nuclear Flashcards
Cardiac uptake on a scan - not PET
MIBG, sestamibi, thallium
MIBG vs. Octreotide
MIBG and octreotide can both localize to neuroendocrine tumors (pheochromocytoma, paraganglioma, **neuroblastoma, and carcinoid). In almost all cases, MIBG is the way to go. The exceptions are **carcinoids and extraadrenal pheochromocytomas, gastrinoma (according to Gainesville)
what nuclear scan to look for PCP pneumonia
Gallium 67
What is thyrogen and when is it used in nuc med?
a highly purified recombinant form of human thyroid stimulating hormone (TSH), given by injection prior to I-131 study as an alternative to going off thyroid hormone
normal distribution of octreoscan?
Liver, spleen, kidneys, thyroid, GB, bladder, Normal pituitary gland
What is MIBG structurally similar to?
Norepinephrine - thus scanning for Pheos, **neuroblastoma, and paragangliomas
half life of Tc-99m
6 hours
In-111 half life
2.8 (3) days
In-111 WBC scan normal distribution
liver, spleen, bone marrow (NO urinary or GI tract activity!)
I-123 half life
13h
Iodine scan normal distribution
thyroid gland (target organ) nasopharynx salivary glands stomach (target organ) colon bladder (target organ) lactating breasts
I-131 half life
8 days
What’s the prep before I-131 scanning?
D/c thyroid hormone or us thyrogen
octreoscan - what radiopharmaceutical?
In-111
Octreoscan - what’s it used for?
Neuroendocrine tumors: carcinoid tumour, paraganglioma(s), glomus jugulare/tympanicum/vagale,
carotid body tumour, pheochromocytoma, small cell lung cancer, pituitary adenoma, neuroblastoma, medullary thyroid carcinoma, islet cell tumour of pancreas
octreotide is an analogue of what?
somatostatin (thus useful for neuroendocrine tumors)
MIBG - what radiopharmaceutical?
I-123
MIBG - used for what?
*phaeochromocytoma.
*neuroblastoma
esthesioneuroblastoma
carcinoid tumour
paraganglioma
phaeochromocytoma
medullary thyroid carcinoma
ganglioneuroma
ganglioneuroblastoma
MIBG normal distribution
liver spleen heart(!) salivary glands urinary bladder gastrointestinal tract (faint) lungs brown fat
FDG - half life
109 minutes
Gallium-67 - half life
78 hours (think 67, 78)
Ga-67 normal distribution
lacrimal glands!
liver (site of highest uptake)
bone marrow
spleen
GI tract
salivary glands
nasopharynx
kidneys and bladder in the first 24 hours (only!)- faint uptake can still be normal for up to 72 hours
breast uptake (especially in pregnant and lactating women)
mild diffuse lung uptake at 24 hours or less
What’s a superscan in a bone scan? What are causes?
intense symmetric activity in the bones with diminished renal and soft tissue activity
diffuse metastatic disease (prostatic, breast cancer, TCC, lymphoma
metabolic bone diseases (renal osteodystrophy, hyperparathyroidism -often secondary hyperparathyroidism-, osteomalacia (will involve distal skeleton smoother uptake)
myelofibrosis / myelosclerosis
mastocytosis
widespread Paget’s disease
sestamibi - normal distribution
thyroid, parathyroid, heart
sestamibi radiopharmaceutical
Tc 99m
sestamibi - used for?
parathyroid adenoma detection cardiac imaging (MIBI)
sulpher colloid - what radiopharmaceutical?
Tc 99m
sulpher colloid normal distribution
spleen, Kupffer cells in the liver and a small proportion by bone marrow
Tc-99m pertechnetate - used for?
Meckel’s scan (also thyroid in pediatrics, parathyroid, testicle)
what’s a bone scan’s pharmaceutical?
Tc 99m MDP
What is lung perfusion imaging done with?
Tc 99m MAA
Tc brain scan radiopharmaceutical?
