FRCR 2A Nuclear Medicine Radiology SBA

A. Correct. A three-phase bone scan is almost always a good choice for the initial evaluation of possible osteomyelitis, especially if the plain radiographs are normal (and there is no other underlying bone pathology which would be likely to cause increased bone uptake of the tracer and limit the usefulness of the exam). It is both highly sensitive and has a very high negative predictive value for osteomyelitis. The radiopharmaceutical is readily available, the exam is easily performed, and the radiation dose is lower than for Ga-67 or In-111 labeled WBC imaging. The normal increased radiopharmaceutical activity at the growth plates is a potential limitation in pediatric patients, but this would also be a limitation with Ga-67 citrate imaging.
B. A three-phase bone scan is the most appropriate next study. In some settings, Ga-67 citrate may be used in addition to bone scan to improve diagnostic accuracy, with the gallium scan performed after the bone scan.
C. In-111 WBCs are generally avoided in pediatric patients if there is a good alternative, because of the high radiation-absorbed dose to the spleen. A three-phase bone scan is a better choice.
D. A bone marrow scan can be used in conjunction with radiolabelled WBC imaging to improve diagnostic accuracy in the evaluation of osteomyelitis, but it has no role as an initial imaging agent in this setting.

A. Size of the adenoma affects sensitivity, not specificity. Parathyroid adenomas must attain a size greater than ~500mg to be generally detectable, although this is usually the threshold at which they are clinically (not chemically) manifest.
B. This is frequently untrue and unrelated.
C. There is no in vitro evidence supporting this statement.
D. Correct. Slow Tc-99m sestamibi wash-out is the hallmark of a parathyroid adenoma (or carcinoma). This phenomenon is specific for hypercellular parathyroid neoplasms and is not a characteristic of thyroid neoplasms.

A. A narrow window would reduce the image count rate.
B. While the count rate for generating the image would be reduced, the actual detected photon count rate would not be changed and the dead time losses would not be reduced.
C. Background radiation counts would be reduced, but this is a minor component compared with the scatter radiation coming from the patient.
D. Correct. Gamma rays are emitted at very specific energies. If the detected photon has a lower energy, it may be assumed that the photon was from a Compton scatter interaction and is not coming directly from the location of the radionuclide tracer.

A. Correct. The basis of this study is that the Helicobacter pylori bacteria present in the stomach in patients with this infection contain the enzyme urease, necessary for the breakdown of urea. This metabolism of C-14 labeled urea results in the formation of C-14 labeled CO2 gas, which is then detected using a liquid scintillation counter. In the absence of the bacterial infection, the cells of the gastric mucosa, which lack the enzyme urease (like all mammalian tissue), are unable to break down the urea, and thus no C-14 labeled CO2 gas is formed, resulting in a negative study.
B. The study has nothing to do with the presence or absence of gastric acid. Only the presence of the enzyme urease, found in the Helicobacter pylori organisms, but not in the gastric cells, can break down the C-14 urea to form C-14 labeled CO2 gas.
C. The physiology of the study is as described above. In no way is the formation of glucose or other aspects of carbohydrate metabolism involved.
D. Again, the metabolism of C-14 labeled urea by bacterial urease is the basis of the study. Renal excretion is not involved, and no urine collections are performed. The study is performed by having the patient ingest the radiopharmaceutical, followed by collection of two breath samples, which are analyzed in a liquid scintillation counter for the presence of C-14 labeled CO2 gas.

A. The normal biodistribution of Tc-99m methylene diphosphonate (MDP) includes the axial and appendicular skeleton, kidneys and bladder. The liver, spleen, mediastinum, and brain, which are visualized in this case, are not seen on a normal bone scintigram.
B. The normal biodistribution of Tc-99m sulfur colloid includes intense liver and spleen activity. Less intense activity is identified in the central bone marrow (skull, ribs, sternum, vertebral bodies, pelvis, proximal humeri and femora). The most intense activity in this study is osseous. Moderate activity is seen within the spleen and low level activity in the liver, mediastinum and brain. This biodistribution is not typical for sulfur colloid.
C. Correct. The normal biodistribution of F-18 fluorodeoxyglucose (FDG) is accumulation in the brain, myocardium, blood vessels, pharynx, liver, spleen, bone marrow, kidneys, ureters, urinary bladder, and GI tract. Intense marrow uptake is seen in this patient with lymphoma after administration of granulocyte colony stimulating factor (G-CSF), which is given to support bone marrow function following therapy. Normal marrow uptake is usually less intense than hepatic uptake. While this distribution is not normal, it is more characteristic of FDG than any of the other tracers listed.
D. The normal biodistribution of F-18 sodium fluoride is osseous, with uptake dependent on regional blood flow and osteoblastic activity by chemisorption. Hydroxyl groups are exchanged to form fluoroapatite in the hydroxyapatite crystals. Because of the superior spatial resolution and threedimensional localization afforded by PET imaging, there is a high sensitivity for the detection of metabolically active skeletal lesions using F-18 sodium fluoride.

A. The abnormal uptake in this case is located in the posterior mediastinum, where adenopathy due to lymphoma may occur. However, the linear configuration of the activity is characteristic of esophageal activity, rather than the typical focal rounded appearance of adenopathy. Furthermore, no other sites of adenopathy are present. The findings are characteristic of an esophageal neoplasm, making squamous cell carcinoma or adenocarcinoma far more likely than lymphoma.
B. As discussed above, the linear uptake located in the posterior mediastinum is characteristic in appearance for an esophageal neoplasm. There are no focal pulmonary nodules or foci of mediastinal or hilar adenopathy, as would be anticipated in the presence of bronchogenic carcinoma.

Findings: There is marked increased activity in the stomach, thyroid, and salivary glands, with some activity seen in bowel and bladder.

A. Patients with severe osteoporosis may demonstrate relatively decreased activity in the skeletal system, with increased soft tissue activity. Diffusely increased skeletal uptake may also occur. However, osteoporosis would not show localization in the sites mentioned above.
B. Metastatic calcifications can result in increased activity in the stomach, lungs, kidneys, and other soft tissue locations. However, it would not demonstrate increased activity in salivary glands or thyroid.
C. Correct. Free Technetium-99m pertechnetate, which occurs when there is poor labeling of the MDP, will localize in the locations mentioned above, the stomach, thyroid, and salivary glands. This condition can be confirmed by performing thin-layer paper chromatography on the radiopharmaceutical.
D. Metastatic papillary thyroid cancer may show areas of increased or decreased activity in the skeleton on a bone scan. Soft tissue metastases in the thyroid bed, cervical lymph nodes, lungs or mediastinum may be seen on a whole body I-131 or I-123 scan, but are not normally visualized on a bone scan. Thus, metastatic papillary thyroid carcinoma would not demonstrate the distribution of radiotracer seen above.

"A. Correct. Hepatobiliary imaging demonstrates non-visualization of the gallbladder and increased pericholecystic hepatic uptake. The latter scintigraphic finding, known as a ""rim sign"", is often associated with acute gangrenous cholecystitis or otherwise more advanced disease. 

A. Zevalin is not indicated for multiple myeloma.
B. Zevalin is not indicated for leukemia.
C. Zevalin is indicated for low-grade or follicular B-cell NHL that has relapsed during or after treatment with other anticancer drugs and newly diagnosed follicular NHL following a response to initial anticancer therapy.
D. Zevalin is not indicated for HD.

A. Although the liver does show activity, the tracer does not localize to the hepatocytes.
B. Tc-99m sulfur colloid localizes to the reticuloendothelial system, therefore the liver, spleen, and bone marrow show activity.
C. Tc-99m is not excreted into the biliary system.
D. Tc-99m is not excreted into the lymphatic system.

A. In-111 leukocyte can be used in infection imaging, but has been shown to have false positive results in discitis osteomyelitis.
B. Tc-99m MDP by itself is not appropriate as positive findings on a scan are nonspecific. Trauma, tumor, inflammation, etc can be present when bone scans are positive.
C. Ga-67 citrate is an infection agent but must be correlated with skeletal scintigraphy for greatest specificity.
D. Correct. The combination of skeletal scintigraphy and Ga-67 citrate is the most appropriate choice to assess discitis osteomyelitis as far as NM exams are concerned. The relative intensity and extent of uptake between the two studies are compared to assess underlying infection.

A. PTU should be held when performing thyroid scans.
B. Correct. Tricyclic antidepressants interfere with uptake of I-123 MIBG, which is the exam shown.
C. Amiodarone can interfere with thyroid function.
D. Levothyroxine would interfere with a thyroid uptake and scan.

A. Solid-phase gastric emptying studies typically demonstrate an initial lag phase followed by linear gastric emptying in normal subjects.
B. Correct. Liquids follow a monoexponential pattern of gastric emptying normal. Liquid gastric emptying studies are less sensitive than solid-phase studies for the assessment of gastroparesis.
C. As discussed above, the normal patterns of gastric emptying are an initial lag phase followed by linear emptying of solids and a monoexponential emptying of liquids.
D. As discussed above, the normal patterns of gastric emptying are an initial lag phase followed by linear emptying of solids and a monoexponential emptying of liquids.

Findings: There are focal areas of increased tracer uptake noted in the left mid-lung field, near the left major fissure, and also in right middle lobe. There are no significant perfusion defects demonstrated.

Findings: There are numerous focal areas of increased tracer uptake noted in the chest, abdomen and pelvis, many of which are clearly located in the subcutaneous tissues of the abdominal wall and chest wall, best seen on the selected transaxial and sagittal images provided.

A. While several of the lesions demonstrated do project over the lung fields on the MIPS image, the sagittal image demonstrates that at least several are located in the soft tissues of the posterior chest wall, rather than in the lungs. In addition, there is no single dominant lesion that appears to be within a lung. While not excluded, bronchogenic carcinoma is a less likely etiology for these findings than melanoma.
B. As discussed above, the predominance of subcutaneous lesions is less characteristic of metastatic breast carcinoma than of melanoma. There is no lesion demonstrated in the breast, and there is also no evidence of axillary adenopathy or hepatic metastases, which would also commonly occur in metastatic breast carcinoma. Therefore, while not excluded, metastatic breast carcinoma is a less likely etiology for the findings than melanoma.
C. As discussed above, the pattern of subcutaneous lesions is more characteristic of melanoma than lymphoma, particularly in the absence of significant lymph node involvement. While some non-Hodgkin’s lymphomas may primarily involve the skin, this pattern of involvement is not common in Hodgkin’s disease.
D. Correct. Metastatic malignant melanoma is the most likely diagnosis. The pattern of extensive, markedly hypermetabolic lesions in the subcutaneous soft tissues is most characteristic of metastatic malignant melanoma.

