CORE - Nucs Flashcards
1
Q
Medications administered prior to Meckel’s scan
A
cimetidine/ranitidine, pentagastrin, glucagon
2
Q
MAG3 is preferred to DTPA in…
A
moderate or severe renal failure, immature kidneys (peds), transplant kidneys
3
Q
Syndromes associated with pheochromocytoma
A
NF1, VHL, MEN 2, Carney’s triad
4
Q
Whole body tracer distribution: liver > spleen, bones, salivary glands
A
Ga-67
5
Q
Whole body tracer distribution: liver = spleen, bones, no salivary glands
A
Tc-99m sulfur colloid
6
Q
Whole body tracer distribution: spleen > liver, bones
A
In-111 WBC or Tc-99m HMPAO WBC
7
Q
Whole body tracer distribution: salivary glands, cardiac, thyroid, parathyroid
A
Tc-99m sestamibi
8
Q
Whole body tracer distribution: liver > spleen, no bones, salivary glands
A
I-123/I-131 MIBG; NO renal uptake (important to see pheo and neuroblastoma)
9
Q
Whole body tracer distribution: spleen > liver, no bones, kidneys
A
In-111 pentetreotide (octreotide scan)
10
Q
Whole body tracer distribution: liver, spleen, kidneys, cardiac, bowel
A
thallium-201
11
Q
Whole body tracer distribution: gastric, salivary glands, thyroid
A
free pertechnetate or I-123/I-131
12
Q
Tracers with cardiac activity
A
sestamibi, tetrofosmin, MIBG (low), thallium-201, F-18 FDG
13
Q
Breast uptake on Ga-67 scan
A
mild uptake is normal in pregnant or lactating women
14
Q
Thyroid uptake on MIBG scan
A
forgot to give Lugol’s (aqueous iodine)
15
Q
Adrenal uptake on MIBG scan
A
normal adrenal uptake of MIBG is seen in some patients
16
Q
SNR and spatial resolution with higher energy radiotracers
A
lower SNR and spatial resolution with high energy tracers (relative to low energy tracers)
17
Q
Is I-123 or I-131 MIBG more likely to have cardiac activity?
A
I-123 MIBG
18
Q
Causes of free pertechnetate
A
insufficient stannous ions or air in vial/syringe
19
Q
Tc-99m HDP is used for which study?
A
bone scan
20
Q
Difference between NaF bone scan vs. FDG PET with marrow stimulation?
A
F-18 NaF bone scan will not have brain uptake
21
Q
Diffuse marrow uptake on FDG PET DDx
A
G-CSF, post-chemotherapy, EPO, myelodysplastic syndromes, thalassemia, CML, severe anemia, diffuse mets (less likely)
22
Q
Focal uptake in shoulder on bone scan
A
consider arthritis (also in hip or knee)
23
Q
Segmental focal rib uptake on bone scan
A
rib fractures
24
Q
Prominent skull sutures on bone scan
A
renal osteodystrophy
25
Focal breast uptake on bone scan
breast cancer; mild diffuse uptake is normal (especially in younger women)
26
Prominent renal cortical uptake on bone scan
hemochromatosis
27
Diffusely increased renal uptake on bone scan (greater than spine on posterior projection)
chemotherapy, ATN; urinary obstruction is not a cause (Core Review)
28
Liver uptake on bone scan
aluminum contamination, amyloidosis, mets (or primary HCC), liver necrosis, metastatic calcification
29
Splenic uptake on bone scan
auto-infarcted spleen in sickle cell (patchy hot and cold areas)
30
Lung uptake on bone scan
osteosarcoma mets, metastatic calcification, alveolar microlithiasis, Wegener's, berylliosis, sarcoidosis
31
How often is a solitary lesion on bone scan benign?