HMPAO
pertechnetate normal distribution
stomach, thyroid, salivary glands, (testicles)
Renal imaging agents:
What’s each for?
MAG3 - good for poor renal function pts (tubular excretion)
DTPA - generally used, need good renal fctn (glomerular filtration)
DMSA - cortical imaging (kids mostly)
What instructions to I-131
drive home alone/sit in rear seat if ride separate bedroom & bathroom flush twice don't share phone store trash/laundry flush tissues
What’s the allowed dose to the Public
5 mSv/year
Lung uptake on bone scan - what is it? Caused by?
Metastatic calcification or pulmonary microlithiasis
met calc: caused by same things as medullary calcinosis: hyperparathyroidism, renal tubular acidosis, milk-alkali, hyper vit. D, sarcoid, diffuse tumors (esp. myeloma)
Ddx for elevated I-123 uptake in thyroid
IF TSH is low (supressed): Graves
Ddx for low I-123 uptake in thyroid
IF TSH is low (supressed): Subacute or postpartum thyroiditis, exogenous (factitious),
WT@#$??: brain and heart, sharp images
FDG PET
WT@#$??: brain and heart, not so sharp
whole body HMPAO
WT@#$??: heart, no brain:
thallium, sestaMIBI, I-123 MIBG
WT@#$??: bone marrow, gut, lacrimal glands (no heart or brain)
Gallium
WT@#$??: liver, spleen, kidneys (no heart or brain)
octreotide
WT@#$??: spleen, liver, bone marrow (no heart or brain)
WBC
WT@#$??: shitty images, no heart or brain
I-131
What’s the full name of a Tc labelled WBC scan?
Tc-99m HMPAO WBC
How do you diagnose infected prosthesis in nucs?
Start with a bone scan - if normal, high negative predictive value
Do sulfur colloid
Do WBC scan - if WBCs go where there’s no marrow, it’s an infection
Dx for normal bone scan with known lytic lesions: in adult? in child?
Older: myeloma/plasmacytoma, RCC
Young: LCH
Abdominal tumor in a child visible (uptake) on bone scan
Neuroblastoma - look for mets
95% take up MDP
75% calcify
How long does radioactive material need to be stored before discarding?
10 half lives (I-131 would be 3 months)
then survey to ensure it’s not above background
What’s the generic (acronym) response to a radioactive spill?
SWIM: Secure the area Warn others Identify the spill/agent Maintain the area (until help arrives)
Heart and liver uptake on bone scan
amyloidosis (also kidneys, but hard to tell since already hot on bone scan)
Radioactive spill categories - discuss
Major spill: >100 mCu or potential for airborne (any I-131), large area, uncontrollable, or catastrophic malfunction of radiation producing equipment
Minor spill: small quantity, not meet criteria for major, recognized and should not result in personnel contamination
What causes “ring artifact” in SPECT?
Center of rotation error
Non-uniform gamma camera
Steps to receive a radioactive package:
Survey, check for damage, wipe test
must be done w/in 3 hours during working hours, w/in 18 hours non-working
features of Lewy body dementia:
occipital abnormality (not seen in Alzheimer’s), visual hallucinations
2nd most common dementia
some think related to Parkinson’s
Absent perfusion to one lung on VQ
If vent is also abnormal: Swyer James, mass, mucus plug
If vent is normal: pulmonary mass, PA agenesis, PE, and fibrosing mediastinitis
unilateral focal spine uptake, young pt
pars fracture, ask for Hx, do SPECT
why would you see heterogeneous liver uptake on bone scan?
liver mets - acute cellular death or calcification in mucinous mets
How often do you have to do wipe tests on the patient waiting area?
Weekly. at least 5 spots per room.
Daily, you survey with the survey meter.
Causes of soft-tissue uptake on bone scan:
Calcification: metastatic calc (hyper Ca2+), calciphylaxis, NSF (nephrogenic systemic fibrosis), actively calcifying tumors (mucinous GI/ovary)
Acute/subacute cellular death: tumors under treatment, infarcts (cerebral, myocardial), polymyositis/dermatomyositis, thermal injury
Ossification: osteosarc mets, myositis ossificans
concerned for spine infxn/discovert osteo: what nuclear study? What could you add to this?
