Nukes CORE - Sheet1 Flashcards
Tc-99m: energy and half life
“low”, 140, 6h
I-123: energy and half life
“low”, 159, 13h
Xe-133: energy and half life
“low”, 81, 125h (biologic t 1/2 30sec)
Thallium-201: energy and half life
“low”, 135 + 167, 73h
Indium-111: energy and half life
“medium”, 173 + 247, 67h
Gallium-67: energy and half life
multiple, 93 + 184 + 300 + 393, 78h
I-131: energy and half life
“high”, 365, 8d
Fluorine-18: energy and half life
“high”, 511, 110min
Strontium 89 t 1/2
50.5 days (14 in bone)
Samarium 153 t 1/2
46h
Yttrium 90 t 1/2
64h
Tc-99 DTPA vs. Xe-133
DTPA - multiple projections + tends to clump in airways
Tc-99 WBC vs. In-111 WBC
Tc Renal + GI, In-111 No renal or GI
Tc-99 WBC 4 vs. 24 hrs
4 hrs - lung uptake, 24 hrs - lungs clear, start to get bowel
Tc MDP vs F-18 bone scan (organ with higher dose)
Tc MDP - Bone, F-18 - bladder
3 agents for bone met therapy
Sr-89, Sm-153, Ra-223
6 cancers that are PET-negative
BAC, carcinoid, RCC, Peritoneal/bowel implants, anything mucinous, prostate
6 things that are not cancer but PET-hot
infection, inflammation, ovaries in follicular phase, muscles, brown fat, thymus
Alzheimer PET findings
low posterior temporoparietal cortical activity
Dementia with Lewy Bodies PET findings
low in lateral occipital cortex
cingulate island sign
preservation of the mid posterior cingulate gyrus in dementia with lewy bodies
Picks/frontotemporal PET findings
low frontal lobe
Huntingtons PET findings
low activity in caudate nucleus and putamen
Uptake: Graves vs. multi-nodular goiter
Graves: uptake high (70s), Multi-nodular goiter: uptake medium (40s)
hot clumps of signal in the lungs on liver spleen SC scan
too much Al in Tc
HOT spleen
WBC or octreotide (SC is warm spleen)
bone scan with hot skull sutures
renal osteodystrophy
bone scan with focal breast uptake
breast CA
bone scan with renal cortex activity
hemochromatosis
bone scan with diffusely decreased bone uptake
- free Tc or 2. bisphosphonate therapy
tramline along periosteum of long bones
lung CA
super hot mandible in adult
fibrous dysplasia
super hot mandible in kid
caffey’s
periarticular uptake of delayed scan
RSD
focal uptake along the lesser trochanter
prosthesis loosening
tracer in the brain on a VQ scan
shunt
tracer over the liver on ventilation with xenon
fatty liver
gallium negative, thallium positive
Kaposi
high T3, high T4, low TSH, low thyroid uptake
quervains/granulomatous thyroiditis
persistent tracer in the lateral ventricles > 24hrs
NPH
renal uptake on sulfur colloid
CHF
renal transplant uptake on sulfur colloid
rejection
filtered renal agent
DTPA (or GH whatever that is)
secreted renal agent
MAG-3
PET with increased muscle uptake
insulin
diffuse FDG uptake in thryoid on PET
hashimoto
I see the skeleton on MIBG
diffuse neuroblastoma bone mets
cardiac tissue taking up FDG more intense than normal myocardium
hibernating myocardium
made with generator
Tc-99 and Rubidium
max dose of geiger mueller counter
100 mR/h
Tc-99 major spill
> 100 mCi
Tl-201 major spill
> 100 mCi
In-111 major spill
> 10 mCi
Ga-67 major spill
> 10 mCi
I-131 major spill
> 1 mCi
annual dose limit to the public
100 mrem
hourly dose limit to the public
2 mrem/hr
body dose limit for workers yearly
5 rem
ocular dose limit for workers yearly
15 rem
extremity dose limit for workers yearly
50 rem
embryo/fetus dose limit for workers yearly
0.5 rem
allowable amount of Mo per 1 mCi of Tc
0.15 mCi of Mo per 1 mCi of Tc (at time of administration)
how do we check chemical purity?
pH paper (Al in Tc)
how do we check radiochemical purity?
thin layer chromatography (free Tc)
allowable amount of Al
<10 micrograms
what causes free Tc
lack of stannous ions or accidental air injection (which oxidizes)
prostate cancer bone mets are uncommon below what PSA?
