Clinical Flashcards
2 reasons for the T-half you get with chromium labeling.
Elution of Cr from normal RBCs
the fact that you’re labeling all ages of RBCs (some of which are already 120d old)
What are the units for bone density?
a. BMD = g/cm2
BMD - basis set determination (I think this is synonymous with basis set decomposition). How does this affect BMD and soft tissue attenuation? (2 marks)
Mathematical theory used in DXA, assumes that the person is made of only two densities (bone and soft tissue). Does not take into account fat density, and assumes that fat density is combination of a positive amount of soft tissue and negative amount of bone. This will falsely decreased the BMD. If the amount of marrow fat is known, a correction factor can be applied to the BMD measurement.
three dimension basis set has more information since we can image bone, soft tissue, and adipose tissue separately while with the two dimension set in Fig. Fig.77 the adipose tissue appears as a positive amount of soft tissue and a negative amount of bone.
.Dimensionality and noise in energy selective x-ray imaging
X-ray transmimssion factor through a physical object can be decomposed into equivalent densiities of two any two designated materials.
Ignoring fat can artifically reduce BMD. When marrow fat is known, DXA estimation of BMD can be corrected
Why is the femoral neck the reference standard for osteoporosis and fracture risk?
This site has been the most extensively validated, and provides a gradient of fracture risk as high as or higher than that of many other techniques.
Advantages of central DXA
Consensus that bone mineral density results can be interpreted using WHO T‐scores
Proven ability to predict fracture risk
Basis of new WHO algorithm for predicting fracture risk
Proven for effective targeting of antifracture treatments
Good precision
Effective at monitoring response to treatment
Acceptable accuracy
Stable calibration
Effective instrument quality control procedures
Short scan times
Rapid patient set up
Low radiation dose
Availability of reliable reference ranges
Name 3 advantages of DEXA over radionuclide bone densitometry.
Improved resolution; Improved image quality; Improved precision; Reduction in scan time to 2-5 minutes
x-ray tube as the radiation source. The device is pulsed alternatively at two energies- usually 70 and 140 keV. The attenuation between bone and soft tissue is greater for the low energy beam. By entering both attenuation profiles into an equation, the soft tissues can be subtracted and an attenuation profile of the bony components can be calculated [3,4]. The radiation dose from the procedure is only about 1/1000 of that from a routine spine film.
What is the LSC in bone densitometry and what does it signify?
Amount by which one BMD value must differ from another in order for the difference to be statistically significant at a 95% confidence level
DXA – times when technologist have to do precision testing
After: basic scanning skills have been learned; 100 patients have been scanned; when a new DXA system is installed; and whenever their skill level has changed.
Name 2 methods of producing photons of two different energies in DXA?
Voltage switching (e.g. Hologic) - continuously switch voltage between high and low values K-edge filtering (e.g. GE, Norland) - Use carefully chosen metal filter (thin sheet of a special metal) to create two separate energy peaks in x-ray spectrum
Why do we use the Robinson formula when calculating GFR? What happens to GFR is we don’t use it?
Robinson formula calculates ideal body weight. Using IDW in a GFR calculation is more accurate than actual body weight. If you don’t apply it, you will overestimate GFR in fatter people.
Cockcroft and Gault equation:
CrCl = [(140 - age) x IBW] / (Scr x 72) (x 0.85 for females)
Robinson is a formula to calculate ideal body weight:
Men: Ideal Body Weight (in kilograms) = 52 kg + 1.9 kg for each inch over 5 feet
Women: Ideal Body Weight (in kilograms) = 49 kg + 1.7 kg for each inch over 5 feet
A patient presents after dental extraction while on bisphosphonates. He presents with pain in the mandible. What is the most likely consideration?
Osteonecrosis of the jaw
Define acronym:
a) RIS
b) PACS
c) DICOM
a) Radiology Information System
b) Picture Archiving and Communication System
c) Digital Imaging and Communications in Medicine
What is a MeSH and what does it mean to explode a MeSH?