Gallium. If it’s discordant with MDP bone scan, very powerful sign of osteomyelitis
Pt with met prostate ca - what are the odds that FDG will be positive?
30-40% (so it’s not zero!)
what tumors take up gallium?
the -omas:
Lymphoma, melanoma, hepatoma (HCC), sarcoma and primary bone, lung ca
distal limb pain - decreased uptake on bone scan - what could it be?
Reflex Sympathetic Dystrophy, chronic
aka Chronic Regional Pain Syndrome
Diffuse muscle uptake on FDG-PET
hyperglycemia, given insulin
reduces sensitivity of the exam
Pt has been given multiple doses of I-131 for metastatic thyroid ca. What dose do you start worrying about lung fibrosis?
600 mCi cumulative
CSF leak study - agent?
In-111 DTPA injected into CSF
FDG in brain used to differentiate what?
recurrent tumor (hot) from radiation necrosis (cold)
What are the legal criteria for brain death?
There are none - dx by doctors, hospital may have criteria
Agents used in a “Brain death” scan
ECD, HMPAO, (DTPA would be flow only - not for static images)
Sagittal sinus is visualized on a “brain death” scan - is this brain death?
No
Study shows blood being pumped through heart - what is it? Who gets one? What do you want to find out?
MUGA scan (Multi Gated Acquisition Scan)
usually using Tc-99m pertechnetate
Pts on Doxorubicin, herceptin
10% drop or <45% EF means stop Rx
big tubular defect over scan
Cracked crystal
What’s plummer’s disease? How treated?
Single, autonomously functioning thyroid disease
Rx high dose I-131
Ddx of lytic bone lesion without uptake on bone scan:
cold osteomyelitis in kids (Surg emergency
aggressive tumor (lung and breast)
AVN
plasmacytoma/myeloma, LCH, radiation
What studies can be used to diagnose pulmonary Kaposi’s sarcoma?
Gallium (which is negative), thallium (which is positive)
What’s the pt prep before MIBG scan?
oral potassium iodide starting day of injection (protect thyroid)
stop sympathomimetic drugs (blood pressure medicines, anti-depressants, antipsychotics, diet pills, and most over-the-counter nasal sprays)
Nuclear study to differentiate FNH from HCC - what is it? What does a hot defect mean? Cold?
Hot: FNH (2/3 are iso to bright)
Cold: not helpful, could be either cancer or FNH
Brain scan for seizures - what agent(s) for ictal and for interictal
Ictal: HMPAO (FDG is too much trouble)
Interictal: FDG is more sensitive
When do you image in a sestamibi scan for parathyroid adenoma?
10 minutes, 2 hours
Causes of false negative sestamibi parathyroid scans
cystic lesion, small, just hyperplasia not adenoma
Uptake in aortic wall on FDG
Aortitis, most likely Takayasu
Captopril renal scan - explain
Looking for stenosis proximal to kidney
Renal scan looks worse after Captopril (relaxes efferent arterioles) than without it
How to distinguish CNS toxo from lymphoma?
Both ring-enhance in immunocompromized patients
Thallium - cold in toxo, hot in lymphoma
decreased uptake (symmetric or asymmetric) in frontal lobes on brain scan
Frontal or frontotemporal dementia
Bone scan appearance of Hypertrophic Pulmonary Osteoarthropathy
Causes:
Linear uptake along tibias and femurs (periosteal)
Lung: NSCLC, pulm lymphoma, abscess
Cause of brain visualization in lung perfusion study
R to L shunt
Ddx cold nodule in thyroid
Cancer (15-20% chance), colloid cyst, abscess, hematoma, lymph node
Odds that a hot thryoid nodule on FDG-PET will be cancer?