A. While both radiopharmaceuticals are efficacious for the detection of abdominal abscesses, Indium-111 leukocyte imaging is often preferred, as the result of the absence of potentially confusing normal bowel activity, as occurs in Gallium-67 scintigraphy. This normal bowel uptake may lead to false positive gallium studies.
B. Indium-111 leukocyte imaging is superior to gallium-67 scintigraphy in the evaluation of suspected infected joint prostheses, in part related to the bone seeking properties of gallium, leading to potential false positive gallium studies due to increased tracer localization secondary to increased bone turnover in the absence of infection.
C. Correct. While sensitive for osteomyelitis, Indium-111 leukocyte scintigraphy has been found to be less sensitive than gallium-67 scintigraphy for the detection of disc space infection.
D. Again, the absence of normal bowel localization makes In-111 leukocyte scintigraphy better suited to the assessment of active inflammatory bowel disease. In gallium-67 scintigraphy, normal bowel uptake, especially in the colon, can be incorrectly attributed to inflammatory bowel disease.

"A. Within the spatial resolution limits of the acquisition system, the offset data can be mathematically shifted or corrected after the fact. Usually the maximum offset is one pixel for a typical 128 x 128 image matrix.
B. Although SPECT phantom imaging results will be adversely affected by an offset center of rotation (COR), the standard analytic method requires SPECT acquisition of either a point or a line source of radioactivity with specialized camera/computer acquisition and processing programs used to identify and correct the COR offset.
C. Misregistration and resultant blurring from COR offset is equally detrimental over the entire field of view.
D. Correct. The difference between the mechanical center of rotation for each SPECT detector assembly and the center of the projected image matrix will produce this characteristic artifact.

"A. The In-111 Zevalin images are not normal. The images demonstrate altered biodistribution of the tracer, with increased uptake in the liver and bone marrow, as well as somewhat prominent bowel activity. Altered biodistribution is a contraindication to Y-90 Zevalin therapy.
B. Altered biodistribution is a contraindication to Y-90 Zevalin therapy.
C. Correct. When administering Y-90 Ibritumomab Tiuxetan (Zevalin) for treatment of relapsed or refractory, low-grade or follicular B-cell Non-Hodgkin’s Lymphoma, including patients with rituximab refractory follicular Non-Hodgkin’s Lymphoma, imaging with In-111 Ibritumomab Tiuxetan (Zevalin) is required prior to therapeutic injection. “The criteria for altered biodistribution are met if any of the following is detected on visual inspection of the required gamma images: Intense localization of radiotracer in the liver and spleen and bone marrow indicative of reticuloendothelial system uptake. Increased uptake in normal organs (not involved by tumor) such as: 1. Diffuse uptake in normal lung more intense than the liver. 2. Kidneys have greater intensity than the liver on the posterior view. 3. Fixed areas (unchanged with time) of uptake in the normal bowel greater than uptake in the liver. 4. In less than 0.5% of patients receiving In-111 Zevalin, prominent bone marrow uptake was observed, characterized by clear visualization of the long bones and ribs.” Altered biodistribution is a contraindication to Y-90 Zevalin administrastion.
D. Demonstration of tumor uptake on In-111 Zevalin images is not a prerequisite for Y-90 Zevalin therapy. In addition, some of the upper abdominal uptake demonstrates on the images may represent sites of tumor uptake.

A. Concurrent antibiotic therapy may result in a false negative test, not a false positive. Patients should be off antibiotic therapy for at least one month prior to the study.
B. Antibiotics and bismuth compounds for 30 days before the test.
C. Sucralfate and proton pump inhibitors(e.g., omeprazole, esomeprazole, lansoprazole, rabeprazole, pantoprazole) for 2 weeks before the test.
D. Correct. False negative studies may occur in patients on antibiotic therapy or in patients receiving bismuth, proton pump inhibitors or sucralfate, which should be discontinued for at least 30 days (antibiotics or bismuth) or 2 weeks (proton pump inhibitors, sucralfate), respectively. However, simple antacid therapy does not affect the results.

D. Correct.

A. The specificity is reduced by increased false positives.

A. Patients should be fasting for a minimum of 4-6 hours prior to injection.
B. Insulin increases muscle uptake and degrades image quality, also resulting in decreased tumor uptake. Diabetic patients may take their normal oral medications or long-acting insulin, but should not receive short-acting insulin for at least 4 hours prior to FDG administration.
C. Correct. Elevated serum glucose levels result in altered biodistribution similar to the effects of insulin, with associated competitive inhibition of tumor uptake. Many laboratories routinely check the serum glucose levels prior to FDG injection.
D. Bowel preparation is not a routine part of patient preparation for a PET oncology study. Bowel uptake is a normal finding, although focal areas of uptake raise suspicion of underlying neoplastic or inflammatory pathology. Similarly, diuretic or muscle relaxant pre-treatment, while useful in selected patients, is generally not considered a standard part of the patient preparation for a PET study.

C. Correct.

C. Correct.

A. This would be a cold lesion on sulfur colloid exam.
B. These lesions are usually cold but can have accumulation of activity.
C. This lesion is also cold.
D. Correct. About two-thirds of these lesions are either isointense or hyperintense compared with the normal liver activity. In addition, FNH most commonly occurs in younger women.

Findings: Whole-body and spot images of the skeleton demonstrate a focal area of decreased tracer uptake within the vertebral body of T12. The remainder of the study demonstrates only mild arthritic changes. The focal “hot spot” in the region of the left elbow is related to a small amount of extravasation of the dose at the site of injection.

A. Dipyridamole should be administered with caution in patients with a history of reactive airway disease or severe obstructive pulmonary disease.

A. Correct. The correct way to wear a ring badge is the TLD detector to the palm as this is the side which would be closest to the radioactive source during daily handling of radioactivity.

A. Incorrect.

A. PET-CT does not have the sensitivity to be used as a screening tool for breast cancer. In addition, the radiation dose and cost are not suited for a screening exam.
B. PET-CT cannot readily differentiate benign from malignant masses.

A. The typical pattern of Alzheimer disease hypometabolism is temporal and parietal lobe involvement.

"A. Correct. If a prior radioisotope study was performed, excreted tracer from that study could falsely elevate the urinary activity creating a false negative exam. 

A. Although there can be increased cortical thickness and density of the dominant forearm in certain populations, the differences in dominant and non-dominant forearm BMD would not account for the normal density of the forearm in this patient with osteoporosis.

A. Correct. The tracer was injected in the reservoir located in the right scalp region. The activity is shown to freely course through the VP shunt catheter. Images of the abdomen and pelvis show free spillage of the tracer into the peritoneal catheter. These findings confirm a patent shunt from the reservoir to the peritoneal cavity. 

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"A. Nodal size is not a factor considered in identifying sentinel lymph nodes. The sentinel node(s) may or may not be the largest ones visualized, but are correctly identified as being the first node(s) visualized.

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C. Correct. A thicker crystal will have worse intrinsic spatial resolution since the scintillation light will spread out more before detection by the photomultiplier tubes, and also there is a greater possibility of multiple scatter events, but will have better efficiency in capturing incident radiation.

A. Diffusely increased activity is more suggestive of infection.
B. Activity localized to the tip and the intertrochanteric region is most suggestive of loosening.
C. Activity around a non-cemented prosthesis may persist for as long as 2 years whereas the activity surrounding a cemented prosthesis typically resolves within 1 year.  
D. It may persist up to 2 years.

A. The image is the same size as the object.
B. Correct.
C. The image is the same size as the object.
D. The size of the image does not vary with object distance from the collimator, although the spatial resolution does vary with distance.

A. A number of drugs are known to interfere with MIBG uptake and must be discontinued prior to administration of the radiopharmaceutical. Medications known to interfere include calcium-channel blockers, labetalol (other beta-blockers have no effect), reserpine, tricyclic antidepressants and sympathomimetics. Other drugs such as antiphsychotics, “atypical” antidepressants and adrenergic neurone blockers (i.e. guanethidine) may potentially impede uptake, but do not need to be discontinued. Unlike calcium-channel blockers and labetalol, the other classes of cardiovascular/antihypertensive such as alpha-blockers, ACE-inhibitors, alpha-methyldopa, digitalis, and beta-blockers (excluding labetalol) have no effect on MIBG uptake and thus do not need to be discontinued.

A. Metformin administration is contraindicated for at least 48 hours following iodinated intravenous contrast administration (usually for a CT scan) and should not be restarted until normal renal function has been confirmed. It does not alter the biodistribution of F-18 FDG and thus does not need to be withheld prior to PET or PET-CT, though it should be temporarily discontinued following a contrast-enhanced PET-CT.
B. Morphine does not alter the biodistribution of F-18 FDG and thus does not need to be withheld prior to PET or PET-CT. Many patients receiving PET-CT exams are on morphine for chronic pain management with no impact on the quality of the study.
C. Many factors effect F-18 FDG uptake and distribution. Serum glucose actively competes with its uptake while endogenous or exogenous insulin will increase uptake to the liver and soft tissues, thereby decreasing uptake by tumors. Given this, it is recommended that short-acting (regular) insulin administration be withheld for at least four hours prior to F-18 FDG injection.
D. Amytriptyline does not alter the biodistribution of F-18 FDG and thus does not need to be withheld prior to PET or PET-CT. Amytriptyline (a tricyclic antidepressant) does impact on the biodistribution of meta-iodobenzylguanidine and thus must be withheld prior to imaging with I-123 or I-131 MIBG.

A. The effective half life Te, in terms of physical half life (Tp) and biological half life (Tb) is given by: In this case for the liver, Tb is 0.5 hr and Tp is 6 hours so Te is 0.5*6/(0.5 + 6) = 3/6.5= 0.46 hour. For the heart, Tb is 6 hours, so Te is 6*6/(6+6)=36/12=3 hours. It is not necessary to calculate this exactly to see that the liver has a shorter effective half-life.

D. 201 Thallium imaging in a patient with high-risk coronary artery disease undergoing stress imaging will likely exhibit transient pulmonary edema at stress due to left ventricular dysfunction related to myocardial ischemia. Normal post exercise lung-to-heart activity is less than 0.50.

