Richard C. Brunken
Manuel D. Cerqueira
Wael A. Jaber
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1. Figure 9.1 shows regadenoson stress (top row) and rest (middle row) 13NH3 perfusion and 18FDG glucose metabolic positron emission tomography (PET) (bottom row) images from a 62-year-old man with a history of type 2 diabetes, hyperlipidemia, and prior myocardial infarction. On a recent echocardiogram, the left ventricular ejection fraction (LVEF) was 42%.
Which of the following best explains the findings on the PET imaging study?
A. Right coronary artery (RCA) infarction, with inducible ischemia predominantly in the circumflex arterial distribution
B. Inducible ischemia in the right coronary and left anterior descending (LAD) coronary distribution
C. Extensive myocardial scar in the LAD coronary distribution
D. Myocardial hibernation in the right and LAD coronary artery distributions
1. ANSWER: B. The stress 13NH3 images demonstrate perfusion defects involving the anterior wall, apex, and apical inferior segments. Full reversibility is noted on the rest 13NH3 perfusion images in the apex, apical inferior, and mid and distal anterior walls, while partial reversibility is noted in the proximal anterior wall. Confirmation of tissue viability in the anterior wall is indicated by preserved 18FDG uptake in this area.
2. Rest 13NH3 perfusion images (RstAC) and 18F-2-fluoro-2-deoxy-2-D-glucose metabolic (FDGAC) PET images from a 59-year-old man with ischemic cardiomyopathy are shown in Figure 9.2. A recent echocardiogram demonstrates diffuse left ventricular (LV) systolic and diastolic dysfunction (LVEF = 26%), 2+ mitral insufficiency, and a right ventricular systolic pressure of 42 mm Hg.
The findings on the PET imaging study are most consistent with which of the following?
A. Infarction in the distribution of the LAD coronary artery, with myocardial hibernation in the RCA distribution
B. Infarction in the right coronary and LAD coronary distributions
D. Myocardial hibernation in the right and LAD coronary artery distributions
2. ANSWER: D. The 13NH3 images demonstrate extensive rest perfusion defects involving the mid and distal anterior wall, apex, anterior and inferior septum, and mid and basal inferior wall. Preserved tissue metabolism is present in these hypoperfused regions on the 18FDG glucose images, indicating viability. Based on the findings of the cardiac PET viability study and suitable coronary anatomy, the patient was referred for multivessel CABG and had an uncomplicated postoperative course.
3. Figure 9.3 shows stress rubidium-82 PET perfusion images (StrAC) obtained following 0.4-mg regadenoson IV, along with rubidium-82 PET perfusion images (RstAc) obtained at rest. The images are from a 63-year-old man with a family history of cardiovascular disease, hypertension, and hyperlipidemia.
Which of the following would be the best interpretation of the PET imaging study?
A. Normal study
B. Inducible ischemia in the RCA distribution
C. Inducible ischemia in the LAD coronary artery distribution
D. Fixed perfusion defect in the RCA distribution
3. ANSWER: A. The stress and rest perfusion images demonstrate a normal pattern of tracer uptake, without findings to suggest inducible ischemia or a fixed myocardial perfusion defect.
4. Measurements of absolute myocardial perfusion and perfusion reserve were also obtained at the time that the PET study illustrated in Figure 9.3 was performed. Segmental rest perfusion measurements ranged from 0.8 to 0.9 mL/min/g of tissue, while hyperemic measurements ranged from 3.1 to 3.3 mL/min/g of tissue. Myocardial perfusion reserve measurements ranged from 3.3 to 3.6. What is the clinical implication of these measurements?
A. In light of the flow reserve measurements, the findings are most consistent with “balanced” ischemia (proximal three-vessel coronary artery disease [CAD]).
B. The patient has normal resting perfusion but impaired hyperemic flows due to the adverse impact of hypertension and hyperlipidemia on the coronary microvasculature. This results in lower than normal myocardial perfusion reserve measurements.