30%
Pt with treated thryoid cancer. Thyroglubulin is increasing but I-123 is negative, what do you do?
FDG-PET
Absent caudate and putamen on nuclear brain scan
Huntington’s chorea
Gastric radiotracer accumulation in bleeding scan - ddx. how do you determine which it is?
Gastric bleed vs free pertechnetate.
Look for thyroid activity to indicate free pertechnetate.
Tc WBC scan - what’s normal GI activity?
In-111 WBC scan - what’s normal GI activity?
Tc HMPAO: under 4 hours is abnormal (later can be okay)
In-111: NO GI activity is normal
What renal imaging agent in renal transplant?
Mag-3
octreotide study - focal uptake in head
meningioma
Nucs study has low resolution: why?
pt too far from camera, wrong photopeak (eg set for Cobalt at 122, not 140 for Tc)
What is star artifact?
septal penetration by eg I-131 with the wrong collimator (needs high energy)
What is the photopeak for I-131?
364keV (high energy collimator)
Nucs: Linear cold defect +/- branching
cracked NaI crystal
Nucs: cold roundish defect
defective photomultiplier tube - ask for a flood image
Nucs: Bright thin line artifact
bent collimator
Reasons for increased blood flow/pool to a limb on bone scan
RSD, cellulitis, tumor in that limb (anything that causes increased blood flow)
Increased bone marrow uptake on PET ddx:
Homogeneous: response to chemo or granulocyte stimulating factor
Heterogeneous: tumor/mets
Nucs study in a baby looking for aspiration
Salivagram - drop of sulfer colloid under the tongue, see if it goes into trachea
Ddx poor liver function in infant on hepatobiliary scan
Poor clearance = poor function
Neonatal hepatitis, TPN cholestasis
(usually functions fine with atresia, just won’t go into bowel)
How to check for residual spleen?
heat damaged RBCs
How do you diagnose NPH on nucs scan?
Cisternogram with In-111 DTPA, should go into lat ventricles (heart or Valentine’s sign) then leave them by 24 hours (Trident sign). If there’s still tracer in lat ventricles at 24 h, it’s NPH
How do Dx hibernating myocardium? What is it?
Area of low/nonperfusion on standard cardiac perfusion study (or PET NH3 study)
Mismached by high uptake on FDG-PET scan
Area of ischemia and low contractility that is amenable to reperfusion
Spleen seen on bone scan
Splenic autoinfaction from sickle cell anemia
What’s the panda sign in nucs? What does it mean?
Increased uptake of Ga-67 in lacrimal and and parotid glands in sarcoid (ddx Sjogren’s)
What’s the lamda sign in nuclear medicine?
Bilateral hilar and right paratracheal lymph-nodes on Ga-67 in sarcoid
What’s the scan that looks for reversible ischemia in the brain?
Diamox scan - works by challenge using vasodilator Diamox just like on cardiac perfusion studies
abnormal uptake in the axilla on nuclear study (e.g. bone scan)
Nodal uptake from infiltration - ask about injection site
What’s the Alzheimer’s specific neuroimaging agent?
Amyvid
Ddx cardiac uptake on bone scan
MI, Amyloid (look for liver), calcified aneurysm or pericardium
How many MAA particles are used in a normal perfusion (Q) scan?
250K (below ~70-100K begins looking mottled
What are reasons for reducing the number of particles used in a nuclear perfusion scan?
Shunt, pulmonary HTN, pregnancy, pediatric patient
What’s a normal T1/2 for renal clearance of MAG3? What’s abnormal?
Nl T1/2: 10 min
Abnl: 20 min
between: indeterminate
Uptake seen on a corrected PET that’s not seen on the uncorrected images =
Barium/oral contrast artifact from the CT
Ddx for no thyroid even seen on an I-123 thyroid scan
acute thyroiditis, factitious hyperthyroidism, s/p resection (should have been known)
What does a 4 quadrant bar phantom evaluate?
Resolution & linearity
What’s stunned myocardium?
acute injury - still has normal perfusion but abnormal wall motion
How often do you have to check constancy of the dose callibrator? What do you use?