MeSH (Medical Subject Headings) is the (U.S.) National Library of Medicine’s controlled vocabulary thesaurus and is used for indexing articles for MEDLINE
n PubMed, MeSH (Medical Subject Headings) terms (as well as any subheading that is the top of a “subheading tree”) are “exploded” automatically to retrieve citations that carry the specified MeSH heading (or subheading) and also retrieve citations that carry any of the more specific MeSH headings (or subheadings) indented beneath it in the Tree structure
What is the difference between a systematic review and a metaanalysis?
Systematic review - literature review that collects and critically analyzes multiple research studies or papers.
Meta-analysis - statistical analysis that combines the results of multiple scientific studies.
The aim then is to use approaches from statistics to derive a pooled estimate closest to the unknown common truth based on how this error is perceived.
Phase 1, 2, 3 trials (know what each phase involves)
1 = initial trial of a drug in humans for dosing, safety, and early efficacy (20-80 patients)
2 = Drug safety and efficacy in a specific disease setting (100-300 patients)
3 = Larger trial comparing to best available therapy to confirm efficacy and safety; often used for drug approval (1000-3000)
4 = after FDA approval to gain info about drug risks and benefits
Name 6 roles of a president of a medical meeting before, during and after the meeting.
- Prepare the agenda
- Convening the Assembly
- Ensure the quorum
- Open meeting
- Facilitate the meeting
- Ensure that meeting keeps to schedule
- Verify the right to speak and interventions
- Close the meeting
- Ensure that minutes are produced
Name 3 ways a nuclear medicine physician can be a health advocate.
- Clearly explain radiation protection standards to others
- Precise information to patients about a possible post-treatment pregnancy with iodine
- Inform nursing patients about the duration of cessation of breastfeeding
Petition for purchasing of CZT semiconductor gamma cameras which would enable reduction of patient dose while maintaining equivalent image quality and scanning time
You see requisition for 12 year old and “hypothyroid”
- Phone the referring physician to clarify the indication for the study (Health advocate, Medical expert)
- If the study was indeed ordered to evaluate hypothyroidism, inform the referring physician that this is not the appropriate test
You work in a small department with two dual head cameras. One head on one of the cameras is not working.
a)List 2 actions to take to decrease chance of equipment breakdown
b) List 3 ways you would prioritize patients if you had to cancel patients c) What studies would you perform on the defective camera to be least disruptive to the day
a) Regular maintenance and QC
b) 1. Urgent/Emergent cases
2. Inpatients
3. Patients who have travelled from out of town
c) - Studies that are unlikely to need SPECT
- Studies that don’t require both anterior and posterior views
Eg. Renogram, thyroid imaging
Patient just received subcutaneous injection. Fever, dyspneic, systolic blood pressure 95, heart rate 110 (and rash?).
a)What is happening (0.5 marks)
List 2 of your first actions to take
a) anaphylactic shock
b) Call a code
Assess ABCs and Get IV access
Maybe give an intramuscular dose of epi (.3-.5 ml 1:1000 in lateral thigh) while obtaining IV access.
List the medication and adult doses that could be used for the following situations: (A)Antidote for dipyridamole. (B) Cerebral perfusion reserve. (C) Hydronephrotic collecting system on renography.
- Aminophylline 100-200 mg IV
- Acetazolamide 1000 mg IV
- Furosemide 40 mg IV
A Nuclear Medicine technologist tells you that a patient has shown up, referred for a bone scan to rule out a metatarsal stress fracture, but the patient thinks she may be pregnant (last period was 4 weeks ago). Do you proceed with the scan? Give reasons.
No, get a pregnancy test first. Especially considering the study is not an emergency. Can consider doing MRI.
