nuclearmedicineflash Flashcards Preview

Radiology > nuclearmedicineflash > Flashcards

Flashcards in nuclearmedicineflash Deck (132):
1

Gallium-67 dose? Gamma energies? Half-life? Time to imaging?

5 mCi (inflam). 10 mCi (tumor). 93, 184, 296, 388 keV. 78 hrs. 6, 24 (inflam). 48-72 (tumor).

2

Gallium-67 mechanism of uptake?

Fe analog via transferrin.

3

Gallium-67 Normal distribution?

Liver > spleen, marrow, bone. Variable: breast, bowel, salivary glands, lacrimal glands.

4

I-131 dose? Gamma energies? Half-life? Time to imaging?

2 mCi. 364 keV. half-life 8 days. 48 hrs.

5

I-131 mechanism of uptake?

Iodine. Thyroid uptake,TSH-mediated

6

I-131 Normal distribution?

Stomach, GI, bladder. Variable: salivary, nasopharynx,

7

I-131 MIBG dose? Gamma energies? Half-life? Time to imaging?

2 mCi. 364 keV. 8 days. 48 hrs.

8

I-131 MIBG mechanism of uptake?

Guanethidine analog. Norepinephrine reuptake.

9

I-131 MIBG normal distribution?

Liver > spleen. Variable: salivary, lung, GI, bladder, skeletal muscle, heart.

10

I-123 MIBG dose? Gamma energies? Half-life? Time to imaging?

1-10 mCi. 159 keV. 13 hrs. 24 hrs.

11

I-123 MIBG normal distribution?

Liver > spleen. Variable: salivary, lung, GI, bladder, skeletal muscle, heart.

12

In-111 octreoscan dose? Gamma energies? Half-life? Time to imaging?

6 mCi. 172, 247 keV. 67 hrs. 4, 24 hrs.

13

Octreoscan mechanism of uptake?

Somatostatin analog. Neuroendocrine tumors.

14

In-111 octreoscan normal distribution?

Intense renal cortex. Spleen, liver, pituitary, salivary, GI, bladder. Variable: breast, thyroid.

15

FDG-PET dose? Gamma energies? Half-life? Time to imaging?

10-15 mCi. 511 keV. 2 hrs. 1 hr.

16

FDG-PET mechanism of uptake?

Glucose analog. Active transport into cell. Phosphorylated and trapped.

17

FDG-Pet normal distribution

Intense urinary activity and cerebral cortex. GU, liver, spleen, marrow. Variable: thyroid, cardiac, GI, muscle.

18

In-111 WBC dose? Gamma energies? Half-life? Time to imaging?

0.5 mCi. 172, 247 keV. 67 hrs. 24 hrs.

19

In-111 WBC mechanism of uptake?

WBC localized at infection.

20

In-111 WBC normal distribution?

Spleen >> Liver > marrow. No renal or GI activity.

21

Tc-99 WBC dose? Gamma energies? Half-life? Time to imaging?

20 mCi. 140 keV. 6 hrs. 1-4, 24 hrs.

22

Intense cardiac activity radiotracer?

MIBG. PET.

23

Intense spleen activity radiotracer?

WBC.

24

Intense renal activity radiotracer?

Octreotide.

25

Lacrimal activity?

Gallium-67.

26

For about __ months after hip replacement surgery, the bone around the prosthesis is expected to have increased osteoblastic activity.

6 months.

27

Refers to a hot spot at the tip of a prosthesis and two areas of increased uptake at the proximal end.

Toggle sign. Prosthetic loosening.

28

Three phases of bone scan osteomyelitis?

First phase: Early arterial flow, seconds after injection. Second phase: Blood pool, few minutes after injection.Third phase: Bone labeling, 3 or more hours after injection. All three positive in infection.

29

Contraindications to perfusion lung scanning include

Severe pulmonary hypertension. Allergy to human serum albumin products.

30

Common indication for V/Q scans

Suspected PE. Preoperative estimates of lung function. To evaluate right-to-left shunts. Serial assessment of inflammatory lung disease.

31

When should a V/Q scan be ordered over CTA?

Low clinical probability. Normal CXR is normal. Pregnant patient. Contraindication to iodinated contrast.

32

Normal ventilation scans

Homogeneous radiopharmaceutical distribution throughout both lungs on all three phases: Initial breath. Equilibrium. Washout.

33

Retention (trapping) of xenon in the lungs in a focal or diffuse pattern is an indication of

Obstructive lung disease.

34

Normal perfusion scans

Well-defined margins of both lungs on all views. Sharply defined costophrenic angles.

35

Hampton hump

Wedge-shaped, pleural-based infarct on CXR.

36

Westermark sign

Wedge-shaped area of oligemia.

