A simplified technique for measuring right ventricular ejection fraction using the equilibrium radionuclide angiocardiogram and the slant-hole collimator.

The authors developed and tested a simplified technique for measuring the right ventricular ejection fraction (RVEF). Following in vivo 99mTc red cell labeling, equilibrium (ECG-gated) radionuclide angiocardiography was performed in the modified left-anterior-oblique projection using a 30 degree slant-hold collimator. A single region-of-interest was defined from the ejection fraction image, and background was corrected. In 11 normal patients, the mean RVEF was 0.59 +/- 0.08 (SD). In 20 patients with suspected disease, who had RVEF measured by both equilibrium and first-pass techniques, the correlation between the two methods was excellent (r = 0.95; RVEF [first-pass] = 0.74 RVEF [equilibrium] + 0.03; Sy,x = 0.05). Interobserver correlation was also excellent (r = 0.98; Sy,x = 0.03), as was the correlation between RVEFs measured at least 60 minutes apart (r = 0.98; Sy,x = 0.03). This method was more accurate than alternative techniques, using either a background region-of-interest adjacent to the right ventricle or a fixed right ventricular region-of-interest which included the infundibulum. This simplified technique provides a reproducible method for the sequential quantitative assessment of right ventricular performance.