Comprehensive Flashcards
Type of radionuclide: spleen > liver
WBC (very low counts)
- in-111
- technetium 99m

Type of radionuclide: liver = spleen
Sulfur colloid
Type of radionuclide: spleen
Gallium (Also shows bowel)
Type of radionuclide: Heart and kidneys seen
MIBI
Type of radionuclide: liver without kidneys or bones
MIBG
Type of radionuclide: very hot spleen and kidneys
octreotide (has very high counts)
Tag for WBCs
In-111
Type of radionuclide: bones and lacrimal glands visible
gallium or free Tc
Type of radionuclide: lacrimal glands visible without bones
Sulfur colloid, WBCs
When to image Tc-WBCs
4 hours (too much lung) vs. 24 hours (too much bowel)
Image difference between Tc-WBCs and In-WBCs
Indium shows no renal or GI
MDP dose
20 mCi +/- 5
Timing for delayed images in MDP
2-4 hours
MDP mechanism
Chemisorption (phosphate binding)
HDP is AKA
Tc-MDP
F-18 vs. FDG with increased bone uptake
FDG shows brain activity
Skull sutures very bright on MDP
renal osteodystrophy
Unilateral breast activity on MDP
- mastitis
- cancer
Bilateral breast activity on MDP
Lactating
Very bright renal activity on MDP
chemotherapy
Liver seen on MDP (3 things)
- Aluminum contamination 2. Malignancy 3. Amyloidosis
Spleen on MDP
Sickle cell disease
Probability that single bright bone lesion on MDP is cancer:
15-20%
Decreased skeletal uptake on MDP
Dose issue
bisphosphonates
Flair phenomenon for bony mets (timing)
Starts at 2 weeks, ends at 3 months.
X-rays show increasing sclerosis.
Reflects osteoblastic reparative activity and
PSA threshold for bone scan
PSA
Radionuclide of choice for bone mets in neuroblastoma
MIBG
Alternative to MDP for lytic mets
skeletal survey
Double density on bone scan
Osteoid osteoma
Hot mandible on MDP
Fibrous dysplasia
Mature heterotopic ossification on MDP
cold lesion
Hot AVN on MDP
repairing (middle phase)
Metabolic vs. metastatic superscan
Metabolic = hotter skull and extremities
Nuc Med for spine
Gallium
Nuc med for bowel
WBC
Positive WBC/Sulfur Colloid study
Hot on WBC, cold on colloid
Prosthetic loosening (Rule in)
Sulfur Colloid/WBC
Prosthetic loosening (rule out)
3 phase bone scan
When to do 4th phase bone scan
PAD or diabetes (slower blood pool clearance)
Tc-HMPAO WBC over In-WBC
Children Small body parts (hands/feet)
Xe-133 physical Halflife
5.3 days
Xe-133 biological halflife
30 seconds (not absorbed)
Xe-133 energy
80 keV
In V/Q, which performed first?
Ventilation
Size of MAA in VQ
10-100 micrometers (capillary = 10 micrometers)
When to halve MAA dose (5 things)
- Children 2. Pneumonectomy 3. Right to left shunt 4. Pulmonary hypertension 5. Pregnancy
Clumped activity on Q portion of VQ
MAA clumped from tech drawing blood into syringe
Hepatic activity on Xe-133
Fatty liver (xe is fat soluble)
Free Tc on VQ
gastric + thyroid
Right to left shunt on VQ
brain +/- gastric or thyroid
Unilateral perfusion defect on VQ (3 things)
Mass Fibrosing mediastinitis Central PE
Gallium mechanism
Iron analogue, bound to lactoferrin (inflammation or rapid cell turnover)
Radionuclide of choice for chronic infection
Gallium binds dead neutrophils; more sensitive than WBC
Gallium production
cyclotron (Zn68)
Ga halflife
78 hours
Gallium photopeak
93, 184, 300, 393
Gallium imaging
24 hours
Gallium critical organ
colon
Panda sign (radionuclide and 3 Dx)
Gallium 1. Sarcoid (classic) 2. Sjogren’s 3. Treated lymphoma
Kaposi Sarcoma (Nuc med results)
Gallium = negative Thallium = Positive
Which thyroid radionuclide is not organified
Tc (I-123 and I-131 are)
Fetal thyroid formation (trimester)
Late first (8-12 weeks)
I-131 Half life
8 days
I 131 photopeak
364 keV
I-123 half life
13 hours
I-123 photopeak