80% are benign
32
Solitary sternal focus of uptake on bone scan
breast cancer met
33
Increased sacral uptake on bone scan
insufficiency fracture (especially if H-shaped)
34
Diffusely decreased skeletal uptake on bone scan
free pertechnetate or bisphosphonate therapy
35
Benign vs. malignant vertebral body fractures (bone scan)
linear = benign; involvement of posterior elements = malignant
36
Flare phenomenon (bone scan)
good response mimics a bad one; increased size and number of lesions on bone scan <3 months after treatment
37
Signs of flare phenomenon
lesions becoming more sclerotic on plain film, lesions improve on bone scan >3 months after treatment
38
Cold mets on bone scan
RCC, thyroid, myeloma, +/- lymphoma
39
Spinal hemangioma on bone scan
cold
40
Active heterotopic ossificaton
hot on bone scan (mature is cold); increased risk of recurrence if resected
41
Long bone periosteal uptake on bone scan + NEXT STEP
hypertrophic osteoarthropathy; next step is CXR or chest CT
42
Paget's in spine on bone scan
involves both vertebral body and posterior elements (classically), may also expand vertebral body
43
Bone scan uptake for AVN
cold (early) => hot => cold (late)
44
3-phase hot on bone scan DDx
osteomyelitis, osteoid osteoma, reflex sympathetic dystrophy, fracture, septic arthritis, neuropathic joint, active Paget's
45
Increased mandible uptake on bone scan
fibrous dysplasia (young), Paget's (old)
46
Benign lesions hot on bone scan
fibrous dysplasia, GCT, ABC, osteoblastoma, osteoid osteoma
47
Benign lesions cold on bone scan
simple bone cyst (without fracture)
48
Causes of metabolic superscan
hyperparathyroidism, renal osteodystrophy, osteomalacia, myelofibrosis, Paget's; HOT skull on metabolic superscan
49
Equivocal lesion on bone scan - NEXT STEP
plain film (if that's also equivocal, get an MRI)
50
Periarticular uptake on delayed phase of bone scan
reflex sympathetic dystrophy
51
Septic arthritis on bone scan
3-phase hot on both sides of joint
52
Shin splints vs. stress fracture (bone scan)
shin splints hot on delayed phase only, while stress fracture is 3-phase hot
53
Indication for sulfur colloid + WBC study
evaluate for osteomyelitis near prosthesis or fracture (photopenic on sulfur colloid)
54
Why is sulfur colloid + WBC no good for spine?
In-111 WBC gives false positives in spine (use Ga-67 instead)
55
Diffuse peri-prosthetic uptake on bone scan DDx
normal for cemented arthroplasty <1 year and cementless arthroplasty <2 year; also may be infection or less likely loosening
56
Prosthetic loosening on bone scan (hip)
focal uptake along stem and lesser trochanter (infection would be diffuse); both are excluded by a negative bone scan
57
When to use Tc-99m HMPAO WBC?
peds (lower absorbed dose and shorter half-life), imaging hands/feet
58
Indications for V/Q scan
contrast allergy or low GFR with concern for PE
59
Probability of PE with a normal perfusion study
none; normal perfusion study excludes PE
60
Xe-133 vs. Tc-99m DTPA differences
Xe only has anterior and posterior projections and has wash-in, equilibrium, and wash out phases; Tc-99m DTPA allows for multiple projections, but has only a single phase, may also see clumping in airways
61
Brain or renal uptake on MAA scan
right-to-left shunt
62
Particle size for MAA
10-100 micrometers
63
Indications to half MAA dose
peds, right-to-left shunt, pulmonary HTN, pregnant; ~100,000 particles (normal is 200k to 500k)
64
Focal "hot spots" in lungs on MAA scan
blood was drawn back into the syringe => clumping
65
Persistent pulmonary activity on washout phase of Xe-133 study
COPD
66
Hepatic uptake on Xe-133 study
hepatic steatosis if diffuse, focal fat if focal
67
Lung shunt fraction study
performed with Tc-99m MAA; <10% is normal, 10-20% needs a decreased Y-90 dose, >20% is at risk for radiation pneumonitis
68
Entire single lung is photopenic on MAA scan + NEXT STEP
mass, fibrosing mediastinitis, or central PE; need to get CT or MRI of chest
69
Ga-67 uptake in lungs
sarcoidosis, PCP, IPF, lymphangitic carcinomatosis, military TB, fungal infection
70
Ga-67/Tl-201 uptake - Kaposi sarcoma
Ga-67 cold, Tl-201 hot
71
Radiotracer to use for suspected abdominal infection
In-111 WBC (no bowel uptake)
72
Meningioma is hot on...
