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35 Cards in this Set
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- Back
- 3rd side (hint)
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What is the primary difference between SPECT and PET scanning?
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SPECT is a single photon detection while PET is 2 annihilation photons enabling 360 deg imaging
What is the resolution that is possible with PET and what is the minimum energy level? |
the energy level is 2 x .511MeV or 1.022 MeV and the resolution is 5 mm or better
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What PET scans are done in 2D and which are done in 3D?
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All are done in 2D except for brain scans which are done in 3D
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When doing QC on a PET scanner what are you looking for?
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uniformity, looks like spool of thread,
what does it mean when there is a dark line? |
It means one of the buckets is not acquiring and it needs to be serviced
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What is the primary nuclide used in PET scanning?
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F-18 FDG
What does it stand for and how does it work? |
fluorodeoxyglucose
taken up as glucose, malignant tissue has increased glucose metabolism, also maps normal brain metabolic activity and delineates ischemic myocardial regions in which glucose metabolism is increased as a consequence of diminished fatty acid metabolism |
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What is the increased level of glucose level uptake of tumor cells?
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>100 fold
what is the primary target organ in terms of radiation burden during FDG scan? |
bladder
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What is the recommended dose for FDG?
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10-25 mCi, children as little as 2.6 mCi, dose is dependent on imaging system requirements, so this will vary
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What is the half life of F-18?
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110 minutes
what is the F-18 used for? |
primarily oncology, can also be used for cerebral, myocardial perfusion and bone
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What other nuclide is used for myocardial perfusion?
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Rubidium 82
how long is its half life? |
96 seconds
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What are the 2 primary crystals used in PET cameras?
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BGO and LSO
what do they stand for and what dose and time can they acquire? |
BGO - bismuth germanate, 10 mCi, 20-30 min
LSO - Cerium doped lutetium oxyorthosilicate, 15 mCi, 10-15 min |
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In terms of detection what is a LOR?
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Line of response, when 2 511 keV photons travel to opposite side detectors and the system is able to detect it, called a true event LOR, there are also Scatter, random and false LORs
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What is the advantage of a PET/CT hybrid system over a stand alone PET scanner?
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The ability to have fused images, with much greater specificity, much better attenuation correction and much faster acquisitions
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What is the timing for the CT part and for the PET portion of the scan?
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25 - 30 sec for the CT scout of topogram, and 2-3 min per bed (7 beds) for PET
what is accomplished in the scout CT? |
mapping of the beds for the PET
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What is considered a whole body scan for an oncology scan?
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skull base to mid thigh.
what about melanoma scan? |
from head to toe
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What are the 2 primary indications for PET/CT scans?
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1. Oncology
2. Surgical alterations |
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What is the patient prep prior to the PET/CT scan?
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1. IV injection 1 hr prior to imaging
accurate dose calibration before and after administration as this effects SUV values 2. Glucose monitoring (150-200) 3. Use of a quiet room |
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What is the special prior scan prep for diabetics?
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1. restrict carbohydrate intake day prior to reduce glucose (carb restriction is important as it takes diabetics many hours to process glucose)
2. dietary control for 2 days prior 3. take 1/2 dose for insulin dependent when awakening if fasting glucose >140, 2-3 hrs prior to injection 4. monitor blood glucose for 2 days prior |
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What is SUV?
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Standardized Uptake Value
what does it mean? |
estimate of tumor metabolism, compared to liver, which should be less than 2.0, over 2.5 is considered malignant, less than 2.0 is inflammatory, dependent on pt's weight and dose and time
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What is seen on a normal PET/CT scan?
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cardiac and brain are the hottest, also see kidneys and bladder, may see brown fat uptake
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Is prostrate cancer an indication for a PET/CT scan?
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no as it does not have glucose uptake,
although prostrate pts are scanned for a check on other metastases |
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Why would you do a thyroid PET/CT scan when it can be done with a regular nm scan?
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at later stages undifferentiated cells don't uptake I-123,131 but may still uptake FDG so it can still be seen
What is given to the pt prior to scan so they can stay on thyroid medications? |
thyrogen
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What is one of the best uses of oncology scans on PET that cant be seen elsewhere?
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lymphoma
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What is a SPN?
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solitary pulmonary nodule
small round or egg shaped lesion in lung, usually 3-4cm in diameter what is the difference with NSCL? |
non small cell lung cancer is metastatic cancer
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What is the dual time SPN protocol?
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image 4 beds, from base of skull to dome of liver 1 hr post injection of FDG and 2 hrs repeat image of chest
why is this done? |
2nd image findings of increased SUV indicative of malignant tumor while stable SUV indicates inflammation
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What is the most likely region of metastatic spread when doing a head and neck scan?
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the neck
what is important prep for patient prior to a head and neck scan? |
they cannot talk for 20 minutes prior to injection and during their quiet time
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What is the general procedure for head and neck scans?
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Dual scan technique
1st wb scan from shoulders to mid thigh (arms over head) 2nd 2 bed scan of head and neck (zoomed( with arms at sides |
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Why is PET such a good imaging modality for detection of melanoma?
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PET is a noninvasive technique with an accuracy of more than 90% in detection of lymph node metastases
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What is the protocol for a Melanoma scan?
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7 bed positions at 4 min/bed from pelvic crest to foot and 5 min/bed, 6 beds for upper body, 1 hr scan
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Why are follow up scans done on oncology patients?
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used for treatment planning, although not officially, we are just looking for metastases but oncologists can see how treatment is working
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3 indications for brain scans?
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1. Brain tumor
2. Alzheimer's 3. Epilepsy why are brain scans difficult and not done often? |
because there is so much uptake in the brain already
most brain scans are to see residual activity after surgery |
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What are most brain scans done for?
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1. per surgical evaluation of refractory seizures
2. post surgical evaluation of residual activity |
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Compare the sensitivity and specificity of SPECT with FDG cardiac scans?
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Sensitivity: SPECT -86%, FDG -90%
Specificity: SPECT-47%, FDG-74% |
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When would a cardiac scan with FDG be indicated?
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cardiac viability is currently approved for patients with equivocal nuclear SPECT imaging studies
why is this done? |
injured portion of the myocardium shifts from amino acid to glucose
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What is the general procedure for FDG cardiac scan?
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pt fasts for 6 hrs, if glucose level is less than normal range, oral load with glucose, wait 45-60 min. less than 130,then inject FDG, greater than 130 to 200 inject with insulin on sliding scale, wait 10 min then inject FDG, scan 45-60 min post inj, 1 bed of the heart for 10 min
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What is the non-malignant disease that can be picked up by PET imaging?
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Sarcoidosis
what is this? |
non-malignant nodules in lymph nodes, lungs, bones and skin
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What are some precautions that should be followed when working with F-18?
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Increase shielding to protect technologists and passersby
Provide separate restrooms for patients post administration of F-18 Keep injected patients separated Limit time spent with injected patients by providing explanations prior to injection Start saline IV in advance View patient via closed circuit monitor Patients void before entering scanning room Maintain 6 foot buffer between patient and technologist (not always possible) Properly shielded rooms Provide additional information from control room Use of F-18 has doubled to technologists extremities from conventional nuclear |
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