COMPARISON OF POSTSTRESS EJECTION FRACTION AND RELATIVE LEFT-VENTRICULAR VOLUMES BY AUTOMATIC-ANALYSIS OF GATED MYOCARDIAL PERFUSION SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY ACQUIRED IN THE SUPINE AND PRONE POSITIONS

Background. We have previously described an automatic method for measu ring left ventricular ejection fraction (LVEF) for myocardial perfusio n single-photon emission computed tomography (SPECT), The repeatabilit y of this method has not been previously described. Methods and Result s. This study compares LVEF and relative end-systolic and end-diastoli c volumes assessed from myocardial perfusion SPECT by our automatic me thod in 180 consecutive patients undergoing gated myocardial perfusion SPECT with injection of Tc-99m-labeled sestamibi in whom the acquisit ions were performed sequentially in supine and prone positions, The al gorithm operated completely automatically in the prone and supine posi tions in 178 of the 180 patients, Very high correlations were observed for LVEF (r = 0.93), relative left ventricular end-systolic volume (r = 0.98), and relative left ventricular end-diastolic volume (r = 0.97 ), The mean paired absolute difference between LVEFs in the prone and supine position was 3.8 +/- 3.2, for left ventricular end-systolic vol ume was 4.9 +/- 4.8 ml, and for left ventricular end-diastolic volume was 7.4 +/- 6.7 ml, When patients were classified by the extent and se verity of stress perfusion defect, there was no significant difference in repeatability for the measurements in any category. Conclusions. O ur algorithm for automatic quantification of LVEF and relative end-sys tolic and end-diastolic volumes from gated Tc-99m sestamibi myocardial perfusion SPECT is repeatable, When performed in the prone position, values of ejection fractions and ventricular volumes are essentially i dentical to those obtained in the supine position.