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267 Cards in this Set
- Front
- Back
Patient for HIDA, question must be asked?
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Time of last meal
|
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Patient for HIDA, been fasting 36 hours
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Administer Sincalide
|
|
Dose?
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0.02mcg/kg IV, infuse over 3 minutes minimum
Wait 30 min before imaging to give GB time to empty, and to be ready to accept more bile. Since T1/2 is 8 min, by 30 min, most of effect is gone. |
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Tracers for HIDA?
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Tc99m DISIDA or BRIDA
|
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Dose?
|
5mci.
Low dose since only one organ gets all the tracer |
|
GB not visualized after 1 hour
|
Do NOT call it acute chole
Must give Morphine |
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When is MS04 given if GB not seen?
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45 min
|
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Dose MSO4?
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3 mg IV
|
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How long after MSO4 do you image before calling it quits?
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another 45 min
|
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baby with HIDA
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Biliary atresia vs. hepatitis
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Diagnosis of atresia
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No filling of small bowel after 24 hours.
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Preparation
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Phenobarb pretreatment for 5 days
|
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Why?
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To make kid with neonatal hepatitis's liver pick up and excrete better, thus can hopefully r/o atresia
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R/O GI bleed; tracers
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Tc99m labeled RBCs
or Tc99m sulfur colloid |
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Dose of RBCs?
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20 mci
|
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Dose of Sulf colloid
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10 mci
|
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RBC labeling
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In vivo - worst - inject Stannous pp to reduce RBCs, then inject TcO4 into blood. Too much free pertechnetate.
In vitro -- Best, but time consuming. Draw blood, put in stannous, add Tc, reinject into pt. In vivtro -- our choice. Balance. >95% labeling. Inject stannous, wait, then draw up aliquot of blood into same tube as TcO4, mix, reinject. |
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Diagnosis of bleed
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Activity that increases over time. Movement is icing on cake.
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Scan with uptake in stomach
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Tc 99m pertechnetate scan
--if focusing on abdomen, Meckel scan -- If focusing elsewhere, probably neck for thyroid scan (not for uptake) |
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Normal Meckel scan
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Blood pool, then stomach uptake that gets excreted into small bowel, then renal excretion (so should see bladder)
|
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Abnormal meckel scan
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Tracer activity increases on same timeframe as stomach upkate.
If you see uptake on first image, its not a meckels. Also, there can be other structures with ectopic mucosa, such as duplication cyst |
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Reasons for whole body scans?
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Look for tumor (FDG, bone scan, octreoscan, MIBG)
Look for infection (gallium, indium) |
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Agents used for tumor imaging
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FDG PET
I-123 or I-131 MIBG Octreoscan |
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Best application of PET
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Lymphoma imaging, because reverts to negative post chemo when in remission. If negative PET but no change in CT, still good sign. Likewise if recurrence on PET, same size on CT, badness.
|
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Caveat in PET tumor imaging
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Reactive lymph nodes. Put in your DDx if unsure. Usually not as dark as tumor. Tumor darker than mediastinum.
Also, thymic rebound post chemotherapy |
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False pos FDG
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Infection (granuloma, pneumonia)
Inflamm (sarcoid, rheum nodules, divertic) BROWN FAT THYMIC REBOUND GRAVES or HASHIMOTOS RIB FX |
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Gallium energies
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95
190 300 (I95 highway, double it, 300 miles to gainesville) Another photopeak of 395, but not used in imaging |
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Gallium T1/2
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76 hours
(I-76 in Philly) |
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Identifying a Ga scan
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Soft tissues prominent
Bone/bone marrow Liver>spleen Large bowel excretion NO cardiac uptake. Don't see kidneys/bladder. |
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MIBG label, uses
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I 123 or I 131
Pheo Neuroblastoma |
|
Recognizing MIBG
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Cardiac
Liver (no spleen) Bladder ADRENALS are key. YOU SEE ADRENALS IN MIBG |
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Octreotide -- what is the radiolabel
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In111
|
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Uses for Octreoscan
|
CARCINOID
ISLET CELL TUMOR Other neuroendocrine (pheo, neuroblastoma, etc) |
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Recognizing Octreoscan
|
Intense uptake in
SPLEEN KIDNEYS Mild uptake in liver (SPLEEN>liver) |
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Inflammation imaging tracers
|
WBC scan
Gallium |
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When is Ga better than WBC?
|
Imaging spinal osteomyelitis (although MRI better)
Imaging lung inflammation (sarcoid, interstitial pneumonia, drug toxicity) |
|
WBC radiolabels
|
In111 oxime
Tc99m-HMPAO |
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Dose of In111 labeled WBC
|
VERY SMALL DOSE
0.5 mCi |
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When image Gallium?
