A new technique for assessing right ventricular ejection fraction using rapid multiple-gated equilibrium cardiac blood pool scintigraphy. Description, validation and findings in chronic coronary artery disease.

A reproducible, noninvasive technique for determining right ventricular ejection fraction (RVEF) was developed using multiple-gated equilibrium blood pool scintigraphy, which allows serial rapid measurements without reinjection of radioactivity. Studies were obtained using in vitro labeled technetium- 99m red blood cells, gamma camera and computer. In 20 patients, RVEF determined by multiple-gated equilibrium imaging in the left anterior oblique view was compared with RVEF measured by first-pass scin- tigraphy. For both types of imaging, multiple regions of interest (ROIs) were used for RVEF. The accuracy of RVEF using equilibrium scintigraphy was also evaluated using a single ROI. In 20 additional patients, rapid (2-minute) equilibrium scintigraphy for RVEF was compared with standard (6-minute) imaging. Excellent cor- relation (r = 0.94) for RVEF was found between multiple-gated equilibrium scintigraphy and the first-pass technique when multiple ROIs were used. Inter-and intraobserver variations for the equilibrium method were small (r = 0.91 and r = 0.98, respectively). RVEF with the 2-minute equilibrium technique correlated well with the 6-minute method (r = 0.98). In contrast to the high correlation when multiple ROIs were used, analysis of equilibrium scintigraphy by single ROI severely underestimated first-pass RVEF and showed poor correlation (r = 0.60).