Visualizing cardiac blood pool: comparison of three labeling methods.

The quality of three different labeling methods of visualizing the cardiac blood pool was investigated in 72 patients: 99mtechnetium labeling of red blood cells in vivo or in vitro and human serum albumin. By the simplified technique of in vitro labeling of RBC from the view point of (1) labeling efficiency, (2) activity in the blood, (3) count rates in a standard ROI over the left ventricle and the paracardiac background, (4) ratio of these count rates, and (5) evaluation of image quality, the best results were obtained. HSA and in vivo labeled RBC led to satisfactory results for visual assessment of ventricular performance in most cases. In spite of the slightly higher technical investment involved in the in vitro labeling method this technique appears to be preferable for gated cardiac blood pool studies in view of the excellent labeling quality.