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Start at 24, often wait until 48 hours. Better SNR. Give enema.
|
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When image In111 WBC scan?
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Can image at 4 hours, but usually wait until next day.
|
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In111 photopeaks
|
170
245 1 plus 7 is 8, divided by 2 is 4 which is one half or .5 of what you started with |
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Normal 111In WBC scan
|
IT GOES IN A WBC DISTRIBUTION
BONE MARROW SPLEEN > LIVER (makes sense, as spleen is the filter for all blood cells) AND THATS ABOUT IT Little soft tissue (unlike Ga) Spleen > liver (unlike Ga) No bowel activity (unlike Ga) Bone MARROW uptake (like Ga) |
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Indications for labeled WBC
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Confirm osteomyelitis
Abdominal infection or inflammatory bowel disease Vascular graft infection |
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Reversible defect on cardiac stress
|
Always means ischemia
Except for one small caveat: some pts with LBBB can get reversible septal defect not related to ischemia. |
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Mild to moderate fixed defect
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Does not always mean infarct
DDx: Incomplete infarct Hibernating myocardium Attenuation artifact |
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Hib myoc
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Chronic low flow state to myocardium, resulting in decreased metabolism. Looks like an incomplete infarct, with poor uptake on rest images and wall motion abnormality.
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Severe fixed defect
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Infarct
Hibernating myoc will not go all the way to no uptake |
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Bruce endpoints
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1) Most people stop due to symptoms (fatigue, dyspnea)
2) Angina or hypotension 3) Severe ECG changes or arrhythmia 4) Attain 85% of target (this is enough to unmask ischemia) |
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Pt who cannot exercise enough to unmask ischemia
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Pharmacologic stress
1) Adenosine or persantine -- both work not by increasing workload, but by causing vasodilation, which causes steal from stenosed vessel, resulting in ischemia. 2) Dobutamine -- positive inotrope and chronotrope, so increases myocardial workload. |
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When dobutamine used
|
Patient taking THEOPHYLLINE -- antagonizes persantine and adenosine, or patient with ASTHMA not on theophylline, because these drugs can exacerbate asthma.
|
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Difference in imaging for Bruce, adenosine, or dobutamine
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NONE
You dont even have to know how patient was stressed in order to interpret the study, as long as the stress was adequate |
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How adenosine given?
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Continuous IV infusion for 3 min, then inject tracer, and continue adenosine infusion for another 2 min
|
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How dobutamine given?
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Keep giving dobutamine via infusion until target HR reached, then maintin for 1 minute BEFORE tracer injection (JUST LIKE FOR BRUCE)
|
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201 Tl characteristics
|
Analogue of K
Long half life, which limits dose that can be given (4mCi) Low energy (80keV = x-ray range) REDISTRIBUTES |
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Our institution
|
Tl first as resting study
Mibi as stress tracer (overpowers Tl with higher energy and higher dose, locks in place, so dont have to image them right after like you do on the rest images with Tl for fear of redistribution) |
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Dose of sestamibi
|
20 mCi
|
|
Waiting time to image?
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30-60 min (waiting for liver to clear)
|
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Sign of ischemia besides uptake
|
Stress dilatation of the LV cavity
|
|
Axes
|
Short
Long - long axis views are named opposite of the way the heart is oriented: Heart laying on it side = VLA; Heart standing up = HLA |
|
septal defect near base
|
Normal membranous septum
|
|
Territories
|
6 segments: Anterior, anteroseptal, inferoseptal, inferior, inferolateral, anterolateral (just look at the polar maps)
LAD is centered over RV insertion (interventric groove), so LAD territory is anterior and anteroseptal. RCA is inferior, so it supplies the 2 segments counterclockwise to LAD: inferoseptal and inferior. Circ is lateral, so circ supplies the 2 segments clockwise to the LAD = anterolateral and inferolateral. |
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PET perfusion
|
Use Rb -- disadv = 1.3 minute half life, so all stress is pharmacologic, very expensive.
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When is viability assessment needed?
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When fixed defect is at least 1/2 of normal uptake, can be sure its viable. But if questionable, then
1) Thallium redistribution (inject extra 1mCi and image next day for redistrib) 2) FDG -- the best choice if there is any question remaining |
|
99mTc-MAA dose
|
4 mci
About 1 million particles total |
|
Injection instructions
|
ALWAYS INJECT PATIENT IN SUPINE POSITION
|
|
When is vent scan done with 99mTc-DTPA? With Xe?
|
BOTH DONE BEFORE MAA INJECTED, because once MAA is in there, it aint goin anywhere and you cant give enough Xe or aerosol to see through it
|
|
Protocol for Xe
|
3 stages: Imaging is performed throughout all 3 stages. All imaging is from POSTERIOR view.
