Calculation of Right and Left Ventricular Ejection Fraction Using First Pass and Gated Blood-Pool Scans

Abstract

Right and left ventricular (RV, LV) ejection fractions (EF) were calculated from first-pass and gated blood-pool scans in 19 patients (mean age ± s.d. 57.4 ± 11.8) with different cardiac diseases and in 5 normal subjects (mean age 29.6 ± 5.7). Both types of scans were obtained after a single adequate bolus injection of technetium pertechnetate. First-pass scans were collected in serial format and subsequently reformatted into gated frame mode prior to collection of gated equilibrium scans.

Ejection fractions from both data collection modes were calculated with a combination of threshold and second derivative computer algorithms. Right ventricular ejection fraction (RVEF) by first-pass technique was 25 ± 11.7 (mean ± s.d.) for patients and 29 ± 2.9 for controls; and by gated equilibrium scan was 34 ± 10.3 for patients and 31 ± 0.9 for controls. Left ventricular ejection fraction (LVEF) by first pass was 28 ± 11.9 for patients and 38 ± 9.6 for controls; and by gated equilibrium scan was 40 ± 12 for patients and 62 ± 8.9 for controls.

Ejection fraction data from first-pass and gated equilibrium scans were analyzed with linear regression techniques. The correlation coefficient for RVEFs by the two methods was 0.46 for patients and 0.99 for controls; for LVEFs it was 0.63 for patients and –0.11 for controls. Although both of these values for patients were statistically significant at the p < 0.05 level, and the R value for the RVEF in the control group was statistically significant at the p < 0.005 level, there was wide scatter between EF values obtained with the two methods in the patient group and in the control group for LVEFs. Thus, one method cannot be substituted for the other to provide reproducible and reliable information concerning RV and LV function in patients with cardiac disease, or for LV function in the controls.