10 mg/ml
flair phenomenon timing
2 weeks - 3 months after therapy
skeletal survey: lytic vs. blastic
better for lytic
AVN: early, middle, late findings
early + late: COLD, middle (repairing): HOT
particle size for VQ scan
10-100 um
what is done first in a VQ scan
Xenon
classic thyroid uptake blocker
amiodarone
hasimotos increases risk for what malignancy
lymphoma
major side effect of methimazole
neutropenia
what drug treatment (even years prior) makes I-131 treatment more difficult?
methimazole
thyroid blocker of choice in pregnancy
PTU
how long to wait after chemo or radiation to do a PET?
2-3 weeks for chemo and 8-12 weeks for radiation
In-111 pentetreotide
somatostatin receptor imaging - carcinoid tumors
random benign tumor that takes up ocretotide
mengiomas
prior to MIBG, you need to give the patient…
lugols iodine or perchlorate
what EKG finding causes false positive septal defect
LBBB
pulmonary uptake of thallium indicates what heart abnormality
LV dysfunction
MIBG analog
norepinephrine (actively transported)
MDP analog
phosphate (chemisorption)
sulfur colloid mechanism
particles are phagocytized by RES
how to pick out octreotide scan?
no bones + liver + DARK SPLEEN + dark kidneys
what’s hot with free Tc
salivary gland, thyroid, stomach
bone scan with diffuse renal uptake
chemotherapy or urinary obstruction
bone scan with liver uptake (4 things)
too much Al in Tc, cancer (hepatoma or mets), amyloidosis, liver necrosis
bone scan with splenic uptake
auto-infarcted spleen 2/2 sickle
honda sign
sacral insufficiency fracture
when to do a bone scan in old people
1 week post injury
what is flair phenomenon?
good response to tx mimicking bad response (increased uptake)
solitary sternal lesion on bone scan
breast CA
MIBG detects what cancer
neuroblastoma
“tramline”
hypertrophic osteoarthropathy (chronic hypoxia + lung cancer)
classic Pagets presentations
super hot enlarged femur, super hot enlarged pelvis, super hot skull, expanded hot “entire” vertebral body, metabolic superscan
double density sign
osteoid osteoma
most common metabolic superscan
hyper PTH (hot skull)
bone uptake is always abnormal on these 3
MIBI, I-131, or ocretotide
preferred for osteomyeltitis in the spine
gallium
downside to Tc99 HMPAO WBC
GI + gb activity
3 reasons to reduce particle amount in Tc99 MAA
- fewer capillaries (kids, one lung) 2. right to left shunt 3. pulmonary HTN
multiple focal hot spots on Tc99 MAA
tech draws blood into syringe prior to injection
persistent pulmonary activity during washout
COPD
most common cause of unilateral whole lung perfusion defect with normal ventilation
lung CA
positive PE study
normal ventilation + multiple areas of abnormal perfusion
CXR within ? hours of VQ
24 hours
gallium analog
Fe +3 (gets bound via lactoferrin to area of inflammation and rapid cell turnover)
target organ for gallium
colon
lambda sign
Ga-67, Sarcoid (uptake in bilateral hila and right paratracheal node)
panda sign
prominent uptake in the nasopharynx, parotids, and lacrimal glands - Sjogren’s + treated lymphoma
hot lungs in PCP
Ga-67
organification
I-123 and I-131, oxidized by thyroid peroxidase and bound to tyrosyl moiety
trapping
transported into thryoid gland (I-123, !-131, and Tc-99)
Tc-99m and breast-feeding
resume in 12-24 hours
I-123 and breast feeding
resume in 2-3 days
I-131 and breast feeding
NEVER
diffuse homogenous uptake on thyroid scan
Graves
most common cause of goitrous hypothyroid
hashimoto
most common thyroid cancer subtype
papillary (papillary is popular)
does medullary thyroid CA light up on I-131?
NO + doesn’t respond to I-131 treatment
what scans are + with medullary thryoid CA?