Wash-in: Pt holds breath for 30s, or takes deep breaths. Equilib: Pt breathes normally through closed system. Washout: System turned to exhaust, patient breathes normal air, exhaling out the Xe. |
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Protocol for DTPA
|
SIMPLER
Breathe from nebulizer 3-5 min Images recorded after breathing (shit aint goin anywhere) ADVANTAGE: Get to take multiple projections, unlike with Xe |
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Slow wash-in and washout on Xe study
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Suggests COPD, especially if patchy
|
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Nonsegmental defect
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Does not conform to segments
Hilar defect, costophrenic angle defect, etc |
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Small defect
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Lies within a segment, but involves LESS THAN 1/4 OF IT
|
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Low probability
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Nonsegmental defects (very low)
Any perf abnl substantially smaller than CXR abnl (very low) Small defects Matched defects with clear CXR (probably due to COPD) Triple match in upper or midlung (very low) Markedly heterogeneous perfusion Stripe sign (very low) |
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Medium size defect
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1/2 of segment
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Large defect
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whole segment
|
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High prob
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at least 2 unmatched perfusion defects or the equivalent with CLEAR CXR
So, you MUST ASK FOR CXR as soon as you see a V/Q scan, just like in real life |
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DDx of V/Q mismatch
|
Acute PE
Chronic PE Node or tumor in hilum compressing vessel (airway more rigid, wont compress) Thats why you need MULTIPLE defects in order to call it High prob |
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Intermediate prob
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Single large or medium defect, unmatched, normal CXR
Triple match lower lobes (intermediate because could be atelectasis, pneumonia, or infarct, and you cant tell them apart, especially infarct and pneumonia) Any other abnormality not in high or low categories |
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High prob PPV
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>85%
|
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Low prob PPV
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<15%
|
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Very low prob
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<5%
|
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V/Q scan with uptake throughout body
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CONCLUSIVE EVIDENCE OF A RIGHT TO LEFT SHUNT -- could be simple like a pulm AVM
|
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When is bone scan hot more often? Lytic or blastic lesion
|
BOTH
Doesnt matter what xray shows. As long as there is new bone formation going on, there will be uptake |
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Bone scan tracer
|
Tc Methylenediphosphonate
(MDP) |
|
Dose
|
20 mCi
|
|
When imaged?
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4 hours later
|
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Where is most of dose then
|
In toilet. Reason you have to wait is to clear out the soft tissues, which occurs via the kidneys. So in older people and those with renal failure, bad bone scans with lots of background.
|
|
Purpose of 3 phase scan
|
Blood flow and pool images tell you what is going on in the SOFT TISSUES. It tells you about hyperemia. So you would want to do it for r/o RSD or osteo.
|
|
Problem with 3 phase
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Very nonspecific. Doesnt tell you anything diagnostic except that there is hyperemia in the soft tissues.
|
|
metastatic disease
|
Central distribution, as it goes to bones with red marrow. Acral lesions are not likely to be mets.
|
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Multiple lesions random distn but predominantly central
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Pathognomonic for mets
|
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Very hot long segment uptake
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Pagets
Goes from one end of bone to other end, and no skip lesion. May have associated deformity. Blade of grass appearance when starting out |
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Skull with hot uptake and sharp zone of transition to normal uptake
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Pagets osteoporosis circumscripta
|
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Increased uptake in an extremity. Uptake increased on all 3 phases. Periarticular bone especially hot.
|
RSD.
Usually post-traumatic. Reverts to normal 6 months after sx resolve. |
|
Diffuse increased cortical uptake, with tram-track appearance
|
HO
Almost always pulm dz, and usu lung CA. |
|
Distribution of HO
|
Lower extremities > Upper
|
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DDx of HO
|
When it occurs in lumpy patchy uptake variety, could be peripheral vascular dz. NOT METS, too far peripheral.
|
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Isolated acral medullary lesion.
|
Not going to be met. Will have to do plain film. If not visible, CT to better define.
|
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Bone imaging
When should you request a CT? |
When looking for matrix
|
|
Bone imaging
When should you request an MRI? |
When you want to evaluate soft tissues
|
|
Bone imaging
When should you request a bone scan? |
When you want to determine whether there is multiplicity of lesions, or evaluate lesion distribution.
|
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Cold lesion DDx
|
Unicameral bone cyst
Hemangioma Eosinophilic granuloma Myeloma (causes little bone response) Mets (so destructive that there is not even enough time to make bone) = Thyroid and RCCA XRT Surgical defect |
|
Cold lesion: What they want to hear on boards
|
Myeloma, thyroid met, RCCA met
Also, just by sheer prevalence, breast can as an unusual manifestation |
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What does a cold lesion require
|
A cold lesion is tough to see on bone scan. A significant amount of bone has to be destroyed in order for it to be visible
|
|
See bone scan with mets. Then few months later, repeat, lesions have gotten hotter.
