Magnetic resonance imaging to evaluate patency of aortocoronary bypass grafts.

To assess the efficacy of magnetic resonance (MR) imaging in evaluating graft patency after coronary bypass surgery, 20 patients who had prior surgery (average 5.5 years, range 1.5 to 14) and recent cardiac catheterization because of chest pain were studied. No patient had surgical intervention or change in symptoms in the time interval between catheterization and MR imaging. These 20 patients had a total of 47 grafts, defined as proximal anastomoses: 20 to the left anterior descending or diagonal artery (LAD), 13 to the left circumflex artery marginal branches (LCX), and 14 to the right coronary artery or posterior descending artery (RCA). The patients underwent cardiac and respiratory gated MR scans in a 0.5 tesla magnet with an echo time of 22 msec and two repetitions in a 128 X 256 matrix. In-plane resolution was 2.7 mm. Every patient had a scan in the transaxial plane and some underwent scanning in the sagittal and coronal planes as well. A graft was considered patent by MR when a signal-free lumen was visualized in an anatomic position consistent with that of a bypass graft, had a lumen larger than the native vessels, was seen on more than one slice, and was seen at a level higher than that of the native vessels. If a known graft was not seen it was considered occluded. The scans were interpreted by consensus of two physicians aware of the operative but not the cardiac catheterization data.(ABSTRACT TRUNCATED AT 250 WORDS)

Videodensitometric quantitation of aortic regurgitation by digital subtraction aortography using a computer-based method analyzing time-density curves.

To assess the clinical role of computer analysis of time-density curves in the evaluation of aortic regurgitation (AR), digital subtraction aortography (DSA) and cineaortography were performed sequentially in 17 patients with varying degrees of AR (1+ to 4+) and in 4 control patients. DSA was performed at a rate of 30 frames/s on a 512 X 512 X 8 bit pixel matrix using the same total volume and injection rate, but with half the amount of contrast agent as standard cineaortography. A 30 X 30 pixel area of interest was identified in the aorta above the valve plane and in the left ventricle where the AR stream was seen. The density of both areas of interest and the ratio of left ventricular/aortic area of interest density was calculated in each frame and then plotted vs time. The ratio at the end of injection (LVd/Aod) had an excellent correlation with cineaortography (chi 2 = 19, p less than 0.001), ranging from 0 to 0.2 in patients with no AR, 0.2 to 0.5 in those with 1+ AR, 0.5 to 0.7 in those with 2+ AR, 0.7 to 0.9 in those with 3+ AR and more than 0.9 in those with 4+ AR. Thus, quantitative assessment of AR by computer analysis of time-density curves derived from DSA is a new and objective technique with significant clinical potential.