37

Most common but nonspecific CXR finding of PE

Atelectasis or opacities in the region of emboli. Elevated diaphragm, small pleural effusion, and/or prominent hilum are also frequently seen.

38

Two moderate (25-50%) or four small (

Full-segment defect.

39

Perfusion defect that demonstrates normal ventilation is termed a

Mismatched defect.

40

Perfusion defects that match ventilation and CXR abnormalities in size and location are called

Triple match defects.

41

Stripe sign.

Central perfusion defects with a rim or stripe of increased activity around them. Less than 10% probability of PE.

42

V/Q scan PIOPED categories?

High (2 or more mismatched perfusion segments). Intermediate. Low. Very low. Normal.

43

Ventilation scan signs in COPD?

Delayed wash-in and delayed washout.

44

Perfusion defects that are significantly larger than the CXR abnormality are

Higher probability for PE.

45

Three principle coronary artery distributions of the LV

Left anterior descending artery (LAD). Left circumflex artery (LCX). Posterior descending artery (PDA).

46

Pharmocologic stress agents in myocardial perfusion imaging?

Adenosine. Dipyridamole (if bronchospasm may give dobutamine).

47

At what percent stenosis can pharmocologic agents not dilate effectively?

> 50% stenosis.

48

Tc-99m Sestamibi is taken up by perfused myocardium by

Passive diffusion. Bound in myocyte, mostly within myocardial mitochondria.

49

Hibernating Myocardium

Severe ischemia with high-grade stenosis may be slow to reverse on Tl-201 rest imaging after stress. Respond to revascularization procedures. Perfusion-metabolism mismatch.

50

Stunned Myocardium

Temporarily damaged cells around infarct. Generally is hypokinetic or akinetic. Will not uptake Tl-201 until recovery several weeks later. Normal perfusion.

51

Solitary palpable thyroid nodules are best evaluated initially

FNA.

52

Discordant thyroid nodule

Increased Tc-99m-O4 uptake but decreased I-123 uptake (lost ability to organify iodine). Increased risk of malignancy.

53

Measurement of the RAIU is usually indicated for one of three reasons:

Differentiation of Graves disease (uptake high, usually >35% at 24 hours) from subacute or factitious hyperthyroidism (uptake usually

54

Lingual thyroid pediatric patients are at high risk of developing

Hypothyroidism, with an estimated risk of ~30%.

55

Hyperthyroidism causes?

Graves disease (diffuse toxic goiter) is most common. Subacute or painless thyroiditis. Toxic nodular goiter. Factitious hyperthyroidism.

56

Substernal goiter imaging?

I-123. Due to large blood pool, Tc-99m-O4 is not useful with substernal goiters.

57

Multinodular goiter

Clinical term for adenomatous hyperplasia. Multiple, discrete hot nodules on a background of normal or cool parenchyma. Photopenic regions should be palpated.

58

All types of thyroiditis are characterized by

Rapid, asymmetric glandular enlargement with or without nodularity. Subacute viral patients have a very low RAIU.

59

Graves disease

Most common cause of hyperthyroidism. Autoimmune disorder, thyroid-stimulating antibodies cause hyperplasia and hyperfunction of thyroid gland.

60

Acute (suppurative) thyroiditis

Bacterial infections caused by Streptococcus, Staphylococcus, or Pneumococcus. Fever, severe sore throat, and asymmetric swelling. May result in sepsis from hematogenous spread or extend into mediastinum via fascial planes.

61

Subacute (viral) thyroiditis (de Quervain or granulomatous thyroiditis).

Thyroid pain and hyperthyroidism following upper respiratory infection. Disrupted gland releases thyroid hormone. Iodine uptake is usually decreased or absent in acute stages.

62

Hashimoto thyroiditis

Most common cause of goiter and primary hypothyroidism in adults in developed countries. Autoimmune disorder with circulating antithyroid antibody.

63

Riedel thyroiditis

Rare inflammatory fibrosiS that involves thyroid and commonly extends into neck. Radionuclide uptake is absent (cold) in involved areas.

64

Secondary hyperthyroidism may develop in patients with

Hydatidiform moles or choriocarcinoma (secrete HCG). Subunit of HCG is similar to TSH, which may directly stimulating thyroid.

65

Single cold nodules have a _______ incidence of malignancy, whereas malignancy is exceedingly rare in hot nodules.

10% to 15%.

66

Thyroid nodule differential

Follicular adenoma. Adenomatous hyperplasia. Thyroid cysts. Hemorrhagic cyst.

67

Most common benign neoplasm of the thyroid and represents about 20% of thyroid nodules.

Follicular adenoma.

