Assessment of Coronary Artery Disease by Hybrid PET/CT

Assessment of Coronary Flow Reserve and CT Angiography By Hybrid PET/CT: Relation to Clinically Indicated SPECT Studies

There have been many advances in the test used to look for heart disease. An example of this newer technology is the Multislice CT scan (MSCT) and Positron Emission Tomography (PET) scans. The use of this type of combined scan may show early coronary artery disease or the degree of damaged heart muscle form a heart attack with a single exam. It may help doctors to know who might benefit from heart surgery or angioplasty to increase the blood flow to the heart. This type of detailed images has previously been available only through cardiac catheterization.

Advances in Non-invasive Multislice CT Imaging: Multislice CT (MSCT) and PET imaging are becoming more widely available and more useful in cardiac assessment. MSCT provides quantification of coronary calcium as well as information about the structures of the coronary vessel walls and atherosclerotic plaques. Multiple studies have demonstrated that MSCT provides information on coronary artery stenosis comparable to that obtained from invasive coronary angiography. PET imaging provides functional data via the measurement of coronary flow reserve (CFR). CFR is a quantitative measure of the increase in coronary blood flow in response to vasodilation; normal coronary flow is able to augment by three- to four-fold; diseased coronary arteries show less ability to increase flow, i.e. less CFR. Assessment of CFR yields functional information about the significance of coronary disease and is often used clinically in conjunction with anatomic imaging to identify early atherosclerosis. There is no current data evaluating the incremental value of hybrid PET/CT assessment of CFR and coronary anatomy in relation to SPECT studies in the clinical setting.

Rest and vasodilation stress rubidium PET and coronary angiography with CT were performed using standard doses for clinically indicated studies.

The Incremental Value of Adenosine Flow Reserve by Rubidium PET to Clinically Acquired Gated Studies.

All data were acquired in list-mode for 8 minutes and retrospectively sorted into static, ECG gated and dynamic images. Rubidium retention was calculated by dividing the late (3-8 minute) whole myocardium region-of-interest data by the integral of the input function over the first minute. Adenosine flow reserve was estimated by dividing rubidium retention during adenosine vasodilation by the same measure at rest. These quantitative flow and flow reserve values were compared to clinically acquired gated studies in the 30 participants.

Inclusion Criteria: Subject must be 18 years of age or older and able to give informed consent. Scheduled for clinically indicated gated Adenoscan SPECT studies at the University of Maryland Medical Center or Baltimore VA Center Documentation from participant's health care provider indicating no objection to subject's participation in study. Exclusion Criteria: Hepatic; thyroid or renal disease (creatinine >1.5 or GFR < 60mL/min) Women of childbearing age not using medically acceptable form of contraception, pregnant or breast-feeding Contrast allergy Inability to cooperate with imaging