MIBG + octreotide (~10%), cold on I-131
ideal TSH for I-131 treatment
50 (>30 at least)
how do you decide on I-131 dosing (for cancer)?
100 for thyroid only, 150 for thyroid + nodes, 200 for distal
when do I-131 patients need to be admitted to hospital?
33 mCi of residual activity or 5-7 mR/h
side effect of I-131 if lung mets
pulmonary fibrosis
main route of elimination for I-131
urine (also sweat, tears, saliva, breast milk)
when can I get pregnant after I-131?
6-12 months
absolute contraindications to I-131 (2)
severe uncontrolled thyrotoxicosis and pregnancy
when to give I-131 to HD patients?
immediate following dialysis (tubing stays in storage)
how do you decide on I-131 dosing (for hyperthyroid)?
15 mCi for Graves, 30 mCi for multinodular
Wolff-Chaikoff Effect
reduction in thyroid hormone levels caused by ingestion of large amount of iodine
sestamibi likes things with
lots of blood flow and mitochondria
Tracers with brain binding
Tc HMPAO and Tc ECD
blood flow tracer
Tc DTPA
seizures: hot vs. cold
HOT: during seizure, COLD: interictal
Thallium analog
potassium (Na/K pump) gotta be alive to work
Crossed Cerebellar Diaschisis
Depressed blood flow and metabolism affecting the cerebellar hemisphere after a contralateral supratentorial insult
what is “tinning”
mixing RBCs with Tin (stannous) to reduce hemoglobin before tagging with Tc99
timing of NPH diagnosis
at 48 hours there should be no activity in the lateral ventricles and there should be activity over the entire convexities
how much activity is allowed in stomach at 4 hrs?
at 4 hours 10% or less of initial activity should remain in the stomach
drug you give to help differentiate biliary atresia vs. neonatal hepatitis
phenobarbital
what results in falsely elevated LVEF?
high background
what do you do if you see lung activity following a treatment dose of I-131?
Non-contrast CT of chest
hyperthyroid patient with low 24-hour uptake and diminished uptake in the thyroid scan
hashimoto
what do you treat Hashimoto with?
NSAIDs
what the heck is a salivagram for?
determine aspiration of pharyngeal contents (don’t confuse with salivary gland scintigraphy)
most common cause of hyperparathyroidism?
- hyperfunctional adenoma (85%) 2. multiple gland hyperplasia (12%) 3. cancer (3%)
4 false positives in sestamibi
- thyroid nodules 2. h&n cancers 3. lymphadenopathy 4. brown fat
“hot nose sign”
2/2 perfusion through external carotid to maxillary branches (2/2 sign of brain death)
what drug can you give to evaluate for TIAs?
acetazolamide (diamox) = vasodilator + perfusion tracer –> expect 3-4 x increase, but TIAs will be hypointense
most common tracer for CSF imaging?
In-111-DTPA given intrathecal by LP
abnormal CSF imaging (2)
- tracer in the lateral ventricles 2. failure to clear from cisterns and localize over convexities by 24 hours
how to tell between NPH vs. non-obstructive hydrocephalus?
NPH will have normal opening pressure on LP
how long is “delayed” to diagnose partial distal obstruction in CSF shunt?
> 10 min to see flow into peritoneum
how long do you fast before a GI emptying study
4 hrs
more sensitive for emptying study: solids vs. liquids
solids are more sensitive
curves in emptying studying: solids vs. liquids
solids have a “lag phase” to get ground up, liquids don’t
2 things that can cause failure of in vivo RBC tagging
heparinized tubing or recent IV contrast
tracer used for Meckel scan
pertechnetate (taken up by gastric mucosal cells)
do a Meckel scan when patient is actively bleeding or not?
NOT - otherwise do a bleeding scan
3 drugs that can enhance a Meckel scan
- Pentagastrin 2. H2 blockers 3. glucagon
false positive Meckel scan can be from
bowel irritation (recent scope, laxative use)
false negative meckel scan
- recent in vivo RBC labeling 2. recent barium study (attenuation)
if the patient has hyperbilirubinemia, do you need higher or lower dose for HIDA scan?
higher doses of tracer
how long to fast for HIDA?
