Quantitative assessment of global and regional left ventricular function with low-contrast dose digital subtraction ventriculography

Comparison of low-volume versus standard-volume left ventriculography

Left ventriculography provides useful information about cardiac function, wall motion, and mitral regurgitation (MR). However, standard volumes of contrast agent frequently are associated with ventricular ectopy. This study compares the use of low-volume (Low-vol) ventriculography to standard volume (Std-vol) ventriculography. Left ventricular (LV) ejection fraction (EF), changes in LV end-diastolic pressure (LVEDP), the incidence of ectopy, and > 2+ MR were prospectively determined from the random order use of standard (15 mL/ second for 3 sec) and low-volume (15 mL/sec for 1 sec) contrast agents in 102 patients. Each patient served as his or her own control. Twenty-seven percent of the 204 ventriculograms were not interpretable due to ectopy. Ectopy > or = 3 beats was more common with Std-vol angiograms (41% vs. 14%, P < 0.001). Post-injection LVEDP increased from baseline after both Std-vol and Low-vol injections (P < 0.001). In patients for whom both angiograms could be interpreted (n = 58), no differences were noted between planimetered EFs (Low-vol = 61 +/- 20% vs. Std-vol = 62 +/- 20%, with r = 0.87; P < 0.001). A Bland-Altman test of agreement indicated a mean difference +/- 95% CI = -2 +/- 19%. Low-volume ventriculography reduces contrast load and ectopy while providing similar estimates of EF compared with standard volumes.

On-line evaluation of systolic performance by densitometry in digital left ventriculography

The angiocardiographic evaluation of left ventricular end-diastolic (LVEDV) and end-systolic (LVESV) volumes and ejection fraction (EF) is routinely performed by the area-length method (ALM) but may lead to erroneous results. Digital imaging in real time allows densitometric procedures 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, establish accuracy and reproducibility, and determine value and limitations in comparison with ALM in single-plane 30 degrees right anterior oblique (RAO) projection. A linear relationship between iodine depth and measured densities is mainly burdened with scatter radiation and beam hardening which reduce primary radiation and suppress iodine depth. However, facilities such as deconvolution and correction algorithms are capable of reducing these sources of error. In the present study, computer-analyzed contrast images of iodine-filled wedges and spheres showed a near-linear relationship between iodine depth between 50-100 mg/cm2 and measured densities. Contrast images of heart casts and LV angio-grams of 54 patients were obtained with a digital image acquisition and processing system, and evaluated by two independent observers. The phantom study resulted in significantly (p < or = 0.01) better densitometric standard errors of estimate for volumes [3.3 ml densitometry (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 comparison between both methods was 8.4 ml for volumes and 7.5% for EF. Densitometric volumes tended to underestimate volumes calculated by ALM. The angiographic study of patients demonstrated significant correlations between 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 +/- 28.9 ml, LVESV +/- 23.4 ml, total volumes (EDV and ESV) +/- 27.1 ml; EF +/- 8.1%). The intra- and interobserver variability, respectively, exhibited significantly smaller (p < or = 0.01 and p < or = 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 found for LVEDV and LVESV. In conclusion, the data presented indicate that the calculation of LV volumes and EF in digital left ventriculography may be performed accurately by densitometric calculation in single-plane 30 degrees RAO projection. Minor underestimations in densitometric volume determination may be anticipated in the evaluation of LV geometry.

Evaluation of the densitometric method of ejection fraction by direct digital subtraction left ventriculography

The aim of the present study was to test the hypothesis that the densitometric ejection fraction (EF) could be calculated by direct contrast digital subtraction left ventriculography in a single heartbeat. Thirty patients underwent direct contrast digital subtraction left ventriculography and biplane conventional left ventriculography. The values of EF were obtained from digital subtraction ventriculograms of the first cardiac cycle after completion of the injection of the contrast medium by the videodensitometric technique and were compared with those obtained from conventional ventriculograms by the area-length method in the same patients. There was a close correlation between the densitometric EF from digital subtraction ventriculograms and the volumetric EF from conventional ventriculograms (r = 0.78). Densitometric EF measured in the 30 degree right anterior oblique projection highly correlated with densitometric EF measured in the 60 degree left anterior projection (r = 0.98). These data suggest that this densitometric technique is available in any projection and is a simple procedure for the accurate measurement of left ventricular EF.

A new video intensity based wall motion analysis technique

A new computerized video intensity based method to evaluate regional wall motion for a frame by frame analysis has been developed. A region of interest is defined, and its average time-intensity curve is computed for the cardiac cycle. For each time interval the video intensity for a pixel in the region of interest is correlated with the average for the whole ventricle and its slope and correlation coefficient are calculated to derive two functional images. This technique utilizes images either from levophase or direct opacification of the left ventricle, and it is insensitive to RR-interval changes.