Clinical application of noninvasive coronary artery examination has been expected. We have wanted to develop the more useful coronary MRA and CTA and have done several approaches for this purpose.
1, Coronary MRA
Our most interesting and challenging project is to develop the clinical useful coronary MRA. We have performed clinical trials of coronary MRA from 2D method to 3D method for 14 years. The navigator echo method permits the entire heart to be imaged from base to apex using of the MDCT technique. Whole Coronary MRA images can be obtained by acquiring sections transverse to the body axis. By displaying these images sequentially, it is possible to localize areas of stenosis or occlusion without using contrast material.
2, Assessment of myocardial viability; delayed contrast-enhanced MRI study
Myocardial viability is a clinically important index in assessing myocardial infarction. We have originally developed short-axis 3D imaging using parallel imaging which is performed to obtain 6 or 7 slices during a breath-hold time of approximately 20 s. As a result, short-and long-axis delayed enhancement images can be obtained in two breath-holds.
3, Coronary CTA
At the begging stage of the study, we have started from evaluation of the scanning thickness by comparison with CTA using 4 row MDCT and conventional angiography for coronary stenosis of clinical patients. As a result, slice images of 1mm in thickness were superior to those of 2 mm by 15.4% for sensitivity, 7.5% for specificity, and 8.2% for accuracy. The recent studies have reached the evaluation of plaque nature, not only detection of stenotic lesion. We have studied over a hundred patients using 40 row MDCT and have done the comparison with the finding of IVUS.