6 absolute contraindication to cardiac stress
Absolute:
- Acute MI (<4d)
- Acute PE
- Acute dissection
- Acute myocarditis/pericarditis
- Severe pulm hypertension
- Severe angina (high risk/unstable)
- Severe CHF (decompensated or poorly controlled)
- Severe HTN (200/110 mmHg)
Relative:
- Known LM disease
- Moderate AS
- Outflow tract obstrution
- Arrhythmia
- High degree AV block
6 contraindications (relative or absolute ) to dipyridamole
Absolute:
1. Asthma with ongoing wheezing (if mild, can pretreat with two puffs of albuterol or a comparable inhaler)
2. 2nd/3rd degree AV block without pacemaker
3. Systolic BP < 90
4. Known hypersensitivity
5. Recent xanthine
+ ones from above
Relative:
1. Profound sinus bradycardia (< 40 bpm)
What are the mechanisms of action of dipyridamole and adenosine?
a. Dipyridamole: Indirectly inhibits the metabolism of adenosine by blocking adenosine deaminase and phosphodiesterase.
b. Adenosine readily diffuses into extracellular space, where it acts on coronary endothelial cells’ A2A receptors, causing vasodilation. It also acts on A1 receptor subtypes (causing AV heart block), and on A2B & A3 receptor subtypes (causing bronchospasm).
Apical hypertrophic cardiomyopathy
a) EKG findings?
b) MPI findings?
a) Typical finding is giant (>10 mm) inverted T waves in the anterolateral leads
b) Increased apical tracer uptake, ‘spade-like’ deformity of the left ventricle, ‘Solar Polar’ map pattern
Stress: relative apical ischemia (reduced apical flow reserve)
Name 2 complications of Kawasaki disease.
a. Coronary artery aneurysms
b. Valvular disease
c. Aortic aneurysms
d. Intestinal ischemia and obstruction
e. Uveitis and conjunctival hemorrhage
f. Cerebral ischemia and infarct
What is Takotsubo cardiomyopathy?
Transient systolic dysfunction of the LV in the absence of obstructive CAD. Most commonly there is ballooning of the LV apex, and it most commonly occurs in women exposed to sudden emotional or physical stress.
What are 4 advantages of thallium in myocardium perfusion imaging.
- Redistribution from single injection
- Viability
- Better target to background
- highest myocardial extraction coefficient (85%)
- peak myocardial concentration at 10 minutes after injection (image earlier)
- Longest shelf life
- Cheaper
Which segment model is standard according to some (?) cardiac paper? What is SDS and how is it calculated? ( I think they also asked importance of SDS?)
17 segment model.
Sum difference score. SSS-SRS=SDS
Many investigators consider a SSS < 4 a negative exam [146]. A SSS of 4-8 is associated with an event rate of 1-3% [144]. More extensive and severe abnormalities, encumbering 10% of more of the myocardium, are associated with up to 5% annual cardiac event rates. Patients with less than 10% ischemic myocardium are candidates for an initial strategy of intensive medical and lifestyle intervention with deferred revascularization.
4 or 5 high risk prognosticators on cardiac nuc study.
1- Multiple perfusion defects in more than one coronary artery distribution- reflective of multivessel disease
2- Single large perfusion defect. PCI fails to offer any prognostic benefit over optimal medical therapy, unless a significant amount (generally more than 10%) of the LV myocardium is ischemic [80].
3- TID
4- Post stress LVEF < 40%
5- Increased lung activity on post stress imaging (>0.5 thallium, >0.4 sestamibi/tetrofosmin)
6- Increased end-systolic volume (greater than 70 mL)
Define TID? What is the cause?
Transient Ischemic DIlatation.
TID is considered to represent severe and extensive subendocardial ischemia and has been shown to be highly specific for critical stenoses in vessels that supply a large portion of the myocardium (ie, proximal left anterior descending/left main or multivessel lesions (90% stenosis). Implies that disease is more extensive than the (sum of the) focal defects alone.
