Determination of left ventricular ejection fraction using ultrafast computed tomography

We evaluated ultrafast CT as a method to measure left ventricular ejection fraction in 16 adults with congenital or acquired heart disease who underwent cardiac catheterization. CT scanning of the left ventricle was performed at 4 to 12 adjacent 1 cm levels (depending on heart size) at 50 msec/scan for one cardiac cycle, with the table positioned with an axial tilt of 10 to 20 degrees and a lateral slew of 5 to 10 degrees to best approximate the long axis of the left ventricle. Image enhancement was achieved by an injection of 25 ml of Renografin-76 via a peripheral vein, with scanning timed to coincide with maximal enhancement of the left ventricular cavity. Ejection fraction was computed by measureing the percent change in area of the left ventricle from diastole (largest area) to systole (smallest area) in a single slice at the mid-left ventricular level. Mean ejection fraction for the group was 58.1 ± 15.1% (range 24% to 84%). The ejection fraction from left ventriculography, computed from biplane images using the Dodge (area-length) formula, was 59.6 ± 12.3% (range 28% to 77%). There was an excellent correlation between left ventricular ejection fraction by CT and ventriculography (r = 0.91, y = 1.1x - 8.5, p < 0.001). This study demonstrates that ultrafast CT can provide an accurate measure of left ventricular ejection fraction by simple methodology.