NM Flashcards
(47 cards)
When should phenobarbital be given to a neonate when evaluating for biliary atresia?
5 days prior to imaging. (5 mg/kg/day) may be given orally in 2 divided doses daily for a minimum of 3-5 days prior to hepatobiliary imaging study to enhance the biliary excretion of the radiotracer and increase the specificity of the test.
What is considered a normal gastric emptying study?
Retention of >10% of the meal activity in the stomach at 4 hours is abnormal and is the best discriminator between normal and abnormal results (SNM practice guidelines)
*E.g. should have >90% clearance at 4 hours
Which of the following radiopharmaceuticals is used to assess renal tubular function?
a) Tc-99m MAG3
b) Tc-99m HMPAO
c) Tc-99m DTPA
d) Tc-99m DMSA
A) Tc-99m MAG3
Which radiopharmaceutical is used to assess glomerular function?
Tc-99m DTPA approximates glomerular function
Which radiopharmaceutical is used for assessment of renal scarring?
Tc-99m DMSA can be used to assess renal cortical integrity (used to assess for scarring or pyelonephritis)
Which pharmaceutical intervention is used for evaluating for chronic cholecystitis?
Sincalide, a synthetic octapeptide of cholecystokinin.
What is the physical half life of Tc-99m?
6 hours
What is the physical half life of I-131 sodium iodide?
8 days
Which one of the following is NOT a normal site of F-18 fluorodeoxyglucose (FDG) localization? A. Salivary glands B. Gallbladder C. Colon D. Kidneys
B. Gallbladder
Reduced occipital lobe glucose metabolism on F-18 FDG (fluorodeoxyglucose) cerebral PET imaging is MOST common in which one of the following progressive dementias? A. Alzheimer’s B. Pick’s C. Parkinson’s D. Lewy body
D. Lewy Body
Which of the following statements about agreement states is CORRECT?
A. They are states that agree to allow the Nuclear Regulatory Commission (NRC) to regulate radioactive by product material within their boundaries.
B. They are states that agree to regulate radioactive by product material within their borders on behalf of the NRC.
C. They are permitted to have less stringent regulations than the NRC.
D. A state can become an agreement state without prior notification of the NRC.
B. They are states that agree to regulate radioactive by product material within their borders on behalf of the NRC.
What is the mechanism of uptake for Tc-99m tetrofosmin?
Passive diffusion.
Although the exact mechanism of uptake is not fully understood, most would agree that it is taken up by passive diffusion. The amount of Tc-99m tetrofosmin delivered to the myocytes is based on perfusion.
What organs are seen if there is free pertechnetate?
- choroid plexus
- thyroid gland
- salivary glands
- gastric mucosa (stomach/meckel’s)
- renal/bladder
- mucous membranes
- sweat glands
What is a distinguishing feature of a gallium scan?
Lacrimal gland activity is a distinctive feature of Ga-67 biodistribution.
What is the risk of malignancy in a cold nodule on a thyroid scan?
15-20% risk of malignancy
What is the energy of the photons emitted from Tc-99m?
140 keV
What is normal range for radioiodine uptake?
10 to 30% of ingested activity is normal.
Some textbooks say
DDx superscan bone scan (characterized by diffuse uptake and non-visualization of the kidneys)
- Metastatic disease (axial > appendicular): Prosate, breast, lung
- Metabolic disease: Renal osteodystrophy, hyperparathyroidism, osteomalacia, myelofibrosis, mastocytosis
What is flare phenomenon?
Two criteria:
- Increased intensity and/or number of lesions
- Subsequent decrease uptake on repeat
Favourable response to tx. Pt asymptomatic and lesions become more sclerotic. 2 weeks to 3 months following therapy.
What is the target HR for cardiac perfusion?
85% of max HR is the target (220-age x 0.85)
What is stunned myocardium?
Stunned myocardium refers to a situation in which an acute transient myocardial ischemic event results in a prolonged wall motion abnormality which eventually resolves.
The appearance of 201-Tl stress-redistribution-reinjection SPECT and rest-redistribution SPECT, as well as 99mTc-MIBI SPECT, are similar to hibernating myocardium
What are findings in hibernating myocardium?
- Hibernating myocardium is myocardial tissue that retains viability, but has reduced perfusion and oxidative metabolism.
- On stress and rest, a perfusion defect will be present (e.g. on both stress-rest images using Tc-99m-sestamibi or Tc-99-m-tetrofosmin SPECT or Rb-82 or N-13 ammonia PET/CT). However, due to retained viability, the tissue will demonstrate uptake of FDG, often more intense than the normal myocardium, and will also demonstrate redistribution of Tl-201 upon delayed imaging, which will discriminate between infarction and hibernating myocardium.
- Differentiation from stunned myocardium can be difficult, but can sometimes be made on the basis of maintained, or nearly maintained, perfusion with a wall motion abnormality (hibernating myocardium will have abnormal perfusion and a wall motion abnormality).
- Hibernating myocardium typically represents a chronic process whereas stunned myocardium is typically related to an acute infarction or ischemic insult resulting in altered wall motion.
What is normal radioactive iodine uptake for a thyroid scan (RAIU)?
- Normal uptake at 24 hrs = 8-35%
- The most useful role of RAIU test is in determining the etiology of thyrotoxicosis. Thyrotoxicosis simply refers to excess thyroid hormone in the body and may be due to overactivity of the thyroid gland (hyperthyroidism), or other causes such as inflammation of the gland (thyroiditis) or ingestion of excess thyroid hormone. In “true hyperthyroidism,” RAIU uptake will be high while thyrotoxic patients with thyroiditis or who abuse thyroid hormones will have a low RAIU.
DDx thyrotoxicosis
- Graves disease
- Thyroiditis
- Toxic nodule
- Toxic multi-nodular gland