C. Normal hyperemic blood flows are present in this patient. The rest perfusion values are elevated due to the adverse impact of hypertension and hyperlipidemia on the coronary microvasculature, resulting in lower than anticipated myocardial perfusion reserve values.
D. Measured rest and hyperemic flows are normal, yielding normal myocardial perfusion reserve values. This patient’s prognosis is therefore better than that of a patient with similar images but with reduced perfusion reserve measurements.
4. ANSWER: D. In this patient, rest and hyperemic perfusion measurements are normal, as are derived perfusion reserve determinations. Resting LV myocardial blood flow parallels tissue oxygen consumption and is generally in the range of 0.7 to 1.2 mL/min/g. Clinical studies have shown a linear relationship between rest perfusion measurements and the resting double product (heart rate × systolic blood pressure) as an index of myocardial oxygen consumption. With vasodilator stress, hyperemic myocardial blood flows generally exceed 2.5 mL/min/g, such that calculated perfusion reserves (ratios of hyperemic/rest perfusion measurements) typically are >2.5. A reduced perfusion reserve determination on PET imaging may reflect either epicardial coronary disease or microvascular disease or both. Recent studies indicate that the 1-year risk of cardiac death or myocardial infarction is significantly lower if myocardial perfusion reserve is 2 or greater, regardless of whether visually assessed stress perfusion defect scores are less than or greater than 4.
Ziadi MC, deKemp RA, Williams KA, et al. Impaired myocardial perfusion reserve on rubidium-82 positron emission tomography imaging predicts adverse outcomes in patients assessed for myocardial ischemia. J Am Coll Cardiol. 2011;58:740-748.
5. Regadenoson stress (StrAC) and rest (RstAC) rubidium-82 cardiac PET perfusion images obtained in a 63-year-old male for evaluation of atypical chest discomfort are shown in Figure 9.4.
The findings on the PET images are concerning for which of the following?
A. The images suggest “balanced” ischemia (proximal three-vessel CAD)
B. Inducible ischemia in a median ramus distribution
C. Inducible ischemia in a RCA distribution
D. Artifact due to diaphragmatic attenuation on the stress perfusion images
5. ANSWER: C. A reversible perfusion defect consistent with stress-induced ischemia is noted in the inferior and basal inferoseptal region of the ventricle, in an RCA distribution. Ischemia involving a median ramus distribution would be expected to involve the anterolateral and apical lateral myocardial segments. No findings such as transient dilation of the left ventricle with stress are noted on the images to suggest balanced three-vessel ischemia. Because attenuation is accurately corrected for by use of transmission images in cardiac PET imaging, artifact due to diaphragmatic attenuation is unlikely.
6. Figure 9.5 shows regadenoson stress (StrAC) and rest (RstAC) 13NH3 perfusion images and 18FDGAC PET images from a 63-year-old woman with known CAD, LV dysfunction, prior myocardial infarction, prior percutaneous coronary intervention (PCI), hyperlipidemia, hypertension, and chest pain.
Which of the following best describes the findings on the cardiac PET imaging study?
A. Stress perfusion images demonstrate a severe perfusion defect in the LAD coronary artery distribution, with minimal reversibility on the rest images.
B. Extensive perfusion-metabolism mismatches indicative of myocardial hibernation are noted in the LAD coronary distribution.
C. A reversible perfusion defect indicative of extensive ischemia in the RCA distribution is present.
D. Both myocardial scar and hibernation are noted in the LAD coronary artery distribution.
6. ANSWER: A. The PET images demonstrate a severe stress perfusion defect in the LAD coronary artery distribution that exhibits minimal improvement on the rest images in the apical, apical septal, and apical anterior segments. No hypoperfused myocardial regions with enhanced FDG uptake are noted to suggest myocardial hibernation. No reversible perfusion defects are identified in right coronary distribution to suggest ischemia.
7. A 63-year-old male with known CAD presents with chest pain and is referred for stress dual-isotope imaging. Based on Figure 9.6, a lesion in what vessel is likely to cause the abnormalities?
