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Nuclear Medicine > NM > Flashcards

NM Flashcards

1
Q

When should phenobarbital be given to a neonate when evaluating for biliary atresia?

A

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.

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2
Q

What is considered a normal gastric emptying study?

A

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

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3
Q

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

A) Tc-99m MAG3

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4
Q

Which radiopharmaceutical is used to assess glomerular function?

A

Tc-99m DTPA approximates glomerular function

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5
Q

Which radiopharmaceutical is used for assessment of renal scarring?

A

Tc-99m DMSA can be used to assess renal cortical integrity (used to assess for scarring or pyelonephritis)

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6
Q

Which pharmaceutical intervention is used for evaluating for chronic cholecystitis?

A

Sincalide, a synthetic octapeptide of cholecystokinin.

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7
Q

What is the physical half life of Tc-99m?

A

6 hours

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8
Q

What is the physical half life of I-131 sodium iodide?

A

8 days

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9
Q 
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
A

B. Gallbladder

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10
Q 
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
A

D. Lewy Body

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11
Q

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.

A

B. They are states that agree to regulate radioactive by product material within their borders on behalf of the NRC.

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12
Q

What is the mechanism of uptake for Tc-99m tetrofosmin?

A

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.

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13
Q

What organs are seen if there is free pertechnetate?

A
  • choroid plexus
  • thyroid gland
  • salivary glands
  • gastric mucosa (stomach/meckel’s)
  • renal/bladder
  • mucous membranes
  • sweat glands
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14
Q

What is a distinguishing feature of a gallium scan?

A

Lacrimal gland activity is a distinctive feature of Ga-67 biodistribution.

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15
Q

What is the risk of malignancy in a cold nodule on a thyroid scan?

A

15-20% risk of malignancy

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16
Q

What is the energy of the photons emitted from Tc-99m?

A

140 keV

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17
Q

What is normal range for radioiodine uptake?

A

10 to 30% of ingested activity is normal.

Some textbooks say

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18
Q

DDx superscan bone scan (characterized by diffuse uptake and non-visualization of the kidneys)

A
  • Metastatic disease (axial > appendicular): Prosate, breast, lung
  • Metabolic disease: Renal osteodystrophy, hyperparathyroidism, osteomalacia, myelofibrosis, mastocytosis
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19
Q

What is flare phenomenon?

A

Two criteria:

  1. Increased intensity and/or number of lesions
  2. Subsequent decrease uptake on repeat

Favourable response to tx. Pt asymptomatic and lesions become more sclerotic. 2 weeks to 3 months following therapy.

20
Q

What is the target HR for cardiac perfusion?

A

85% of max HR is the target (220-age x 0.85)

21
Q

What is stunned myocardium?

A

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

22
Q

What are findings in hibernating myocardium?

A
  • 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.
23
Q

What is normal radioactive iodine uptake for a thyroid scan (RAIU)?

A
  • 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.
24
Q

DDx thyrotoxicosis

A
  1. Graves disease
  2. Thyroiditis
  3. Toxic nodule
  4. Toxic multi-nodular gland
25
Q

Once a medical event has been discovered, how many days are allowed to notify the Nuclear Regulatory Commission (NRC) in writing?

A

15 days

26
Q

What is abnormal T1/2 for renal scintigraphy?

A

T(1/2) > 20 min is abnormal

27
Q

DDx of decreased activity in femoral capital epiphysis on bone scan in a child

A
  • Avascular phase of AVN (Legg-Calve-Perthes)
  • Septic arthritis
  • Transient synovitis
  • Post-traumatic hemarthrosis
28
Q

False positive HIDA scan DDx

A
  • Alcoholism
  • TPN/prolonged fasting
  • Severe intercurrent illness
  • Eating within 2 hours of study
  • Gallbladder cancer
  • chronic cholecystitis
  • liver failure
29
Q

False negative HIDA scan DDx

A
  • Intermittently obstructive or passed stone
  • Misinterpretation of images: rim sign interpreted as GB; duodenal activity interpreted as GB
  • Uncommon to have false negative studies
30
Q

Preferred modality for GI bleeding scintigraphy?

