Tracer elimination in I-123-heptadecanoic acid: half-life, component ratio and circumferential washout profiles in patients with cardiac disease.

Sixty patients with different cardiac diseases and healthy volunteers were given omega-I-123-heptadecanoic acid (HDA) intravenously. Tracer kinetics were followed for 90 min, and tracer elimination curves were obtained regionally. In addition, circumferential washout profiles were evaluated for 26 patients and interpolative as well as constant background subtraction was performed for comparison in selected patients. Rest and stress radionuclide ventriculography allowed formation of a group with normal ventricular function (control group); the remaining patients had an abnormal ventricular function at rest or under stress. Regions of patients in the control group were significantly different (P less than 0.005) from regions of patients with CHD or CMP with regard to the initial half-life or the component ratio between a fast and a slow component (Ca/Cb). Regions of patients after MI without exercise-induced angina did not differ strikingly from control regions. Circumferential washout analysis showed homogeneous tracer kinetics in healthy subjects, bus some individuals showed increasing regional activity, mainly by late activity uptake of the stomach. Dynamic heart scintigraphy with HDA is an additional nuclear cardiologic tool that makes possible the classification of patients with myocardial disease and abnormal ventricular function already under resting conditions. Initial half-life allows reasonable discrimination between different severely diseased patient groups; expansion of acquisition time to 90 min refines biexponential tracer analysis which, by means of an altered component ratio Ca/Cb, may allow better clinical judgement of the individual patient. Circumferential washout analysis and interpolative background correction lead to a better specificity of examination.