159 keV
I-131 decay type
beta emission
I-123 decay type
electron capture
Breast feeding (thyroid imaging; 3 radionuclides)
Rule of thumb - 4 half-lives: 1. I-131 = stop entirely 2. I-123 = 2-3 days 3. Tc = 12-24 hours
Normal thyroid uptake (4 hours and 24 hours)
6-18% (4 hours) 10-30% (24 hours)
Increased thyroid uptake
Graves, hashimotos, medication rebound, I deficiency
Decreased thyroid uptake
Renal failure (increased free I pool), medications (anti thyroidals, nitrates, IV contrast, amiodarone), toxicosis
Plummer disease
Toxic multinodular goiter
Non-toxic multinodular goiter
Background uptake not entirely suppressed
Graves antibody
Anti-thyroTROPIN
Hashimotos antibodies (2)
Anti-TPO and antithyroGLOBULIN
Hashimotos co-morbidity
Primary thyroid lymphoma
Hashimotos appearance on thyroid scan
Acute (hyperthyroid) = identical to Graves Later = heterogeneous with cold spots
Graves vs. De Quervains thyroiditis
DeQuervains = granulomatous thyroiditis = Decreased uptake (Graves is increased)
Discordant nodule on thyroid scan
Hot on Tc, cold on I123
Most common thyroid cancer
papillary
Thyroid cancer that does not organify
Medullary (don’t give I-131)
Medullary thyroid cancer syndromes
MEN 2A and 2B
Retreatment dose for I-131 in cancer
150% original dose
Medicine associated with I-131 resistant cancer
methimazole
Ideal post-surgical thyroid uptake for I-131 treatment
5% will be painful, treat with steroids/NSAIDs)
I-131 pre-treatment (2)
- Stop thyroid hormone 2. Give thyrogen (AKA TSH)
Initial I-131 cancer dose (3 different doses)
- Thyroid only = 100 2. Nodal disease = 150 3. Distal disease = 200 Alternative = volumetric
I-131 hospital admission rules
NRC: > 7mR/h at 1 meter from chest 33 mCi residual activity
At increased risk for non-target injury in I-131
Sjogrens (salivary)
Home I-131 precaution duration (33 mCi dose)
3 days
Abstinence from pregnancy post I131
6-12 months
How to identify post-treatment Iodine scan
Activity in the liver
Absolute contraindications to I-131 treatment (2)
- Pregnancy 2. Acute or severe thyrotoxicosis
I-131 treatment on dialysis (2 considerations)
- Tubing goes into storage (liquids can get dumped) 2. Decrease dose
I-131 dose for graves vs. multinodular goiter
Graves = 15 mCi Goiter = 30 mCi
Thyroid eye disease and I-131
I-131 may worsen
Wolff-Chaikoff
Large iodine ingestion followed by decreased hormone production (10 days)
False positives on parathyroid sestamibi (4)
Cancer Lymphadenopathy Thyroid nodules Brown fat
Hot nodule on sestamibi and Tc
Thyroid nodule
Hot nodule on sestamibi, but cold on Tc
Parathyroid adenoma
Tc DTPA vs. HMPAO for brain imaging (2)
- Perfusion imaging only 2. Can be repeated (no parenchymal localization) in epilepsy cases
Thallium 201 Mechanism
Potassium analogue (Na/K) –Needs living cells to work (viability detector)
Thallium half life
73 hours
Thallium photopeaks
69 and 81 keV
Thallium decay
electron capture
Thallium brain (infection vs cancer)
Lymphoma positive Toxo negative
Kaposi on nuclear medicine (2 tests)
Thallium positive Gallium negative (opposite of PJP)
Thallium brain (recurrent cancer vs. radiation necrosis)
Cancer = thallium positive Necrosis = negative
Vasovagal pt, poorly responsive to IV fluids (med and dose).
Atropine 0.6-1.0 mg (max dose ~3 mg)
Epi dose for severe urticaria (and route).
0.1 - 0.3 ml 1:1000 (IM)
Bronchospasm/facial and laryngeal edema/Hypotension treatment algorithm (3 steps)
- Albuterol 2a. Epi 1:1000 (IM) 0.1-0.3 ml (0.1 - 0.3 mg), up to 1 mg or 2b. Epi 1:10k (IV) 1-3 ml (0.1 - 0.3 mg), up to 1 mg If hypotension, add IV fluids
Seizure treatment
Diazepam 5 mg vs. midazolam 0.5-1 mg