Tc-99m MDP and In-111 pentetreotide
73
Malignant otitis externa findings
hot on Ga-67 and bone scan
74
Radiotracer that "traps but does not organify" (thyroid imaging)
Tc-99m pertechnetate (slowly washes out of thyroid); I-123/I-131 are organified
75
Radiotracers used for thyroid uptake quantification
I-123 or I-131 (NOT Tc-99m pertechnetate)
76
Hot caudate sign
Budd-Chiari; increase caudate uptake on sulfur colloid scan
77
High probability on V/Q scan
2+ large mismatched segmental defects (without assoc. radiographic abnormality); "large" = >75% of segment; may involve contiguous segments (confluent appearance)
78
Very low probability on V/Q scan (4)
solitary triple-matched defect in mid-to-upper lung, non-segmental lesion, stripe sign, 1-3 small segmental defects
79
Indications for Tc-99m pertechnetate for thyroid scan (over I-123/I-131)
recent thyroid blocker, recent iodinated contrast; Tc-99m pertechnetate slowly washes out of thyroid
80
Normal RAIU (radioactive iodine uptake) values
5-15% at 4 hours, 10-30% at 24 hours; only with I-123 or I-131; thigh used for background correction
81
Medications causing decreased RAIU (radioactive iodine uptake)
thyroid blockers (PTU/MZ), nitrates, amiodarone, iodinated contrast
82
Increased RAIU (radioactive iodine uptake) DDx
Graves, multinodular goiter, early Hashimoto's, dietary iodine deficiency, rebound (after cessation of PTU/MZ), lithium
83
Decreased RAIU (radioactive iodine uptake) DDx
late Hashimoto's, subacute thyroiditis, renal failure, iodine load (Wolff-Chaikoff effect), thyroid hormone replacement, ectopic thyroid hormone, PTU/MZ (does not block Tc-99m uptake)
84
Visualization of pyramidal lobe (thyroid scan)
Graves disease; also seen in 10% of normal patients
85
RAIU (radioactive iodine uptake) in Graves and multinodular goiter
>50% and >30%, respectively (Core Review; Prometheus says >70% and >40%)
86
Plummer disease
multinodular goiter or thyroid adenoma associated with hyperthyroidism
87
Panda sign DDx
Ga-67 scan; sarcoidosis, Sjogren's, treated lymphoma
88
Clinical hyperthyroidism with decreased RAIU (radioactive iodine uptake)
subacute thyroiditis (a.k.a. de Quervain's or granulomatous); viral etiology
89
Discordant nodule (thyroid scan)
lesion traps (Tc-99m hot), but does not organify (I-123/131 cold); suspicious => biopsy indicated
90
Thyroid cancer types which respond poorly to I-131 therapy
medullary, anaplastic, Hurthle cell
91
Diffuse Tc-99m pertechnetate uptake, but no I-123/131 uptake (thyroid)
congenital enzyme deficiency inhibiting organification or taking PTU (blocks organification)
92
Things that make patient I-131 treatment resistant
medullary, anaplastic, or Hurthle cell subtype, prior I-131 treatment (need 50% higher dose), prior MZ treatment
93
Ideal TSH prior to I-131 treatment
goal is 30-50 mU/L; stop levothyroxine or give recombinant TSH (thyrogen)
94
I-131 treatment dosing
100 mCi if cancer confined to thyroid, 150 mCi if nodal mets, 200 mCi if distant mets; 30 mCi for multinodular goiter or toxic adenoma, 15 mCi for Graves
95
I-131 treatment + lung mets
risk of pulmonary fibrosis
96
I-131 treatment + Sjogren's
salivary gland damage (higher dose => more damage)
97
I-131 scan with liver uptake
post-treatment scan (always)
98
Contraindications to I-131 treatment
severe thyrotoxicosis (use PTU/MZ to calm down first), pregnancy
99
Lab test to monitor for thyroid cancer recurrence
thyroglobulin; after thyroidectomy anything >0 is abnormal (but trend is most important)
100
Wolff-Chaikoff effect
ingestion of large amount iodine => decreased thyroid hormone; can be used to calm down hyperthyroidism
101
Most common cause of hyperparathyroidism
hyperfunctioning adenoma > hyperplasia
102
Dual-phase parathyroid scan technique
Tc-99m sestamibi; imaging at 10 minutes and 3 hours; depends on mitochondrial density and blood flow
103
Tc-99m sestamibi scan with lymph node uptake
suspicious for cancer; next step is ultrasound (or other imaging modality)
104
Tc-99m sestamibi scan with breast uptake
suspicious for breast cancer; next step is mammogram
105
Lipophilic CNS tracers
Tc-99m HMPAO, Tc-99m ECD; cross BBB, used to assess perfusion (parenchymal uptake)
106
CNS tracer with slow washout
Tc-99m ECD, while Tc-99m HMPAO has fast washout
107
CNS studies using DTPA tracer
cisternogram and CSF leak studies use In-111 DTPA; shunt and brain death studies use Tc-99m DTPA (shorter half-life)
108
Ictal vs. inter-ictal seizure focus radiotracer uptake
ictal is hot, inter-ictal is cold
109
Which tracer is used first in Tl-201 + Ga-67 comparison study?