You read a MIBI scan that shows mild to moderately severe ischemia involving the entire inferior wall. The EF is normal. The patient is asymptomatic, is not on any medications, does not have known coronary artery disease, has a normal ECG and no risk factors. According to the Courage trial, what would you recommend as the most appropriate next step? The family physician contacts you and asks whether PCI would reduce his chances of myocardial infarction and death?
Next step
o Assuming that I am satisfied that the inferior wall defect is not due to attenuation artifact, since
the patient is asymptomatic, I would recommend conservative medical management as the first
step
Benefit?
o No significant difference between conservative best medical management and PTCA/PCI for
mortality
The COURAGE trial (reported in NEJM 2007): Optimization of medical therapy alone without PCI is sufficient for initial treatment of patients with stable coronary artery disease. The addition of PCI to optimal medical therapy does not improve mortality or cardiovascular outcomes as evidenced by the COURAGE trial, and given its risks as an invasive procedure, should not be offered as initial treatment strategy for this patient population.
A fixed perfusion defect is seen on a MIBI SPECT study. What are 3 ways to differentiate attenuation artifact from a true defect?
- cine data for motion artifact and attenuation
- Review attenuation corrected images
- Perform prone imaging, which separates the subdiaphragmatic structures further from the heart and
can reduce attenuation artifact
What is the length of each stage in a Bruce protocol stress test? After completing 1 stage in a Bruce protocol stress test, how many METS will the patient have achieved?
- Length: 3 minutes
* METS: 4.6
4 causes of decreased PFR (peak filling rate) on MUGA (peak filling rate)
Coronary artery disease CHF Cardiomyopathies Aortic valve disease Rejection post cardiac transplant Normal aging HTN LVH due to aortic stenosis mitral stenosis Medications: e.g., doxorubicin, nitro, beta blockers Pericardial disease
Diastolic function assessment. The lower normal limit of PFR is 2.50 end diastolic volume per second (EDV/s).
Describe 3 methods to prepare a patient for cardiac viability study using FDG-PET.
- Oral glucose load
o 50-100 g glucose po 1-2h before exam
o In a diabetic check serum glucose and administer insulin per sliding scale
2. Hyperinsulinemia euglycemic clamp o Start 2 IV’s o Run insulin 100 mIU/kg/h in one IV o Run glucose (20% in 500 ml) + KCl (20 ml of 15%) solution in second IV o Adjust to maintain euglycemia
- Nicotinic acid derivatives
o Acimipox 250 mg
a) List 4 imaging patterns for cardiac perfusion and FDG
b) Give most typical cause for each of the FDG patterns
Pattern Perfusion FDG metabolism
Normal Present Present
Ischemic Absent or decreased Present
Infarcted Absent Absent
Hibernating Decreased Normal or increased
Stunned Present Present
Indications for cardiac PET
•A) prior stress imaging study of poor quality or inconclusive
•B) body characteristics affecting image quality
–Obesity, large breasts/implants, pleural effusion
•C) High-risk patients
–Chronic kidney disease, DM, CABG, suspected LM or 3VD
•D) Young patients with established CAD
–To decrease radiation
•E) If myocardial blood flow quantification is desired
Fixed stress and 4 hr delayed thallium defect (give 2 non artifactual causes, and 2 pet tracers to differentiate it.
Causes: Infarct vs hibernating myocardium (Thallium not 100% sensitive/specific)
FDG or C11-palmitate or C11-acetate for viability
4 causes for reversed mismatch perfusion and FDG.
Reverse mismatch pattern denotes normal perfusion with relatively reduced metabolism.
○ non-ischemic cardiomyopathy ○ LBBB ○ repetitive stunning ○ following revascularization early post-MI when the myocardium is stunned ○ in some patients with diabetes
In hibernating myocardium, what is type of metabolism is the main source of energy? In the fasting state, what is the usual substrate for normal myocardium? What is observed on an FDG-PET study in hibernating myocardium.
• Hibernating: glycolytic
• Fasting: fatty acids
• What is observed in hibernating:
o Preserved uptake on FDG-PET imaging (perfusion-metabolism mismatch)
Name 3 causes of cardiac uptake on pyrophosphate scan.
