Half-life for solid phase is 20-30 minutes e. Half-life are not reproducible to evaluate treatment response f. Solid phase is exponential g. Lipids increase the rate of emptying |
• A. solid phase is more sensitive for early gastroparesis than liquid phase“…the solid phase is more sensitive than the liquid phase for delayed gastric emptying…” [Mettler 4th p. 278].
• t1/2 for solid emptying is given as 90 min. (range 45 to 110 min); for liquids, it is 40 min. (range 12 to 65 min.) [Mettler 4th p. 278] • Liquid meals show exponential emptying; it is solid meals that show nearly linear emptying (after a short lag phase). [Requ 2nd p. 273]The NM Reqisites, 2nd. Ed., does describe a “geometric mean” method for data acquisition as being the gold standard; however, it is certainly not essential, as a single-camera technique is listed in the next paragraph (p. 277).Lipids, acids, proteins, and foods with high osmolality all slow the rate of emptying (Nucs Requisites 273; Weissleder 836). |
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• An HMPAO diamox perfusion scan is used to (or increases sensitivity for):
a. Evaluate perfusion reserve b. Assess an old CVA c. Evaluate Parkinson’s disease d. |
• A. Evaluate perfusion reserve
• The distribution of Tc99m-HMPAO is proportional to cerebral blood flow. Normally, the administration of Diamox causes a fourfold increase in blood flow (Diamox = acetazolamide = carbonic anhydrase inhibitor). However, regions of the brain without a reserve are already maximally dilated, and therefore will show a regional perfusion defect when compared with the baseline study. Source: Nuc Requisites 2nd ed. p.310Alzheimer’s: classically bilateral posterior temporal and parietal hypoperfusion on SPECTSeizures: hypoperfusion interictally, hyperperfusion ictally. [p. 313]Acetazolamide (Diamox) and Spect Brain imaging are used for cerebrovascular reserve in cases of TIA or cerebral ischemia. HMPAO brain imaging without acetazolamide is used for diagnosis of Alzeimer’s disease. The most common SPECT finding in Alzheimer's disease is a bilateral decrease in perfusion to the parietal and posterior temporal regions. Taveras’ Radiology on CD-ROM, Chapter 27A. |
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• What is the pattern of Alzheimers on an HMPAO scan?
a. decreased uptake in the calcarine cortex b. decreased activity in the parietal cortex c. increased activity in the frontal lobe d. increased activity in the temporal lobes |
• B. decreased activity in the parietal cortex The typical pattern of Alzheimer’s disease on SPECT is decreased activity in the parietal and posterior temporal lobes bilaterally and symmetrically, but this pattern is variable, occasionally with asymmetry and/or frontal lobe involvement, and these findings may be seen in carbon monoxide poisoning, hypoglycemia, mitochondrial encephalomyelopathy, and frontotemporal degeneration Increased perfusion in basal ganglia: Parkinson’s Asymmetric perfusion defects: multi-infarct dementia Decreased striatal metabolism: Huntington’s Mettler 4th ed. p.93, B&H Fundamentals 2nd ed p. 1339
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• Which of the following shows no uptake on an octreotide scan?
a. meningioma b. renal cell carcinoma c. carcinoid d. medullary thyroid Ca |
• B. renal cell carcinoma
• Octreotide is a synthetic cyclic octapeptide (8aa) with similar pharmacologic action as somatostatin and can be labeled with 123I or 111In after certain molecular modification. T1/2 of octreotide = 6h, with urine excretion 50% at 6h. Normal distribution (outside of tumor): spleen, kidneys, liver.Somatostatin is a natural neuropolypeptide (cyclic 14 aa with T1/2 of few min) which usually has inhibitory action. Neuroendocrine cells often have somatostatin receptors. Useful for: -paraganglioma -pit adenoma -islet cell tumors (sens: 80-100%, x for insulinoma and thyroid (less)) -pheochromocytoma -adrenal neuroblastoma -pulmonary oat cell tumors -lymphoma -med thyroid CA -GI, chest carcinoids Unpredictable uptake: lymphoma, breast, glioma, meningioma e non-neuroendocrine tumors (variable) Reference: Mettler, Essentials of Nuclear Medicine. |
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• Regarding stress imaging, which of the following is true?