Tl-201 should be used first (otherwise downscatter from Ga-67 peaks)
110
CNS Tl-201+Ga-67: lymphoma vs. infection (e.g. toxo, abscess, crypto, TB)
all will be hot on Ga-67 portion, but only lymphoma will be hot on Tl-201
111
CNS tumor necrosis vs. residual/recurrent disease
residual or recurrent disease is Tl-201 hot, while tumor necrosis will be Tl-201 cold; similar findings on PET
112
Normal variants in brain death
scalp activity, radiotracer in superior sagittal sinus
113
Use of Diamox in CNS imaging
a.k.a. acetazolamide; to identify ischemic areas that may benefit from revascularization
114
Effect of bright lights on PET imaging (CNS)
increased uptake in occipital lobes
115
Decreased uptake in caudate and putamen (CNS imaging)
Huntington's disease
116
Pathway involved in crossed cerebellar diaschisis
corticopontine-cerebellar pathway (connects cerebral hemisphere to contralateral cerebellar hemisphere)
117
NPH findings (CNS)
radiotracer in lateral ventricles at 24 hours ("heart-shaped"); NPH has a normal opening pressure on LP
118
Pledget-to-plasma activity ratio in CSF leak
1.5:1 or greater; pledget activity is quantified using a well counter
119
Distal CSF shunt obstruction findings
>10 minutes without flow of radiotracer into abdomen suggests at least partial distal obstruction
120
Indication for 4th phase of bone scan
patients with renal failure or poor soft tissue clearance (diabetics or vasculopaths) at 24 hours; normal delayed phase is at 3 hours
121
Uptake in thyroid, stomach, lungs, liver, and kidneys on bone scan
metastatic calcification (CKD, hyperparathyroidism, multiple myeloma, hypervitaminosis D)
122
Particle released during I-131 treatment (decay type)
beta particle (beta-minus decay)
123
Collimator used for thyroid imaging
pinhole
124
Three forms of subacute thyroiditis
granulomatous (painful, de Quervain's), lymphocytic (painless), postpartum
125
Patient post-ablation for papillary thyroid cancer with increasing thyroglobulin and negative I-123 scan - NEXT STEP
FDG PET; if there is recurrent cancer which has de-differentiated, it will be hot on PET (papillary is normal not active on PET)
126
Most common cause of false positive parathyroid scintigraphy
thyroid adenoma (hot thyroid nodule)
127
Difference between solid and liquid curves (gastric emptying)
solids have a lag phase
128
Normal gastric emptying thresholds
<90% remaining at 1 hour, <60% at 2 hours, <30% at 3 hours, <10% at 4 hours (most sensitive time point for gastroparesis)
129
Rapid emptying on gastric emptying study
rapid emptying <30% remaining at 1 hour (or <70% at 30 minutes according to Crack)
130
Medications to stop before gastric emptying study
stop 2 days prior; pro-motility agents (e.g. metoclopramide, erythromycin), opiates, CCBs, anticholinergics (e.g. bentyl)
131
Sensitivity of tagged-RBC scan vs. angiography
tagged RBC is 0.1-0.2 ml/min, angiography is 1.0 ml/min; sulfur colloid is even more sensitive than tagged RBC
132
RBC tagging: in vivo labeling
inject stannous ions => wait 30 min => inject Tc-99m pertechnetate; end up with lots of free pertechnetate and a dirty image
133
Causes of in vivo or modified RBC labeling failure
drug interactions (e.g. heparin), heparinized tubing, recent IV contrast administration
134
RBC tagging: modified approach
inject stannous ions => wait 30 min => draw 5 cc of blood => add Tc-99m pertechnetate => re-inject
135
RBC tagging: in vitro labeling
draw 5 cc of blood => add stannous ions and pertechnetate => re-inject
136
RBC tagging: best to worst methods
in vitro (best) > modified > in vivo (worst); based on labeling efficiency
137
Gastric activity on GI bleeding scan
gastric bleed or free pertechnetate (check thyroid and salivary glands)
138
HIDA scan for patient with hyperbilirubinemia
higher dose of radiotracer required
139
HIDA scan prep
fast for >4 hours, but eaten within 24 hours (give CCK if >24 hours or on TPN); phenobarbitol in neonates
140
Dose of phenobarbitol for HIDA scan (neonate)
