NM Flashcards
All spills and contaminations of ____should be considered major spills.
radium 226
NRC anual dose limits for radiation workers (Troy and Mat) 1) Whole body total effective dose: ? 2) Dose to the lense of the eye: 3) Shallow dose equivalent to the skin and dose to the internal organs:
Dose in (Sv) .05 .15 .5
A written directive must be dated and signed by an authorized user before the administration of 131I sodium iodide greater than
1.11 MBq (30 µCi), any therapeutic dose of unsealed byproduct material, or any therapeutic dose of radiation from byproduct material other than 131I sodium iodide. This appears also to apply to the newer alpha-emitter therapies.
If the total effective dose equivalent to any other individual from exposure to the released individual is not likely to exceed ____ the individual can be released
5 mSv
physiologic distribution of radiopharmaceutical within the gray matter of the brain, lymphoid and glandular tissues of the neck, myocardium, liver, and GI and GU systems. Radiotracer?
F-18FDG
collimators are used for small organs such as thyroid.
Pinhole
collimators are used when the target organ is smaller than the size of the detector
Converging
collimators are used for most examinations and are considered the workhorse of the nuclear medicine department.
Parallel
Increasing the thickness of gamma camera crystals will result in… inc or dec sensitivity and resolution?
increased sensitivity decreased resolution.
organ visualized with excessive aluminum in the Tc-99m sulfur colloid kit
Lung
sensitive handheld instruments that are used to detect small amounts of radioactive contamination. - gas filled - high dead time
Geiger-Mueller counters
used to measure low or high exposure rates. -gas or air filled - short dead time
Ionization chamber
type of ionization chamber used to assay the amount of activity in vials/syringes from a known radiopharmaceutical.
Dose calibrators
composed of NaI crystals with a hole in them to place the sample resulting in the ability to detect very small quantities of radioactivity.
Well counters. Used for the wipe test.
Quality assurance that tests whether correct measurements are obtained regardless of sample size or geometry. uses diff syringe sizes of Tc-99m.
Geometry
is the fraction of emitted radioactivity that falls on the detector. Surrounding the well in scintillator crystals achieves this.
Geometric efficiency
the ability of the calibrator to accurately measure radioactivity at all clinically applicable low to high levels.
Linearity Using various activity levels of Tc99m
refers to the ability of the calibrator to accurately assay samples with all clinically applicable radionuclide energies (low, medium, and high). No matter what isotope I look at are my average readings at the bulls-eye? checked?
Accuracy quarterly-annualy
measures the instrument’s precision and is intended to show the reproducibility of measurements.
Constancy using Cesium 137
Quality assurance tests
CLAG constancy, linearity, accuracy and geometry. daily, quarterly, annually and after recalibration, usage etc.
quality assurance is being performed when the nuclear pharmacist assays a high activity vial of Tc-99m using calibrated lead shields to simulate lower levels of radioactivity?
Linearity This can be evaluated by one of two following methods: (1) Assay a high activity vial of Tc-99m over an 80-hour period, or (2) assay a high-activity vial of Tc-99m using calibrated lead shields to simulate lower levels of radioactivity.
peripheral crescent-shaped defect on the flood image, this is classic for a nonfunctioning
photomultiplier tube.
Center of rotation (COR) errors are seen on
SPECT images. Tested monthly
The maximal uncorrected COR error allowable is
0.5 pixels
Bar phantoms are used to evaluate
spatial resolution (ability to resolve the lines) and linearity (are the lines straight or wavy) on a weekly basis.
Checked by doing flood images daily to correct field inhomogeneities
Extrinsic uniformity (COLLIMATOR ON) tested with cobalt 57
Can be Used to Assess Contrast, Uniformity, Resolution, Attenuation and COR
jaszczak phantom (overall system performance) tested quarterly
Delivered dose must be within ___ of prescribed dose Good Practice say dose should be within ___.
20%, 10%.
Systems are more susceptible to non-uniformities High Count Floods ( > 40 million counts)
SPECT
Light collection is more efficient at the _____ of the PMT
center
____ is tested by doing a high count rate flood.
Collimator integrity
How often should the uniformity flood images be acquired?
Daily - to evaluate both the intrinsic function of the camera and the extrinsic function of the collimators.
How often should spatial resolution be tested?
Weekly
the ability of the crystal, photomultiplier tube detector, and accompanying electronics to record the exact location of the light pulse on the sodium iodide crystal.
Inherent spatial resolution
Overall spatial resolution can be tested with __ or ___.
bar phantoms or with full width at half maximum.
the width of a spectrum curve measured between those points on the y-axis which are half the maximum amplitude.
FWHM
What is the maximum allowable molybdenum-99 breakthrough? What is it measured with?
0.15 μCi per 1 mCi of Tc-99m microCurie, milliCurie. Measured with dose calibrator with lead shield surrounding the sample
What is the max allowed exposure to public from a pt who received an outpatient I-131 therapy?
5 mSv
typically evaluated with a three-phase bone scan and would demonstrate increased or decreased periarticular uptake on the delayed images depending on the stage
Reflex sympathetic dystrophy (RSD) or complex regional pain syndrome (CRPS)
equivalent dose to the embryo/fetus during the entire pregnancy from the occupational exposure
5 mSv (0.5 rem)
What is the occupational whole body dose limit?
