[Automated method of determining blood circulation time in nuclear medicine cardiology]

In this paper a method of computer-assisted evaluation of circulation times using a scintillation camera is described. Eight segments of the central circulation are defined on a graphic display unit. Then the analysis of time-activity curves and the normalization of circulation times to hear rate is performed. The automatic analysis is based upon the hydrodynamic meaning of the first inflection point of a time-activity curve. The differences between inflection points are nearly identical with appearance time differences under the experimental conditions used in 131 cases. A mathematical model is presented to defined the conditions for this behaviour and to explain some deviations observed if time differences exceeded a certain value. It can be shown that the method described is largely independent of extraneous influences. It offers haemodynamically relevant parameters that correspond to the minimal cardiac transit times.