68

Adenomatous nodules, also called ________, are not true neoplasms but are the result of cycles of hyperplasia and involution of a thyroid lobule.

Colloid nodules.

69

Signs Suggesting Benign Etiology of Thyroid Nodules

Extensive cystic component. Multiple nodules. Hot on radionuclide scan. Peripheral calcification. Shrinkage in size following levothyroxine suppression hormone therapy. Sudden onset. Female gender. Older patient.

70

Signs Suggesting Malignancy of Thyroid Nodules

Solid nodule. Cold on radionuclide scan.ÿIrregular contour.ÿPoor margination.ÿSize >4 to 5 cm.

71

Thyroid malignancies

Papillary carcinoma. Follicular carcinoma. Medullary thyroid carcinoma. Anaplastic carcinoma.

72

This thyroid malignancy does not take up I-131?

Medullary thyroid carcinoma.

73

Most authorities agree with postthyroidectomy ablation in primary thyroid tumors that are > _____ cm?

> 1.5 cm.

74

The patient should be hypothyroid with a serum TSH greater than_______ prior to whole body I-131 imaging or ablation,

40 IU/Ml.

75

Radioiodine therapy side effects?

Sialoadenitis. Xerostomia. Pulmonary fibrosis. Leukemia.

76

Ectopic locations for abnormal parathyroid tissue include:

Thymus (10% to 15%). Posterior mediastinum (5%). Retroesophageal (1%). Within carotid sheath (1%). Parapharyngeal (0.5%).

77

Sestamibi and Tetrofosmin Imaging of parathyroid adenoma?

Immediate and delayed images of neck and mediastinum. May be cold on initial imaging. Hot on delayed (1-2 hours) imaging. Normal thyroid gland washes out.

78

Which parathyroid glands are more commonly ectopic?

Inferior parathyroid glands (from third branchial pouch along with thymus). Usually within mediastinum.

79

Positive GI bleeding studies demonstrate three cardinal findings:

Focal activity appears out of nowhere. Activity persists and may increase with time. Activity moves with peristalsis antegrade, retrograde, or in both directions.

80

Meckel Scan

Tc-99mO4. Activity concentrates within right lower quadrant or mid abdomen in synchrony with stomach (ectopic gastric mucosa).

81

Liver/Spleen Scan

Tc-99m-radiolabeled albumin or sulfur colloid. RES cells phagocytize colloid particles.

82

FNH sulfur colloid scan features

Isointense or hotter than liver parenchyma.

83

Heat-Damaged Red Blood Cell Scan

Tc-99m-labeled heat damaged red blood cells are preferentially extracted from circulation by splenic tissue. Useful for: Polysplenia. Splenosis. Accessory splenic tissue.

84

Normal HIDA scan (Tc-mebrofenin)

Activity should be seen in major extrahepatic ducts, gallbladder, and small bowel within 1 hour.

85

Hallmark of acute cholecystitis by cholescintigraphy is

Nonvisualization of gallbladder at both 1- and 4-hour intervals or 30 minutes after morphine administration.

86

Chronic cholecystitis scintigraphy features

Gallbladder is not visualized at 1 hour but is seen by 4 hours.

87

Rim sign on hepatobiliary scan images

Band of increased activity around gallbladder fossa. Represents poor excretion of radiotracer from inflamed hepatocytes. Usually associated with gangrenous cholecystitis

88

Normal gallbladder ejection fraction is greater than

35%.

89

Acalculous biliary disease

Chronic acalculous cholecystitis. Cystic duct syndrome. Gallbladder dyskinesis.

90

CCK-assisted cholescintigraphy in acalculous biliary disease demonstrates

Decreased gallbladder contraction. Decreased gallbladder ejection fraction.

91

Which scintigraphy study is used in diagnosing liver cavernous hemangiomas?

Tc-99m-labeled red blood cells using an in vitro labeling technique.

92

________ is the agent of choice for imaging kidneys in moderate to severe renal failure.

Tc-99m-MAG3.

93

Agent of choice for renal cortical imaging?

Tc-99m-DMSA has minimal urinary excretion (

94

Radiotracers used to assess GFR and ERPF (plasma flow)?

GFR with Tc-99m-DTPA. ERPF with Tc-99m-MAG3.

95

Renal vein thrombosis scintigraphic findings?

Decreased perfusion of enlarged kidney with prolonged cortical retention of tracer.

96

Renal transplant complication timeline?

ATN 1st week. Urinomas early. Acute rejection 2nd-4th week. Lymphoceles several weeks. Chronic rejection later.

97

ACEi effect on RAS?

Angiotensin II causes constriction of efferent arteriole. ACEi blocks Angiotensin II. In RAS ACEi causes relaxation of constricted efferent arteriole, decreasing GFR.

