EKG gated first-transit radionuclide angiocardiography.

Radioisotopic assessment of left ventricular ejection fraction and wall motion has previously required either EKG gated blood pool imaging or nongated single-transit angiography. A simplified technique involving EKG gated image acquisition during the first cardiac transit of an isotope bolus was evaluated in 36 patients and compared to results obtained from EKG gated blood pool imaging and contrast ventriculography. The method required rapid intravenous injection of 20 mCi of any Tc-99m agent. EKG gated scintillation camera data collection was started after activity entered the left ventricle and resulted in simultaneous acquisition of end-diastolic and end-systolic images on a dedicated computer system. Thus, images representing summed intervals from eight to ten beats were immediately available for calculation of ejection fraction and subjective evaluation of wall motion. Ejection fraction from the gated first-pass images using the area length method was well correlated (r = .95, P less than .001) but tended to be slightly underestimated when compared to contrast values. Abnormal wall motion was identified with a sensitivity of 92%, a specificity of 100%, and an accuracy of 95%. When compared to EKG gated blood pool imaging, inferior wall motion abnormalities, in particular, were more evident on the first-pass study. This method provided simple and accurate assessment of ejection fraction and wall motion and appears to be a useful technique for the noninvasive assessment of left ventricular function.