7. ANSWER: C. The images show a moderately severe lateral wall defect extending from the apex to the midcavity. There is also visual transient ischemic dilation of the left ventricle with a calculated ratio of 1.33, which is increased even for a dual-isotope study.
Coronary angiography found a 70% stenosis in a large first obtuse marginal branch that was treated with PCI.
8. A 79-year-old female with diabetes presents with chest pain and palpitations. She is referred for a rest/stress 1-day pharmacologic stress technetium-99m study. A resting low dose is administered and the images in Figure 9.7 are acquired. When the patient returns for the stress study, an electrocardiogram (ECG) shows a supraventricular tachycardia (SVT) with a heart rate of 150 to 175. The stress study is rescheduled 2 days later after rhythm conversion. What is the most likely explanation for the image findings?
B. Artifact due to the low-dose/high-dose technique
C. Normal study
D. Technically inadequate study
8. ANSWER: C. The images show transient ischemic dilation, but this was most consistent with the patient being in an SVT at the time of imaging with a rate in the 150 to 175 range and diminished filling of the left ventricle due to marked shortening of the diastolic filling period. In essence, this was a stress study due to the very rapid heart rate. When the patient returned for the stress study following cardioversion, the rate was in the 60s at rest with a longer filling period and the cavity is bigger. With pharmacologic stress, there was no evidence of ischemia just mild diaphragmatic attenuation. The low-dose/high-dose technique does not make the cavity appear different in size between the two studies.
9. Which of the following cardiovascular imaging studies will give the highest radiation exposure, measured in mSv, to a patient?
A. Diagnostic coronary angiography
B. Computed tomography (CT) coronary angiography with prospective gating
C. 1-day Tc/Tc myocardial perfusion imaging (MPI) study
D. Dual-isotope thallium-201/technetium-99m
9. ANSWER: D. Since the dual-isotope study uses 3 to 4 mCi of thallium-201, which has a 72-hour half-life, it will give the highest radiation exposure to the patient at ˜27 mSv. The other three studies will usually result in values <15 mSv and with some of the newest systems, MDCT systems and acquisition software, maybe as low as 1 to 2 mSv.
10. A patient is seen in the emergency department for chest pain and shortness of breath. He is referred for MPI. Based on the rotating projection image in the left anterior oblique (LAO) position in Figure 9.8A and the representative midcavity horizontal long-axis stress image in Figure 9.8B, what is the most likely cause of the patient’s symptoms?
A. Pulmonary embolus
B. Intestinal obstruction
C. Pericardial effusion
10. ANSWER: C. The patient has a lateral and right ventricular halo surrounding the heart on the projection image (Fig. 9.8A) and can be seen on the horizontal long-axis image (Fig. 9.8B) and is most consistent with a pericardial effusion. A pulmonary embolus cannot be detected on perfusion imaging, and even though there is a distended stomach bubble below the heart, this is usually a result of giving the patient fluids to get greater separation between the inferior wall and gastric and intestinal activity that may be close to the heart. The single stress perfusion image shows uniform perfusion, and this does not definitively exclude CAD but makes it less likely.
11. Which of the following radionuclide agents can be used for the detection of a recent acute coronary syndrome?
A. Technetium-99m pyrophosphate
B. Technetium-99m Myoscint
C. I-123 BMIPP
D. All of the choices
11. ANSWER: D. Technetium-99m pyrophosphate is retained in areas of healing infarction and has been used for detection of infarcts that are 3 to 7 days old. Technetium-99m Myoscint is an antibody directed to myosin that is exposed following acute damage and detects damage earlier than technetium-99m pyrophosphate.
BMIPP is a fatty acid analog that is not taken up in areas of infarction due to cell damage. Areas of surrounding ischemia at the time of the infarction also fail to use fatty acids and may overestimate the area of actual infarction.
12. A patient with breast cancer is scheduled for an equilibrium radionuclide angiogram to monitor cardiotoxicity. The end-diastolic LAO view is shown in Figure 9.9. Based on the available image, what is the most likely method of red blood cell labeling that was used?
