Improved densitometric analysis of ventricular volumes in on-line digital cardiac imaging

In digital angiocardiography left ventricular volumes are routinely calculated by the area-length-method (ALM) which is considered to be a standard and with which other techniques are compared. Densitometric analysis (DENS) is an alternative method and can be performed on-line but may lead to erroneous results. A novel technique of densitometric calculation of left ventricular enddiastolic and endsystolic volume (LVEDV resp. LVESV) is presented. Digital images were analyzed by measuring densities of iodine signals and transforming these into calculated volumes by applying appropriate computer algorithms. The evaluation of volumes in cardiac models demonstrated significant correlations between true volumes and both DENS and ALM. An algorithmic approach to volume correction in patient evaluation of left ventricular volumes was drawn from the linear regression analysis of DENS and true volumes in the cardiac models. LVEDV and LVESV calculated by DENS correlated significantly with volumes determined by ALM in patients (r=0.78 resp. r=0.83) but showed a systematic underestimation for volumes > or =45 ml without densitometric correction. Following correction for DENS, an improvement in calculation was observed for volumes < or =200 ml without systematic deviations. In conclusion, our study demonstrates that corrected densitometric volumetry offers the potential for a reliable on-line analysis of enddiastolic and endsystolic volumes. Modest, but no systematic deviations for densitometric analysis may be anticipated in myogene dilatation with volumes larger than 200 ml. However, when comparing both DENS and ALM, method-related errors of both techniques are present and account for volume deviations.