Acute MI Unstable angina Valvular calcification (very focal) Resuscitation / cardioversion Myocarditis / pericarditis Amyloidosis Cardiomyopathy
What does heparin do in cardiac imaging
IV unfractionated heparin activates lipoprotein and hepatic lipases, thereby increasing plasma free fatty acid levels, and ultimately causing a reduction in glucose consumption of normal myocytes. Doses as high as 50 IU/Kg were used in prior studies.
Rpt 23: What energy sources (plural) does heart use
a) typically? Free fatty acids(major), Glucose
b) in fasting conditions? Free fatty acids
c) in carbohydrate-rich conditions? Glucose
Regarding hibernating myocardium:
a. What is metabolic substrate of hibernating myocardium? Glucose
b. What is metabolic substrate of normal myocardium? Fatty acids
Name 4 contraindications to atropine.
- Narrow angle glaucoma
- Obstructive uropathy
- A-fib with uncontrolled HR
- Obstructive GI disease or paralytic ileus
- Known hypersensitivity
Name 2 surgical procedures that would be performed in a repair for transposition of the great arteries.
a. Historical: Senning and Mustard
b. Today: Jatene
Patient is mildly hypocalcemic and has mild elevation of parathyroid hormone. What is cause of increased PTH? What will the scan look like (which scan are they talking about)?
Secondary hyperparathyroidism due to chronic renal disease.
Sestamibi: will be negative for parathyroid adenoma
Bone scan: can have metabolic superscan
Overproduction of parathyroid hormone occurs in response to hyperphosphatemia, hypocalcemia, and impaired 1,25-dihydroxyvitamin D production by the diseased kidneys.
3 ways parathyroid functions in the body
- Promotes bone resorption by osteoclasts
- Calcium absorption in bowel via vit D
- Calcium resorption in the renal tubules
Parathyroid imaging: up to how many parathyroid glands can one have, and what is the typical number? Where can ectopic parathyroid glands lie? The technologist informs you that instead of Tc-MIBI, Tc-Tetrofosmin was delivered instead. Can you use this instead?
How many: up to 6-7, typically 4
Ectopic locations
- Typically along the thyrothymic tract, most commonly in the anterior mediastinum, although
can be anywhere from high cervical to inferior to the heart
- Can lie anywhere along the migratory paths of the 3rd and 4th branchial pouches; from the cricothyroid cartilage superiorly to the tracheal carina inferiorly.
Literature indicates no, tetrofosmin inferior to sestamibi
Describe 3 types of Hyperparathyroidism.
- Primary - hyperfunction of glands themselves. There is oversecretion of PTH due to a parathyroid adenoma, parathyroid hyperplasia or, rarely, a parathyroid carcinoma. This disease is often characterized by the quartet stones, bones, groans, and psychic overtones referring to the presence of kidney stones, hypercalcemia, constipation and peptic ulcers, as well as depression, respectively
- Secondary - physiological (i.e. appropriate) secretion of parathyroid hormone (PTH) by the parathyroid glands in response to hypocalcemia (low blood calcium levels). The most common causes are vitamin D deficiency (caused by lack of sunlight, diet or malabsorption) and chronic kidney failure.
- Tertiary - long-term secondary hyperparathyroidism which eventually leads to hyperplasia of the parathyroid glands and a loss of response to serum calcium levels. This disorder is most often seen in patients with chronic renal failure and is an autonomous activity.
For a parathyroid scan, what is the difference between a dual phase vs. a dual isotope study?
o A dual phase scan relies upon differential washout characteristics between thyroid tissue and
parathyroid tissue at early and late time points with sestamibi (i.e., thyroid washes out,
parathyroid does not)
o A dual isotope study compares or subtracts a thyroid uptake scan (pertechnetate or 123I) from a
sestamibi study, to determine what constitutes parathyroid uptake
Thyroid surgeon to take out thyroid and do central compartment clearance. What are the anatomical boundaries of central compartment?