a. 6 hrs. following a non-Q wave MI, adenosine can show abnormalities b. adenosine-sestamibi at rest excludes ischemia c. sestamibi can be used to re-image heart with one dose |
• C. sestamibi can be used to reimage heart with one doseAdvantages [of sestamibi] over thallium:
(1) Improved dosimetry related to shorter half-life allows larger doses with less patient radiation (2) Improved photon flux means faster imaging + allows cardiac gating (3) Higher photon energy means less attenuation artifact from breast tissue / diaphragm + less scatter (4) NO redistribution (5) Temporal separation of injection and imaging allows injection during acute myocardial infarct when patient may not be stable for imaging; after stabilization + intervention (angioplasty / urokinase) imaging can demonstrate the pre-intervention defect Dähnert CD ROM. |
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• A 40 y/o woman with a family history of thyroid disease has had a sore throat, neck pain, tremulousness, and restlessness for 4 weeks. Her T3 and T4 are both elevated. She undergoes I-123 scan 8 weeks after a contrast-enhanced CT study. Her uptake is <1%. She has:
a. Graves disease b. Hashimoto thyroiditis c. subacute thyroiditis (also called Dequervain thyroiditis) d. acute suppurative thyroiditis e. triiodothyronine(T3) intoxication |
• C. subacute thyroiditis
• DDX Increased thyroid hormones with low uptake in a hyperthyroid patient = exogenous or subacute thyroidiits, [p. 366,376 Nucs Requisites] Because both T3 and T4 are elevated and the study was performed beyond the 4-6 week post IV contrast window,.Graves is out because the uptake is low. Hashimoto’s thyroiditis is usually chronic and slightly hypothyroid. This is the appropriate answer because of the patient’s history of neck pain and sore throat. The CT contrast is a diverting tactic, 8 weeks is the correct amount of time to wait. |
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• Which of the following is negative on a Gallium scan?
• Kaposi’s Sarcoma • Nocardia • Lympoma • PCP • CMV • MTB |
• A. Kaposi’s Sarcoma
• Gallium has been largely replaced with WBC imaging but can be used in chronic infection1. Inflamed / infarcted bowel (eg, Crohn disease) DDx: normal bowel excretions (must be cleared by enema; bowel pathology shows persistent activity)2. Diffuse lung uptake sarcoidosis, diffuse infections (TB, CMV, PCP), lymphangitic metastases, pneumoconioses (asbestosis, silicosis), diffuse interstitial fibrosis (UIP), drug-induced pneumonitis (bleomycin, cyclophosphamide, busulfan), acute radiation pneumonitis, recent lymphangiographic contrast3. Lymph node involvement sarcoidosis, TB, MAI, Hodgkin disease DDx: NOT seen in Kaposi sarcoma, a useful distinction in AIDS patients with hilar nodes. KS is seen well on thallium scan Dähnert 5th p1067 |
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• Persistently increased MAG3 activity is seen with each except:
a. ATN b. RAS premedicated with captopril c. hypotension d. acute pyelonephritis e. renal vein thrombosis |
• D. acute pyelonephritis Acute pyelonephritis causes decreased renal perfusion (Mettler 4th p. 344, Fig. 12-6) case at http://www.uhrad.com/spectarc/nucs007.htmRenal vein thrombosis: there may be decreased perfusion and delayed and diminished accumulation and excretion of 99mTc-MAG3 by an enlarged, engorged kidney. Mettler 4th p. 343. View a case at http://gamma.wustl.edu/rs024rs287.gif; Baum p. 201.In general, anything that decreases GFR will cause persistent activity of MAG3. This is because it’s extracted in the renal tubules (97%) and washed out by GFR:
- RAS with captopril (* see related question from ’02) - Hypotension (decreases renal blood flow and therefore GFR)ATN: Progressive parenchymal accumulation of 99mTc-MAG3 (Dähnert 5th p. 908; Mettler 4th p. 345). Scan findings in renal dysfunction (Palmer, 262) • Cause Sz Perfusion Uptake(1-2m) Uptake(30m) • Prerenal nl nl nl increased • Obstructed lg ? decreased decreased • Vascular nl(acute)decreased decreased decreased sm(chronic) Parench. nl(acute)reduced reduced reduced sm(chronic) ATN nl nl reduced reduce/increase*(*reduced glomerular agents, increased tubular) |
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• A baby has hyperbilirubin and no excretion into bowel on DISIDA, with a normal US.