50 mSv (5 rems)
annual limits to the lens
150mSv (15 rems (0.15 Sv))
annual limits to the skin (whole body)
500mSv 50 rem (0.5 Sv)
To decreasing beam hardening artifact
Increase tube current but you increase patient dose.
wavy appearance of the image
Moire interference
What is the annual institutional limit for the amount of radioactivity that can be disposed of in the “hot sink”?
1 Ci / year for all liquid wastes for the entire institution. Includes pts shit.
Contaminated waste/trash/clothing is kept until it has decayed back to background or ______ if the physical half-life of the radioactive material is ____days.
10 half-lives, <120
Free pertechnetate would be seen as increased uptake in
salivary glands, thyroid, stomach and renal collecting system
Energy of photons emitted by PET (including F18 and Rubidium)
511 keV
Energy of photons emitted on bone scan
140 keV
Diffuse liver uptake on a bone scan is abnormal and most likely do to
aluminum contamination (aluminum breakthrough in eluate) and subsequent colloid formation.
Thin-layer chromatography is used to determine labeling efficiency also known as
radiochemical purity CHromatography, CHemical
allowable limit of aluminum breakthrough in molybdenum-99/technetium-99m generator?
10 μg/mL of Tc99m eluate micrograms/mL
Too much aluminum causes technetium–aluminum particles to form, which can be seen as uptake in the _____
liver
Label: White I surface radiation, at 1 m ?
< 0.5 mrem / hr, N/A
Label: White II surface radiation, at 1 m ?
< 50mrem / hr, < 1 mrem / hr
Label: White III surface radiation, at 1 m ?
50-200 mrem / hr, 1-10 mrem/ hr
highest radiation level at 1 m from the surface of the package
transport index (TI)
Limulus amebocyte lysate at a pH of 7. What does the formation of gel after 30 minutes of incubation indicate?
presence of pyrogens. The thicker the gel the greater # of pyrogens.
Maximum buildup of Tc-99m activity occurs at __ hours after elution.
23
For TI of 2, what should be the max dose rate?
Radiation level at 1 m should be no more than 2 mrem/h.
adjustment of the differential absorption of signal from tissues deeper in the body compared to the periphery
Attenuation correction
one of the most common causes of altered biodistribution of MIBG….
Medications Known interfering medications with MIBG include the following: Antihypertensives: Labetalol and calcium channel blockers (i.e., diltiazem, nifedipine, verapamil) Tricyclic Antidepressants: amitriptyline, imipramine, doxepin, etc. Sympathomimetics (i.e., cold medications): phenylephrine, pseudoephedrine, ephedrine, etc. Cocaine
What is responsible for the increased detection of counts with positron emission tomography (PET) compared to single photon emission tomography (SPECT)?
Electronic collimation
What happens to the amount of I-124 contamination in an I-123 dose over time?
Increases with time. This is why I-123 doses should be used as soon as possible after their receipt. I124 has longer half life and gives higher energy photons.
Main source of radiation is from close proximity to the breast. As a result, some authors suggest patient to suspend breast-feeding for __ hours after the FDG injection.
8
Full width at half-maximum of a photopeak is a measurement of a system’s…
energy resolution. and should be performed anualy.
The _____________ is measured daily by checking a radionuclide photopeak.
energy spectrum
What happens when one uses a low-energy collimator to image a medium-energy isotope?
decreased resolution bc of increased septal penetration (thinner septa w lower energy collimators).
Uptake in lacrimal glands, nasal mucosa, liver, kidneys, bowel, and bone marrow. NOT SPLEEN.
Ga-67
Ga 67 energy photopeaks
93,185,200 ~100,200,300
Low-energy collimators are generally used to image energy up to
150 keV
medium-energy collimators have a maximum suggested energy of about
400 keV
I-123 MIBG is typically imaged with what collimator?
medium-energy parallel-hole collimator.
High-energy collimator is used to image
I-131
Low-energy, high-resolution collimator or a low-energy, all-purpose collimator can be used to image
Tc-99m-labeled agents.
critical organ for Tl-201
Kidneys
critical organ for Tc-99m-labeled myocardial perfusion agents (tetrofosmin and sestamibi)
Gallbladder
For myocardial perfusion agents, if intense activity is seen in the liver _____. If renal excretion ______.
Tetrofosmin or Sestamibi; TI-201
Only pharmaceuticals w distribution to the skeleton and renal collecting system.
bone scintigraphy agents Tc-99m MDP or Tc-99m HDP.
Liver and spleen are part of the physiologic distribution of
Ga-67, Tc-99m sulfur colloid, tagged leukocytes, and F-18 FDG.
pharmaceuticals w physiologic distribution of nasopharynx, salivary glands, thyroid, stomach, bladder, and bowel.