4 hours, but have eaten something in 24 hours (so your gb isn’t totally full)
if you haven’t eaten in over 24 hours (gb is super full!), what drug can you give for a HIDA scan?
CCK
“hot rim sign”
hyperemia in gb fossa - suggests a more angry gallbladder
“cystic duct sign”
nub of activity in cystic duct, rest is obstructed = acute cholecystitis
2 ways of showing chronic cholecystitis
- delayed filling of gb (not at 1 hr, but at 4) 2. low EF (<30%) with CCK
dose of CCK
0.02 ug/kg over 60 min (micrograms!)
dose of morphine in HIDA
0.02-0.04 mg/kg over 30-60 min (milligrams!)
HIDA: No Bowel Activity , Persistent Blood Pool
Hepatocyte Dysfunction (Hepatitis)
HIDA: No Bowel Activity, Blood Pool Goes Away Normally
common duct obstruction
HIDA: No Gallbladder Activity x 4 hours (or 1 hour + morphine)
Acute Cholecystitis
HIDA: Abnormal GB emptying (EF < 30%)
Chronic Cholecystitis
2 drugs that can cause prompt HIDA tracer uptake and delayed clearance
dilantin (chlorpromazine) + birth control pills - mimics biliary obstruction
what drug do you give babies in biliary atresia vs. hepatitis?
phenobarbital
“reappearing liver sign”
BILE LEAK - liver starts to empty into bowel, then liver gets dark again b/c of leak
what liver lesion is HOT on sulfur colloid?
FNH (actually only 40% hot)
“colloid shift”
normally 85% of SC is taken up by liver, in cirrhosis this shifts to spleen and bone marrow (also in diffuse liver mets, diabetes, blunt splenic trauma)
sulfur colloid + diffuse pulmonary activity
NOT normal - 1. excess Al in colloid 2. diffuse lung disease
sulfur colloid + renal activity
- CHF 2. renal tx rejection
what’s a hemangioma scan
Tc-RBCs - want marked HOT on delays, with no hot on immediate flow/pool
critical organ: DTPA
bladder
critical organ: Mag3
bladder
renal tracer best for poor renal function
MAG-3
what 3 abnormalities will all be NORMAL on perfusion/flow
ATN, interstitial nephritis, cyclosporin toxicity
phases for basic renal scan
flow (20 sec), cortical/parenchymal (1 min), clearance/excretory (half peak by 7-10 min)
20/3 or 20/peak ratio (renal scan)
peak count at 20 min/peak count at 3 min (normal < 0.8) or /peak count (normal 0.3)
when to give lasix in suspected obstruction?
wait 30 min after clearance
“dilated but not obstructed” (renal)
washout of 50% of tracer within 10-20 min of lasix
“reservoir effect” (renal)
very dilated renal pelvis, delays transit time
“back pressure effects” (renal)
full or neurogenic bladder generates back pressure, not allowing kidneys to empty
2 reasons for poor response to lasix (besides obstruction)
- bad renal function 2. dehydration
appearance of RAS on DTPA
decreased uptake and flow (loss of perfusion pressure)
appearance of RAS on MAG-3
marked tracer retention (secreted tracer)
when to stop ace-inhibitor before RAS scan
3-5 days if its captopril, NPO for 6 hrs (for PO ACE inhibitors)
when does ATN occur s/p tx?
immediate post-op (3-4 days)
when does cylosporin toxicity occur s/p tx?
long standing
perfusion in ATN vs. cyclosporin tox vs. acute rejection
ATN + cyclosporin tox will have normal perfusion - acute rejection will have POOR perfusion
excretion in ATN vs. cyclosporin tox vs. acute rejection
delayed in all 3
fluid collection s/p renal tx: timing
urinoma/hematoma - first 2 weeks, lymphocele - 4-8 weeks delay
fluid collection s/p renal tx: appearance
urinoma - tracer between bladder and tx kidney, hematoma + lymphocele - photopenia
critical organ: DMSA
kidney
why is DMSA preferred for cortical imaging in peds?