• give phenobarb and repeat DISIDA • Repeat DISIDA in 24 h • give CCK and repeat • do ERCP |
• A. give phenobarb and repeat DISIDA May be diff to differentiate biliary atresia from severe hepatobiliary disease, which needs to be done early to facilitate more successful surgical intervention. Can’t image beyond 24h cuz of Tc-99 short half life. May be useful to give 5-7 days phenobarb prior to exam, which stimulates better hepatic excretion (Mettler)
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• Regarding MUGA ventriculogram:A graph was given and the condition associated with the abnormal curve was requested.
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• Don’t have any more info so here is a synopsisRadionuclide ventriculography is done to evaluate global and regional ventricular function. The pharmaceutical of choice for equilibrium gated blood pool imaging is Tc99m-labeled RBC. Labeling can be done using three approaches: in vivo (lowest labeling, 60%, and sensitivity), modified in vivo (intermediate labeling, 90%, and sensitivity) and in vitro (best, >95%). Another agent is Tc99m-HSA of human serum albumin. This has the advantage that can be prepared ahead of time, but is leaks out of the blood quickly, so imaging can not be repeated like with the RBC that they recirculate over and over and multiple images can be acquired. For imaging they do a first pass study with or without EKG gating and they obtain 16-30 frames/sec for about 30 secs. If the patient has a cardiac condition, they image for 60 secs. The patient is typically positioned in the RAO view with 20-30 degrees of angulation. This can measure EF from the RV and LV.The other approach is the Equilibrium gated blood pool study. This is preferred because it has better counts and more images that are added. The EKG is synchronized to the R wave. The cardiac cycle is divided into 16-24 frames and the duration of each frame is 40-50 msec. They image about 100-300 cardiac cycles, having about 250,000 counts/frame. For studies at rest (those done for adriamycin toxicity for example) multiple views are used including, shallow 10 RAO, a 30-60 LAO and LPO. The LAO angle is the one that best divides the RV and LV activities. For stress imaging, the camera is left in the LAO position.
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• The pleural stripe sign in VQ scans is most likely to be associated with:
• Pleural effusion • COPD • Pulmonary hemorrhage • Indicates nonperfusion of peripheral lung • suggestive of pulmonary embolisms |
• B. COPD. (best answer)B. True.: COPD: Associated with patchy, uneven ventilation, reduced lung compliance, and increased periperal resistance. On V/Q scans, these changes result in matched ventilation-perfusion abnormalities that typify airway dz.
