Use of Radioiodinated Fatty Acid for Photoscans of the Heart

Radioiodinated fatty acid bound to albumin (RIFA) was given by intravenous injection to dogs and moribund human subjects in order to label heart muscle.Photoscans of the thorax of dogs given RIFA revealed concentration of radioactivity in the ventricular region of the heart due to incorporation of the labeled fatty acid into myocardial triglyceride and phospholipid.Photoscans of the thorax following intravenous injection of radioiodinated serum albumin or NaI showed a different density pattern in the region of the heart due to radioactivity in blood within the cardiac chambers.Areas of myocardial infarction were detected in photoscans of the thorax in 11 of 14 dogs in which one coronary artery was ligated. At necropsy the concentration of radioactivity was much higher in healthy myocardium than in infarcted muscle. The same distribution of radioactivity was observed in hearts from three human subjects with myocardial infarction given RIFA shortly before death. It is proposed that areas of myocardial infarction might be demonstrated during life by photoscans of the thorax following intravenous injection of RIFA.