Calibration methods for measuring splenic sequestration by external scanning.

Conventional methods for measuring splenic sequestration of labeled cells rely on stationary probe counting over the liver and spleen. A quantitative spleen-scanning method is proposed as a means of performing a more accurate diagnosis of the degree of splenic sequestration. Improved methods for calibrating a rectilinear scanner employing "constant resolutions" collimators, designed for the in vivo measurement, are reported, Clinical evaluation of this method was performed by scanning several patients scheduled for splenectomy. Good correlation between in vivo and in vitro measurements of splenic radioactivity for 29 patients was obtained. A least-squares fit to the data yielded a coefficient of determination r2=0.93.