Myocardial Oxygenation Imaging: New Methods for Ischemia Detection

Abstract

Myocardial ischemia is associated with many cardiovascular diseases, including coronary artery disease, congestive heart failure, hypertensive left ventricular hypertrophy, and diabetic cardiomyopathy, etc. The ischemia is caused by the imbalance of myocardial oxygen supply and demand. Positron emission tomography (PET) is the only noninvasive imaging technique to directly measure myocardial oxygenation. However, its low spatial resolution, limited availability, and ionizing radiation discourage the widespread use of PET to detect myocardial ischemia in clinical practice. The cardiac BOLD (bloodoxygen-level dependence) effect allows the measurement of myocardial oxygenation through T 2 or T 2 * change using cardiac magnetic resonance (CMR) imaging techniques. Many efforts were made to improve the sensitivity of detecting this change and image quality for clinical evaluations. With relatively high spatial resolution, oxygenation in the subendocardium, a common location for myocardial ischemia, for the first time could be directly assessed by CMR oxygenation imaging. This method, combined with other CMR functional and anatomic imaging, will offer a one-stop shop for the detection of myocardial ischemia, even in the absence of angiographically significant coronary artery stenosis.