Hyoid bone (superior)
Carotid arteries (laterally)
Superficial layer of deep cervical fascia (anteriorly)
Deep layer of deep cervical fascia (posteriorly)
Innominate artery on right and corresponding axial plane on left (inferior)
List mechanism of PTU and methimazole
PTU: Affects thyroid peroxidase therefore decreases oxidation/iodination/coupling, Non-competitive inhibitor for T4 to T3 conversion
Methimazole: Affects thyroid peroxidase therefore decreases oxidation/iodination/coupling
List 4-5 reasons for increased RAIU, excluding hyperthyroidism (Graves) and iodine deficiency
- TSH-secreting pituitary adenoma
- Early Hashimoto’s thyroiditis
- Rebound after subacute thyroiditis
- Rebound after thyroid hormone withdrawal
- Lithium
- Pregnancy
- Medications – overtreatment with PTU
- Dyshormonogenesis (decompensated)
What is a discordant nodule?
A discordant nodule is hot on Tc-99m images, but cold on the I-123 exam. Discordant nodules can be explained by either the preservation of Tc-pertechnetate trapping, but failure of organification or the rapid release of organified iodine from the nodule (iodine has washed out of gland by time of scanning at 24 hours)
Solitary discordant thyroid nodules are generally considered to be rare (2 to 8%) and cases of discrepancy between the Tc-99m and I-123 studies appear most often in multinodular goiters [6,17]. Discrepancies are also far more likely to be caused by benign thyroid disorders rather than malignancy
A conservative approach to this problem would be to re-scan any patient with a hot nodule on the Tc-99m pertechnetate exam with I-123. However, the risk of cancer in a nodule appearing hot with Tc-99m and cold with radioiodine is probably so low that routine reimaging is not necessary
List 5 high risk thyroid cancer pathologies or cell types
Anaplastic, medullary, Tall cell, Hurthle, follicular
Papillary thyroid cancer. Thyroglobulin remains high post-surgery. What measurement do you use for 2 sequential thyroglobulin?
Thyroglobulin doubling time (< 1 year, 1-3 years and > 3 years all different prognoses)
b) What prognosis does it indicate?
Increased chance of death
Thyroid cancer
a) List 2 cell types of thyroid cells (2 marks)
b) List cancers associated with these cell types and biochemical markers (2 marks)
a) Follicular and C (parafollicular) cell
b) Papillary and follicular – thyroglobulin
Medullary – calcitonin and CEA
Radioiodine treatment for hyperthyroidism. How long to stop medications?
b) thioamides (PTU and methimazole) – 3 days
e) iodine-containing multivitamins 7-10 days
c) Lugol’s 2-3 weeks
d) CT contrast 6-8 weeks
a) amiodarone – 3-6 months
f) SSKI 2-3 weeks
What is the role of lithium in thyroid cancer treatment? What is a condition in which it could be used?
Combining with radioiodine in the treatment of metastatic radioiodine resistant thyroid cancer (increases radioiodine uptake).
2 causes of thyrotoxicosis and decreased RAIU
- Thyroiditis
- Iodinated contrast
- Exogeneous
a) Facticious hyperthyroidism
b) Exogeneous thyroid hormone in food/medication - Ectopic
a) struma ovarii
b) follicular thyroid CA with functioning mets - Jod-Basedow
Name 4 causes of absent or low uptake of the thyroid on thyroid scan.
- Thyroidectomy
- Thyroiditis
- Iodinated contrast
- Iodine rich diet
Name 4 medications that can decrease RAIU.
- PTU
- Methimazole
- Iodinated contrast
- Amiodarone
- Synthroid
.What is the reason for doing perchlorate washout test?
To identify thyroid iodine organification defects
in patients with defects in peroxidase activity (usually hypothyoid), trapped radioiodine is rapidly discharged when sodium perchlorate (an inhibitor of thyroid iodide trapping) is administered.