|
Think FLARE PHENOMENON
Pt was given chemo in interim, which killed tumor cells, and now bone is repairing, but laying down more new bone to do it. So scan temporarily (3-6 mo) shows increase. |
|
When fx hot
|
by 24 hours
|
|
How long fx stay hot?
|
Ribs 6 mo to years
Wt bearing up to 10 years, slowly fading away |
|
Stress fx, positive on what phases?
|
All 3
|
|
Bilat uptake or unilat uptake at L5
|
Think spondylolysis
|
|
Diffuse linear uptake in tibia
|
Shin splints.
If uptake was more focal, stress fx. |
|
WBC scan to r/o osteo
|
WBCs are in marrow, and there is very modest uptake in fracture, but not a lot. If you have a lot of uptake on WBC scan, you can suspect that the bone is infected.
|
|
How long can bone scan be abnormal after placement of a prosthesis?
|
1 year or more. So during this time, you can't really diagnose anything. But years out, if there is a question of infection, then imaging becomes more useful
|
|
What is best way to screen a prosthesis for infection?
|
Compare a baseline MDP to a current one.
|
|
Prosthesis imaging
|
You normally do a WBC scan to rule in or out osteomyelitis. But in the case of prosthesis, there can be expansion of the marrow in that region. Thus, when you do a WBC scan, you will see increased uptake in the same area as the prosthesis, and suspect infection. But it might just be marrow expansion. How do you tell?
By doing a sulfur colloid scan, you can evaluate the marrow volume in that area. So, lets say you get a TcMDP bone scan which is very hot in the region of the prosthesis. You then do a WBC scan, and it is normal. Then you don't have to worry about infection. Its either postop changes or osteolysis. But what if the WBC scan is positive? Then you can't just say its infected so tap the joint, you go on to sulfur colloid to evaluate marrow in that region. If the sulfur colloid shows increased uptake in the same regions, you are probably just dealing with marrow expansion. But if the sulfur colloid scan is not hot in that region, that is suggestive of WBC infiltration exclusive of marrow proliferation, and thus suspicious for infection. You would recommend tapping the joint. |
|
Case with distinct bones, no kidneys, no bladder, minimal soft tissue
|
Superscan. Bone has extracted more tracer than it normally does, so that by 3-4 hours when you are imaging, there is minimal left in soft tissues, including kidneys and even sometimes bladder.
|
|
Superscan ddx
|
Metabolic bone disease
Metastatic disease |
|
Metabolic causes of superscan
|
#1 Renal osteodystrophy
#2 Osteomalacia Myelofibrosis Rare for hyperparathyroidism to be so bad as to cause superscan |
|
Metastatic causes of superscan
|
Breast or Prostate
Even in diffuse metastatic dz, should still be able to see some irregularity to suggest metastatic disease over metabolic |
|
Suspect superscan, but not sure
|
Ask for any plain film.
|
|
Intense uptake in humeral or femoral head
|
Think AVN
Could be other bones too of course |
|
MDP scan with focal liver uptake
|
Metastatic disease
|
|
Diffuse liver uptake
|
Due to colloid formation in the MDP. Occurs when there is excess aluminum coming out with the Tc from the moly generator
|
|
Why aluminum?
|
Aluminum is used as a reducing eluting agent for the moly generator.
|
|
Splenic uptake on MDP scan
|
Splenic infarct (sickle cell)
|
|
Myocardial uptake
|
MI (occurs a few days out from an MI. Can also get uptake in calcified aneurysm)
|
|
Brain uptake
|
Infarct
Tumor |
|
Chest uptake, diffuse
|
Pleural effusion
|
|
Uptake in stomach, kidneys and lungs
|
Metastatic calcification due to hypercalcemia
|
|
Focal muscle uptake
|
Myositis ossificans
Soft tissue tumor |
|
Diffuse muscle uptake
|
Inflammatory (rhabdomyolysis or polymyositis)
|
|
Lost 15 cards for renal
|
Lost
|
|
Types of renal scanning - basic
|
standard -- typified by MAG-3
Cortical -- typified by DMSA |
|
Tracers for standard imaging
|
MAG3
DTPA |
|
Dose of tracer for study
|
10 mCi, whether DTPA or MAG3
|
|
Differences between MAG3 and DTPA
|
DTPA is filtered only. Thus it is excreted proportionally to the glomerular filtration rate.
