AUTOMATED-DETERMINATION OF LEFT-VENTRICULAR VOLUME CURVES FROM BI-PLANE DIGITAL ANGIOGRAPHY WITHOUT EXPLICIT USE OF EDGE-DETECTION ALGORITHMS

Automated computation of left ventricular (LV) global and regional fun ction using contrast angiography has not yet become a routine procedur e with the advent of digital cardiac imaging systems. We describe a ne w technique to compute LV volume curves which does not require the use of manual or semi-automated detection of endocardial borders and prov ides on-line implementation of volumetric curves and computation of pr essure volume loops during catheterization. The approach uses the conc epts of variable entropy (or information) of left ventricular images t hroughout the cardiac cycle. LV volume curves are computed with an int erpolation scheme using those LV volume curves of a patient data base which are associated with the closest variation in entropy in the RAO projection to the analyzed patient data according to a simple metric. Computed LV volume curves were correlated with those obtained with man ual tracing. Left ventricular ejection fraction (LVBF), time to end sy stole (TES) and angiographic cardiac output (CO) were compared to thos e obtained with the manual method. Results using a data base of 365 pa tients revealed excellent correlation (r = 0.97) between manually deri ved volume curves and volume curves computed with the automated techni que within a large range of LVEFs. In 87% of all cases the computed LV EF values were found within +/- 10% of the value obtained with the gol d standard method. The systolic phase of the volume curves showed that 81% of all cases had the same accuracy. The TES showed much more vari ation due to undersampling of the cardiac cycle in time (r = 0.71).