Thyroid uptake is then determined between 2 and 4 hours after administration of the dose. Potassium perchlorate 109 mg/kg is then administered orally and a repeat measurement of RAIU performed in 30 to 60 minutes. A decrease in RAIU greater than 10-15% following perchlorate administration is indicative of any organification defect.
When do you stop methimazole before treatment and when to re-start.
SEE NOTES FOR STOPPAGE TIMES
Can be restarted 2-3 days after therapy.
4 clinical risk factors for thyroid cancer.
- Hx of childhood head and neck radiation.
- Total body irradiation for bone marrow transplant.
- Family history 1st degree relative.
- Cowden’s, FAP, Carney complex, MEN2.
. 2 reasons to image congenital hypothyroidism.
It can be transient (maternal antibodies or maternal meds) or permanent.
Aplasia, hypoplasia/ectopic thyroid or dyshormonogenesis.
Image to differentiate anatomical causes from functional causes.
List 6 causes for focal uptake on FDG-PET in thyroid gland.
- Thyroid adenoma
- Thyroid malignancy (e.g., papillary or follicular carcinoma)
- Thyroid abscess
- Thyroid hematoma
- Thyroid lymphoma
- Intrathyroidal parathyroid lesions (e.g., parathyroid adenoma, parathyroid carcinoma)
What are 3 causes of jaundice in an infant.
Biliary atresia Neonatal hepatitis Sepsis/TORCH infection Breast feeding/breast milk Choledochal cyst Alagile syndrome
List 4 clinical/laboratory/pathology (non-imaging) findings that may differentiate between biliary atresia and hepatitis.
Onset - earlier onset of jaundice and of acholic stools in biliary atresia compared with those who have neonatal hepatitis.
Associated abnormalities – congenital heart disease and polysplenia syndromes associated with biliary atresia.
GGT – usually elevated in biliary atresia; if low or normal should look for other diagnosis
Patient demographics - Neonatal hepatitis – more common among males, especially low birth weight or preterm; biliary atresia - more common in females of normal weight
Liver biopsy – can look for obstructive vs. non-obstructive features
What tracer is used for biliary atresia versus hepatitis? What is interpretation criteria for each? What is the dose and time of the pre-medication given.
Tcc99m – mebrofenin 1mCi IV
Mebrofenin recommended over other IDA agents because of better hepatic excretion.
Standard dose of 1mCi is given because of the potential need for 24hr imaging and the decay of Tc99m at 24hrs (normal max IDA dose is 0.5mCi)
Pharmacologic enhancement with phenobarbitol: 2.5mg/kg po bid x 5 days:
o phenobarbitol enhances hepatic excretion of the tracer, which should allow earlier visualization of excretion into the bowl → this is an issue because we are imaging with Tc99m, which decays significantly by the time we get to doing 24hr images
Lack of biliary excretion into the bowel at 24 hrs
o Image first at 1hr, return in 4hrs and 24hrs to confirm
o not diagnostic of biliary atresia, but supportive of the diagnosis
o False +ves:
▪ Immature intrahepatic transport mechanisms
▪ Severe intrahepatic cholestatsis (alagille’s syndrome)
What is a Kasai procedure. What is a Kasai procedure used to treat?
Portoenterostomy: to bypass atretic biliary duct
Used to treat biliary atresia
List 4(6) actions of CCK
Moving a bolus into stomach and another bolus out of stomach.
- relax LES
- increase pyloric tone
- decrease gastric motility
- increase pancreatic secretions
- increase gall bladder contraction
- increase small bowel motility
6 causes of non vis of GB after 1 hr of hida study (excluding acute cholecystitis and chronic cholecystitis)
Prolonged fast (resulting in gall bladder filled with bile) Complete common duct obstruction Postcholecystectomy Acute pancreatitis Nonfasting normals Severe hepatocellular disease
Name 2 advantages of using a longer (60 minute) rather than a short (3 minute) infusion for Sincalide. List 4 clinical conditions (not medications) that cause decreased gallbladder contraction.