MAG3 is filtered and secreted. It is excreted proportionally to the ERPF - effective renal plasma flow. This is the entire volume of plasma available for clearance by the kidney. 20% of ERPF is due to the filtration (GFR), the other 80% is due to tubular secretion. Thus MAG 3 can be excreted at 5 times the rate of DTPA. This results in better count density and better excretion, which makes for better images, which makes MAG 3 studies more accurate and easier to read. |
|
What is renal scan not used for
|
to "check" the kidneys.
It is used for specific purposes only |
|
What are those purposes?
|
Determining split function
Assessing degree of obstruction Evaluation of RVH (captopril) Eval of suspected ATN Transplant eval (limited) |
|
What does decreased renal flow indicate
|
Totally nonspecific. Decreased renal function results in decreased renal flow.
|
|
What is exception to this
|
ATN. Renal perfusion is classically preserved when there is ATN, despite poor function. That is why it so frequently recovers function.
|
|
When is split function calculated
|
2 minutes, before tracer in coll system
|
|
Normal split function
|
45/55
40/60 definitely abnormal In between is equivocal |
|
Patient with hydronephrosis
|
Use diuresis renography to determine if hydro is obstructive or nonobstructive.
Give lasix, if you can "flush" out activity through the collecting system, it is not obstructed |
|
Dose of lasix
|
Adult = 40mg IV
Kid -- 1mg/kg IV |
|
Caveat to this
|
If bladder distended, may not be able to flush out kidneys, so pt must be able to pee
|
|
Interpreting diuresis renography
|
Draw ROI over entire kidney, including coll system.
Measure half-time of emptying s/p administering lasix T1/2 < 10 min = NORMAL T1/2 > 20 min = ABNORMAL T1/2 in between is equivocal |
|
When is lasix given
|
Usually 20 min s/p tracer, but can give when coll system full, at same time as tracer (babies) and even 15 minutes BEFORE injection (if you know the entire purpose is to evaluate hydronephrosis for obstruction, this way is best, because you are giving tracer 3 minutes before peak lasix activity (18 min), thus allowing 3 minutes for perfusion/split fcn calculation, then you immediately begin to calculate the T1/2 of emptying 3 min into the study).
|
|
Why is captopril scan necessary to evaluate for RVH
|
2 Reasons
1) You can't just calculate renal blood flow as estimate of RAS, because renal blood flow is preserved until the stenosis is very very severe. It is preserved by the renin angiotensin system. By knocking out this mechanism, and comparing perfusion to the kidney after knocking out the system to before knocking out the system, you can then get an accurate estimation, not of renal artery stenosis, but of renovascular hypertension. This is because if you have a renal artery stenosis that is not physiologically significant, there will be no change in perfusion after giving captopril. So what you are evaluating is for RENOVASCULAR HTN. 2) Renal blood flow can be diminished due to non-vascular causes, i.e. anything except ATN that reduces renal function |
|
How does renin angiotensin system work
|
Compensates for decreased renal perfusion by causing increased constriction of the efferent arteriole, which increases filtration pressure at the glomerulus, maintaining GFR
|
|
What happens when captopril given
|
Efferent arteriole opens, decreasing pressure across glomerulus, and less filtration occurs, which can result in renal failure. On scan, see it as decreased perfusion (delayed uptake)
|
|
What is goal of captopril scan
|
Get a baseline,
Then induce transient renal failure, and get picture of it happening |
|
Preparation
|
No ACE inhibitor for 3 days
Preferably no BP medicine at all and pt must be well hydrated. These steps to prevent hypotension, which is dangerous. If it occurs, you stop scan and treat the patient. If it occurs, it does suggest that the patient is relying on AII to maintain BP. |
|
When is captopril given relative to tracer?
|
Given P.O., 1 hour prior to tracer and scan time
|
|
Contraindication to captopril scan
|
Elevated creatinine. If patient already in renal failure, since goal is to induce renal failure, it is going to be hard to tell if there is any difference.
|
|
What does positive study look like
|
MAG-3 -- Initial uptake not affected because GFR is only 20% of uptake with MAG3. But there is delayed washout looking like a prolonged nephrogram.
DTPA -- Decreased initial uptake (split function falls), also slow washout. |
|
Bilateral prolonged nephrogram with MAG3 post capto
|
DDX:
Severe Hypotension Bilateral symmetric RAS So if you see this appearance, check the BP |
|
Transplant evaluation
|
Simply do renal scan to visualize perfusion to the kidney.