5 mg/kg for 5 days (split into 2 doses per day)
141
No gallbladder activity on HIDA at 1 hour - NEXT STEP
wait an additional 3 hours, or give morphine and wait 30 minutes (must see bowel activity before giving morphine)
142
Rim sign (HIDA)
suggests acute cholecystitis, possibly gangrenous
143
Acute cholecystitis on HIDA scan
no gallbladder activity after 4 hours, or 1 hour + 30 minutes after giving morphine
144
Chronic cholecystitis on HIDA scan
gallbladder activity at >1 hour (either while waiting 3 more hours or after giving morphine), or EF <35% after CCK administration
145
Dose of sinaclide for HIDA scan
a.k.a. CCK; 0.02 ug/kg (slow infusion); if administered pre-exam, need to wait 2 hours before starting exam
146
Dose of morphine for HIDA scan
0.04 mg/kg (max of 4 mg)
147
Normal timing of liver and gallbladder activity on HIDA scan
5 minutes and 15 minutes, respectively
148
Most common finding in chronic cholecystitis on HIDA scan
normal HIDA scan
149
Causes of false positive HIDA scan
meal within <4 hours, fasting >24 hours, CCK immediately before exam, TPN, pancreatitis, chronic cholecystitis, severe illness
150
Causes of false negative HIDA scan
acalculous cholecystitis, duodenal diverticulum or biliary cyst simulating gallbladder
151
Poor hepatic extraction and non-visualization of biliary tree on HIDA scan (adult)
hepatocyte dysfunction or common duct obstruction (former will empty into bowel on 24 hour delayed phase, while latter will not)
152
Focal photopenic defect in liver on HIDA scan
cyst, mass (HCC, adenoma), abscess
153
Focal liver uptake on HIDA scan
FNH
154
Reappearing liver sign on HIDA scan
bile leak
155
Focal liver uptake on sulfur colloid scan
FNH, regenerative nodule (in cirrhosis), Budd-Chiari syndrome (caudate lobe)
156
Focal liver uptake on tagged RBC scan
hemangioma (on delayed phase, not flow or blood pool); angiosarcoma could be hot on blood pool and delayed phases
157
Focal liver uptake on Ga-67 scan
HCC, abscess
158
Particle size for sulfur colloid scan
0.1 to 1.0 micrometers (if too big spleen will eat them)
159
Increased splenic and marrow activity on sulfur colloid scan
colloid shift due to hepatic dysfunction (cirrhosis, diffuse mets), diabetes, or blunt splenic trauma
160
Diffuse pulmonary activity on sulfur colloid scan
aluminum contamination, cirrhosis, LCH, COPD with superimposed infection
161
Renal activity on sulfur colloid scan
CHF, rejection (for transplants)
162
Test(s) for ectopic splenic tissue (e.g. intrapancreatic, accessory)
heat-damaged RBC scan, sulfur colloid scan
163
Normal distrbution of Tc-99m HMPAO vs. ECD (brain)
HMPAO favors frontal lobes, thalami, and cerebellum; ECD favors parietal and occipital lobes; need to use same agent across examinations
164
Normal DaT scan in patient with a movement disorder
suggests essential tremor
165
Abnormal DaT scan
Parkinsonian syndrome; decreased uptake in posterior putamen which progresses anteriorly as disease progresses
166
Timing of FDG-PET post-chemotherapy to avoid false positive or negative
2-3 weeks after treatment; false positive from inflammatory changes, false negative from stunning
167
Timing of FDG-PET post-radiation to avoid false positive or negative
2-3 months affter treatment; false positive from inflammatory changes, false negative from stunning
168
Ventilation study with tracer in airway and/or stomach
Tc-99m DTPA clumping (aerosol)
169
Perfusion scan (MAA) with renal and/or thyroid uptake - NEXT STEP
planar images of brain (to differentiate free pertechnetate from right-to-left shunt)
170
Indications for anterior projection in renal scintigraphy
horseshoe kidney, transplant kidney
171
Timing of cortical and clearance phases (renal scintigraphy)
1-3 minutes and 3+ minutes, respectively
172
Decreased renal tracer uptake DDx
renal artery thrombosis, renal vein thrombosis, high grade obstruction, acute rejection, acute pyelonephritis, poor bolus (symmetric)
173
ATN vs. acute rejection (renal scintigraphy)