I-123 and I-131
Physical Half life of TI-201
3d
Physical Half life of Tc-99m
6h
Physical Half life of I-123
13.2h
Physical Half life of Ga-67
3.2d
Physical Half life of In-111
2.8d
Physical Half life of I-131
8d
Physical Half life of Xe-133
5.2d
Principal photon energy, keV of TI-201
69-83 (Hg xrays)
Principal photon energy, keV of Tc 99m
140
Principal photon energy, keV of I-123
160
Principal photon energy, keV of Ga 67
90,200,300,400
Principal photon energy, keV of In III
170, 245
Principal photon energy, keV of I-131
364
Principal photon energy, keV of Xe-133
81
spleen > liver > bone marrow
In III
used for the detection of beta amyloid plaques in the diagnosis of Alzheimer disease by PET imaging
F-18 Florbetaben
myocardial perfusion imaging agents that bind to the cytoplasmic mitochondria and are excreted through the liver by the hepatobiliary system.
Tc-99m tetrofosmin and Tc-99m sestamibi
a K+ analogue that localizes within the cytoplasm of the myocardial cells by sodium potassium ATPase pump and excreted by the kidneys
Thallium-201
radiolabeled analog of choline, a precursor essential for the biosynthesis of cell membrane phospholipids; it has been approved by the FDA to evaluate prostate cancer.
C-11 choline
Radiopharmaceutical used for the detection of hypoxia in tumor
F-18 fluoromisonidazole (FMISO) and Cu-64 ATSM
Radiopharmaceutical is a marker of cell proliferation
F-18 fluorothymidine (FLT)
radiopharmaceuticals used to image apoptosis, mainly in tumors to evaluate early response to therapy.
Tc-99m annexin V
a somatostatin receptor binding agent, mainly used in the evaluation of neuroendocrine tumors.
Ga-68 DOTA
measures the fraction of total radioactivity that is present in the form of the undesired radionuclide. In the Tc-99m case, it is measured in the form of ratio of Mo-99 to Tc-99m.
Radionuclide impurity.
Mo-99 is the most important radionuclide contaminant in the Tc-99m based radiopharmaceutical. Its ______ and _________ result in a very high radiation dose.
long half-life; beta emission
What is being measured when Mo-99/Tc-99m generator eluate is placed on a special test paper that changes color?
Chemical impurity
maximum allowable limit for alumina breakthrough in the generator eluate in the case of Tc-99 is …
10 μg/mL of eluate. Detected with paper strip test.
What is being measured when the radiopharmacist performs thin-layer chromatography on Tc-99m MDP?
Radiochemical impurity
An example would be fraction of the free Tc-99m pertechnetate and insoluble colloids in a Tc-99m MDP dose prepared for bone scintigraphy.
Radiochemical impurity, tested with thin layer chromatography.
Effective half-life =
(physical HL × biologic HL)/(physical HL + biologic HL)
I-131 destroys the thyroid follicular cells by what particulate emission during its radioactive decay?
Beta
Iodine-123 (I-123) decays by
electron capture
radiopharmaceuticals is trapped by the thyroid follicular cells but NOT organified?
Tc-99m pertechnetate. As such, it can gradually wash out of the thyroid gland, requiring imaging at 20 minutes after IV administration.
radiopharmaceuticals organified in the thyroid follicular cells …
I-123 and I-131 are organified into T3 and T4 and stored in the colloid-filled follicular lumen. Antithyroid medication such as propylthiouracil and methimazole block this organification process.
What three “devices” utilize crystal-based scintillation detectors (NaI, CdZnTe, etc.) coupled to a photomultiplier tube for radiation detection?
Scintillation probes, well counters, and gamma cameras
highly sensitive device used to detect a very small amount of radioactivity (up to 1 mCi) such as those of wipe tests or in vitro studies (GFR, shillings test, etc.).
well counter
are typically used to measure high exposure rates (range from 0.1 mR to 100 R) such as those from the patients receiving radioiodine therapy for cancer.
Ionization chambers
The typical 24-hour RAIU of 50% to 80%.
Graves
The typical 24-hour RAIU of 20-30%
TMNG & toxic autonomously functioning nodule
Normal %RAIU is 4-15% at and 10-30%
4 to 6 hours at 24 hours.
Absent or poor visualization of thyroid gland and decreased RAIU are seen with
Hypothyroidism, acute phase of subacute thyroiditis, amiodarone tox, exposure to excess iodine (contrast, amiodarone) or suppression from exogenous thyroid hormone.
Antithyroid peroxidase antibodies are typically seen with
Hashimoto’s thyroiditis.
I-131 dose to treat the patients with Graves disease
5 to 20 mCi Symptomatic improvement is usually noted by 3 weeks with full therapeutic effect typically in 3 to 6 months.
I-131 dose to treat the patients with MNG
20 to 30 mCi. More resistant than graves and lower RAIU.
lactating women undergoing I-131 therapy should be asked to stop breast-feeding for…
that child. May resume for next child.
How long after administration of I-123 radioiodine can the patient resume breast-feeding?
48 hours. Unlike 131 this has short half life and no beta emission.
How long after administration of Tc-99 radioiodine can the patient resume breast-feeding?
24 hours
most accurate tumor marker to detect recurrence of a well-differentiated thyroid carcinoma (papillary and follicular)
Serum thyroglobulin (Tg)
Thyroid hormone undergoes conversion from T4 to T3 by type I iodothyronine deiodinase within the ____. Thus, presence of uptake there suggests evidence of functioning thyroid tissue elsewhere in the body.
liver
Serum TSH value greater than what level is desirable to ensure maximal effect of the ablation?