A. Lead bricks are often used for shielding but concrete can also be used as well.
B. Most CT scanners used on PET-CT systems are not used as a diagnostic CT scanner. The amount of shielding for the PET portion of the scanner typically far exceed that of the CT portion.
C. Due to the high energy of annihilation radiation used in PET imaging, significantly larger amounts of shielding are required in PET-CT suites and uptake rooms when compared to other diagnostic imaging modalities.  
D. Self-contained delivery systems are new to the market and just beginning to be used in the US on a widescale basis. This technology has promise but is not required under any license conditions.

B. Assessment of the respectability of bronchogenic carcinoma
C. Preoperative assessment of lung transplant recipients

Mainly C, a little of D

A. Tagged RBCs are utilized for the assessment of liver hemangiomas, not focal nodular hyperplasia (FNH). Increased tagged RBC activity on delayed images is characteristic of hemangiomas, with SPECT providing nearly 100% sensitivity for lesions 1.5 cm or greater.
B. Tc-99m sulfur colloid is taken up by the hepatic reticuloendothelial cells (Kupffer cells), which are present in focal nodular hyperplasia (FNH). FNH is unique in the lesions may contain sufficient Kupffer cells to concentrate or even hyperconcentrate radiocolloid, a distinguishing feature from other hepatic lesions. As a rule of thumb, approximately 1/3 of FNH lesions demonstrate greater uptake the surrounding normal hepatic parenchyma, 1/3 equal uptake and 1/3 less uptake.
C. Tc-99m IDA agents are not utilized for primary imaging of hepatic masses. They may have a secondary role in the assessment of suspected hepatic adenomas, which may demonstrate increased tracer uptake.
D. Gallium-67 citrate can be utilized for the assessment of hepatocellular carcinoma versus a regenerating nodule. When a lesion is found to have greater uptake than the surrounding liver parenchyma, it is a strong indication of hepatocellular carcinoma, although similar findings may occur with hepatic abscesses and occasionally with hepatic metastases.

D. The activity is reduced by ½ for each half life that elapses. The question asks how much activity is left 24 hours later, which is four half lives. This can be solved by using the formula that the activity after n half lives, is equal to the original activity divided by 2n. In this case n=4, so divide 100 mCi by 16 to get 6.25 mCi. Alternatively, recognize that 100 mCi decays to 50 mCi in one half life, then to 25 mCi after two half lives, then 12.5 mCi after 3 half lives, then 6.25 mCi after 4 half lives.

B. According to the 10 CFR 20 document, the limit to the general public is less than 2 mrem (0.02 mSv) in any one hour from external radiation sources in any unrestricted area. This would apply to a Nuclear Medicine waiting room, as well as hallways and any unused imaging areas. For that matter, this limit would also apply anywhere in the hospital where the general public is present.

A. Lung uptake is usually minimal by 24 hours.
B. Imaging at 18 hours or later should not demonstrate significant pulmonary uptake in normal patients.
C. Early uptake with clearance by 18-24 hours is a normal finding. Metastatic calcification can result in diffusely increased pulmonary uptake on a Tc-99m MDP bone scan.
D. Early activity in the lungs, in the first 3-4 hours, is a normal finding that gradually clears.

A. The parent atom is transformed into a different element with an atomic number of Z-1.
B. The positron is not detected directly. The positron annihilates with an electron, two 511 keV photons are emitted, and these photons are detected in the PET scanner.
C. The available energy is shared between the positron and a neutrino which is also emitted, and the amount of energy sharing is variable.
D. The transition energy between parent and daughter particle must be at least 1.022 MeV, this is the energy threshold for the decay to occur.

A. 1-2 weeks is too early to detect clinical improvement in hyperthyroid symptoms.
B. 4-6 weeks is also too early to clinically detect symptomatic improvement in hyperthyroidism.
C. If signs and symptoms of hyperthyroidism persist 3-4 months after I-131 therapy, it can be concluded that the treatment was inadequate, and a second therapeutic dose, typically of equal or higher dosage, may be administered.  
D. By 3-4 months, there should be clinical evidence of resolution of signs and symptoms of hyperthyroidism, if I-131 therapy was successful. One exception to this would be Graves' ophthalmopathy, which may or may not respond to I-131 therapy, even if the patient becomes euthyroid. In fact, this condition may even progress after I-131 therapy, necessitating other medical or rarely, surgical treatment for the eye findings.

A. 1-2 weeks is too early to detect clinical improvement in hyperthyroid symptoms.
B. 4-6 weeks is also too early to clinically detect symptomatic improvement in hyperthyroidism.
C. If signs and symptoms of hyperthyroidism persist 3-4 months after I-131 therapy, it can be concluded that the treatment was inadequate, and a second therapeutic dose, typically of equal or higher dosage, may be administered.  
D. By 3-4 months, there should be clinical evidence of resolution of signs and symptoms of hyperthyroidism, if I-131 therapy was successful. One exception to this would be Graves' ophthalmopathy, which may or may not respond to I-131 therapy, even if the patient becomes euthyroid. In fact, this condition may even progress after I-131 therapy, necessitating other medical or rarely, surgical treatment for the eye findings.

A. Linearity should be assessed on a weekly basis, commonly with a bar phantom, in conjunction with resolution testing.
B. Field uniformity should be tested daily before patient imaging using point sources or planar sources to obtain flood field images.
C. Center of rotation correction is performed on cameras used for SPECT imaging typically monthly, using a point or line source.
D. Spatial resolution is tested weekly, commonly with a bar phantom.

A. This study demonstrates significant stress-induced ischemia in the inferoseptal wall, most consistent either with graft stenosis or another, new site of ischemia, the latter of which is not one of the options for this question.
B. While the reversibility of the defect in the inferoseptal region is incomplete, the findings are nontheless indicative of a predominantly reversible defect, more consistent with ischemia rather than infarction.
C. The inferoseptal region is not a common site for breast attenuation artifact, which more often involves either the anterior, anteroseptal or anterolateral walls. In addition, breast attenuation is not a common finding on Rb-81 PET studies, which intrinsically employ attenuation correction, which largely eliminates this artifact.
D. The finding of significant partial reversibility demonstrated in this case is strong evidence for the presence of myocardial viability in the involved region. In addition, the use of PET for assessment of myocardial viability is optimally performed using FDG myocardial imaging, which assesses myocardial glucose metabolism, rather than Rb-81 myocardial imaging, which assesses myocardial perfusion, similar to Tl-201 and Tc-99m sestamibi or tetrofosmin SPECT myocardial imaging studies.

A. While the flow, initial renal uptake and early excretion are normal, the bilateral cortical retention evident at the conclusion of the study, also manifested by failure of the renogram curves to return to the baseline, is abnormal, and indicates the presence of an element of bilateral renal tubular dysfunction.
B. While the study may appear to be relatively normal on initial examination, there is definite evidence of moderate, bilateral cortical retention at the conclusion of the study, also manifested by failure of the renogram curves to return toward the baseline at the conclusion of the study. These findings are consistent with an element of tubular dysfunction, which in turn could be the result of a number of medical renal disorders, including acute tubular necrosis, drug toxicity, glomerulonephritis, bilateral pyelonephritis or others.
C. There is no evidence of dilatation of the renal collecting systems on either side, and renal function is sufficient that the collecting systems are visualized. The findings are not suggestive of obstruction.
D. While the symmetrical impairment in renal function demonstrated on this study could conceivably be related to renovascular disease, the finding of normal renal perfusion bilaterally and normal renal size, as well as the symmetry of the findings demonstrated, make this diagnosis less likely.

A. The finding of multiple foci of left cervical and left supraclavicular adenopathy is consistent with lymphoma, which is a common cause for this finding. However, the additional ipsilateral focal lesion at the base of the tongue, while also conceivably secondary to lymphoma, makes squamous cell carcinoma of the head and neck with lymph node metastases a more likely diagnosis in this case.
B. The finding of a focal hypermetabolic lesion at the base of the tongue with associated ipsilateral lymphadenopathy in the neck is highly suggestive of squamous cell carcinoma of the head & neck with lymph node metastases.
C. Sarcoidosis is a known cause of a false positive study in a patient with a known neoplasm likely to metastasis to regional lymph nodes. However, the asymmetric distribution of the findings in the left neck, as well as the presence of the additional focal lesion at the base of the tongue, make sarcoidosis a much less likely diagnosis than squamous cell carcinoma of the head and neck.
D. Thermogenic or brown fat may result in increased FDG uptake on PET and PET/CT imaging, usually as the result of the patient being either cold and/or anxious during the examination. However, the typical distribution of findings in the instance of brown fat uptake is distinctly different from the findings in this case, namely symmetrical foci of uptake in the neck and supraclavicular regions bilaterally, often extending into the axillary regions, superior mediastinum and/or thoracic paravertebral regions.

A. The rim sign is a finding on hepatobiliary scintigraphy studies in the gallbladder fossa, suggesting the presence of acute cholecystitis. There is no rim sign used in pulmonary perfusion imaging.
B. The fissure sign refers to the finding of a linear defect located along one of the pulmonary interlobar fissures. It is most often associated with the presence of pleural fluid within the fissure, but may be simulated by a perfusion defect located in a segment abutting on a fissure. It is not present in this case.
C. A stripe sign refers to a defect on a perfusion lung scintigram that is centrally located and does not extend to the peripheral surface of the lung, with an intact stripe of perfused lung present distal to it. Such a finding is highly unlikely to be due to a pulmonary embolism in the involved segment, and can be ignored in the overall interpretation of the study. There is a stripe sign demonstrated in the right lower lobe on the RPO image in this case.
D. The silhouette sign is a finding on a chest radiograph that helps indicate the location of a pulmonary infiltrate. There is no corresponding scintigraphic sign.

A. The measured bone mineral density is within normal limits. According to World Health Organization guidelines, the diagnosis of osteoporosis should be made with the T-score < -2.5. The image demonstrates the presence of multiple lumbar compression fractures, which may lead to an overestimation of the bone mineral density of the lumbar spine in this patient.
B. There are multiple compression deformities noted throughout the lumbar spine on the scanned image, which may result in overestimation of the bone mineral density at the involved levels, not underestimation, since the patient's bone mineral is compressed into a smaller volume as a result of the fractures.
C. There are multiple compression deformities noted throughout the lumbar spine on the scanned image, which may result in overestimation of the bone mineral density at the involved levels, since the patient's bone mineral is compressed into a smaller volume as a result of the fractures. The patient's measured bone mineral density is normal, but likely represents an overestimate as a result of the compression fractures. In addition, the overall appearance of the lumbar spine appears osteopenic visually. Analysis of the hip (not shown) more accurately demonstrated the presence of moderate to marked osteopenia.
D. There are multiple compression deformities noted throughout the lumbar spine on the scanned image, which may result in overestimation of the bone mineral density at the involved levels, since the patient's bone mineral is compressed into a smaller volume as a result of the fractures. The patient's measured bone mineral density is normal, but likely represents an overestimate. Analysis of the hip (not shown) more accurately demonstrated the presence of moderate osteopenia.

