Methods of Evaluating the Sequestration Site of Red Cells Labelled with 5ICr: a Review of 96 Cases

Publisher Website
Google Scholar
Abstract
Summary. The technical conditions for surface counting and the methods for calculating splenic and liver sequestration after injection of51 Cr‐labelled cells were studied in 96 patients. A comparative study of different sites of positioning of the detection probes leads us to recommend the mid‐line at the third intercostal space for the precordial area, the point of maximum count‐rate obtained at each measurement for the splenic area, with the patient in right lateral decubitus position and the probe vertical, and a point situated on the midclavicular line 4 cm above the right costal margin for the liver area.A comparative study of different methods of calculation leads us to recommend the method known as ‘excess counts’, but with a correction of the gross values based on the evolution of circulating radioactivity and not of the count‐rate measured over the precordial area. Measurement of urinary excretion of radioactivity showed that only a minor part was due to the loss of the tracer from the sequestration sites, and that the level varied only slightly between subjects. Thus the loss of tracer does not interfere with the interpretation of external counting data.Much of the disagreement regarding interpretation of the results of external counting in clinical practice is due to technical problems. Standardization of techniques of measurement and interpretation of results, selecting those which this study indicates as the most reliable, would permit better exchange of information between laboratories and clearer conclusions as to the practical use of surface counting.