30 mIU/L is desirable, and a level greater than 50 mIU/L is optimal. Synthroid should be stopped 4 weeks before study.
radiopharmaceutical of choice for the evaluation of substernal goiter.
I-123. better target to background ratio, better tissue penetration, and improved specificity (compared to pertechnetate) as well as ability to perform SPECT–CT images (compared to I-131).
The diagnostic accuracy of FDG PET/CT for de-differentiated thyroid cancers increases with increasing stimulated Tg levels and is most promising at levels ___ ng/mL.
>20
FDG PET/CT also has high sensitivity and specificity in evaluation of what recurrent thyroid malignancies?
Hurthle, anaplastic and medullary “HAM”
A cold nodule in the thyroid has what % chance of malignancy?
10-20. Pt would require f/u US +/- bx depending on the US findings.
Thyroid incidentalomas detected w FDG PET carry a higher risk of malignancy ~ ___ and detected cancers are more aggressive.
33%. When found require prompt w/u w US guided FNA
For parathyroid adenomas you inject Tc99 Sestamibi and image at _____. Then, a thyroid scan using Tc-99 pertechnetate follows.
15 min and 2 hrs. Parathyroid adenomas are best seen on delayed images.
MIBG is an analog of
norepinephrine
used for the evaluation of neuroendocrine tumors such as carcinoid and gastrinoma with very high sensitivity.
This is an In-111-DTPA-pentetreotide (OctreoScan)
Planar images using medium-energy collimator and symmetrical 20% energy window over 173 and 247 keV are acquired at 4 and 24 hours.
This is an In-111-DTPA-pentetreotide (OctreoScan)
In-111 pentetreotide is an analog of octreotide, which binds with high affinity to
somatostatin receptors type II and type V
. Of the neuroendocrine tumors, In-111 OctreoScan has the least sensitivity for
insulinoma (50% to 60%) and medullary thyroid carcinoma (65% to 70%).
Nonneuroendocrine tumors, which express somatostatin receptors, are also positive on OctreoScan. These include:
lymphoma, low-grade gliomas, meningioma, RCC, and breast Ca.
potassium iodide (SSKI) or Lugol solution to block unwanted radioiodine accumulation in the normal thyroid gland
I-131 or I-123 MIBG
main clearance of In-111-DTPA-pentetreotide (OctreoScan)
kidneys. 2% of the radiopharmaceutical is cleared by the hepatobiliary system and physiologic GB activity may be seen.
Where does Tc-99m MDP localize within the bone?
Mineralized portion - Calcium hydroxyapatite
Excessive air in the mixing vial will result in poor tagging of the radiopharmaceutical and will result in
free pertechnetate. Can also be seen if injection is delayed > 4hr.
Phases of 3 phase bone scan
- angio 2. blood pool/soft tissue perfusion 3. delayed (2-3hrs) A 18-24hr can be added in pts with renal failure or poor soft tissue clearance.
Indications for three phase bone scan
- cellulitis vs OM 2. Fx or malignancy. 3. Painful joint prosthesis 4. CRPS (RSD)
Superscan or beautiful scan associated with ______ and __________ often demonstrates increased radiotracer uptake within an enlarged mandible, which is referred to as a “Lincoln sign,” as well as increased uptake within periarticular bones.
primary hyperparathyroidism renal osteodystrophy (secondary hyperparathyroidism)
Lung metastasis from _______ demonstrates intense bisphosphonate radiotracer uptake
osteosarcoma
OM and Osteosarcoma on three phase bone scan?
++++
Osteosarcoma has (hetero/homogenous) Tc-99 MDP uptake on bone scan?
hetero w areas of photopenia. Vs OM which is homo inc uptake.
“Lincoln sign,” is more closely assoc. w _______
Pagets
Activity surrounding a cemented prosthesis usually returns to normal within _____ after surgery.
12 months
generalized increased activity may be seen for more than 2 years after surgery with a ___
noncemented, porous-coated prosthesis.
Persistent activity at the tip of the femoral shaft component and at the trochanter may represent
hardware loosening
generalized increase in activity around a hip prosthesis, especially the stem, may indicate
osteomyelitis.
Combined _______ is the radionuclide study of choice for diagnosing prosthetic joint infection.
labeled leukocyte & SC-marrow imaging. Both accumulate in BM but WBC will only accumulate in infxn.
increased blood flow and blood pool to the affected extremity with increased periarticular radiotracer uptake on the delayed phase
Complex regional pain syndrome
Shin splints involve what part of the tibia?
posteriomedial diaphyseal region
incongruent increase in periprosthetic leukocyte accumulation w/o corresponding increase in marrow activity on colloid imaging, the study is positive for
infxn
T-score represents the SD by which the patient’s BMD differs from the mean BMD of a ____.
young adult, same sex and ethnicity
Z-score represents the SD by which the patient’s BMD differs from the mean BMD of a ____.
healthy population of the same sex, ethnicity, and age
The posterior–anterior (PA) spine and total body less head (TBLH) best for BMD in
children
optimal site for monitoring response to treatment for osteoporosis
VB
________is the region of choice in the assessment of osteoporosis. when the three scenarios requiring forearm assessment are met
Distal 1/3 radius of non dominant forearm.
cold defects on Tc-99m MDP can be seen with mets from what malignancies?