A. The increased blood flow and blood pool activity are more prominent and diffuse than the delayed periprosthetic bone uptake, more consistent with inflammation of the surrounding soft tissues. The absence of any corresponding leukocyte activity indicates it is most likely not an infectious etiology.
B. The increased blood flow and pool activity on bone scintigraphy have a more diffuse periarticular distribution that is different than the periprosthetic delayed bone activity. The periprosthetic delayed bone activity is therefore non-specific, and can simply be normal for a knee prosthesis.
C. The absence of increased leukocyte activity makes an infection of the prosthetic joint very unlikely. Although false positive leukocyte scans may be seen when evaluating joint prostheses as a result of the presence of normal bone marrow activity, it is a very sensitive test for infection, and false negative studies are uncommon. In addition, the bone scan findings suggest a periarticular inflammation rather than infection of the prosthetic components.
D. Although the periprosthetic delayed bone activity may be a normal finding, the increased periarticular blood flow and pool activity is not normal, and is also more diffuse than the bone activity, suggesting hyperemia and inflammation of the periarticular soft tissues.

A. Although some of the focal rib activity demonstrated could be the result of trauma, the constellation of findings is most concerning for metastatic malignancy and probable malignant pleural effusion.
B. The posterior right rib activity has a more linear configuration concerning for neoplastic involvement. In addition, the findings in the proximal femora are highly suspicious for skeletal metastases. Trauma is also not a likely explanation for the diffusely increased soft tissue activity noted in the right hemithorax, which is most likely due to a malignant pleural effusion.
C. The increased activity throughout the right hemithorax in a patient with other evidence of a metastatic malignancy is concerning for large malignant effusion, and therefore likely to have opacification of the right hemithorax on chest radiograph. The most common etiologies for this finding would include bronchogenic carcinoma and breast carcinoma. Occasionally, an inflammatory process can result in increased uptake within a pleural effusion as well, but would not be associated with multiple focal skeletal lesions consistent with skeletal metastases.
D. Although the focal skeletal lesions demonstrated could represent metastases from prostate carcinoma, it would be uncommon to have a malignant pleural effusion in that entity.

A. An activity level greater than 100 mCi of Tc-99m is considered to constitute a major spill.
B. An activity level greater than 100 mCi of Tl-201 Tl is considered to represent a major spill.
C. An activity level greater than 10 mCi of In-111 is considered to represent a major spill.
D. An activity level greater than 1 mCi of I-131 is considered to constitute a major spill. The Radiation Safety Officer needs to be notified immediately when a major spill occurs, to direct the decontamination process.

A. In-111 pentetreotide uptake commonly occurs in carcinoid tumors, but this would represent a highly atypical location, especially in the absence of other sites of involvement, making it a less likely etiology for the finding than a meningioma.
B. In-111 pentetreotide uptake occurs in a variety of neuroendocrine tumors, but also in some non-neuroendocrine tumors, including meningiomas. The location of the activity in this case is also more consistent with a meningioma than any of the other options.
C. In-111 pentetreotide uptake occurs in the vast majority of pheochromocytomas. However, this location is not typical for a primary pheochromocytoma, and there are no other abnormal lesions to suggest the presence of metastatic pheochromocytoma, making this a less likely etiology for the finding demonstrated.
D. Increased In-111 pentetrotide uptake is not common in multiple myeloma. In addition, multiple myeloma is usually associated with multifocal bone marrow and/or skeletal involvement.

A. At 2 hours, biliary atresia and neonatal hepatitis may appear identical, without visualization of the biliary tree or bowel.
B. As noted in A above, biliary atresia and neonatal hepatitis may be indistinguishable at 4 hours as well.

A. Swyer-James Syndrome is characterized by bronchiolitis obliterans, a primary ventilatory disorder, which produces a whole-lung matching abnormality on the V/Q scan.
B. Correct. This condition is associated with vascular compression or compromise, without airway involvement, which can produce a whole-lung V/Q mismatch, mimicking the presence of massive pulmonary embolism involving the ipsilateral main pulmonary artery.
C. A foreign body produces a primary central airway obstruction, resulting in a large ventilation defect, possibly involving the entire lung, if located in a mainstem bronchus.  There may be secondary diffuse hypoperfusion resulting from reflex vasoconstriction, producing matching findings, but a V/Q mismatch (i.e., abnormal perfusion with normal ventilation) would not occur.
D. The pathophysiology of mucous plugging is the same as for a foreign body (see C above), and may involve either selected segments, an entire lung or portions of both lungs. Again, this is a primary ventilatory disorder, and V/Q mismatch would not be observed.

"A. Based on a study by Kwai et al published in 1988. Lesions in the sternum in breast carcinoma may be secondary either to hematogenous spread or direct extension of tumor.
B. In this setting, the incidence of bone metastases is less than 1%.
C. The paradoxical worsening of the bone scan with the ""flare"" phenomenon may also be accompanied by a worsening of bone pain as well as increasing sclerosis on radiographs. The radiographic finding of sclerotic healing of lesions and the time course following chemotherapy are better clues as to the presence of a flare phenomenon. For this reason, follow-up bone scintigraphy in patients with skeletal metastases is most often performed no sooner than 3 months and typically at 6-12 months or later.
D. Bone scintigraphy does not reliably determine the extent of primary bone malignancies, and may overestimate the extent of involvement. Assessment of the extent of the primary lesion is better accomplished with MRI and plain radiographs. Bone scintigraphy is useful as a whole body survey to assess for additional sites of involvement (metastatic or multicentric disease).

Flare Phenomenon: The radionuclide bone scan 3 months after the initiation of treatment for advanced cancer of the prostate occasionally shows apparent progression of individual lesions despite clinical improvement.

A. There is no significant difference in radiation exposure between DEXA and DPA techniques, and given the higher photon flux, DEXA may result in a slightly higher exposure than DPA.
B. Soft tissue attenuation correction is needed for accurate density measurement of bony structures such as the spine or hip. This is accomplished with dual-energy techniques by assessing the differential attenuation of photons by bone vs. soft tissue at different energies. Both DPA and DEXA are dual-energy techniques that allow for such attenuation correction.

A. Pulmonary embolism involving the main pulmonary artery would most likely result in a whole-lung V/Q mismatch, not whole-lung matching findings, as are illustrated in this case.
B. Swyer-James Syndrome results from presumed postinfectious unilateral bronchiolitis obliterans, and may produce a whole lung matching abnormality, as demonstrated in this case. The decreased ventilation in the involved lung results in reflex vascoconstriction, producing matching ventilation and perfusion findings.
C. Takayasu's arteritis may involve the pulmonary arteries or other great vessels, without affecting the airways, and may result in a whole-lung V/Q mismatch, not whole-lung matching findings, as are illustrated in this case.
D. Radiation therapy causes an obliterative endarteritis, without significant effects on the airways, and therefore may result in a segmental or even whole-lung V/Q mismatch, not whole-lung matching findings, as are illustrated in this case.

Findings: Tc-99m MAA was injected via hepatic artery catheter into the right hepatic artery. There is no visualization of activity within the left hepatic lobe.

A. Intra-arterial administration of Tc-99m MAA is used to document the vascular distribution at the time of injection and assess tracer arteriovenous shunting to the lungs and GI tract. If there is >20% shunting to the lungs, treatment with Y-90 microspheres is contraindicated. If >10% pulmonary shunting is detected, the therapeutic radionuclide dose may be decreased to prevent radiation pneumonitis. If significant gastrointestinal activity is seen, embolization(s) of these vessels is indicated prior to Y-90 therapy. In this case, the distribution of activity within the liver is consistent with visualization of the right hepatic lobe only. In the absence of previous hepatic resection, this finding is most likely the result of injection of the radiotracer into the right hepatic artery.
B. The images demonstrate activity only in the right lobe of the liver, therefore, unless the patient has undergone prior left hepatic lobe resection or the catheter is not correctly positioned, this option is incorrect.
C. The tracer was injected into the right hepatic artery, but MAA (macroaggregated albumin), rather than sulfur colloid, is typically used for this study.
D. Again, only the right hepatic lobe is visualized, which would not be expected if the above procedure were performed. In addition, Tc-99m MAA is usually used for this procedure, not Tc-99m sulfur colloid.

Findings: The baseline study demonstrates left hydronephrosis with high-grade drainage impairment at the left ureteropelvic junction, which persists on an upright post-void image. The renogram curve demonstrates a progressive accumulation pattern on the left. The post-furosemide images demonstrate only minimal clearance from the left collecting system, with a clearance half-time > 30 minutes, consistent with high-grade left UPJ obstruction.

A. The baseline study demonstrates left hydronephrosis with high-grade drainage impairment at the level of the left ureteropelvic junction (UPJ), with an associated progressive accumulation pattern noted on the left renogram curve. The intervention, intravenous administration of 40 mg of furosemide (Lasix) produced no significant change, consistent with high-grade left UPJ obstruction. The baseline findings would not represent an indication for Captopril administration, nor are the findings suggestive of renal artery stenosis on either side.
B. The baseline study demonstrates left hydronephrosis with high-grade drainage impairment at the level of the left ureteropelvic junction (UPJ), with an associated progressive accumulation pattern noted on the left renogram curve. The intervention, intravenous administration of 40 mg of furosemide (Lasix) produced no significant change, consistent with high-grade left UPJ obstruction. The baseline findings would not represent an indication for Captopril administration, nor are the findings suggestive of renal artery stenosis on either side.
C. The study demonstrates left hydronephrosis, with high-grade drainage impairment at the left UPJ, which does not respond to furosemide administration, consistent with high-grade obstruction at the left UPJ.

"Findings: There is a large area of marked reversible ischemia involving the anterior and anteroseptal walls of the left ventricle, corresponding to the left anterior descending coronary artery territory.

