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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. ANSWER: D. The patient has a severe fixed perfusion defect in the inferior and inferolateral wall with reversible component at the edges of the defect as depicted in the semiquantitative analysis in Figure 9.21.

18. ANSWER: C. The patient has a mixture of a large area of hibernation (green arrow, Fig. 9.22) and ischemia (red arrow) in the LAD artery territory. Surgical revascularization of her LAD, first and second diagonal, was performed.

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. 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. ANSWER: B. The patient had excellent functional capacity, and the MPI images do not demonstrate ischemia or infarcts. Semiquantitative analysis of the rest and stress images and comparison to a normal male database are shown in Figure 9.25.

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.