Lymphoma, MM, RCC, thyroid…. vs breast blastic uptake would be hot.
Heterotopic ossification is differentiated from bone-forming malignancies such as parosteal or periosteal osteosarcoma by
mature calcifications along the periphery rather than in the center
Differential considerations of increased breast activity on bone scintigraphy include
malignancy, mastitis and trauma
LIver should NOT be visualized on normal bone scint. Differential dx for liver uptake on bone scintigraphy
hepatic metastases, hepatic necrosis, amyloidosis, metastatic calcifications, and excessive aluminum breakthrough from the generator.
etiologies of abnormality increased renal radiopharmaceutical uptake (greater than lumbar spine on post projection)
chemotherapy-induced nephrotoxicity and ATN, Iron overload, high grade bilateral renal obstruction (marked delay ST uptake and lack of bladder activity)
How do F-18 sodium fluoride PET/CT scans compare to the Tc-99m MDP bone scans?
decreased uptake, better sens and spec but more expensive w/o adding much value.
osteoporosis
T-score < -2.5
Osteopenia
-2.5 - (-1)
a Z-score ____ indicates bone mineral density (BMD) below the expected range for age in adults or low density for chronologic age in children.
less than −2
the reference standard for the description of osteoporosis is BMD at
femoral neck
Bone Marrow hyperplasia secondary to G-CSF commonly persists for about
2-4w after cessation of therapy.
Highest sensitivity for neuroblastoma mets
combination of MIBG (more sensitive) + bone scint
Baby with bone scintigraphy and abdominal mass
Neuroblastoma
Only approved tx for prostate mets refractory to pain meds and its side effect.
Radium 223 through alpha particle emission/diarhea
Shin splints three phase bone scan vs tibial stress fx.
SS: normal, normal, increased TS fx: increased, increased, more focal and fusiform on delayed images.
stress-induced periosteal reaction at the insertion of the soleus and tibialis muscles onto the tibia
shin splints
Modality for evaluation of vertebral OM
FDG-18 PET/CT
Differential considerations for small cavitary lung lesions
septic emboli, rheumatoid nodules, metastatic squamous cell carcinoma, or Wegener granulomatosis.
Images for HMPAO and ECD are taken at
30-90 and 30-60min respectively
Used to dx brain death, has rapid clearance from blood, does not cross BBB and is not retained in the gray matter
DTPA
lipophilic radiopharmaceuticals that readily cross the blood–brain barrier and are retained in the brain parenchyma soon after their injection.
Tc-99m HMPAO and ECD. Once inside the neuron, both become trapped by metabolic conversion into nondiffusible forms.
blood flow in the region of epileptic foci is either _______ soon after or in between seizures
normal or reduced
interictal F-18 FDG-PET will show
normal or reduced activity at seizure focus do to decreased blood flow between seizures.
Where do you see increase and decreased blood flow regarding ictal and interictal times.
increased BF in ictal normal or decreased in interictal
Interictal (study?) is very sensitive (80%) in localizing refractory complex partial seizures, which typically originate from the TEMPORAL lobe.
FDG-PET
Most sensitive procedure for diagnosing seizures of EXTRATEMPORAL origin?
Ictal perfusion SPECT with ECD or HMPAO (both Tc99m)
For ictal studies, the patients are 1. taken off their seizure medications 2. admitted 3. ? 4. radiopharmaceutical is kept at the bedside until 5. Once seizure is identified, radiotracer is _______
- continuously monitored for the onset of seizure. 5. injected after the seizure is over but within 30 seconds.
used for evaluation of CSF dynamics (cysternogram) and CSF leaks.
DTPA
used for renal cortical imaging
Tc-99m DMSA
Retention of the radiopharmaceutical within the brain parenchyma on delayed images suggests that the exam was performed with
HMPAO or ECD
hypometabolism in which region helps differentiate dementia with Lewy bodies from Alzheimer disease
Occipital cortex
DaTscan is abnormal in parkinsonian syndromes, which include
Parkinson disease, progressive supranuclear palsy, and multiple system atrophy.
asymmetric hypometabolism involving bilateral posterior parietal and temporal lobes is seen in
Alzheimer
I-123 ioflupane is an analog of
cocaine. used for DaT scan
Dementia with Lewy bodies (DLB)
visual hallucinations, fluctuating mental status, and parkinsonism.
ormal CSF dynamics demonstrate migration of intrathecally injected radiopharmaceutical into the basal cisterns by _____, frontal poles and sylvian fissures by _____, and cerebral convexities by _____.
1 hour; 2 to 6 hours; 12 hours.
A standard dose of _______ is used for the ACZ challenge test
1000 mg intravenously
radiopharmaceuticals utilized to evaluate for CSF shunt patency
Tc-99m DTPA and In-111 DTPA. injected through the reservoir***
Primary CNS malignancy that typically demonstrates the highest degree of FDG uptake, more than that of the cortical gray matter.
lymphoma
The best sensitivity and specificity for FDG PET/CT to detect residual/recurrent malignancy in patients receiving combination therapy is _____ after the completion of the radiation therapy.