ATN shows normal perfusion + delayed excretion; acute rejection shows delayed perfusion + delayed excretion
174
20/3 or 20/peak ratio (renal scintigraphy)
to quantify tracer retention; compare counts at 20 minutes to counts at 3 minutes or peak count; <0.3 for normal MAG3 scan
175
Diuretic renogram technique
normal renogram => at 20 minutes inject 40 mg lasix; clearance half-time <10 minutes after lasix is normal, >20 minutes suggests obstruction
176
Causes of false positive diuretic renogram
poor response to lasix (renal failure), dehydration, reservoir effect, back pressure from neurogenic or full bladder
177
Radiotracer with a lower peak on captopril renogram
DTPA will demonstrate decreased uptake in affected kidney (compared to MAG3)
178
Findings in positive captopril renogram (DTPA and MAG3)
DTPA shows decreased uptake in affected kidney after captopril; MAG3 demonstrates marked tracer retention after captopril
179
When to stop ACE inhibitor prior to captopril renogram?
3-5 days prior; also need to be NPO for 6 hours, stop CCBs also
180
Causes of false positive captopril renogram
dehydration, CCBs, captopril-induced hypotension; consider false positive especially if bilateral (more common than bilateral RAS)
181
Immediate post-op complications of renal transplant
ATN vs. acute rejection (as far as scintigraphy)
182
Normal perfusion + delayed excretion in a long-standing renal transplant (renal scintigraphy)
cyclosporin toxicity (looks like ATN but not acute)
183
Urinoma vs. hematoma vs. lymphocele (renal transplant scintigraphy)
urinoma = <2 weeks, tracer between kidney and bladder; hematoma = <2 weeks, photopenic area; lymphocele = >4 weeks, photopenic area
184
Photopenic area on DMSA renal scintigraphy
acute = pyelonephritis; chronic = mass or scarring (scarring is associated with volume loss)
185
Halo of activity with central photopenia (testicular scintigraphy)
late/missed torsion or testicular abscess; acute torsion demonstrates total absence of activity; tracer is Tc-99m pertechnetate
186
Radionuclide cystography (RNC)
to evaluate for reflux; pertechnetate, DTPA, or sulfur colloid; grade 1 is ureter only, grade 2 is pelvicalyceal, grade 3 is tortuous ureter and/or pelvicalyceal dilatation
187
FDG uptake biology
enters cell via GLUT1 => phosphorylated by hexokinase to form FDG-6-phosphate
188
Cause(s) of artificially low SUVs (PET)
high blood glucose (competition)
189
PET with diffuse muscle uptake
recent insulin administration or recent meal; consider rhabdomyolysis (distribution dependent)
190
PET with increased colonic uptake
metformin; may see small bowel uptake as well
191
PET cold tumors
BAC, carcinoid, RCC, prostate, mucinous neoplasms, peritoneal implants
192
Focal thyroid uptake (PET)
suspicious for malignancy; needs further workup (ultrasound)
193
Diffuse thyroid uptake (PET)
most commonly Hashimoto's
194
RCC vs. oncocytoma (PET)
RCC is cold, oncocytoma is hot
195
Cold ground glass nodule (PET)
cancer
196
Hot ground glass nodule (PET)
infection
197
Seminoma vs. NSGCT (PET)
seminoma is hot, NSGCT is cold; true for retroperitoneal mets as well
198
PET hot ovaries in post-menopausal patient
suspicious for malignancy; needs ultrasound
199
Adrenal uptake on PET
mild is normal; if adrenal is hotter than liver => suspicious for malignancy
200
Thymic rebound vs. recurrent lymphoma
thymic rebound may be warm, lymphoma is HOT (super hot)
201
Solitary pulmonary nodule on PET
8 mm is smallest size that can be reliably evaluated; active granulomatosis disease may be a false positive
202
Perchlorate
a.k.a. Lugol's solution or SSKI
203
Skeletal uptake on MIBG scan
bone mets (especially neuroblastoma)
204
Medications to hold prior to MIBG
CCBs, labetalol, TCAs, reserpine, sympathomimetics; other beta-blockers are ok to continue
205
Studies that may show brown fat
PET, MIBG
206
Islet cell tumor subtype with poor In-111 pentetreotide uptake
insulinoma
207
When to stop octreotide medication prior to In-111 pentetreotide scan?
