Cyclic precordial variations of radiation after i.v. administration of 15 mCi 99mTc-HSA correspond to cyclic volume changes of ventricular volumes of the heart. The "gated blood pool procedure" yields reliable data. Extensive analysis of these data results in subsequent information concerning left ventricular myocardial behaviour: 1. extent of the regional myocardial contraction 2. homogeneity of the contraction 3. regional contraction velocity 4. regional relaxation velocity. Four parametric scans present the distribution of each one of those parameters within the heart. Gated blood pool data have been compared with angiographic data. Reliability of those parameters obtained by extensive analysis of the gated blood pool data could be proven.