ONLINE EVALUATION OF SYSTOLIC PERFORMANCE BY DENSITOMETRY IN DIGITAL LEFT VENTRICULOGRAPHY

The angiocardiographic evaluation of left ventricular end-diastolic (L VEDV) and end-systolic (LVESV) volumes and ejection fraction (EF) is r outinely performed by the area-length method (ALM) but may lead to err oneous re suits. Digital imaging in real time allows densitometric pro cedures of determining left ventricular (LV) performance to be applied alternatively. In this study, we present densitometric algorithms for the analysis of LVEDV, LVESV, and EF from digital image data, establi sh accuracy and reproducibility, and determine value and limitations i n comparison with ALM in single-plane 30 degrees right anterior obliqu e (RAO) projection. A linear relationship between iodine depth and mea sured densities is mainly burdened with scatter radiation and beam har dening which reduce primary radiation and suppress iodine depth. Howev er, facilities such as deconvolution and correction algorithms are cap able of reducing these sources of error. In the present study, compute r-analyzed contrast images of iodine-filled wedges and spheres showed a near-linear relationship between iodine depth between 50-100 mg/cm(2 ) and measured densities. Contrast images of heart casts and LV angio- grams of 54 patients were obtained with a digital image acquisition an d processing system, and evaluated by two independent observers. The p hantom study resulted in significantly (p less than or equal to 0.01) better densitometric standard errors of estimate for volumes [3.3 ml d ensitometry (DENS) vs. 8.9 ml (ALM)] and simulated EF [4.3% (DENS) vs. 7.8% (ALM)] than ALM. The standard error of estimate for the comparis on between both methods was 5.4 ml for volumes and 7.5% for EE Densito metric volumes tended to underestimate volumes calculated by ALM. The angiographic study of patients demonstrated significant correlations b etween both methods (LVEDV r = 0.78, LVESV r = 0.83, total volumes: r = 0.89; EF r = 0.88). The standard errors of estimate can be ascribed to systematic, method-related errors of both DENS and ALM (LVEDV +/- 2 8.9 ml, LVESV +/- 23.4 ml, total volumes (EDV and ESV) +/- 27.1 ml; EF +/- 8.1%). The intra- and interobserver variability, respectively, ex hibited significantly smaller (p less than or equal to 0.01 and p less than or equal to 0.05, respectively) standard errors of estimate for densitometric EF [4.6% (DENS) vs. 8.5% (ALM) and 7.1% (DENS) vs. 10.3% (ALM), respectively]. Inclined but not significant differences were f ound for LVEDV and LVESV. In conclusion, the data presented indicate t hat the calculation of LV volumes and EF in digital left ventriculogra phy may be performed accurately by densitometric calculation in single -plane 30 degrees RAO projection. Minor underestimations in densitomet ric volume determination may be anticipated in the evaluation of LV ge ometry.