A. The study demonstrates a large area of marked reversible ischemia involving the anterior and anteroseptal walls, which is most consistent with stress-induced ischemia in the left anterior descending (LAD) coronary artery territory.
B. The findings in the anterior and anteroseptal walls do correspond to the left anterior descending coronary artery territory, but the perfusion defect demonstrated is reversible, not fixed. Reversible stress-induced ischemia is consistent with ischemia without infarction. A fixed defect would be anticipated in the presence of an area of myocardial infarction.
C. Coronary artery vascular territories are somewhat variable, based on whether the patient has a right or left coronary dominant system. Nevertheless, involvement of the anterior and anteroseptal walls is highly predictive of involvement of the left anterior descending coronary artery. Ischemia in the distribution of the right coronary artery is more often associated with findings in the inferior, inferoapical, inferoseptal or inferolateral walls of the left ventricle, none of which are present in this case.
D. Breast attenuation artifact can result in apparent perfusion defects underlying the patient's breast tissue due to soft tissue attenuation artifact. When present, these defects may occur in the anterior, anteroseptal or anterolateral walls. However, breast attenuation artifact is more likely to be present both on stress and resting images, more often resulting in a fixed, rather than a reversible defect. In addition, the severity of the findings in this case are more striking than typically seen due to breast attenuation, especially given the history that the patient is not obese.

Findings: There are multiple focal areas of increased MDP uptake noted in the axial and proximal appendicular skeleton. In addition, there is a large, asymmetrical focal area of increased soft tissue uptake noted in the right breast, as well as a milder degree of diffusely soft tissue uptake and soft tissue swelling of the remainder of the right breast.

A. The skeletal findings are consistent with multiple skeletal metastases, for which bronchogenic carcinoma is a common etiology. However, the additional findings in the right breast of a focal, asymmetrical soft tissue mass and overall swelling and increased soft tissue uptake throughout the right breast suggest the presence of a right breast mass, possibly representing an inflammatory carcinoma. Thus, metastatic breast carcinoma is a more likely etiology for the overall findings in this case.
B. The skeletal findings are most consistent with multiple skeletal metastases, with multiple focal areas of increased tracer uptake demonstrated in the axial and proximal appendicular skeleton. In addition, there is a focal, rounded area of asymmetrically increased soft tissue uptake noted in the right breast, which is highly suspicious for uptake within a right breast mass, as well as a milder degree of diffusely increased soft tissue uptake and soft tissue swelling of the entire right breast, suggestive of the presence of inflammatory carcinoma. Thus, metastatic breast carcinoma is the most likely diagnosis.
C. The skeletal findings are consistent with multiple skeletal neoplastic lesions, for which multiple myeloma is a possible etiology, although the sensitivity of bone scintigraphy in multiple myeloma is significantly less than for a variety of skeletal metastatic lesions. In addition, skeletal metastases, either from breast carcinoma or bronchogenic carcinoma, are more common than multiple myeloma. Finally, the additional findings in the right breast of a focal, asymmetrical soft tissue mass and overall swelling and increased soft tissue uptake throughout the right breast suggest the presence of a right breast mass, possibly representing an inflammatory carcinoma. Thus, metastatic breast carcinoma is a much more likely etiology for the overall findings in this case.
D. The skeletal findings in this case are most consistent with multiple skeletal metastases or other malignancy. The distribution of the lesions is relatively random, though distributed in the axial and proximal appendicular skeleton, which is a typical for most skeletal metastases. Fractures most often occur in one or several adjacent sites, are more common in the more distal extremities than metastases, and when involving the ribs, usually demonstrate a linear distribution of focal lesions. In addition, it is unusual to observe fractures this numerous in widely separated locations. Furthermore, the additional findings in the right breast of a focal, asymmetrical soft tissue mass and overall swelling and increased soft tissue uptake throughout the right breast suggest the presence of a right breast mass, possibly representing an inflammatory carcinoma. Thus, metastatic breast carcinoma is a much more likely etiology for the overall findings in this case.

"Findings: There is early reflux of radiotracer into the lateral ventricles, which persists over 48 hours. There is also significantly delayed migration of the radiotracer over the convexities.

A. This is a cisternogram and not a study assessing VP shunt patency. There is no VP shunt present.
B. The early and persistent ventricular activity in this case is consistent with free communication between the ventricles and the extraventricular CSF space. In non-communicating hydrocephalus, a normal pattern would be observed, without evidence of ventricular reflux.
C. Cisternography is sometimes performed in the pre-operative evaluation of patients with clinical and imaging findings of normal pressure hydrocephalus (a type of communicating hydrocephalus). Although somewhat controversial, cisternography demonstrating both early and persistent lateral ventricular activity and significantly delayed migration of the radiotracer over the cerebral convexities (Type IV pattern of CSF flow) suggests that the patient is more likely to benefit from CSF shunting than if these findings are not present.
D. This type of procedure can certainly be performed for suspected CSF leak. However, the images do not demonstrate a leak.

In a normal cisternogram, In-111 DTPA should fill the cisterna magna and circulate around to the arachnoid granulations before being resorbed. The ventricles should not be visible. If there is NPH, the ventricle will collect radionuclide.

Findings: The anterior FDG PET MIP image demonstrates a focal area of increased tracer uptake in the superior mediastinum to the left of midline.

A. FDG PET imaging is neither appropriate nor approved for use in the initial staging of medullary thyroid carcinoma, although it may be useful in the follow-up of selected patients with medullary carcinoma of the thyroid presenting with recurrent elevated serum calcitonin levels. Its main utility in thyroid carcinoma is in patients with well-differentiated thyroid carcinoma who present on follow-up evaluation after prior thyroidectomy with elevated serum thyroglobulin levels without findings on I-131 or I-123 whole-body scintigraphy.
B. FDG PET imaging is not an appropriate routine follow-up examination for use in patients after thyroidectomy for thyroid carcinoma. Its use is limited to the evaluation of patients with thryoid carcinoma derived from follicular elements (ie., follicular, papillary or mixed papillary/follicular types only) who present on follow-up one or more years after thyroidectomy with elevated serum thyroglobulin levels and negative I-131 whole-body scans.
C. FDG PET imaging is not indicated in patients with demonstrable residual or recurrent thyroid carcinoma on standard I-131 or I-123 whole-body scintigraphy. Such patients can be treated and/or followed based on the iodine imaging studies, without the need for further scintigraphic evaluation.
D. This is the appropriate setting for the use of FDG PET imaging in patients with thyroid carcinoma. The rationale for the study is that these patients have biochemical evidence of residual or recurrent disease that is not identifiable on radioiodine imaging, suggesting less well-differentiated disease, which is more likely to be FDG positive.

A. Correct.
B. This failure in the basic (planar) operation of the camera and is too severe to be corrected by a high count flood.
C. No collimator will be present in an intrinsic uniformity test and, even if this were an extrinsic test, the damage shown would be more extreme than is common with mechanical collimator damage.
D. A COR correction would be appropriate if certain types of SPECT artifacts were present.

A. Delayed clearance of the radiopharmaceutical from the blood pool (>10 minutes clearance) is seen in the setting of hepatocellular dysfunction, and is not associated with chronic cholecystitis. Another finding of hepatocellular dysfunction is increased renal excretion, due to alternative clearance of activity by the kidneys.
B. Increased renal excretion of the radiopharmaceutical is seen in the setting of hepatocellular dysfunction, and is not associated with chronic cholecystitis. When increased renal excretion is present, there is generally also delayed clearance of radiopharmaceutical from the blood pool, further confirming the presence of poor hepatic function.
C. Prolonged biliary-to-bowel transit time is associated with chronic cholecystitis, with the diagnosis becoming more likely the greater the delay. This finding may be associated with prolonged retention of activity within the gallbladder, in turn secondary to impaired gallbladder motility related to chronic inflammation. In such cases, infusion of a cholecystokinin analog may demonstrate the presence of impaired gallbladder motility, confirming the diagnosis.
D. The rim sign is seen is seen in the setting of acute cholecystitis. It is associated with a significant increased incidence of gangrenous or perforated gallbladder. Its mechanism is not clear, but is postulated to be due to reactive regional hyperemia in the liver due to adjacent gallbladder inflammation.

A. Imaging on the day of the therapy would not optimally reflect the ultimate biodistribution of the I-131, not permitting adequate localization time for assessing thyroid tumor tissue uptake, and would also result in a higher radiation exposure to the Nuclear Medicine technologist performing the study.
B. Again, imaging at 24 hours would be too soon to optimally assess the distribution of the therapy dose, with significant blood pool and urinary activity still present.
C. This is probably the optimal timeframe for post-therapy imaging, after initial blood pool clearance has largely occurred, permitting adequate assessment of the biodistribution of the therapy dose, while at the same time providing the improved resolution afforded by the larger amount of radioactivity present in the patient.
D. By 3 months post-therapy, greater than 10 half-lives of the I-131 therapy dose have passed (T 1/2 = 8 days), resulting in minimal residual activity and non-diagnostic images. Therefore, images obtained at this time would be of no clinical value.

C. § 35.75 Release of individuals containing unsealed byproduct material or implants containing byproduct material. (a) A licensee may authorize the release from its control of any individual who has been administered unsealed byproduct material or implants containing byproduct material if the total effective dose equivalent to any other individual from exposure to the released individual is not likely to exceed 5 mSv (0.5 rem).

C. The half-life of F-13 is 120 minutes (2 hours) and therefore 24 hours is approximately 10 half-life which indicates a safe time before breast feeding can be resumed.

A. Metastatic lymphadenopathy is not a common cause of this finding.
B. Melanoma is not a common cause of focal axillary lymph node uptake on a bone scan. Lymphoscintigraphy in melanoma is performed by injecting filtered Tc-99m sulfur colloid intradermally surrounding the site of the primary cutaneous lesion or previous biopsy site.
C. Intra-arterial injection may result in diffusely increased soft tissue uptake within the involved extremity, distal to the injection site, in a stocking/glove distribution. It does not cause focal axillary lymph node uptake.
D. Extravasation at the injection site is a common cause of uptake in an axillary node, secondary to formation of small colloidal particles that are taken up by lymphatics and deposited in ipsilateral axillary nodes. This finding should not be mistaken for disease, and can be confirmed by imaging the injection site to identify the extravasation of the dose.

A. In-111 labeled WBCs have lower sensitivity for this entity.
B. Because of the low sensitivity of In-111 WBC scintigraphy for the detection of infection in the spine, especially in the case of chronic infection, gallium-67 citrate is considered to be the better agent for this indication.
C. Bone scans are frequently non-diagnostic or falsely positive in the evaluation for osteomyelitis superimposed on an underlying process, such as fracture or a painful orthopedic prosthesis, since increased tracer uptake may also result from increased bone turnover related to metabolic activity associated with these other conditions.
D. False positive studies with In-111 WBC imaging of the spine are common, and can occur up to 20% of the time.