3 to 4 months
the most readily available and widely used technique for the assessment of cerebral hemodynamics to help identify CVD patients who would benefit from ECIC bypass surgery.
Brain perfusion SPECT with ACZ challenge
study of choice for differentiating posttreatment changes from residual/recurrent disease
F-18 FDG-PET/CT. Also in the initial staging of H&N malignancy and evaluation of unk H&N primary*****
study of choice for evaluating perineural extension or local extent
CT/MRI over FDG PET
MC parotid tumor
benign mixed-cell tumors (pleomorphic adenomas)
second MC parotid tumor
Warthin
the most common causes of incidental FDG-avid parotid mass
Warthin tumor and pleomorphic adenoma
Radiotracer for gastroparesis
1 mCi of Tc-99m sulfur colloid***
used for salivagram in infants, for thyroid scintigraphy, or for the evaluation of Meckel diverticulum.
Tc-99m pertechnetate
used for the hepatobiliary scintigraphy.
Tc-99m mebrofenin
Insulin-dependent diabetics should be scheduled for _________ and should generally take ___ of their usual morning insulin dose, followed by the radiolabeled meal.
an early morning study; 1/2
Gastric emptying study should be rescheduled if the fasting blood glucose level is _____ mg/dL.
>200. hyperGlycemia delays gastric emptying
Counts preferred to generate the time activity curve in the gastric emptying study
Geometric mean
Gastric emptying study images should be taken at
1 min immediately after meal ingestion, 1,2 and 4 hrs.
agents that delay gastric emptying (GE) and would result in false positive & should be discontinued 48 to 72 hours before gastric emptying scan
- Opiate analgesic medications (e.g., morphine, codeine, Demerol, and oxycodone) 2. calcium channel blockers 3. antacids 4. anticholinergic agents
Where in the liver & spleen does the Tc-99m sulfur colloid localize?
Kupffer cells & macrophages respectively
The _____ time point is more sensitive for detection of delayed gastric emptying compared to the 2-hour time point.
4-hour
In a tagged red blood cell (RBC) scan, where does the Tc-99m bind in the red blood cells?
beta chain of the hemoglobin
The SMA supplies the bowel from the
Second portion of the duodenum as far distally as the Splenic flexure
The celiac artery supplies the
distal esophagus, stomach, and the 1st portion of the duodenum
The inferior mesenteric artery (IMA) supplies
distal third of the transverse colon to proximal rectum.
Tc-99m–tagged RBC scintigraphy has a high sensitivity in detecting bleeding rates of. Easy to perform, requires no patient preparation, and is noninvasive
0.04 to 0.2 mL/min
angiography will locate GI bleeding sites with bleeding rate
> 1mL/min. Also, the bleeding must be occurring during the 20 to 30 seconds of contrast injection
If Tc-99m–labeled RBC scintigraphy cannot be performed, which other radiotracer may be used for the evaluation of gastrointestinal bleeding?
Tc-99m sulfur colloid
For a liver–spleen scan imaging is initiated how long after IV injection of Tc99-SC? .
20 minutes
If lesion is adjacent to liver, what scan is preferred to evaluate for splenosis?
Heat damaged RBC over Tc99-SC.
Scan with intense delayed activity in the blood pool and spleen?
Heat damaged RBC
Tc-99m RBC scintigraphy has near ____ positive predictive value for diagnosing hemangioma.
100%. If lesion is small < 3cm performing SPECT over planar images will improve sensitivity.
A lesion with increased tracer Tc-99m uptake (more than that of the adjacent liver) is seen with
FNH
intraperitoneal injection of Tc-99m sulfur colloid (SC) with radiotracer uptake in the right pleural cavity
hepatic hydrothorax*****
Intraperitoneal injection of either ______ can also be used to evaluate the patency of a LeVeen or a Denver peritoneal–venous shunt, which are used to drain intractable ascites from the peritoneal cavity into the superior vena cava
Tc-99m SC or MAA
critical organ for Tc-99m mebrofenin and disofenin
gallbladder
critical organs for Tc-99m RBCs
Spleen and heart
critical organ for Tc-99m sulfur colloid scintigraphy and In-111 WBC scans
Spleen
drug used to squeeze GB for various reasons: patients who have fasted for longer than 24 hours, are on parenteral hyperalimentation, or have a severe intercurrent illness, calculate GB EF, evaluate sphincter of Oddi dysinkesia
0.02 μg/kg of sincalide 15 to 30 minutes before the injection of the hepatobiliary radiotracer. (0.02mcg/kg) slow IV infusion over 1 hr (rapid causes painful GB squeeze)
A HIDA scan is performed with
Tc-99m mebrofenin
Normal timings for HIDA scan
< 10min: clearance of blood pool < 20min hepatic ducts ~20min: CBD/duodenum < 60min bowel should be seen.
rim sign
HIDA scan sign of severe late stage acute chole maybe gangrenous. Should perform open chole vs laparoscopic
calculated lower range of normal GBEF for 60-minute infusion is
38%
when the gallbladder is not visualized within 60 minutes, what are the two options
- 3-4 hr delayed images 2. Morphine (0.04 mg/kg, maximum 3 mg)
may be given for 3 to 5 days before imaging infants in whom biliary atresia is suspected.
