Work in progress: a correction for tissue iodine accumulation in videodensitometric measurements of left ventricular ejection fraction.

Abstract

Left ventricular ejection fractions were determined following eight intravenous injections in three dogs using area/length and digital videodensitometric techniques. Ejection fractions were measured by both techniques for all beats during left ventricular opacification. Even after noniodinated background corrections, tissue iodine accumulation produced large errors in measured iodine content late in the contrast material curve. By using a model for tissue iodine accumulation, an algorithm was developed that appears to reduce these errors. The measured ejection fraction for ten beats following the peak of the contrast material curve declined an average of 1.8% following correction, compared with 14% prior to correction. Following correction for tissue iodine accumulation, correlation between area/length and video-densitometric ejection fractions was 0.94. By correcting for tissue iodine accumulation, much more of the contrast material curve provides usable data for estimating ejection fractions.

Determination of cardiac ejection and valvular regurgitant fraction by on-line digital densitometry — methodology, validation, and application

“…As discussed earlier [3,9,11,12,13] there are several further problems when the density of X-ray images is evaluated quantitatively. Four main sources of errors can be distinguished: cyclic density fluctuations modifying the contrast wash-out curve, accumulation of iodine in tissue superposing the ventricular region, image degradation due to scatter radiation and veiling glare, and data scattering due to physiologic beat-to-beat variations, motion artifacts, and inhomogeneous indicator mixing.…”

“…i upper panel). Proposed solutions to this problem are to approximate that rise functionally [3,12,13] or to record it with the aid of a region next to the ventricle [4,5,8]. We found that the application of the method of differences introduced for the determination of FEF for analog densitometry by Falliner and coworkers [11] was both simple and reliable.…”

“…It has been modified and applied since then by several authors for the assessment of EF [3][4][5][6][7][8][9][10] as well as for RGF [11][12][13][14][15][16]. Nevertheless, until now the method is not used routinely.…”