[Planar scintigraphy versus PET in measuring fatty acid metabolism of the heart].
In addition to radionuclide ventriculography and thallium scintigraphy, already well established in nuclear medicine, assessment of myocardial metabolism is also of interest for diagnosis and follow-up observations in heart disease. Under aerobic conditions and in the fasting state, the heart muscle primarily oxidizes fatty acids; during ischemia, in contrast, there is slowing of fatty acid turnover and increased anaerobic glycolysis. With 11C-palmitic acid, in humans, reduced fatty acid uptake has been documented in infarcted myocardial regions. The analysis of 11C-palmitic acid in dogs showed a three-phased elimination curve in normal myocardium. In ischemic myocardium, there was diminished utilization of free fatty acids and the glucose utilization was concomitantly increased. After insulin-glucose infusion, as well, there was increased glucose utilization and a reduction in fatty acid utilization. Studies with 11C-palmitic acid require the equipment for positron emission tomography (PET); because of the short half-life of 20.3 minutes, the nuclide must be generated by a cyclotron in the immediate vicinity. In the search for well-suited isotopes for use in planar scintigraphy employing a gamma camera, the uptake and elimination of a variety of isotopically-marked fatty acids were measured and compared with the characteristics of 14C-palmitic acid. For 17-123I-heptadecanic acid (IHA) the elimination curve was similar to that of 14C-palmitate: disadvantage, however, was the relatively high percentage of water soluble marked catabolites which required dual parameter analysis by means of 99-m-technetium pertechnetate or 123I sodium iodide to quantify the amount of myocardial fatty acid utilization through subtraction of the externally measured water soluble catabolite from the externally measured total activity. In studies with the gamma camera in fasting patients in whom 2 to 3 mCi IHA was injected intravenously after symptom limited bicycle ergometry, in healthy subjects the elimination halftime for the first rapid phase was 24.4 +/- 4.7 minutes. Patients with angiographically-documented coronary artery disease, in the afflicted myocardial segments, had diminished fatty acid uptake and prolonged elimination halftime as compared with normally perfused segments. In patients with dilated cardiomyopathy there was an inhomogeneous distribution of activity in the myocardium and, in contrast to coronary artery disease, a discordance between local fatty acid uptake and turnover rate. After chronic and acute alcohol consumption there were comparable findings which were shown to be reversible after several weeks of abstinence.(ABSTRACT TRUNCATED AT 400 WORDS)
D000818:Animals; D002250:Carbon Radioisotopes; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D003921:Diabetes Mellitus, Experimental / Q000000981:diagnostic imaging; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D007457:Iodine Radioisotopes; D009206:Myocardium / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D051381:Rats; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D005227:Fatty Acids; D007457:Iodine Radioisotopes; D010169:Palmitic Acids; D019308:Palmitic Acid; C013102:margaric acid
Planare Szintigraphie versus PET bei der Messung des Fettsäuremetabolismus am Herzen.