98

Ga-67 imaging is the radionuclide procedure of choice in what patient population?

Immunocompromised patients. Patients with FUO.

99

_________ is the radionuclide procedure of choice for diagnosing osteomyelitis.

Three-phase bone scintigraphy.

100

Three-phase bone scan findings in osteomyelitis?

Focal hyperperfusion. Focal hyperemia. Focally increased bony uptake on delayed (2 to 4 hours postinjection).

101

Can all produce a positive three-phase bone scan, even in the absence of infection.

Fractures. Orthopedic hardware. Neuropathic joint.

102

Pores of Kohn

Connect adjacent alveoli.

103

Canals of Lambert

Connect alveoli with respiratory, terminal, and preterminal bronchioles.

104

Typical V/Q scan finding for PE

Mismatched segmental or subsegmental distribution pattern, usually peripheral and wedge shaped in nature.

105

Xenon-133 properties

Half-life of 5.3 days. Beta emitter. Photon energy 81 keV. Trachea is critical organ. Should be performed before perfusion lung scans due to Compton scatter from Tc-99m.

106

Patients who should receive fewer particles of Tc-99m-MAA?

Pulmonary hypertension. Right to left shunts. Children.

107

Standard cisternogram features

Intrathecal indium-111-DTPA. Ascends to basilar cisterns in about 4 hours. Flows over convexities within 24 hours in normals.

108

NPH cisternogram features

Early localization of activity within lateral ventricles persisting beyond 24 hours. Delayed clearance over convexities.

109

Procedure of choice for CSF leak

Cisternogram.

110

Classic findings in PET brain imaging of Alzheimer's disease

Bilateral temporoparietal defects.

111

PET brain imaging basics of brain tumors

High-grade tumors are hypermetabolic. Low-grade tumors are hypometabolic (except juvenile pilocystic astrocytoma).

112

FDG activity in gallbladder bed suggests

Acute or chronic cholecystitis. Gallbladder cancer. Adjacent liver tumor.

113

Common brown fat location?

Symmetric uptake in paraspinal regions, mediastinum, neck, and supraclavicular area.

114

Most malignant tumors have an SUV of

2.5 to 3.0.

115

Physiologic activity usually has an SUV of

0.5 to 2.5.

116

PET is utilized in oncology for three major indications:

Initial staging. Evaluation of response to treatment. Assessment for recurrence.

117

Malignant pulmonary nodule at PET imaging

SUV greater than 2.5 is considered indicative of malignancy. SUV under 1.5 is considered a benign nodule.

118

With small nodules less than _______cm, the partial volume averaging effect may falsely lower the SUV below 2.5, even though the nodule is malignant.

less than 1.5 cm

119

PET false-positives for malignant pulmonary nodule

Tuberculosis, Fungal infections. Sarcoidosis.

120

Pulmonary nodule false-negative cases are usually hypometabolic malignancies, such as

Bronchoalveolar carcinoma. Carcinoid tumor.

121

Radiation pneumonitis is metabolically active in the first ___ months following radiotherapy, making detection of tumor recurrence by PET difficult

6 months

122

PET false positives for lymphoma search

Hypermetabolic sarcoidosis. Tuberculosis. Pyogenic abscesses. Histoplasmosis and other fungal infections. Discitis.

123

Diffuse splenic activity greater than that of _______ is consistent with diffuse lymphomatous infiltration of the spleen.

Liver activity.

124

Preferred diagnostic modality for melanoma region lymph node involvement

Sentinel lymph node mapping.

125

Benign causes of distal esophagus PET activity

Distal esophagitis. Gastric reflux. Barrett's esophagus. Hiatal hernia. Retained saliva.

126

Tumor activity more than ____ times that of white matter or more than ____ times that of gray matter has very high sensitivity and specificity for malignancy

1.5 times white matter. 0.6 times gray matter.

127

PET features of Alzheimer disease

Bilateral hypometabolism of temporal and parietal lobes. Sparing of visual and motor cortices.

128

PET featurs of Pick disease

Hypometabolic areas involving both frontal and anterior temporal lobes.

129

PET features of Multi-infarct dementia

Multiple defects throughout brain parenchyma without sparing of visual and motor cortices.

130

PET features of Parkinson disease

High FDG activity in lentiform nuclei and thalami related to lack of dopaminergic inhibition. Caudate nuclei are spared.

131

PET features of CNS lymphoma versus toxoplasmosis

CNS lymphoma is hypermetabolic. Toxoplasmosis shows little or no FDG activity.

132

Low PET Uptake by Malignant Tumors

Lobular breast carcinoma. Low-grade lymphoma. Salivary gland neoplasms. Necrotic primary tumors and lymph nodes.