- “…the stripe sign suggests another diagnosis, often emphysema…” NM Req. p. 396. - “A stripe sign of peripheral activity around a perfusion defect is frequently seen with COPD and indicates a low probability defect…” Mettler p. 235. - Think about a typical day at the chest board—what do you see more of, COPD or pulmonary hemorrhage? (see below)C. True, but less frequent than B: The stripe sign consists of a thin line or stripe of activity representing perfused lung tissue between a perfusion defect and the adjacent pleural surface. Because the pulmonary circulation branches progressively toward the pleural surface, most pulmonary emboli result in pleura-based and wedge-shaped defects. The presence of interposed activity (the stripe) suggest a parenchymal abnormality such as pulmonary hemorrhage or other fluid accumulation rather than PE. A. False: Pleural Effusion: Pleural effusions may produce perfusion defects by loculation or compression of lung parenchyma. All pleural effusion-related matched ventilation-perfusion abnormalities should be assigned an intermediate probability of PE regardless of size. In general , pleural effusions that do not produce perfusion defects are irrelevant. These defects would not have interposed perfused lung.D. False: syn with Infarct thus would be wedge shaped and pleural basedE. False: see C. Nuclear Requisites 2nd p160 |
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• The characteristic appearance of shin splints in bone scan imaging is:
• Hot on all three phases of the scan • Hot on the third phase only • Hot on vascular and blood pool stages only |
• Hot on the third phase only
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• Molybdenum breakthrough is a concern because:
a. Beta emitter b. 60 hour half life c. pyogenic d. Photon energy is high e. interferes with 99mTc localization |
. Beta emitter
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• On a 123I thyroid scan:
• Multiple hot nodules in the gland are diagnostic of Plummer’s disease. • Autonomously functioning nodule should supress activity of the remaining gland • TSH should be decreased in toxic nodule |
• B. Autonomously functioning nodule should suprress activity in remaining gland
• A "hot" nodule concentrates tracer more avidly than does the adjacent normal thyroid. Assuming that an abnormality on scan corresponds to a functioning nodule, and not to a region of normal thyroid surrounded by nonfunctioning tissue (e.g., focal thyroiditis), the "hot" nodule may represent either a TSH-independent, autonomous lesion or a TSH-dependent lesion. Neither autonomy of the nodule nor the presence of a "hot" nodule in general indicates hyperfunction of the thyroid. In fact, hyperthyroidism secondary to a functioning nodule is usually seen only with rather large nodules. Establishing the functional status of a nodule is extremely important, since a true "hot" nodule is virtually never malignant. Although there have been reports of cancer coexisting with a "hot" nodule, these appear frequently to be incidentally noted occult carcinomas that happen to be located adjacent to a benign lesion. For all practical purposes, a "hot" nodule is a benign lesion, generally an adenoma. There is a spectrum of scan appearances of "hot" nodules ranging from a region of minimally more activity than adjacent thyroid to intense uptake with complete suppression of extranodular tissue, so that only the nodule is visible. The degree of suppression of the remainder of the thyroid will depend on the amount of thyroid hormone being produced by the nodule. As indicated above, a diagnosis of hyperthyroidism cannot be made from the scan appearance of the nodule. If the remainder of the thyroid is incompletely suppressed, however, it is usually true that the patient is euthyroid (this assumption would, however, be incorrect if the remainder of the thyroid contained autonomous tissue, as in a multinodular goiter) • .PLUMMER DISEASE: (Toxic nodular goiter) autonomous function of one / more thyroid adenomas Peak age: 4 - 5th decade; M:F = 1:3. Elevated T4, suppressed TSH, nodular thyroid with hot nodule + suppression of remainder of gland, stimulation scan will disclose normal uptake in remainder of gland, increased radioiodine uptake by 24 hours of approximately 80% (1) I-131 treatment with empirical dose of 25 - 29 mCi (hypothyroidism in 5 - 30%) (2) Surgery (hypothyroidism in 11%) (3) Percutaneous ethanol injection (hypothyroidism in <1%, transient damage of recurrent laryngeal nerve in 4%)Ref. Taveras’ CD. |
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• In the treatment of a solitary toxic thyroid nodule:
• Requires a higher dose than would treatment of graves disease • Requires a lower does than would treatment of graves disease |