A. This is too small.
B. This is just the PET dose.
C. The PET scan alone with 10-12 mCi of F-18 FDG delivers about 10 mSv. A CT of the chest and abdomen will deliver another 10-20 mSv, depending on technique.
D. This is too high.

A. Although classically all triple matched findings (ie., corresponding ventilation, perfusion and radiographic abnormalities) are consistent with an intermediate probability for pulmonary embolism, according to the revised PIOPED criteria, a triple match in the upper lobes is much less likely to be due to pulmonary embolism than a lower lobe triple match. This finding is consistent with the fact that pulmonary emboli occur much more commonly in the lower lobes than the upper lobes, most likely as a result of the relatively greater blood flow to those areas.
B. A lower lobe triple match is more likely to be associated with pulmonary embolism than an upper lobe match, and according to the modified PIOPED criteria, is more worrisome than the finding of a triple match overall, which is generally considered to be consistent with an intermediate probability for pulmonary embolism.
C. A whole-lung V/Q match is most often associated with primary ventilatory disorders associated with secondary reflex vasoconstriction, such as airway obstruction due to central foreign bodies, mucus plugging, endobronchial masses or other unilateral primary ventilatory disorders, such as Swyer-James Syndrome. This finding is consistent with a low probability for acute pulmonary embolism.
D. While classically this finding is consistent with an intermediate probability for pulmonary embolism, in general, the larger the corresponding pleural effusion, the less likely it is due to pulmonary embolism.

A. Tc-99m sestamibi SPECT imaging is affected by soft tissue attenuation artifacts, such as breast and diaphragmatic attenuation, unless the data specifically undergoes some type of attenuation correction, either by means of software correction of hardware correction, such as the use of a hybrid SPECT-CT imaging device.
B. As in the case of Tc-99m sestamibi SPECT imaging, the dual-isotope method is also subject to soft tissue attenuation artifacts, unless specifically corrected. In fact, because of the lower gamma photon energies used in thallium-201 chloride myocardial perfusion imaging, the thallium images are even more prone to these artifacts than the images obtained using Tc-99m labeled radiopharmaceuticals.
C. There is attenuation correction in FDG PET images, whether performed on a dedicated PET imaging device which uses external radioactive sources for attenuation correction, or on a hybrid PET-CT imaging device. However, FDG myocardial scintigraphy is used to assess myocardial glucose metabolism, and is not a myocardial perfusion imaging study.
D. Rb-82 is a positron-emitting isotope with a short half-life of 75 seconds that is used for assessment of myocardial perfusion. It is a potassium analog, and exhibits biochemical properties similar to those of Tl-201 chloride. In addition, being a PET radiopharmaceutical, the use of Rb-82 for myocardial perfusion imaging benefits from the image attenuation correction that is intrinsic to all PET and PET-CT studies.

Findings: WHO definition of osteoporosis is a bone mineral content measurement that is equal to or greater than 2.5 standard deviations below the expected measurement of a young normal control group (T score <-2.5).

A. The WHO defines osteoporosis as a T score < -2.5.
B. This is the WHO definition for osteoporosis, although this finding may also be seen in osteomalacia. In addition, many patients with T scores higher than -2.5 are deemed to be appropriate candidates for treatment of bone loss. The T score is derived by comparison with a young adult normal control group.
C. The Z score is derived from comparison with age, sex and race-matched controls, and is not a direct indicator of osteoporosis.
D. Again, the T score rather than the Z score is used to define the presence of osteoporosis. A highly negative Z score indicates bone loss out of proportion to the patient's age, sex and race.

A. The ratio of Mo-99 to Tc-99m is a measure of radionuclidic purity.
B. The presence of alumina in the eluate represents a type of chemical impurity, involving a non-radioactive contaminant within the radiopharmaceutical, and does not represent a radiochemical impurity.
C. Radiochemical purity is defined by the fraction of radioactivity in a dose that is in the desired chemical form, such as the amount of properly labeled Tc-99m MDP versus the remaining free Tc-99m pertechnetate within a bone scan dose. Thin-layer chromatography is the most common method of testing radiochemical purity with Tc-99m labeled compounds.
D. The amount of alumina in the eluate, which is a measure of chemical purity, is commonly measured using this technique.

A. The opposite is true.
B. Seizure foci, particularly in the temporal lobes, typically demonstrate decreased perfusion (SPECT) and decreased metabolic activity (PET) during the interictal phase and increased perfusion and metabolic activity during the ictal phase.
C. Metabolic activity is typically decreased during the interictal phase.
D. This finding can be seen in the setting of a supratentorial lesion, such as a stroke or tumor that results in decreased activity in the contralateral cerebellar hemisphere. It is not a typical finding in patients with isolated seizure disorders.

"C. Individuals with toxic multinodular goiter or a solitary autonomous functioning nodule generally require higher doses of radioactive iodine for successful ablation than patients with Graves' disease. Furthermore, partial treatment with lower doses may result in partial loss of suppression of uptake by the remainder of the gland, resulting in a lower percentage of a subsequently administered therapeutic dose being taken up by the lesion. Treatment doses given are usually in the ""high outpatient"" range of 20-30 mCi, although under current NRC guidelines, even higher doses may be given to many patients without hospitalization required.

C. The fetal thyroid begins functioning between 8 and 12 weeks post conception. The initial effective half-life of the I-131 is about 6.5 days. By the time the fetal thyroid begins functioning less than about 5% of the administered dose will remain. Almost all this remaining I-131 will have been trapped in the mother’s thyroid. The circulating I-131 will be in the I-131 labeled T3 and T4 released from the mother’s thyroid. By the time the fetal thyroid begins functioning the circulating I-131 level will be much less than the 5% estimate. The dose to the fetus depends on many factors but is probably in the range of 0.025-0.050 mGy per MBq (0.1- 0.2 rad/mCi). A conservative estimate of the increased risk of leukemia due to this dose would be less than 1%. For this reason choices A and B are false. Blocking doses of KI would have to be given daily because of the risk of fetal goiter.

B. Several agents have been developed which readily bind to somatostatin receptors. In-111 pentreotide (Octreoscan) binds with high affinity with the SSTR2 and SSTR5 subtypes and to a lesser degree with the SSTR3 subtype. A total of 5 subtypes are present in humans.

C. Thyroglobulin (Tg) is produced by the thyroid epithelial cells and is used by the thyroid gland to produce the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Serum thyroglobulin (Tg) is the most accurate tumor marker to detect the recurrence of tumor in well differentiated thyroid carcinomas (papillary and follicular). It is not useful in patients with the anaplastic or medullary forms of thyroid cancer.

D. Phenobarbital is used to augment the cholescintigraphy in neonates suspected of biliary atresia. The dose is 5mg/kg/day in divided doses for 5-7 days before the exam to increase the metabolic activity of the liver. The serum phenobarbital level should be checked prior to imaging.

D. Tc-99m Dimercaptosuccinic acid (DMSA). is the radiopharmaceutical of choice for renal cortical scintigraphy. There is minimal urinary excretion at 2 hours and approximately 40% of the injected dose localized and remains fixed to the renal cortex, binding to sulfhydryl groups of proximal tubular cells. With this agent, both static imaging using parallel hole and pinhole collimators as well as SPECT imaging may be performed.

C. Angiotensin I is cleaved to angiotensin II by the angiotensin-converting enzyme (ACE) mostly within the lungs. Captopril, an ACE inhibitor blocks the conversion of angiotensin I to angiotensin II, thus alleviating renovascular hypertension, but in the process, also further reducing the glomerular filtration rate of the affected kidney that has compensated by means of the renin-angiotensin system.

B. The ventilation scan improves the relatively low specificity of the perfusion scan, particularly in patients with obstructive pulmonary physiology or a variety of other parenchymal lung disorders.

B. Image indicates that the photomultiplier tube positioned behind the scintillator is bad and therefore shows non-uniformity in the shape of photomultipler tube.

D. A platelet count of >150k is desireable and permits use of the higher dose range of Y-90 Zevalin of 0.4mCi/kg, with a maximum dose of 32 mCi. Patients with platelet counts in the 100-150k range may be treated with a lower dose of 0.3mCi/kg, but treatment is contraindicated if the platelet count is lower because of concerns for bleeding secondary to the hematologic toxicity of the agent.

B. A written directive is required for any administration of >30 uCi of I-131 or any therapeutic administration of an unsealed radionuclide.

D. A lung abscess, like other active inflammmatory lesions, may be associated with increased metabolic activity, and could produce significantly increased FDG uptake on a PET study. In fact, the use of PET for the detection of infectious and other inflammatory processes is currently under evaluation as a significant potential future indication for PET imaging.

B. In-111 WBC scintigraphy is superior to gallium scintigraphy for detection of active inflammatory bowel disease because there is no interfering normal bowel uptake, as does occur with gallium imaging.

B. The fraction of the total radioactivity in the administered radiopharmaceutical (tc-99m MDP bone agent) is not in the desired bound range of >95%. More than 5% of the Tc-99m added to the diphosphonate bone agent kit is free or unbound, resulting in uptake corresponding to the biodistribution of Tc-99m pertechnetate, which includes gastric, salivary gland, thyroid, renal and choroid plexus uptake.

B. In-111 DTPA is the agent of choice for cisternography performed to assess CSF kinetics, to demonstrate persistent ventricular reflux pattern with/without convexity blocks in patients with suspected NPH, or in the assessment of patients with suspected CSF leakage. Migration of the tracer is evaluated up to 48-72 hours.

Findings: There is a hyperfunctioning nodule in the superior aspect of the isthmus, with associated partial suppression of uptake by the remainder of the thyroid gland, which also appears inhomogeneous.