lower dose to gonads (compared with glucoheptonate, whatever that is)
DMSA study: 3 appearances of acute pyelo
- focal area of decreased uptake 2. MF areas of decreased uptake 3. diffuse decreased uptake
DMSA study: column of bertin vs. mass
mass is COLD, bertin takes up tracer, cause it’s normal
DMSA study: acute vs. chronic
acute defect = pyelo, chronic defect = scar/mass
FDG enters cells via what transporter
GLUT-1
FDG is phosphorylated by what enzyme
hexokinase to FDG-6Phosphate
2 ways to decrease brown fat uptake
- warm room 2. benzodiazepines or beta blocker
6 classic PET COLD tumors
- BAC 2. carcinoid 3. RCC 4. peritoneal bowel/liver implants 5. anything mucinous 6. prostate
what is the effect of high glucose (>150-200) on SUV?
artificially lowers SUV (increase competition for FDG)
what is the effect of insulin on PET?
diffuse muscle uptake
what is the effect of being a fat person on SUV?
HIGHER SUV b/c fat takes up less glucose
if you see the RV on PET?
think about RVH
PET: diffuse thyroid uptake
autoimmune/hashimoto thyroiditis
PET: RCC vs. oncocytoma
RCC is COLD, oncocytoma is HOT
why is HCC often cold on PET?
variable glucose-6-phosphatase and can’t trap the FDG
random fact: meningiomas are hot on
octreotide and Tc-MDP
most common agent for somatostatin receptor imaging
In-111 pentetreotide
4 tumors showing I-131 MIBG uptake
- paraganglioma 2. pheochromocytoma 3. carcinoid 4. medullary thyroid
I-123 vs. I-131 basics
I-123 better imaging quality, I-131 cheaper + longer half life allows for delayed imaging
meds that need to be held for MIBG
Ca-channel blockers, labetalol specifically, reserpine, TCAs, sympathomimetics
MIBG vs. MBP bone scan for neuroblastoma mets?
MIBG is superior
Prostascint = In-111 + ?
antibody capromab to PSA + pendetide chelating agent
when do you use prostascint?
rising PSA and negative bone scan (localized to soft tissue mets, not bone mets)
agent used for sentinel node detection
10-50nm Tc99m sulfur colloid.
what lesion depth do we use sentinel node detection for in melanoma
1-4mm deep - intradermal injection in 4 spots around the lesion
what % of time does breast cancer go to internal mammary chain nodes?
3%
particle size for lymphoscintigraphy
< 0.2 microns (<200 nm)
particle size for liver/spleen
“unfiltered”
how is the agent administered in BSGI?
20-30 mCi of Tc99 Sestamibi in the contralateral arm then image 20 mins later.
what if you want to image both breasts in BSGI?
give sestamibi in the foot instead of contralateral arm
when is background mibi-activity lowest?
mid-cycle in premenopausal women
3 false positives in BSGI
- fibroadenoma 2. fibrocystic change 3. inflammation (how is the test useful??)
2 false negatives in BSGI
- small <1 cm lesions 2. located in medial breast and/or overlapping the heart activity
what if you see lymph nodes on a BSGI scan?
NOT normal - concerning for mets
cardiac imaging: sestamibi vs. tetrofosmin
Tetrofosmin is cleared from the liver more rapidly and decreases the chance or a hepatic uptake artifact.
how to sestamibi and tetrofosmin enter the cells?
passive diffusion (localized in mitochondria)
redistribution: cardaic imaging agents
thallium - redistributes; sestamibi + tetrofosmin - does NOT redistribute (better flexibility)
timing of imaging: cardiac imaging agents
thallium - immediately after injection; sestamibi + tetrofosmin - 30-90 min after injection to allow for background to clear
thallium: lung/heart ratio
If there is more uptake in the lungs, this correlates with multi-vessel disease or high grade LAD or LCX lesions.
what % stenosis do you need to see a defect with stress imaging?
50%
what % stenosis do you need to see a defect with rest imaging?