• A. Requires a higher does than would treatment of graves disease
• Grave’s Disease is the most common cause of hyperthyroidism. Usually requiring an empiric dosing of I131 for therapy in the range of 5-25 mCi. The therapeutic dose of I131 for a solitary toxic thyroid nodule is given in the range of 30 mCi. (Brant & Helms p.1272, 1275. • GRAVES DISEASE = DIFFUSE TOXIC GOITER = autoimmune disorder with thyroid stimulating antibodies (LATS) producing hyperplasia + hypertrophy of thyroid glandPeak age: 3rd - 4th decade; M:F = 1:7• elevated T3 + T4• depressed TSH production• dermopathy = pretibial myxedema (5%)• ophthalmopathy = periorbital edema, lid retraction, ophthalmoplegia, proptosis, malignant exophthalmus- diffuse thyroid enlargement- uniformly increased uptake- incidental nodules superimposed on preexisting adenomatous goiter (5%)Dähnert CD-ROM |
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• All of the following lesions would be expected to have increased uptake on bone scan except:
• Breast Cancer metastasis • Renal Cell Carcinoma metastasis • Prostate Ca metastasis • Thyroid Ca metastasis • Multiple Myeloma |
• E. Multiple Myeloma Pb KTL (lead kettle) = mets that go to bone: prostate, breast, kidney, thyroid, and lung Photon-deficient bone lesion = decreased radiotracer uptake (a) Interruption in local bone blood flow = vessel trauma or vascular obstruction by thrombus / tumor 1. Early osteomyelitis 2. Radiation therapy 3. Posttraumatic aseptic necrosis 4. Sickle cell crisis (b) Replacement of bone by destructive process 1. Metastases (most common cause): central axis skeleton > extremity, most commonly in carcinoma of kidney + lung + breast + multiple myeloma 2. Primary bone tumor (exceptional) mnemonic: "HM RANT" Histiocytosis X; Multiple myeloma; Renal cell carcinoma; Anaplastic tumors (reticulum cell sarcoma); Neuroblastoma; Thyroid carcinomaDähnert 5th p1081
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• Regarding bleeding scans obtained with Tc labeled RBCs which is FALSE:
• In vivo labeling is sufficient • Detection of intermittent bleeds increases with 24 hr delayed images • Higher rate of blood loss is needed for detection when compared to conventional angiography • A focal area of increased activity in the bowel which moves over time is diagnostic of GI bleed • Can be useful in upper GI bleeds • It is better than sulfur colloid studies for the examination of intermittent bleeds |
• C. Higher rate of blood loss is needed for detection when compared to conventional angiography.
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• Regarding the use of Sr 89 in the treatment of bone metastases, which of the following is a relative contraindication
• the previous treatment with chemotherapy • the previous treatment with radiation • a plt count of < 100, 000 • a life expectency of <3 month • patient does not have breast or prostate mets |
• B. Platelets < 100,000 is absolute contraindicationGuidelines
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• Cardiac imaging Sestamibi versus Thallium
• Sestamibi has better redistribution • Sestamibi uptake is by passive transport • Sestamibi has Increased cardiac uptake |
• Sestamibi uptake is by passive transport
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• Bone scan imaging:
• Incorporated in tumor metastasis mass • Most metastatic lesions will appear hot • Uptake is seen in lytic bone mets • The flare phenomenon means worsening disease |
• Most metastatic lesions will appear hot
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• 80 year old man has had a myocardial infarct 2 years prior in the LAD distribution now shows decreased activity on NH3 myocardial perfusion imaging with normal viability demonstrated on FDG imaging in the anteroseptal region. What is the most likely etiology?
• Hybernating myocardium • Stunned myocardium • New area of infarct • Scar with periinfarct ischemia |
• A. hibernating myocardium Both stunned and hibernating myocardium are terms which describe abnormal but viable tissue. Stunned myocardium does take up myocardial perfusion agents (consistent with viability), but the myocardial segment is akinetic (stunned). Hibernating myocardium refers to chronically ischemic tissue, that is cold on perfusion imaging (and also nonfunctional on ventriculography or echo), but is viable as demonstrated by PET imaging with F-18 fluordeoxyglucose. Reference: Nucs Requisites p 60, 1995
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• FDG is not avidly taken up in which tumor:
• lymphoma • breast carcinoma • melanoma • bronchogenic carcinoma • prostate |
