[Right ventricular ejection and regional wall motion evaluated by cardiac blood pool emission computed tomography]

Calculating right ventricular (RV) ejection fraction (EF) is difficult because of geometrical problems such as irregular trabeculations, a separate infundibulum, and variations in the right ventricular shape. We performed 99mTc ECG-(dual)gated cardiac blood pool emission computed tomography (ECT) in 10 patients with ischemic heart disease, three patients with dilated cardiomyopathy (DCM), and eight normal subjects as controls, and RVEF and % shortening of the RV were calculated to evaluate right ventricular function. Methods were as follows: 1) RVEF: The region of interest (ROI) of the RV was determined on reconstructed short-axial images, and then the RV counts in the ROI were summed from the apical slice to the RA-RV boundary slice. (Formula: see text) 2) % shortening of the RV: At the RV mid-portion, the contour from the short-axial image was obtained using the threshold method; the end-diastolic contour was superimposed on the end-systolic contour, and then shortenings in the RV free wall and septum respectively, were calculated. To evaluate reliability of RVEF obtained by this method, left ventricular ejection fraction (LVEF) calculated using the same method was compared with results obtained by the previously validated method: There were significant correlations with contrast cineangiography (r = 0.69) and the conventional multigated method (r = 0.90), respectively. Cases with decreased RVEF showed a variety of right ventricular abnormal findings, including positive uptake on 99mTc-PYP scintigraphy, occlusion of the right coronary artery, RV dilatation on echocardiography. The mean RV free wall shortening in the decreased RVEF group was lower than that of the normal group (p less than 0.01), whereas there was no significant difference in the decreased LVEF group.(ABSTRACT TRUNCATED AT 250 WORDS)