Cardiac studies using red blood cells labeled with Tc-99m in vivo with single intravenous injections--first pass technique, gating and blood pool scanning.

The investigations were carried out in 51 patients with different cardiovascular diseases using a gamma camera coupled to a computer. Pyrophosphate (Sn) injection followed by technetium-99m injection were administered through only one puncture of an antecubital vein. Tc-99m was given as a bolus and its passage through the cardiac cavities was recorded and ejection fraction and wall motion of left ventricle were estimated. It was observed that 10-30 min after Tc-99m injection a steady activity Tc-99m-labeled RBCs was maintained in the vascular bed which made possible evaluation of the motility of cardiac walls by the gating technique. Presence of labeled RBCs also permitted blood pool scans and spleen scans to be obtained. Cases investigated by this method for pericardial effusion and splenomegaly are described for illustration.