3 days prior to scan
208
Best study for a non-functioning islet cell tumor
PET
209
In-111 pentetreotide is most sensitive for what neoplasms?
carcinoid, paraganglioma (extra-adrenal pheo), islet cell tumors (not insulinoma), medullary thyroid cancer
210
Indication for ProstaScint
to evaluate for soft tissue prostate mets (rising PSA + negative bone scan)
211
Radiotracer for ProstaScint
In-111 capromab pendetide; critical organ is liver
212
Radiotracer for lymphoscintigraphy + particle size
Tc-99m sulfur colloid; 100-200 nm particles
213
Lymphoscintigraphy technique for breast cancer or melanoma
inject superfical or deep to lesion for breast cancer; intradermal injection at 4 sites around lesion for melanoma
214
Breast-specific gamma imaging technique
inject Tc-99m sestamibi in contralateral arm (or foot if imaging both breasts)
215
False positives in breast-specific gamma imaging
fibroadenoma, fibrocystic change, inflammation
216
Lymph node uptake on breast-specific gamma imaging
highly suspicious for spread of malignancy
217
Study that uses Tc-99m mebrofenin or disofenin
HIDA scan
218
Best radiotracer for determination of differential renal function
DMSA > MAG3
219
Study type to detect H. pylori
C-14 urea breath test
220
Cardiac nucs: photopenic area on stress that improves on rest
reversible defect (ischemic myocardium)
221
Cardiac nucs: photopenic area on stress and rest
fixed defect (hibernating myocardium or infarct/scar); need viability portion to differentiate
222
Cardiac nucs: perfusion agents
Tc-99m sestamibi/tetrofosmin, rubidium-82, Tl-201, nitrogen-13 ammonia
223
Cardiac nucs: stress agents
adenosine, dipyridamole, regadenoson, dobutamine
224
Cardiac nucs: normal myocardial perfusion with abnormal wall motion
stunned myocardium (acute phenomenon)
225
Cardiac nucs: fixed defect with abnormal wall motion
hibermating myocardium (chronic ischemic process) or infarct/scar
226
Cardiac nucs: LV cavity larger on stress images
transient ischemic dilation (left main or 3-vessel disease)
227
Cardiac nucs: fixed LV dilation on stress and rest
dilated cardiomyopathy
228
Cardiac nucs: RV activity on rest
RV hypertrophy
229
Cardiac nucs: defect on rest that improves with pharmacologic stress
vasospasm (improves with administration of vasodilators)
230
Cardiac nucs: purpose of viability portion
to identify areas of viable myocardium that may benefit from revascularization (hibernating myocardium)
231
Cardiac nucs: fixed perfusion defect that takes up FDG
mismatch; indicates viable myocardium (hibernating); will take up FDG and redistribute Tl-201
232
Vasomotor nephropathy (renal scintigraphy)
a.k.a. ATN or delayed graft function or ischemic nephropathy (all are synonyms)
233
Cardiac nucs: fixed perfusion defect that does not take up FDG
matched defect; indicates non-viable myocardium (infarct/scar)
234
Cardiac nucs: viability agents
FDG PET, Tl-201
235
Cardiac nucs: elevated lung-heart ratio (thallium)
>0.45 correlates with multivessel or high-grade LAD/LCx disease; occurs on stress images
236
Cardiac nucs: % coronary stenosis for perfusion defect
50% stenosis during stress, 90% stenosis at rest
237
Cardiac nucs: medications to discontinue prior to exam
CCBs, beta-blockers, and long-acting nitrates should be stopped 24 hours before; NPO for 4 hours; no caffeine
238
Cardiac nucs: bronchospasm
dipyridamole > regadenoson (adenosine has a super short half-life); Tx albuterol
239
Cardiac nucs: known LBBB
need pharmocologic stress test (not exercise); don't use dobutamine (more false positives)
240
Cardiac nucs: reversible perfusion defect in anterior septal region
suspicious for LBBB (false positive); occurs more often with dobutamine or exercise stress
241
Cardiac nucs: fixed defect with surrounding reversible defect
infarct with peri-infarct ischemia
242
Cardiac nucs: too much liver or bowel activity
patient is not exercising hard enough
243
What is a MUGA scan?
