[Measurement of renal circulation using isotope dilution technique after selective arterial injection of 99m-Tc-pertechnetate (author's transl)].

Report on a method of measuring the middle transit-time (t) which represents a measure for renal circulation. Time-activity curves obtained after arterial injection of 99m-Tc and registration with the Anger camera, could be subdivided into 4 individual curves using a program of calculation (initial drop, 2 waves of recirculation, underlying activity); t characterizes the exponential, perfusion-specific initial drop as reciprocal to the constant k 1. The suitability of 99m-Tc for measuring renal circulation is discussed. The various methods for calculation of the middle transit-time are compared.