Compare level of oliguria with perfusion. If there is good perfusion but oliguria, suggests ATN, and lower liklihood of rejection. If there is diminished perfusion, suggests rejection. But the distinction between ATN and rejection is not clear cut. Other complications of transplant (urinoma) are not well defined with renal scintigraphy |
|
Appearance of rejection
|
= appearance of renal failure
MAG3 -- Prolonged nephrogram phase = prolonged washout DTPA -- Fades to background, without excretion visible |
|
Role of renal scan in chronic renal failure
|
NONE
Will have poor perfusion to both kidneys, poor excretion, no information given |
|
Difference in DMSA renal cortical scan
|
More like a bone scan. DMSA gets adsorbed to the tubules, so you wait for it to adsorb and for background to clear out, and then get your delayed images of cortex
|
|
Indications
|
Evaluate pyelonephritis or scarring
NO OTHER USE |
|
Protocol
|
Inject DMSA
No dynamic imaging Wait 4 hours. Take pictures. |
|
Dose
|
Wt dependent
.05 mCi/kg. So, 10 kg baby, give 0.5 mCi |
|
Imaging
|
Pinhole is desired because need high resolution. Also SPECT.
|
|
RN cystography -- protocol
|
Inject tracer into bladder catheter first
Then hook up bag of saline, and drip it in Image continuously during filling and voiding |
|
Indications for RNC
|
Follow-up after positive VCUG
Primary screening tool in girls, since no chance of urethral abnormality as cause of reflux (but if positive, would have to do more eval to look for Hutch divertic, etc) Screening for sibling of pt with reflux (20% incidence in sibs) |
|
Testicular torsion protocol
|
Inject Tc pertechnetate
Look at blood flow and pool images Normally dont see anything. But if torsed, you see a large cold region, with ring of hyperemia around it if it is a late torsion. If inflammed due to epididymoorchitis, you will see large round area of hyperemia |
|
Indications for brain PET
|
only 2 reasons clinically:
1) Epileptogenic foci 2) Eval of dementia |
|
Parietal decreased uptake bilaterally, no other abnormality
|
Early alzheimers
|
|
Frontal decreased uptake bilaterally, no other abnormality
|
Picks disease. If there is just frontal or frontotemoral decreased uptake, its Picks.
|
|
Bilateral decreased parietal with decreased frontal uptake also
|
More advanced Alzheimers.
When very advanced, decreased uptake in whole cortex. |
|
DDx diffuse decreased cortical uptake
|
Lewy body dementia
Advanced alzheimer High serum glucose levels causing competetive inhibition |
|
Goal of PET in epilepsy
|
For refractory cases, localize focus for surgical planning
|
|
Identifying Sz focus
|
FDG used for identifying foci in interictal period
See cold focus, usually right or left temporal lobe. |
|
Complementary tests
|
MRI
EEG |
|
How is PET for intraictal imaging?
|
FDG gets locked into cells once it is phosphorylated by hexokinase. If seizure occurs sometime in the 40 min between injection and imaging, you will see the focus and all of the places it generalized to, making it useless for intraictal imaging.
|
|
DDx for hot foci on brain PET
|
Tumor - met or primary
Epileptogenic focus plus wherever it generalizes to if that occurred Motor-sensory activation |
|
Other big use of brain PET
|
Differentiating radiation changes from recurrent tumor
|
|
Setup of gamma camera
|
Top layer = collimator
Next layer = scintillation crystal -- converts high energy photon to light Next layer -- lots of photomultiplier tubes -- amplify the light Next layer -- a wire coming out of each PMT going to computer to give information to make the image |
|
Tests for Gamma camera
|
1) Field uniformity
2) Resolution 3) Center of rotation |
|
Field uniformity frequency
|
Done daily
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Extrinsic flood
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Collimator kept on
Cobalt SHEET source put below camera, where patient would be Should see salt and pepper appearance |
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Causes of abnormalities on extrinsic flood
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Collimator damage
Collimator contamination Crystal crack PMT out |
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Intrinsic flood
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Collimator taken off
Point source |
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What can you see with intrinsic flood?
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Cracked crystal
PMT out |
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Failed PMT
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Round defect with no bright around it
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Appearance of cracked crystal
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Jagged or linear area of no counts, with rim of increased counts due to confused PMTs
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Thyroid scan with large nodule
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Hot -- benign
Cold -- If it is a dominant nodule (larger than the others), it must be biopsied by FNA |
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Given 2 images from scan. Performed 30 min apart. One scan very blurry. Next one looks normal.
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Off peak image.
You can predict this was done as first case of the day, because the technologist does the flood with Cobalt 57, which has peak of 122 keV. This is close enough to Tc to image it, but all you are imaging is the scatter. |
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No excretion after 24 hours into bowel on HIDA in kid
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Cannot exclude biliary atresia. Recommend biopsy.
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Telling difference between Tc and I thyroid scans
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If Tc, imaged immediately, and see background plus salivary glands
If Iodine, no background, just thyroid. So if given scan with two adjacent structures, and no background, its probably thyroid, or maybe DMSA renal scan with lots of defects making it look like a thyroid. |
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Thyroid scan with decreased uptake
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Subacute (Hashimoto) thyroiditis
Extrinsic thyroid hormone suppressing TSH Large iodine load PTU or methimazole |
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No excretion after 24 hours into bowel on HIDA in kid
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Cannot exclude biliary atresia. Recommend biopsy.