tagged RBCs used to estimate cardiac EF; MUlti-Gated Acquistion
244
Photopenic halo around cardiac blood pool (MUGA)
pericardial effusion
245
Cause(s) of falsely low EF on MUGA
incorrect LAO view resulting in overlapping structures (e.g. LA, RV)
246
Cause(s) of falsely high EF on MUGA
incorrect background ROI (may be drawn over spleen)
247
MUGA EF equation
EF = (end-diastolic counts - end-systolic counts) / (end-diastolic counts - background counts)
248
Cardiac nucs: fixed anterior or anteroseptal wall defect
consider breast attenuation artifact (check ECG and wall motion)
249
Cardiac nucs: fixed inferior wall defect
consider diaphragmatic attenuation artifact (check ECG and wall motion)
250
Cardiac nucs: apical thinning
normal variant
251
Cardiac nucs: indications for dobutamine stress
patients with asthma or COPD, or who had caffeine within 12 hours prior
252
Cardiac nucs: antidote for dipyridamole
aminophylline (shorter half-life than dipyridamole => must continue to monitor)
253
Cardiac nucs: contraindications to adenosine/dipyridamole stress
severe COPD, asthma, 2nd/3rd degree heart block, recent caffeine or aminophylline
254
Cardiac nucs: contraindications to regadenoson stress
history of seizures is a relative contraindication (lowers seizure threshold)
255
Cardiac nucs: D-shaped LV
RV hypertrophy (causing septal flattening)
256
Cardiac nucs: normal perfusion with decreased EF
consider non-ischemic cardiomyopathy
257
Approved agents for treatment of bone pain from breast/prostate mets
Ra-223 (xofigo) > Sm-153 (quadramet) > Sr-89 (metastron); best to worst
258
Contraindications to Sr-89 and Sm-153 treatment
pregnant, breastfeeding, GFR <30
259
Decay type of bone pain agents
alpha decay = Ra-223; beta-negative decay = Sm-153, Sr-89
260
Side effect of Sr-89 and Sm-153
bone marrow suppression; Sm-153 has less than Sr-89 => 6-8 weeks vs. 8-12 weeks for full recovery
261
Y-90 particle size
20-40 micrometers; Y-90 is a pure beta emitter
262
Y-90 imageable energy peaks
175 keV, 185 keV
263
Radioimmune therapy (RIT)
for treatment of NHL; In-111 ibritumomab tiuxetan (Zevalin) given to evaluate tumor burden, then give Y-90 labeled antibody if biodistribution is ok; antibody binds to CD-20 receptors
264
Altered biodistributions for RIT (reasons not to treat)
lung > heart (day 1), lung > liver (day 2-3), kidneys > liver (day 3), fixed bowel uptake, bowel > liver, or bone marrow uptake >25%
265
Most common side effect of RIT
thrombocytopenia, neutropenia
266
Diffuse soft tissue uptake on bone scan + no kidneys visualized
renal failure
267
Ga-67 hot + Tl-201 cold DDx
TB, atypical mycobacteria, PCP, toxoplasmosis
268
Ga-67 cold + Tl-201 hot DDx
Kaposi sarcoma
269
Salivagram technique
Tc-99m sulfur colloid administered PO to evaluate for aspiration
270
Interventions to reduce brown fat uptake
increase ambient temperature, administer beta-blocker or benzodiazepine
271
Most common cold nodule (thyroid)
benign colloid cyst
272
Indication to stop doxorubicin due to cardiotoxicity (MUGA findings)
relative drop in LVEF of >10% from previous plus an absolute LVEF of <50% is an indication to stop treatment
273
Mickey mouse sign (bone scan)
Paget disease
274
Cardiac uptake on bone scan
infarction, myocarditis, pericarditis, amyloidosis
275
Adequate percent of maximum HR for exercise stress
85%; max HR = 220-age
