DENSITOMETRIC ASSESSMENT OF REGIONAL LEFT-VENTRICULAR SYSTOLIC FUNCTION DURING GRADED ISCHEMIA IN THE DOG BY USE OF DUAL-ENERGY DIGITAL SUBTRACTION VENTRICULOGRAPHY

Densitometric analysis of images obtained by digital subtraction angio graphy (DSA) allows for more reproducible and less operator-dependent quantitation of ventricular function. Conventional DSA uses temporal s ubtraction but is limited by misregistration artifacts. Dual-energy di gital subtraction angiography (DE-DSA) is immune to such misregistrati on artifacts. The ability of DE-DSA to quantitate changes in regional ventricular volume resulting from ischemia was tested. Densitometric a nalysis of both phase-matched and ejection fraction DE-DSA images was used to quantitate regional left ventricular systolic function during four levels of ischemia ranging from mild to severe in open-chest dogs (n = 10). DE-DSA left ventriculograms were obtained by means of centr al venous injections of iodinated contrast medium. Ischemia was graded according to percentage of systolic wall thickening as measured by so nomicrometry. Phase-matched end-systolic images were obtained at each of four levels of ischemia by subtracting an end-systolic control imag e from each end-systolic ischemic image. Ejection fraction images were obtained at the control level and at each level of ischemia by subtra cting an end-systolic image from an end-diastolic image of the same ca rdiac cycle. The resulting wall motion difference signals represent th e changes in regional ventricular volumes and were quantitated by dens itometry. Densitometry was able to detect the effect of all levels of ischemia on regional function, even the mildest. Densitometric analysi s of both phase-matched and ejection fraction DE-DSA images provides a sensitive technique for detecting and quantitating the changes in reg ional left ventricular systolic volume that occur with ischemia.