A. The images depict a multinodular goiter (MNG) with a dominant hyperfunctioning nodule in the isthmus, with probable partial suppression of uptake by the remainder of the gland. Given that the patient is clinically hyperthyroid, this case would represent a toxic nodular goiter. The 24 hour RAIU in individuals with toxic nodular goiter is typically in the 20-30% range (upper-normal to mildly elevated). An uptake of 5% would be typical for patients with primary/secondary hypothyroidism, subacute thyroiditis in the acute phase, struma ovarii, or in some instances, excess exogenous iodine intake or administration of thyroid hormone. This value would not be consistent with the combination of the images and clinical setting of this case.
B. Again, the images depict a multinodular goiter (MNG) with a dominant hyperfunctioning nodule in the isthmus, with probable partial suppression of uptake by the remainder of the gland. Given that the patient is clinically hyperthyroid, these findings are consistent with a toxic nodular goiter. The 24 hour thyroid uptake in individuals with toxic nodular goiter is typically in the 20-30% range (upper-normal to mildly elevated). An uptake of 15% is normal, which would not typically occur in this clinical setting of a clinically hyperthyroid patient.
C. The images in this case are consistent with toxic nodular goiter, given the history of a clinically hyperthyroid patient. The 24 hour thyroid uptake in individuals with toxic nodular goiter is typically in the 20-30% (upper-normal to mildly elevated), and is generally lower than the uptake values commonly observed in Graves' disease (diffuse toxic goiter).
D. In the setting of a hyperthyroid patient, a 24 hour thyroid uptake of 60% or higher is much more often associated with Graves' disease than toxic nodular goiter, the latter being present in this case.

Findings: Dynamic images from a Tc-99m tagged RBC scintigraphy study demonstrate abnormal tracer activity originating in the left lower quadrant, corresponding to the region of the distal descending colon or sigmoid colon. This activity increases over time, conforms to the large bowel, and moves antegrade/retrograde, confirming the presence of a distal colonic bleed. Stable activity noted in the left upper quadrant probably represents activity within the left kidney (similar, less striking finding also noted on the right), of no clinical significance.

A. The abnormal activity in this exam corresponds to the left colon (distal descending or sigmoid). The inferior mesenteric artery (IMA) supplies the portions of the large intestine from the splenic flexure to the superior aspect of the rectum, which includes the descending colon, the sigmoid colon, and part of the rectum. By contrast, the celiac artery supplies the liver, stomach, abdominal portion of distal esophagus, spleen and superior half of both the duodenum and pancreas.
B. Again, the bleeding site in this case arises in the distal descending or sigmoid colon, which are supplied by the inferior mesenteric artery. The superior mesenteric artery supplies the intestine from the distal portion of duodenum through two-thirds of the transverse colon, as well as the pancreas.
C. The IMA supplies the site of origin of hemorrhage in this case, which arises in the distal descending colon or sigmoid colon. The IMA supplies the distal large intestine, from the splenic flexure to the superior portion of the rectum, which includes the descending colon, the sigmoid colon, and part of the rectum.
D. The images show abnormal tracer activity originating in the left lower quadrant. This activity increases over time, conforms to large bowel, and moves both antegradely and retrogradely, confirming the presence of a lower GI bleed. This is not a normal study.

Findings: There is delayed appearance of vesicoureteral reflux on the left, extending proximally to the left renal pelvis, which is dilated. Remember image left is patient left. Mild would be only in the ureter, which is not present in this case.

A. The absence of visualization of activity within the right renal collecting system reflects the absence of right-sided vesicoureteral reflux, not impaired right renal function, since this is not an antegrade (intravenous) renogram study.
B. The presence of activity within the left renal collecting system is the result of reflux into the left ureter, not antegrade secretion from the left kidney with distal obstruction.
C. There is relatively prompt reflux of radiopharmaceutical into the left renal collecting system, with a dilated left renal pelvis also demonstrated. Since the reflux extends proximally to the level of the renal pelvis and is also associated with renal pelvic dilatation, this is a case of severe, not mild, reflux.
D. This study is a direct radionuclide cystogram, as indicated by the presence of radiopharmaceutical only in the bladder initially, where it was administered. There is relatively prompt reflux of radiopharmaceutical into the left renal collecting system, with a dilated left renal pelvis also demonstrated. These findings are consistent with severe reflux.

A. Anticoagulant therapy is irrelevant to this choice, and would not interfere with either study.
B. Again, the presence or absence of deep venous thrombosis, a precursor of pulmonary embolism, is irrelevant to the choice of examination.
C. In the presence of renal insufficiency, there is a contraindication to the administration of intravenous contrast material, therefore a CT study should not be performed. Renal insufficiency will have no effect on the performance of a ventilation-perfusion lung scintigram. V/Q scintigraphy would also be a superior choice in patients with intravenous contrast allergies, patients exceeding the CT imaging table weight limits and in patients too ill to cooperate for CT imaging.
D. The presence of COPD does not preclude the performance of either examination, but could result in an increased likelihood of a non-diagnostic V/Q study, therefore it would not represent an advantage of V/Q scintigraphy over CT imaging.

A. MRI is a sensitive method for evaluating patients with suspected primary breast lesions, especially when indeterminate on other imaging methods, such as mammography or ultrasound. However, it is not a sensitive examination for the initial STAGING of the axillary lymph nodes. Like CT, the evaluation of the axillary nodes by MRI is based primarily on nodal size, resulting in relatively poor sensitivity and specificity (see rationale B below).
B. As for MRI, CT is not sensitive for staging the axillary lymph nodes. CT criteria for lymph node involvement relate primarily to nodal size, and it is unable to reliably detect tumor involvement in normal-sized nodes or the absence of tumor involvement in enlarged nodes.
C. Lymphoscintigraphy with sentinel node sampling permits immunohistochemical examination of nodes most likely to be involved, resulting in highly accurate surgical staging of the axillae.
D. FDG PET imaging is useful in the detection of recurrent breast cancer, detection of distant metastases and in the monitoring of treatment response. However, it is significantly less sensitive for the staging of axillary lymph node involvement than lymphoscintigraphy with sentinel lymph node mapping.

A. While largely evaluating trabecular bone, DEXA studies of the lumbar spine are frequently associated with overestimation of the bone mineral density in this region, secondary to degenerative and post-traumatic changes, such as degenerative joint disease, scoliosis and compression fractures, especially in older patients. Evaluation of the hip, femoral neck or Ward's triangle is overall more reliable in these patients.
B. For each T score standard deviation below normal (-1.0 or lower), the fracture risk is increased approximately three-fold when compared to normal young patients of the same gender.
C. The Z score is a statistical value used to assess for bone loss out of proportion to the patient's age, and takes into account the patient's age, sex and race. By comparison, the T score is an absolute assessment of bone density for patients of all ages, and is used for the diagnosis of osteoporosis. The World Health Organization has defined osteoporosis as being present in patients having T score values less than -2.5, although in practice, many patients with higher T score values are still treated for bone loss.
D. Both osteoporosis and osteomalacia are associated with bone loss, or osteopenia, and cannot be differentiated either by bone mineral density levels or by the T or Z scores.

A. The superscan is classically associated with diffusely increased skeletal uptake, although it may occur in different forms, based upon the etiology. However, while sometimes multifocal, especially in children, osteomyelitis is not usually extensive enough to produce a superscan appearance.
B. While not the most common pattern of involvement with skeletal metastases, widespread metastases may be associated with a superscan appearance in which there is accentuation of uptake primarily in the axial and proximal appendicular skeleton, often with superimposed focal areas of increased MDP uptake also present.
C. While the kidneys are often poorly visualized in the case of a superscan, this finding is primarily due to the diffusely increased skeletal uptake, rather than impaired renal function. Renal function may be normal in many such cases. In acute renal failure, skeletal uptake is not increased, but renal visualization may be decreased, in conjunction with increased soft tissue background activity. By contrast, chronic renal insufficiency may be associated with renal osteodystrophy, and is in the differential diagnosis of a superscan.
D. Paget's disease is included in the differential diagnosis of a superscan, but is a much less likely cause than skeletal metastases. Paget's disease may be multifocal, but does not typically result in large areas of diffuse involvement, more often limited to individual long bones or flat bones, such a one hemi-pelvis, clavicle or scapula.

A. Gallium-67 citrate scintigraphy provides non-specific targeting of both infectious and non-infectious inflammatory causes of fever, as well as a number of neoplastic causes for FUO. Indium-111 WBC scintigraphy is overall more specific for infection, and is therefore preferred when infection is the primary diagnostic consideration.
B. At least 25% of the dose of Ga-67 citrate is excreted via the GI tract, and can obscure sub-diaphragmatic focal infection/inflammation, as well as representing a normal site of tracer uptake. In-111-WBCs are not normally taken up by bowel, and are therefore more sensitive and specific for the presence of an inflammatory process within the bowel, including inflammatory bowel disease.
C. Again, while relatively sensitive, gallium scintigraphy is less specific than In-111 WBCs in this setting, since gallium may result in false positive studies for lung absecess in the presence of a necrotic bronchogenic carcinoma, which may also be intensely gallium-avid.
D. There are several classical patterns of Ga-67 uptake in active sarcoidosis (eg. panda sign, sigma sign, etc.), which may strongly point toward the diagnosis of sarcoidosis, although lymphoma or other neoplastic involvement may not entirely be excluded. In-111 WBC imaging is much less useful in this clinical setting, with false negative studies likely.

A. The in vitro technique yields the highest labeling efficiency followed by the modified in vivo and in vivo methods, respectively.
B. Labeled red cell imaging can detect bleeding rates approximately ten times lower than conventional angiography.
C. The exam is most useful in patients who are clinically suspected to be actively bleeding at the time of the exam.
D. Both sulfur colloid and labeled red blood cell techniques are limited by the presence of normal background activity in the upper abdomen that can limit the detection of gastric and duodenal sites of bleeding. The normal activity in the liver and spleen with sulfur colloid imaging is even more intense than with labeled red blood cells, making it a poorer choice for patients with suspected upper gastrointestinal hemorrhage.

A. Most radioactive waste used for diagnostic imaging purposes have relatively short half-lives. Because of tremendous costs involved in shipping radioactive materials and burying them, this is not typically performed.
B. Human excreta is typically disposed through the sewer system, allowed because of the great dilution that minimizes impact of materials on the environment.
C. While incineration will get rid of the “visible” radioactive waste, the materials will still be radioactive and easily contaminate accessible areas nearby. Not a good option.
D. This is the option recommended, since the half-live of most radioactive materials is reasonably short. Knowing the type of contaminants, any waste will be stored over a time period equal to 10 times the half-live of the longest-lived isotope, which will be at background levels. The waste then goes through normal hazardous waste disposal channels.

A. The patient should be well hydrated for the exam, by mouth or with intravenous fluids.
B. The exam can be used to differentiate obstructive from nonobstructive hydronephrosis as well as to assess the effectiveness of a surgical correction or stent.
C. A tubular agent such as MAG3 is the agent of choice in the newborn setting as glomerular filtration is incompletely developed in the neonatal kidney.
D. A distended bladder can result in a false appearance of obstruction, and a catheter may be used in patients who cannot voluntarily empty their bladder prior to the exam (such as with infants, children, or in the setting of bladder outlet obstruction) or in the setting of neurogenic bladder.