90%
meds that interfere with cardiac imaging
beta-blockers, Ca-channel blockers, long-acting nitrates (stop for 24 hours)
how long NPO for cardiac imaging
4 hours (decreased GI blood flow)
dose: rest vs. stress
low for rest, high for stress
cardiac imaging: fixed defect
scar (prior infarct)
cardiac imaging: reversible defect
ischemia
cardiac imaging: fixed defect with surrounding reversible defect
infarct with peri-infarct ischemia
cardiac imaging: transient ischemic dilation (LV bigger on stress)
apparent cavity dilation from diffuse subendocardial hypoperfusion (high risk dz - left main or 3 vessel)
cardiac imaging: fixed cavity dilation
dilated cardiomyopathy
cardiac imaging: Right Ventricular Activity on Rest
RVH
cardiac imaging: Lots of splanchnic (liver and bowel) activity
not exercising hard enough! more stress needed!
cardiac imaging: stunned myocardium
This is the result of ischemia and reperfusion injury. Normal perfusion, but contractility will be crap.
cardiac imaging: hibernating myocardium
Won’t take up tracer on rest or stress (it’s not dead, just asleep - like a bad soap opera plot). The difference between hibernating muscle and scar is that the hibernating muscle will take up FDG and redistribute thallium.
what agent is used for MUGA
Tc 99 RBCs
photopenic halo around cardiac blood pool on MUGA
pericardial effusion
regional wall motion abnormality on MUGA
usually infarct (less likely stunned or hibernating)
how to get false low EF on MUGA
Screwed up LAO view can cause overlap of LV with LA or RV or even great vessels
how to get false high EF on MUGA
Wrong background ROI (over the spleen), will cause over-subtraction of background and elevate the EF.
only PET agent made in a generator
Rb-82 (half life 75 seconds!)
cardiac artifacts: breast tissue
anterior wall decreased attenuation, may need to repeat in prone position
cardiac artifacts: left hemidiaphragm
decreased activity in inferior wall
cardiac artifacts: subdiaphragmatic radiotracer activity
increased activity in inferior wall, can mask true defect - exercise to reduce GI blood flow
cardiac artifacts: patient motion/breathing
repeat b/c tracer is fixed for 2 hours
cardiac artifacts: LBBB
reversible or fixed septal defects - seen more in exercise or dobutamine stress vs. vasodilators
cardiac artifacts: normal apical thinning
normal variant, fixed “defect” with preserved wall motion
mechanism: dipyridamole
inhibits breakdown of adenosine (potent vasodilator) - basically an indirect way of giving adenosine
mechanism: adenosine
vasodilator (worse side effects than dipyramidole, incld AV block)
mechanism: regadenoson
selective A2A - causes less side effects
mechanism: dobutamine
B-1 agonist - acts like exercise by increasing HR and contraction
mechanism: aminophylline
antidote for adenosine
patients who should get dobutamine
those who can’t have adenosine/dipyramidole - COPD or ashtma or have taken caffeine in 12 hrs
3 agents that treat bone pain
(I) Sr89-Chloride, (2) Sm153 EDTMP, and (3) Ra223-dichloride.
(I) Sr89-Chloride vs (2) Sm153 EDTMP for bone pain
Sr-89 is oldest and worst, pure beta emitter - Sm153 (“samarium is a good samaritan”) is a beta decayer
major bad side effects of (I) Sr89-Chloride vs (2) Sm153 EDTMP for bone pain
myelosuppression - Sr89 takes longer to recover than Sm153
why is Ra-223 the “best” agent for bone pain
- alpha emitter - less heme tox 2. one trial showed a survival benefit in prostate ca 3. long t1/2 (11.4 days), allows for easy shipping
Y-90 mechanism
pure beta emitter - penetration of 10mm (sparing most normal liver)
ideally the lung shunt fraction for Y-90 treatment is
<10% (need decreased dose for 10-20% and can’t do if >20%) - measured with 99mTc MAA
optimal particle size for Y-90
20-40 um
Y-90 emissions for imaging
175 + 185 keV
In-111 ibritumomab (zevalin) for non-Hodgkin lymphoma binds to what receptors
CD-20 receptors on B-cells
contraindication to In-111 ibritumomab (zevalin)
patients with platelets less than 100K
common side effects In-111 ibritumomab (zevalin)
Thrombocytopenia and neutropenia (about 90% of cases).
liver or spleen: hotter on SC liver/spleen scan
liver > spleen (except in severe liver dysfunction)
liver or spleen: hotter on In111 WBC
spleen > liver
bone scan w/hot lungs + kidneys + stomach
hyperparathyroidsim - metastatic calcification
timing of SC scan
very rapid uptake - 20-30 min scan