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Telling difference between Tc and I thyroid scans
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If Tc, imaged immediately, and see background plus salivary glands
If Iodine, no background, just thyroid. So if given scan with two adjacent structures, and no background, its probably thyroid, or maybe DMSA renal scan with lots of defects making it look like a thyroid. |
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Thyroid scan with large nodule
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Hot -- benign
Cold -- If it is a dominant nodule (larger than the others), it must be biopsied by FNA |
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How can you tell difference
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1) Does patient have thyrotoxicosis -- if yes, eliminates PTU, methimazole as cause
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Thyroid scan with decreased uptake
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Subacute (Hashimoto) thyroiditis
Extrinsic thyroid hormone suppressing TSH Large iodine load PTU or methimazole |
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How else can you tell if decrease activity is related to PTU/methimazole
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Tc scan:
TcO4 is trapped by the thyroid, not organified, like Iodine is. PTU and methimazole block organification, thus blocking Iodine from being concentrated. But they do not block trapping, so Tc can still accumulate in there. |
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How can you tell difference
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1) Does patient have thyrotoxicosis -- if yes, eliminates PTU, methimazole as cause
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Gallium face
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Normally see lacrimal glands and nose. Do not NORMALLY see salivary glands.
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How else can you tell if decrease activity is related to PTU/methimazole
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Tc scan:
TcO4 is trapped by the thyroid, not organified, like Iodine is. PTU and methimazole block organification, thus blocking Iodine from being concentrated. But they do not block trapping, so Tc can still accumulate in there. |
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Gallium face
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Normally see lacrimal glands and nose. Do not NORMALLY see salivary glands.
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What can you see with intrinsic flood?
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Cracked crystal
PMT out |
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Appearance of cracked crystal
|
Jagged or linear area of no counts, with rim of increased counts due to confused PMTs
|
|
Failed PMT
|
Round defect with no bright around it
|
|
Given 2 images from scan. Performed 30 min apart. One scan very blurry. Next one looks normal.
|
Off peak image.
You can predict this was done as first case of the day, because the technologist does the flood with Cobalt 57, which has peak of 122 keV. This is close enough to Tc to image it, but all you are imaging is the scatter. |
|
No excretion after 24 hours into bowel on HIDA in kid
|
Cannot exclude biliary atresia. Recommend biopsy.
|
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Telling difference between Tc and I thyroid scans
|
If Tc, imaged immediately, and see background plus salivary glands
If Iodine, no background, just thyroid. So if given scan with two adjacent structures, and no background, its probably thyroid, or maybe DMSA renal scan with lots of defects making it look like a thyroid. |
|
Thyroid scan with large nodule
|
Hot -- benign
Cold -- If it is a dominant nodule (larger than the others), it must be biopsied by FNA |
|
Thyroid scan with decreased uptake
|
Subacute (Hashimoto) thyroiditis
Extrinsic thyroid hormone suppressing TSH Large iodine load PTU or methimazole |
|
How can you tell difference
|
1) Does patient have thyrotoxicosis -- if yes, eliminates PTU, methimazole as cause
|
|
How else can you tell if decrease activity is related to PTU/methimazole
|
Tc scan:
TcO4 is trapped by the thyroid, not organified, like Iodine is. PTU and methimazole block organification, thus blocking Iodine from being concentrated. But they do not block trapping, so Tc can still accumulate in there. |
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Gallium face
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Normally see lacrimal glands and nose. Do not NORMALLY see salivary glands.
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Soft tissues, no bones, liver, no spleen, heart, salivary glands, bladder
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MIBG.
When you see salivary glands and myocardium on same scan you are looking at autonomic innervated organs, which should make you think MIBG. MIBG is the only normal whole body scan that you will see heart on except for PET. Should also be able to see adrenal faintly, although if shown it will probably be the adrenal that is the mass |
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MIBG scan with mass
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Adult -- PHEO
Kid -- Neuroblastoma |
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Brain uptake on whole body scan
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Its FDG PET
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Spleen and liver, central bone marrow activity
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Could be sulfur colloid or In111 WBC scan
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How do you tell difference
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InWBC scan -- No bladder activity
Sulfur colloid -- get bladder activity |
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Liver, hot spleen, very hot kidneys, soft tissue but no bone
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Octreotide scan
Carcinoid or islet cell tumor |
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I131 indications
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Pre-therapy to look for mets
S/P ablation therapy, to get a baseline, and because with such a high dose given, will see everything that takes up I131 Screening for recurrence |
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What scan can look like gallium?