A. In vivo
B. In vivitro
C. In vitro
D. None of the choices
12. ANSWER: C. The image shows excellent delineation of the ventricular blood volumes with a very low background activity. Based on the excellent image quality, the in vitro method is likely to give the best results and is the best answer.
13. A patient with atypical chest pain undergoes an exercise stress single photon emission computed tomography myocardial perfusion imaging (SPECT MPI) study. The short-axis images are shown in Figure 9.10. Which coronary artery is most likely to have a tight stenosis?
13. ANSWER: A. The images show a classic distribution for right coronary artery ischemia with involvement of the inferior wall from the apex to the base and extending to involve the inferolateral wall at the base. There is no evidence of infarction.
14. A female with multiple cardiac risk factors is being evaluated for atypical chest pain of 2 weeks’ duration. The results of a pharmacologic stress SPECT are shown in Figure 9.11. Which combination of CAD distribution is most likely to explain these findings?
14. ANSWER: A. The study shows an apical and lateral wall infarction with periinfarct ischemia in the lateral wall. A tight stenosis in the left main would not involve the apex and spare the majority of the anterior wall and septum. Although the RCA may sometimes supply the inferolateral wall, it seldom supplies blood to the anterolateral wall, and there is no inferior wall involvement. Thus, distal LAD infarct in combination with an LCX infarction and residual ischemia is the most likely explanation for these findings.
15. A 35-year-old female with atypical chest pain and no cardiovascular risk factors walks into the office for evaluation. She has a normal baseline ECG. What is the most appropriate cardiovascular test to order for this patient?
A. Stress treadmill ECG
B. Stress echocardiogram
C. CT coronary angiography
D. Stress-only SPECT MPI
15. ANSWER: A. With such a low pretest probability of coronary artery disease, it could be argued that no testing is needed. If testing is felt necessary, the stress ECG avoids the risks of radiation and contrast reactions. A stress echocardiogram avoids radiation and contrast, but the ECG offers sufficient accuracy in this low-risk patient that it is the appropriate first test.
16. A 56-year-old female with a remote history of CAD and bypass surgery presents with atypical chest pain and mild dyspnea on exertion. She had an uneventful pharmacologic stress dual-isotope (rest thallium, stress techne-tium-99m) MPI study.
Rest and stress images are shown in Figure 9.12.
The images demonstrate:
A. Normal with diaphragmatic attenuation.
B. Abnormal due to a circumflex infarct.
C. Abnormal due to a circumflex ischemia.
D. Multivessel ischemia.
16. ANSWER: C. There is a moderate perfusion defect involving the entire inferior and inferolateral wall.
Her coronary angiogram showed a patent left mammary graft to the LAD artery and severe disease of the saphenous vein graft to the left circumflex coronary artery and total occlusion of the vein graft to the RCA.
A semiquantitative map showing inferior and inferolateral ischemia is shown in Figure 9.20.
17. A 62-year-old male 10 years S/P coronary artery bypass graft (CABG) with a left internal mammary graft to the LAD artery and saphenous vein graft to the RCA is scheduled for abdominal aortic aneurysm surgery. The pharmacologic stress dual-isotope (rest thallium, stress technetium-99m) MPI study shown in Figure 9.13 demonstrates which of the following?
A. Normal study with diaphragmatic attenuation
B. RCA territory infarct
C. Circumflex territory ischemia
D. Right and circumflex coronary artery infarct and ischemia
18. A 53-year-old female with an old anterior wall myocardial infarction presents with heart failure symptoms and is being considered for surgical revascularization. Her LVEF is 28% by echocardiography.
A rest/pharmacologic stress rubidium-82 and FDG metabolic PET study was performed to assess the presence of hibernating myocardium. Rest and stress and FDG images are shown in Figure 9.14.