• E. ProstateFDG PET scan is used to detect: Lung cancer, Breast cancer, Colon cancer recurrence, Lymph node metastases from head and neck cancer, Brain tumor, Pancreatic cancer, Lymphoma Prostate cancer: “some cancers may show variable or low FDG accumulation (e.g. prostate cancer, liver cancer, etc.). However, close correlation with clinical and anatomic imaging findings, or use of tracers other than FDG, usually help in the proper assessment of PET findings.” – CLINICAL APPLICATIONS OF POSITRON EMISSION TOMOGRAPHY By Hossein Jadvar, M.D., Ph.D. Assistant Professor of Radiology Keck School of Medicine University of Southern California Los Angeles, California http://www.rh.edu/~houman/alborznameh/jadvar.htmMelanoma: Role of PET in Malignant Melanoma: Isolated lesions found on PET can be excised. If multiple lesions are identified, can avoid unnecessary surgery Chemotherapy ImmunotherapyQuantification of FDG uptake may have a role in monitoring treatment responseStudies: Sensitivity for intra-abdominal visceral and lymph node metastases: 100%; Superficial nodes: accuracy of 100%; Overall 93 % of metastases detected by PET; Joint Program in Nuclear Medicine, PET and Melanoma Staging, Pritinder K. Thind, MD, Kevin J. Donohoe, MD, February 15, 2000, http://www.med.harvard.edu/JPNM/TF99_00/Feb15/WriteUp.html
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• Which of the following is true regarding Tc99m-HMPAO CNS imaging
• focus of decreased activity is seen with HSV encephalitis • 90% Alzhiemer’s patients have decreased uptake in the posterior parietal and temproal lobes • increased CNS uptake compared to ECD • acetazolamide administration results in distribution of radiotacer to areas with intact vascular reserve |
• D. acetazolamide administration results in distribution of radiotacer to areas with intact vascular reserve
• Hexamethylpropyleneamine oxime is a lipophyllic agent that gets trapped in neurons, remains for several hours, must be administered immediately, brain activity is maximum at 1minute, plateau at 2 minutes, remains constant for 8hours, gray>white, brain 4%, liver 11%, kidneys 4%, bladder/urine 4%, indications: dementia: bilateral perfusion defects temporoparietal, multiinfarct dementia, parkinson’s increased perfusion in basal ganglia, huntington’s disease, decreased striatal metabolism, tumor, residual ves radiation necrosisDiamox(acetazolamide) is a carbonic anhydrase inhibitor that causes vasodilation, leading to increased hmpao uptake in brain tissue with feeding vessels that can respond (dilate) after its administration. • 60% of Alzheimer pts have the decreased uptake in the temp/parital, this pattern has a 80% predictive value BUT do see this pattern so be careful of the percent givenHiv encephalitis:Neurology volume 46, number 4 april 1996: reported a case of hiv encephalitis with normal mri and ct with abnormal HMPAO perfusion but did not specifically state focal defect.Hsv encephalitis = increased blood flow and increased hmpao uptake within the temporal lobeECD: 99m tc ethyl cysteinate dimer, longer invitro stability than hmpao, but crosses bbb the same – brain uptake is about the sameReferences: Nuclear Medicine The Requisites 2nd ed. pages 300, 305, 306, 311 |
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• Gated SPECT cardiac imaging is superior static spect for evaluation of except:
• Ejection fraction • assessing scar tissue/ viable myocardium • can demonstrate akinetic segment • can demonstrate reversible/ischemic segment better in comparison to non-gated SPECT • can better evaluate av valve |
• E. can bette evaluate av valveDuke Review 2001 pg 807 gated perfusion - more information than static SPECT. Perfusion and function from a single study. Information about wall thickening and motion. Differentiate infarct from attenuation artifact. Fewer false positive studies.Dähnert 5th p1100:Gated Blood pool imaging:
Records: Ejection fraction; regional wall motion of ventriculat chambers showing myocardial infarction, aneurysm, contusion, ischemic dyskinesia; regurgitant index Pros: higher information density than 1st pass method, assessment of pharmacologic effect possible, bad beat rejection possible Cons: significant background activity, cant monitor individual chambers in other than lao 45 projection, plane of av valve difficult to identify |
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• Abnormal wall motion on FDG cardiac PET can be related to
• Decreased NH3 • hibernating myocardium • stunned myocardium • myocardial scar • all of the above |
• E. All of the aboveLinear relationship with FDG. Therefore if perfusion/wall motion were abnormally decreased, then NH3 uptake and FDG uptake would be low. Myocardial accumulation dependent on regulation of blood flow and metabolic trapping. J AM Coll Cardio 3/99FDG is the gold standard for myocardial viability. Preserved areas of FDG uptake indicate viable myocardium. Stunned, Hibernating, and scar are all related to perfusion and wall motion abnormalities and therefore assessible by PET. Duke Review 2001 pg 801-802