Phenobarbital, 5 mg/kg/d
Relative regional decrease in activity along the superior lateral aspect of the right hepatic lobe on HIDA is secondary to
breast artifact
two of the common complications after a liver transplant.
Bile leak and biliary obstruction
radiopharmaceutical most commonly used for sentinel lymph node (SLN) localization by lymphoscintigraphy
filtered Tc-99m sulfur colloid (particle size 100 to 200 NANOm). Tc-99m tilmanocept (Lymphoseek) is an alternative to radiocolloid, which was approved by the FDA in 2013. It targets dextran-mannose receptors on the surface of macrophages.
gold standard for lymph node staging in breast cancer and melanoma.
Sentinel lymph nodes (SLN)
the ideal injection site to visualize internal mammary nodes would be
with deep peritumoral injections
Typical indications for lymphatic drainage evaluation by lymphoscintigraphy include
lymphedema, chyluria, chylothorax, and chyloperitoneum
periareolar injection are specifically recommended for lesions located within the
upper outer quadrant near the area of the axilla.
threshold at which dose reduction would be considered with SIR-Spheres
10% pulmonary shunting. If more than that dose needs to be adjusted to prevent radiation pneumonitis
HL of Y90 and emits?
64hrs (Nintendo). pure B emitter.
Intra-arterial ________ is used to document the vascular distribution and assess for arteriovenous shunting to nontarget organs as well as lungs prior to the administration of Y-90 microsphere therapy.
Tc-99m MAA
Percentage of lung shunting where SIR is contraindicated
> 20%
If significant GI activity is seen after Intra-arterial Tc-99m MAA to document the vascular distribution and assess AV shunting to nontarget organs
embolization of the supplying vessels is indicated prior to Y-90 therapy.
With TheraSpheres, the upper limit of injected activity shunted to the lung (percentage of shunting to the lungs times the planned therapy activity) is
16.5 mCi (610.5 mBq)
In general, there should not be any abnormal accumulation of Ga-67 around prosthesis on
48-hour delayed images
Because of increased attenuation from metallic portions of the LVAD, falsely increased activity can be seen on SPECT/CT images from overcorrection of attenuation. As such, correlation should be made with
nonattenuation corrected and/or planar images.
Is preferred for the evaluation of abd infxn bc they lack normal physiologic bowel activity associated with Ga-67 and Tc-99m HMPAO-labeled WBC scan.
In-111 labeled WBC.
When present, In-111-labeled leukocytes activity in the gastrointestinal tract is nonspecific and may indicate etiologies including
Crohn disease, ulcerative colitis, pseudomembranous colitis, diverticulitis, or ischemia.
is more sensitive than I-111WBC for vertebral OM
Ga-67
Does VQ or CTPA have lower FETAL radiation?
CTPA
Reduction of # of parties of MAA (200k-500k) for VQ study should be performed in
Neonates (10k), Children(50-150k) and (100k-150k) for pulm HTN, R to L shunt, and pregnancy****
same # of protons
isotope (I123 and I131)
same # of everything (protons and neutrons) but different energies
isomer
high-energy proton produced from nucleus. What am I?
Gamma ray
high-energy proton produced from interactions with orbital electrons. What am I?
XRay
What is the decay mode for T-99m to its daughter T-99?
isomeric transition
1 mCi = ? MBq
37
Half life of F-18
110min
Radioisotopes used in nuclear medicine are ___ emitters
Gamma. Except thallium (XR)
The hallmark appearance of aluminum breakthrough is
splotchy uptake in the liver
Gamma camera steps
- gamma emission from pt to detector 2. collimator focuses by rejecting photons at weird angles 3. NaI scintillator: photons to light 4. PMT: light photons into electrical signals 5. Pulse height analyzer: determines photon and energy 6. computer creates map 7. Compton scatter falls outside photopeak window 8. Image
________ results when photons that are so strong (such as I-131, with 356 keV) or that are so numerous (injection site of Tc-99m sulfur colloid for lymphoscintigraphy) that photons leak (penetrate) through septa into neighboring scintillation crystals
Septal penetration, star artifact
SPECT almost exclusively uses what type of collimator?
parallel
Reconstruction algorithm used in SPECT?
iterative (preferred), filtered back projection
Main difference between 2D and 3D PET systems
2D uses septa collimator rings to reject scatter. Also, therefore 3D is more sensitive.
Radipharms used for brain death
Tc-99m DTPA, Pertech, HMPAO, ECD
Radiopharms used in CSF imaging
In-111 DTPA for NPH and Tc-99m DTPA for Shunt Patency
Radiopharm for parathyroid
Tc-99 Sestamibi
Ventilation Perfusion agents
Tc99m DTPA aerosolized and Xe-133
pulm ventilation study with 1-3 view? with multiple views
Xe-133, Tc99m DTPA
Antidote for Regadenoson (Lexiscan) and Dipyridamole (Persantine)
Theo or Aminophylline
Half life of adenosine
10s. no antidote.