Constantly! Daily
Cesium 137
premedication for Meckel’s scan?
cimetidine
premed for hepatobiliary scan in an infant
phenobarbital x 5 days
Octreotide uptake other than neuroendocrine tumors
parathyroid, medullary thyroid, SCLC, lymphoma, meningioma
You just gave the radiopharmaceutical to the wrong patient - what is that called? What do you do now?
Medical event (not misadmin)
at least 20% of intended dose, exposure of >5Rem to whole body, or >50Rem to any organ
Report to NRC (or DoH in agreement state) by the next day, in writing in 15 days
Any I-131 over 30microCi gets reported
Inform patient, referring MD, do root cause analysis to prevent future errors
contraindications to exercise cardiac stress testing:
What do you do instead?
pt cannot exercise, LBBB, severe HTN, recent MI, unstable angina, recent PE Use regadenoson (Lexiscan)
Dose callibrator QC - what needs to be done?
Geometry once (or after major move)
Accuracy annually
Linearity quarterly
Constancy daily (constantly)
Occupational dose limit to a declared pregnant worker?
5mSv per pregnancy (the general public)
Radiopharmaceutical for bone pain
Strontium or samarium
Maximal amount of aluminum permitted in Tc99m? how do you check for this?
10ug/mL
Turns indicator paper red
Little uptake of Mag3 in a renal transplant (not recent)
rejection, cyclosporine toxicity, renal artery stenosis, renal vein thrombosis
What are the radiation dose limits to: Whole body (worker): Fetus of worker: General Public: Family of an I-131 patient:
Whole body (worker): 50 mSv
Fetus of worker: 5mSv
General Public: 1mSv
Family of an I-131 patient: 5mSv
T1/2 of Cobalt 57
270 days
T1/2 of Cesium (Cs 137)
30 years
Radioactive packages - three types and acceptable radiation at surface and 30cm
White 1: 0.5mrem/hr, 0mrem/hr
Yellow 2: 50mrem/hr, 1 mrem/hr
Yellow 3: 200mrem/hr, 10 mrem/hr
Procedure for accepting a radioactive package
wear protective equipment
Check for damage, monitor with survey
meter, wipe tests. If any of these fail, call the shipper.
Check the slip, open and inspect contents.
Log it in.
Report any anomalies to RSO
What do you do in the nuc med department at the end of the day?
Daily survey - with GM survey meter (must be done after all procedures are finished
<5mrem/hr restricted
QC for gamma cameras
Daily flood
Weekly bar phantom
How do you perform an intrinsic flood on a gamma camera? An extrinsic flood?
Intrinsic: point source (between heads, curvature corrected)
Extrinsic: uniform source (Cobalt)
Nuc med artifact: freckling / small spots
water got into NaI crystal and is dissolving spots
Which radionuclides are beta emitters?
I-131, Xe133, Mo99
Which radionuclides are positron emitters?
F18 (others C11, N13, O15 not used much)
How does Tc99m produce radiation?
Isomeric transition
What radionuclides use electron capture?
I123, Ga67, In111, Tl201 (guess electron capture if you don’t know)
What’s the maximum amount of Mo contamination allowed in Tc99m?
how do you check for it?
0.15uCi/1mCi Tc (that’s micro per milli!)
Use the dose calibrator
What are the rules for nursing after various radiopharmaceuticals?
FDG: 1 day
all Tc99m: 1 day
I123, In111: 2-3 days
I131, Ga: cease completely
What is flare phenomenon?
healing from chemotherapy, occurs 3 weeks - 3 months after initiation of therapy.
If unsure, repeat bone or PET scan at 6 months after start of therapy.
Difference between shin splints and stress fracture on bone scan?
Shin splints are diffuse - linear
Stress fracture is focal
What’s used for radionuclide cystography?
What are indications for this study?
pertechnetate
Initial diagnosis of reflux, post-op, screening siblings