D. Sm-153 labeled lexidronam (Quadramet) is a high energy beta emitting radiopharmaceutical that localizes in bone, and demonstrates increased localization in sites of osteoblastic metastases, with a distribution similar to that of Tc-99m MDP. In addition, it also emits a gamma ray of 103 KeV energy, permitting imaging as well as therapy for painful bony metastases. This treatment is most often employed in patients with numerous symptomatic sites, precluding spot radiotherapy treatment alone. It is associated with significant pain relief in a high percentage of patients, often lasting months, and with generally manageable hematologic toxicity.

"D. The initial images during the first hour of the study demonstrate normal transit of radiopharmaceutical through the liver and biliary system to the duodenum. The gallbladder is not visualized throughout the first hour. The 4 hour delayed image, in lieu of a post morphine imaging series, confirms the absence of gallbladder visualization. This constellation of findings is consistent with acute cholecystitis. While these findings may also occur in chronic cholecystitis, they are more characteristic of acute cholecystitis.

C. The findings demonstrated are typical for a benign hepatic hemangioma. This lesion is classically associated with focal areas of increased tracer uptake on delayed images, secondary to the increased blood volume within the lesion. Early images may demonstrate less intense uptake which gradually increases over time, similar to the phenomenon of delayed contrast enhancement observed on CT.

C. The combination of a primary lesion of T1 - T3 (in this case, T1), with mediastinal and supraclavicular adenopathy but no distant metastases is consistent with a Stage IIIB lesion (T1N3M0), which makes the patient not a surgical candidate for an attempted cure.

T1: Solitary pulmonary nodule < 3 cm diameter

Stage 4
Any T; any N; M1

B. Tc-99m DTPA is a GFR agent, with physiology similar to insulin, although approximately 5-10% is bound to plasma proteins, therefore it tends to underestimate GFR slightly. Of the agents listed in this question, it is the best choice for estimation of the patient's GFR value.

DTPA is a pure glomerular agent. It measures GFR.
MAG3 is both a tubular and a glomerular agent. It measures effective blood flow.
Combine the two and you get the filtration rate (normal 5:1)

C. Bar phantom studies performed at least weekly are usually obtained four ways by rotating through all quadrants to check both resolution and linearity without employing a separate linearity phantom.

"D. Octreotide scintigraphy is commonly used to evaluate patients with suspected or known carcinoid tumor involvement, to assess for recurrence or metastatic disease with high sensitivity, as well as to stratify patients for sandostatin therapy. This is a case of metastatic carcinoid tumor involving the liver.

A. Medical x-rays are the most significant source of man-made radiation sources. They contribute an annual effective dose of 0.39 mSv or 39 mrem to the U.S. population.
B. Radon is a naturally occurring source of radiation.
C. High-altitude air travel adds to an individual’s cosmic ray exposure, and is of very small quantity.
D. Nuclear does not contribute as much as medical x-rays as a source of exposure to the U.S. population. They contribute an annual effective dose of 0.14 mSv or 14 mrem to the U.S. population.

A. Correct. The intrinsic uniformity or flood test is performed without the collimator and is an indication of the uniformity of the camera itself. The extrinsic test is performed with the collimator on using a large flood source.
B. Either source material may be used. Typically a syringe of Tc-99m at a distance several time larger than the camera crystal is used for the intrinsic test, and the extrinsic test is performed with a large water and Tc-99m filled flood source, or a solid Co-57 flood source.
C. Internal electronic checks are different from the measured uniformity tests.
D. There are no internal radiation sources to a gamma camera used for uniformity testing.

"A. There is lateral wall ischemia demonstrated, most likely corresponding to the left circumflex coronary artery territory. Right coronary artery ischemia most often involves the inferior and or inferoapical walls.
B. Correct. The patient has a large lateral wall ischemia, consistent with a left circumflex artery distribution.
C. There is lateral wall ischemia demonstrated, most likely corresponding to the left circumflex coronary artery territory. Left main coronary artery ischemia most often results in large areas of striking reversible ischemia in the anterior, anteroseptal and/or anterolateral walls.
D. There is lateral wall ischemia demonstrated, most likely corresponding to the left circumflex coronary artery territory. Balanced three vessel disease may result in false negative studies, since there is uniform, global ischemia without focal defects present. Such cases may be diagnosed using quantitative analysis methods.

Findings: A NaI thyroid uptake probe is illustrated.

A. In the performance of the Schilling test, Co-57 is used and the urine sample is counted in a well counter. An external NaI probe is not used.
B. C-14 urea breath samples are analyzed in a liquid scintillation counter. C-14 is a pure beta emitter, and would not be appropriately measured using a NaI external probe.
C. I-125 iothalamate is used for GFR measurement, and the activity is counted in a well counter, not using an external probe.
D. This is an external probe with a flat field collimator for thyroid uptake measurement.  

Findings: Anterior images of the chest obtained 15 and 30 minutes after intradermal injection of Tc-99m filtered sulfur colloid surrounding the site of the patient's cutaneous melanoma of the chest wall demonstrate activity in the injection sites and visualization of lymphatic drainage to three contralateral left axillary lymph nodes only.

A. This study is used only to map lymphatic drainage from the site of the primary melanoma, not to assess for the presence or absence of metastastic disease within the draining nodes.
B. Again, the study merely maps the lymphatic drainage from the site of the lesion, it does not assess either for lymph node metastases directly or for additional primary sites of involvement. The latter could be accomplished by F-18 FDG (fluorodeoxyglucose) PET imaging.
C. This case demonstrates unanticipated contralateral axillary lymph node drainage from the site of a lesion located slightly to the right of the midline. In addition to this pattern, other atypical patterns that may be observed include bilateral axillary drainage and/or unilateral, contralateral or bilateral inguinal lymph node drainage.
D. There is no evidence of incorrect injection technique in this case. In fact, the lymph node localization demonstrated lend support to the fact that the injections were probably performed adequately. For this clinical indication, intradermal injections in ~ 4 divided aliquots surrounding the site of the primary cutaneous lesion are recommended.

"Findings: There are symmetrical foci of increased FDG uptake noted in both supraclavicular regions, characteristic in appearance for physiologic thermogenic, ""USA"" (uptake in supraclavicular area) or brown fat uptake. There is no evidence of residual or recurrent Hodgkin's Disease.

C. Again, the finding of symmetrical uptake in the supraclavicular regions is characteristic of physiologic, thermogenic or brown fat uptake, a common normal variant. Based on these findings, there is no indication for further treatment of the patient at this time. Furthermore, if the patient were suspected of having active disease in the above sites, a more appropriate course of action would be administration of additional chemotherapy and/or radiotherapy to this region.
D. The finding of symmetrical uptake in the supraclavicular regions is characteristic of physiologic, thermogenic or brown fat uptake, a common normal variant. Based on these findings, there is no indication for further treatment of the patient at this time. Follow-up PET imaging in 6 months is a reasonable measure to re-evaluate the patient for recurrent disease following an initial successful course of treatment.

"Findings: The expanded, hypermetabolic confluent osteoid activity of the right hemipelvis and single upper lumbar vertebra on the 2005 study is typical of Paget's disease, as is the subsequent normalization of hypermetabolism as the disorder reaches end-stage in 2007. The 2007 study also demonstrates incidental degenerative changes in the thoracic spine as well.

A. There is right hemipelvic abnormality on both studies, typical of Paget's disease, with considerable improvement on the follow-up examination.
B. The pattern of diffusely increased right hemipelvic activity and expansion of the bone is much less characteristic of metastasis than Paget's disease. The lumbar spine lesion is also more diffuse than typically seen with a metastasis, and no other lesions are identified elsewhere.
C. Again, the relatively diffuse distribution of findings in the right hemi-pelvis and within an upper lumbar vertebra are more characteristic of Paget's disease than resolving fractures. In addition, the 2007 follow-up images also demonstrate an expanded, hypertrophic right hemi-pelvis, with relatively reduced osteoblastic activity than on the earlier study, consistent with more chronic, ""burned out"" Paget's disease. Pelvis fractures are usually more focal in appearance, often located within the pubic rami, sacrum or sacroiliac joints. Osteoporotic lumbar fractures usually are limited to the vertebral bodies, with associated loss of height of the corresponding vertebrae.
D. As discussed above, the pattern of findings in this case is characteristic for Paget's disease involving the right hemipelvis and lumbar spine, with subsequent subsidence of increased bone turnover during the ""burned out"" phase of the disease, even in a patient with known prostatic carcinoma. The pathologic process involves destruction of the entire metabolic bone unit, resulting in hypertrophic but osteoblastic-poor osteoid, typical of end-stage Paget's disease.  

Findings: An abnormal focus of uptake is present in the right lower quadrant of the abdomen on the immediate images and persists throughout the exam.

A. This is not a tagged RBC gastrointestinal bleeding study. Furthermore, the activity is focal and stationary, which is inconsistent with activity related to gastrointestinal bleeding. The uptake in this case reflects the presence of a Meckel's diverticulum containing ectopic gastric mucosa, though not necessarily actively bleeding at the time of the study.
B. The activity at the right lower quadrant is the result of heterotopic gastric mucosa in a Meckel's diverticulum. The uptake most likely occurs in mucin-producing cells of the stomach.
C. Although most Meckel's diverticula do not contain heterotopic gastric mucosa, the presence of radiotracer activity indicates gastric mucosa is present. In addition, of those Meckel's diverticula that bleed, a very high percentage do contain ectopic gastric mucosa.
D. Pre-treatment with cimetidine may increase the uptake of radiotracer within gastric mucosa, thereby reducing the liklihood of a false-negative result (i.e. non-visualization of a Meckel's diverticulum that does contain gastric mucosa). As this examination already demonstrates the presence of abnormal activity, there is no need for a repeat exam. Cimetidine would not prevent a false positive study, which may occur in the presence of other lesions, such as a hemangioma or bowel duplication or uptake within the distal right ureter.

D. In patients with dyskinetic walls, the dyskinesis represent a ventricular aneurysm. The aneurismal portion of the wall bulges out and the count activity of the volume associated with the damaged wall increases while the true left ventricular chamber volume activity decreases. This is represented as being 180 degrees out of phase with the left ventricle.