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• During a dipyridamole MIBI study, the patient has severe chest pain
• titrate down the infusion • stop the infusion • stop the infusion and give nitro • stop the infusion and give amiophylline |
• D. stop infusion and give aniophylline Adenosine has the advantage of a very short plasma half-life. If patients experience symptoms, no antidote to the adenosine is necessary. Infusion is simply terminated. The action of dipyridamole, on the other hand, is more prolonged. The symptoms to watch for include chest pain (angina), nausea and vomiting, dizziness, headache, shortness of breath, and a drop in blood pressure. The antidote is IV aminophylline (125-250 mg) and may require repeating. In clinical experience, approximately 20% to 25% of patients undergoing dipyridamole pharmacologic stress testing experience chest pain. S-T segment depression is also noted in approximately 10% of cases. When using dipyridamole, some laboratories routinely administer 50 mg of aminophylline after tracer uptake is complete. In severe cases of angina, sublingual nitroglycerin is also administered (requisites pp. 69). If the angina is severe you are expected to stop the procedure. Dähnert 5th p1005
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• In SPECT imaging of the spine, findings more consistent than not with metastatic disease in the spine.
• involvement of body only • body and lamina • body and pedicles |
• body and pedicles
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• Which of the following tumors is NOT picked up by MIBG
• aldosteronoma • medullary thyroid • pheochromocytoma • paraganglioma • neuroblastoma |
• aldosteronoma
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• Which of the following is false with regards to sestamibi vs. Tl-201
• increased first pass extraction • increased cardiac activity • less redistribution • greater flexibility with respect to imaging time after administration |
• A. increased first-pass extraction (False)
• 201Tl has a very high first-pass extraction efficiency; remember, “Gone (90%) in 90 seconds…”.Sestamibi, on the other hand, “concentrates” by passive diffusion, and is only 40% 1st-pass extracted. see Dähnert 5th p. 1101-1103 • .Advantages of sestamibi over thal per primer: better dosimetry, better for spect, higher energy photons, less tissue attenuation, preferred for obese patients, no myocardial redistribution, so can image in 1 – 2 hours after you let biliary exretion ease up, increased first pass extraction.Ed. Note: although Dähnert says there is “higher total accumulation of 201Tl” in the heart, it also says that Sestamibi has the advantage of improved photon flux. Since photon flux should correlate most closely with activity, this would make ‘B’ technically true. |
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• NRC regulations specify that the activity of an administered radiopharmceutical must be within what range of the
• 5% • 10% • 15% • 20% • 25% |
• 10%
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• A neonate presents with increased uptake in a liver scan but with no activity in the bowel. What do you do next?
• Pretreat with CCK • Pretreat with phenobarbitol • Wait 24 hr and reimage |
• Wait 24 hr and reimage
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• When Technician 99m aerosol is used in the ventilation portion of a ventilation perfusion scan following the perfusion portion, the following adjustment must be made in counts:
• Count rate should be 3 to 5 times • count rate should be at least 10 times • Count rate does not need to be adjusted, may be the same • Other answers |
• B. count rate should be 10 times
• There are two methods of performing V/Q scans:Perfusion / ventilationVentilation/ perfusionFor perfusion , we use Tc99mMAA (particle size 10-90um, inject 200,000-500000 particles – need to reduce in infancy and R-L shunts).For ventilation, you have three choices: 1. Xe 133 gas (kev 81……. 1/2 life 5.2 days) 2. Xe 133 gas (kev 203……..1/2 life 36.4 days) 3. Tc99m aerosol (kev 140 ……..1/2 life 6 hours)The problem that arises is that you need to either use a radioisotope with a higher energy than that which you used for perfusion (so there is no interference with the perfusion images) or you have to use more of a compound with lower or equal energy. The dose given in 10X so I would assume the count rate would be 10x – dose always discussed – never found reference for count rate Dähnert 5th 1090-1091 |
