Hello, everyone. My name is Dennis Calnon. I'm a multimodality cardiac imager in Columbus, Ohio, and Director of Nuclear Imaging at Ohio Health Heart and Vascular Physicians at Riverside Methodist Hospital. I'm going to present a case that demonstrates the value of cardiac PET for detection of multivessel coronary artery disease. The case is of a 65-year-old woman who presented to our hospital with an episode of prolonged chest pressure at rest, relieved by nitroglycerin. She had not seen a physician in more than nine years and had many untreated risk factors, including untreated hypertension, type 2 diabetes, dyslipidemia, and current tobacco use. Her high-sensitivity troponin T was slightly above normal range, but the pattern was flat with measurements of 21 and 22 nanograms per liter. These are the stress and rest myocardial perfusion images acquired on our rubidium PET scanner. And I think it's pretty obvious that there's a large area of ischemia that you can see involving the lateral wall extending into the inferior wall. You can see it quite clearly on the short axis images as well as on the horizontal long axis and vertical long axis images. The TID ratio here was elevated at 1.32. We use a threshold of less than 1.14 with our cardiac PET with rubidium. And so you can see visually there's quite a bit of TID or transient ischemic dilation present as well. So already, based on these perfusion images, we have a sense that there's extensive ischemia. The rubidium polar maps shown here show that the extent of ischemia is quite large, 47% of the left ventricular myocardium. And you can see on the overlay of the vessels that it really fits quite nicely in the right coronary artery and left circumflex coronary artery territories, whereas the LAD territory looks relatively good. So my question for you at this point would be, based on the perfusion images, these suggest RCA disease, circumflex disease, RCA and left circumflex disease, or three-vessel disease? Those of you who said right coronary and left circumflex disease would be correct. Based on the perfusion images, the defect certainly is in the territory of the right coronary artery, the inferior wall, and the lateral wall of the circumflex. The LAD territory looks normal based on the relative perfusion images. But let's look at the other information that's provided with cardiac PET. These are the gated images we acquire with our rubidium images at rest and at peak rubidium stress. And unlike gated SPECT images that are acquired post-stress, gated PET images are acquired at peak stress because the whole study is performed on the camera and the images have more information because of this. In this case, the patient's resting ejection fraction was mildly reduced at 40% at rest, but during peak stress, the ejection fraction declined further to 36%. Additionally, the encystolic volume went up from 78 milliliters at rest to 107 millimeters at peak stress. This negative left ventricular ejection fraction reserve of minus 4% is a high-risk marker, and the increase in encystolic volume is a high-risk marker as well, often seen in patients who have multivessel coronary artery disease. The myocardial blood flow information is shown on this slide, and here you can see the quality control images, and when you compute the global myocardial blood flow reserve, it's severely reduced at 1.12, and if you look at the individual coronary arteries, you see that the left circumflex regional myocardial blood flow reserve is 0.78 and the RCA is 0.96. When we see regional blood flow reserves less than 1, this typically indicates the presence of very severe coronary stenosis, often a total coronary artery occlusion dependent on collaterals and coronary steel phenomenon, so this represents very high-risk, very severe ischemia, which is what we saw in the perfusion images, but pay attention to the LAD territory, which is color-coded yellow and has also reduced regional myocardial blood flow reserve in the LAD territory of 1.54, suggesting that not only are the circumflex and RCA territories abnormal, but the LAD territory is also abnormal. The CT attenuation correction images that are acquired for attenuation correction purposes show that there's calcification in the left main, in the LAD, and in the circumflex, as well as the right coronary artery, implying the presence of multivessel coronary atherosclerosis. So I'll ask you the question again, now that we're incorporating all of the findings of the cardiac PET study, do you think that the patient has RCA disease, circumflex disease, two-vessel disease, like we said, based on the perfusion imaging, or three-vessel disease? And those of you who recognize that the patient likely has three-vessel disease, based on all of the information, would be correct. The patient went on to have invasive coronary angiography. We specifically did not load the patient with clopidogrel, because we felt that there was a high likelihood that bypass surgery was going to be recommended, based on the findings of the PET study, rather than PCI. And in fact, the invasive coronary angiogram confirmed, just like we suspected, the right coronary artery was totally occluded, which correlates quite well with that blood flow reserve below one. The circumflex was a small vessel, and the circumflex territory was mostly supplied by a ramus artery, which was quite large, and was also 100% occluded, and again, that fit with the blood flow reserve less than one. And the LED territory, which looked normal on the relative perfusion images, had 80% proximal stenosis, and the left main actually had 80% stenosis as well, in the mid-portion of the vessel, with some catheter damping as well. So based on this, the patient was referred for bypass surgery. And so the teaching points of this case are that the spatially relative perfusion imaging, which we're all used to seeing with SPECT imaging, compares perfusion to the most normal myocardial region, and so in this case, the most normal region was the LED territory, which then was displayed and looked normal, compared to the abnormal areas. Spatially relative perfusion imaging underestimates the extent of ischemia, as was demonstrated in this case, and the ancillary findings on PET perfusion imaging, myocardial blood flow reserve, the left ventricular ejection fracture reserve, and the presence of coronary calcium allow for detection of the full extent of coronary artery disease. Thank you for listening.

cardiac PET imaging

multivessel coronary artery disease

myocardial blood flow reserve

invasive coronary angiography

bypass surgery