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MIBG. Both have soft tissue uptake, both have uptake in face.
Differentiate by observing for bone marrow uptake. If bones are visible, its gallium. If not, its MIBG. |
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DDx diffuse lung uptage on gallium
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Sarcoidosis (stage 2 or 3)
PCP Pneumoconioses Hypersensitivity pneumonitis UIP Drug toxicity (bleomycin) |
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Diffuse homogeneous liver uptake on MDP bone scan
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Colloid formation by MDP, due to too much alumina in eluate
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Focal or multifocal liver uptake on MDP bone scan
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Metastatic lesions. Adenocarcinomas (breast, colon) commonly do it. Of course any met with calcification also.
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Gallium dose
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Depends whether imaging for tumor or inflammatory disease
If for tumor, give 10 mCi For inflammation, give 5 mCi |
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Size for hemangioma on RBC scan
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2 cm
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Criteria
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Not seen on immediate, seen on delayed images
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What type of hemangioma is this
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CAVERNOUS. Think it has to slowly fill in the caverns. Capillaries fill immediately, so those are the flash fillers.
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When are delayed images taken for hemangioma
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1 to 2 hours
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Bleeding scan tracers
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Tc labeled RBCs
Sulfur colloid -- no ability for delayed imaging but better signal to noise since blood pooc clears rapidly |
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drugs for enhancement of meckel scan
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Pentagastrin -- increases rapidity of uptake, used with glucagon to decrease motility
cimetidine |
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Meckels
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2% of popn
2 cm from ileocecal junction |
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Gastric emptying study
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GOO vs. diabetic gastroparesis
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position acquired
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Ant and posterior or just LAO
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characterizing reflux
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Milk study
high -- more than 1/2 way to mouth low and short long -- greater than 10 seconds |
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differentiate DTPA from HMPAO brain death study
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HMPAO has salivary gland uptake
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HMPAO
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Binds irreversibly to brain cells on first pass
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Advantage of HMPAO
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Do not need good bolus
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Luxury perfusion
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cerebral blood flow increased or not decreased 3-7 days after stroke because of loss of autoregulation even though brain dead
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agents for radionuclide VCUG
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sulfur colloid or DTPA
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methods for performing
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direct or indirect
Direct -- put in catheter indirect -- do renal flow study first, then image |
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why kids reflux
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short intramural UVJ segment
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limitations of renography
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dehydration limits study
as does renal insufficiency |
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quantitative side
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washout half time post lasix
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transplant evaluation
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Slow washout indicates some degree of failure. Look at it just like any other renal scan.
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patient with UPJ obstruction for follow up renal scan shows persistent dilatation of collecting system
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Will look like this for life. The coll system will never return to normal. BUT on post lasix imaging, will still have NORMAL WASHOUT.
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COllections around transplant kidneys
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Urinoma, hematoma, abscess -- first 2 weeks postop
Lymphocele -- 4 to 8 weeks |
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Complications after transplant
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ATN
Obstruction hyperacute/acute rejection Cyclosporin toxicity -- months after |
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Photopenic kidney 24 hours post transplant
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renal vein thrombosis
Renal artery thrombosis -- more common after 2 months Hyperacute rejection -- rare because of prescreening Acute cortical necrosis |
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Post transplant renal scan with good uptake. No excretion.
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ATN
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common first week complications
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ATN
Accelerated acute rejection Urinary leak Urinary obstruction |
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When does acute rejection begin
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5 to 7 days = accelerated
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tracer used for evaluation of transplant kidneys
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MAG-3
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bell clapper testis
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tunica invests whole testicle, allowing free rotation
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Post transplant renal scan with good uptake. No excretion.
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ATN
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common first week complications
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ATN
Accelerated acute rejection Urinary leak Urinary obstruction |
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When does acute rejection begin
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5 to 7 days = accelerated
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tracer used for evaluation of transplant kidneys
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MAG-3
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bell clapper testis
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tunica invests whole testicle, allowing free rotation
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Post transplant renal scan with good uptake. No excretion.
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ATN
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common first week complications
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ATN
Accelerated acute rejection Urinary leak Urinary obstruction |
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When does acute rejection begin
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5 to 7 days = accelerated
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tracer used for evaluation of transplant kidneys
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MAG-3
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bell clapper testis
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tunica invests whole testicle, allowing free rotation
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Photopeak -- I123
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160
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Half life -- I 123
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8 hours
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Difference in way body handles I123 versus Tc?
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Tc trapped by follicular cells
I trapped AND organified |
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Incidence of Ca in multinodular goiter
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5%
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Measuring size of lesion
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NOT a good idea with nucs, especially thyroid, which uses pinhole collimator and causes magnification because of that
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