Based on the PET perfusion and metabolic study, you would recommend:
A. Continue medical therapy and no revascularization.
B. Medical Rx + biventricular pacing.
C. Medical therapy and revascularization.
D. Heart transplantation.
19. A 71-year-old male with no prior medical history presents with dyspnea on mild exertion. His baseline ECG showed normal sinus rhythm with left bundle-branch block (LBBB). He underwent a pharmacologic stress MPI with no symptoms. Rest and stress images are shown in Figure 9.15.
Based on these images:
A. Breast attenuation artifact is present and a PET scan is recommended.
B. Extensive ischemia is seen and coronary angiography followed by revascularization is recommended.
C. No significant ischemia is seen, but hibernation cannot be excluded.
D. An abnormal wall motion in the rest images would indicate absence of viability.
19. ANSWER: C. This scan shows a large fixed and severe perfusion defect in the LAD artery and the RCA distributions. A semiquantitative analysis of the images with polar maps is shown in Figure 9.23. The LVEF was 28%. No significant ischemia is demonstrated and coronary angiography is not yet indicated. However, if on further testing (PET or MRI) a significant amount of myocardium at risk is demonstrated (hibernation), an angiogram and revascularization would be indicated. Ischemic, stunned, infarcted, or hibernating segments of myocardium may all present as a wall motion abnormality.
20. A 55-year-old female with diabetes, obesity, and hypertension is being considered for bariatric gastric bypass surgery. She is inactive and is asymptomatic. She underwent a treadmill stress MPI as part of her preoperative risk assessment. She walked for 5 minutes on a modified Bruce protocol and reached 78% of the predicted heart rate with significant dyspnea and 1-mm diffuse ST depression.
Rest and stress images are shown in Figure 9.16.
Based on these stress results:
A. There is ischemia at a low workload and the patient is at high risk for future cardiovascular events.
B. The test is nondiagnostic due to failure to achieve target heart rate.
C. The MPI images show breast attenuation and therefore the test is normal.
D. Pharmacologic stress testing is recommended to better define the extent of ischemia and risk.
20. ANSWER: A. Despite failure to achieve target MPHR, the patient had ST changes and a large area of LAD artery territory ischemia with transient ischemic dilation. The presence of defects on the stress images and not on the rest images is unlikely to be due to breast attenuation. Enough diagnostic and prognostic information were derived from this test, and therefore, there is no need for a pharmacologic stress test. Semiquantitative analysis of the images is depicted in Figure 9.24.
21. A 53-year-old male with hypertension and atypical chest pain presents to the emergency department. He has T-wave changes on resting ECG. As part of a MPI single photon emission computed tomography study, he exercised for 10.5 METs and 110% of the MPHR. He had 1- to 2-mm ST depression in the anterolateral leads with no chest pain.
Rest and stress images are shown in Figure 9.17.
Based on the totality of the test:
A. Proceed with cath given the symptoms and ECG changes.
B. No further studies are indicated.
C. Get a CT angiography.
D. Many artifacts, order a stress echo.
22. A 56-year-old female with 2 days of chest pain several months earlier now presents with dyspnea on exertion but no chest pain. An echocardiogram demonstrated regional wall motion abnormalities with an LVEF of 40%. A baseline ECG shows normal sinus rhythm (NSR) with right bundle-branch block and small q waves in leads 2 and AVF.
A rest/pharmacologic stress rubidium-82 PET with metabolic imaging for hibernation was ordered.
Based on the images:
A. There is evidence of hibernation in the RCA territory and coronary angiography is warranted.
B. There is evidence of “scar” in the inferior wall.
C. The right ventricle is normal.
D. Dobutamine echocardiography is needed to assess hibernating myocardium.
22. ANSWER: B. The rubidium images show a fixed perfusion defect with a matched defect in the FDG images consistent with scarred myocardium in the RCA distribution (see semiquantitative analysis in Fig. 9.26). In this setting, revascularization is unlikely to improve prognosis. There is intense uptake in the right ventricle consistent with hypertrophy due to pulmonary hypertension. Although dobutamine echocardiography is a more specific modality to predict recovery of wall motion and contractility, its sensitivity for hibernation is lower than PET.
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