[An adaptation function for describing time-activity curves in nuclear medicine (author's transl)].

Radioisotopic time-activity curves can be described by a function known from the physics of heat conduction. This function, called in this paper "tracer function", is a special solution of one-dimensional differential equation of heat conduction. The function is especially useful in the quantitation of left-to-right cardiac shunts by analysis of the pulmonary time-activity curve. The first transit curve is determined from the amplitudes on the ascending slope of the curve only including the maximum. The shunt curve analysis uses two parameters derived from the first transit curve and then the position and amplitude of the shunt curve maximum only.