Mechanism of adenosine
Potent coronary vasodilator
Contraindications to adenosine, regadenoson and dipyridamole
asthma, COPD.
How much activity on gastric emptying should remain after 4 hrs?
< 10%
Radiopharm used to measure GFR and renal perfusion
Tc-99m DTPA
I-123 MIBG used to image
pheos and neuroblastomas
Lymphoma vs Kaposi on Gallium and Thallium
+ +, - +
In 111 Octreotide distribution
left and right kidneys, liver and spleen (4 organs, “oct”)
In 111 Octreotide used for
Carcinoid and paraganglioma
Agent used for Lymphoscintigraphy
Tc-99m-SC
Records for waste disposal and package receipt records are kept for
3 yrs
Packages should be checked within
3 hrs on the same business day or start of the next day if received after hrs.
“occurs when the daughter half-life is much less than the parent half-life, so the parent activity essentially stays constant.
Secular Equilibrium parent activity constant (straight line above zero), daughter activity is a half rainbow increasing from zerow.
“occurs when the daughter element half-life is slightly less than to the parent element half-life. Transient equilibrium occurs at ~ 4 daughter half-lives.”
Transient equilibrium
According to the International Harmonization Project, following completion of radiation therapy in patients with lymphoma, how many weeks should elapse before performing PET to assess response to therapy?
At least 2 weeks after chemotherapy and 2-3 months after radiation (2007).
What is the approximate effective radiation in mSv from an FDG PET/CT low dose?
~ 15 mSv
How does NPH present on In 111 DTPA study?
Persistent tracer in the ventricles > 24 hrs. If ventricular activity is seen in 2 consecutive image sets at 4 to 6 hours, and at 24 hours postinjection, the diagnosis of NPH is made.
Biliary atresia on hepatobiliary scan
Good hepatic uptake without excretion of activity into the bowel at 24 hours
Gamma camera quality assurance tests performed weekly… What is it performed with?
Spatial resolution, linearity, and distortion… A four-quadrant bar phantom.
On breast lymphoscintigraphy studies, if several nodes are visible, what factor is the most important to identify which is the sentinel node?
Timing of visualization
Three interpretation categories for PIOPED II:
- High prob 2. non diagnostic 3. Very low prob/normal
A triple match defect in the MID/UPPER lung falls into what category under PIOPED?
very low probability for PE
A triple match defect in the LOWER lung would be in the ______ PIOPED II category.
non-diagnostic
Pts with LBBB present with what on perfusion imaging during maximal exercise?
Reversible septal perfusion defects
In order to supervise the performance of NM studies and interpret the results, what specific radiologist qualifications are required?
Be listed as an authorized user in your institution
What low grade lymphomas have minimal or low FDG activity on PET?
- MALT marginal zone lymphoma and - Small lymphocytic lymphomas.
An infected prosthesis is assessed with what two studies?
WBC and SC
Spinal OM can be assessed with what scintigraphic study?
Ga 67
What is the feature of Ga 67 that prevents it from being useful to evaluate bowel pathology?
too much normal excretion in the bowel
What view is used on MUGA to evaluate EF?
45 degree left lateral LAO
Name some factors that affect the accuracy of SUV measurements
- patient body size and weight composition - blood glucose level - FDG dose injected - post injection uptake time
What effect does hyperglycemia (especially > 200) have on SUV values?
Competitively inhibits cellular uptake of F18-FDG, decreasing SUV
In an agreement state, who is responsible for regulating byproducts, source, and special nuclear materials?
The state
On an MDP bone scan, absent renal and bladder activity is consistent with renal failure. This is accompanied by diffusely increased radiotracer activity throughout the axial and appendicular skeleton is seen with
renal osteodystrophy.
On an MDP bone scan, absent renal and bladder activity is consistent with renal failure. This is accompanied by diffusely increased radiotracer activity throughout the axial and appendicular skeleton is seen with
Renal osteodystrophy
Free pertechnetate results in visualization of what two organs?
thyroid & stomach
Activity seen in which organ on a Tc-99m MDP bone scan would suggest the presence of the radiochemical impurity hydrolyzed reduced Tc-99m (technetium dioxide)?
Liver
How would hibernating myocardium behave on SPECT (perfusion) and FDG pet (viability)?
Low perfusion, normal FDG uptake (perfusio-metabolism mismatch)
What does a Meckel scan detect?
ectopic gastric mucosa
How do you differentiate urinary tract activity causing a false + Meckel scan?
Urinary activity should occur later and should change in position with time
What % of Meckel diverticulum have ectopic gastric mucosa?
50%
When there is ectopic gastric mucosa in a Meckel, what is the sensitivity and specificity of the study?
90%
What are known possible side effects of administration of high dose I-131 for cancer therapy.
Pulmonary fibrosis, sialadenitis, nausea, and hypospermia
What is the name of the project created to help standardize performance and interpretation of PET in patients with lymphoma
International Harmonization Project (IHP)
At what times are images obtained in a In-111 DTPA for NPH?
4-6, 24, 48, and 72 hours