2 advantages
o Longer infusion is more physiologic and results in fewer symptoms
o Largest study to date using 60 minute infusion found less variability in gallbladder ejection fraction
4 causes o Chronic acalculous cholecystitis o Sphincter of Oddi syndrome o Biliary dyskinesia o Cystic duct syndrome
List one effect and one use of the following agents in hepatobiliary scintigraphy: CCK, morphine, phenobarbital
CCK:
o Induces gallbladder contraction
o Can be used to evaluate gallbladder ejection fraction
Morphine:
o Causes sphincter of Oddi contraction
o Can be used to reduce time of hepatobiliary scintigraphy for acute cholecystitis if have nonvisualization of GB at 30-60 min
Phenobarbital:
o Induces hepatic enzymes and improves uptake
o ↑ specificity of hepatobiliary scintigraphy for biliary atresia
Name 3 lesions that show uptake on a hepatobiliary scan.
Hepatocellular carcinoma
Focal nodular hyperplasia
Hepatic adenoma
How to detect aspiration post feeds in a child?
Radionuclide Salivagram
List 4 medications or classes of medications that decrease gastric emptying
Drugs that increase motility o erythromycin o metoclopramide o domperidone o cisapride o tegaserod o thyroxine
Drugs which delay motility o opiates o antispasmodic agents (anticholinergic) o atropine o nifedipine o progesterone o octreotide o theophylline o benzodiazepine o phentolamine
Conditions that change gastric emptying:
o Increased gastric emptying: Gastritis, Hyperthyroidism
o Decreased gastric emptying: Anorexia, fatty meal, protein meal, hypothyroidism
List amount and quantities of meal for gastric emptying as per SNM
meal eaten within 10 minutes ▪ 4oz liquid egg white ▪ 2 slices white toast ▪ 30g jam ▪ 120mL water
Describe the meals used for liquid and solid gastric emptying.
Solid: 0.5-1.0mCi 99m-Tc Sulfur Colloid, 4oz. egg white equivalent, 2 slices white toast, 30g strawberry jam, 120 cc H20, consumed within 10 minutes
Liquid: Not as sensitive a test for delayed emptying as solid. Can use any liquid. Ensure used locally.
- Solid gastric emptying has three phases in the stomach, accommodation, trituration and emptying, and the last phase is linear. The liquid emptying does not require trituration, and it is exponential
Name a tracer being investigated for congenital hyperinsulinism.
- F-18 DOPA PET/CT
Urea breath test
a) Urease. What happens to 14C-urea. (What are products of urease?)
b) Explain reason for achlorhyrdia causing positive test
a) 14C urea is hydrolyzed into ammonia and 14CO2 in the presence of urease
b) Achlorhydria (absence of hydrochloric acid in gastric secretions) can cause overgrowth of non-H.Pylori bacteria (resulting in a false positive)
How does partial gastrectomy lead to a false positive urea breath test?
Potential resultant bacterial overgrowth (achlorhydria) with resultant non-H. pylori urease
In a C-14 urea breath test, what is the bacterial enzyme responsible for degrading the urea? What two components is the urea degraded to in the stomach?
List 2 causes of false positive C-14 urea breath tests.
List 3 classes of medications that can cause false negative C-14 urea breath test.
Enzyme: urease
Two components: NH3 and 14CO2
False positives
o Chewing capsule
o Chemiluminescence
- achlorhydria
False negative medications
o Antibiotics
o Proton pump inhibitor
o Bismuth
What does aminopyrine test measure?
The 14C-Aminopyrine Breath Test provides quantitative assessment of liver function in conditions such as established chronic hepatitis and cirrhosis.
Name 2 causes of focal decreased activity on a liver sulfur colloid scan.
CYST, METASTASIS, HEPATOMA, HEMATOMA, ABSCESS, HEMANGIOMA