A

Tc-99m sodium pertechnetate labeled RBC’s

31
Q

DDx causes of Rapid gastric emptying

A
  • Post surgical: pyloroplasty; hemigastrectomy
  • Gastrinoma
  • Hyperthyroidism
  • Malabsorption syndrome; pancreatic insufficiency
32
Q

DDx causes of Delayed gastric emptying

A
  • Anatomic obstruction (peptic ulcer, surgery, cancer, hypertrophic pyloric stenosis)
  • Metabolic (diabetic acidosis, hypothyroidism)
  • Neurologic (diabetic gastroparesis, autonomic neuropathy)
  • Systemic dz (scleroderma, anorexia nervosa)
  • Drug induced (anticholinergics, opiates)
  • Iatrogenic (vagotomy)
33
Q

Normal values for gastric emptying?

A

4-hours: >90% clearance

34
Q

How many segments in the cardiac polar map?

A

17

35
Q

What is an abnormal TID (transient ischemic dilation)?

A

TID > 1.20 is abnormal

36
Q

Tracer for brain death scan?

What signs to look for?

A

Tc-99m HMPAO or ECD

  • “empty light bulb” sign
  • “hot nose” sign- hyperemia of the nasal mucosa
37
Q

Brain scan findings of Alzheimer’s?

A

Decreased activity in the temporal and parietal lobes

38
Q

Findings of biliary atresia? Tracer?

A
  • Tc-99m IDA; hx neonate with persistent jaundice
  • No GB or bowel activity seen on early or delayed images
  • Pt given phenobarbital for several days before study to stimulate liver activity.
  • Biliary atresia can be ruled out by this study but cannot be ruled in.
  • no activity in the biliary system or bowel at 24 hrs could still represent atresia or hepatitis
39
Q

DDx cold nodule on thyroid scan

A

“CATCH PALM”

  • *Carcinoma (15-20%)
  • *Adenoma (non-functioning)
  • Thyroiditis (focal)
  • *Colloid cyst
  • Hemorrhage
  • Parathyroid adenoma
  • Abscess
  • Lymphoma, Lymph node)
  • Metastasis
40
Q

Tracer used for evaluation of normal pressure hydrocephalus?

Findings of NPH?

A
  • In-111 DTPA used
    1) Persistent tracer in the lateral ventricles
    2) Delayed flow over the convexities at 24 hrs
41
Q

Normal GB ejection fraction?

A

CCK can help rule out acalculous chole. A normal GB EF (>35%) excludes this dx.

42
Q

How can shin splints be differentiated from stress fractures?

A
  • Stress fractures, like completed fractures, tend to be hot on all 3 phases of a bone scan. Shin splints are hot only on delayed phase.
  • Shin splints tend to be linear and often bilateral
  • Stress fracture tend to be more focal and asymmetric.
43
Q

For renal scintigraphy (Tc-99m MAG3) following diuretic, what are the expect half-times for clearance?

A

Half-time renal pelvic washout of tracer:

-20 min = obstructed

44
Q

On V/Q scan, what is the significance of a “triple match” in the upper lung vs. the lower lung?

A

By PIOPED:

  • a single moderate or large triple match in the lower third of the lung is intermediate probability;
  • in the upper two-thirds, it is very low probability.
45
Q

Minimum number of MAA particles needed for a V/Q scan?

A

-at least 60,000

“A minimum of 70,000 particles is necessary to obtain a diagnostic quality scan in an adult.” -AuntMinnie.com

46
Q

What are high-risk imaging features at myocardial perfusion imaging?

A
  • resting LVEF 1.15
  • Large reversible perfusion defect
  • Multiple reversible perfusion defects of moderate size
  • Large fixed perfusion defect with LV dilation or with increased lung uptake (if imaged with Th-201)
  • Duke treadmill risk score
47
Q

DDx HOA appearance

A 
Primary bronchogenic carcinoma
Solitary fibrous tumor of the pleura
CF
Cyanotic heart disease
IBD
Fluorosis
Pachydermoperiostosis
Thyroid acropachy
Venous insufficiency
Hypervitaminosis D

Nuclear Medicine (1 decks)

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