title: [Positron computed tomography for myocardial uptake of N-13 ammonia in patients with hypertrophic cardiomyopathy: a preliminary study].
abstract: In the present study, positron computed tomography (PCT) was used to evaluate the myocardial uptake of N-13 ammonia in patients with hypertrophic cardiomyopathy (HCM). Eight subjects including two normal persons, four patients with HCM, and two with old myocardial infarction (OMI) were selected for the study. N-13 ammonia was administered intravenously as a bolus and, commencing with the tracer injection, serial 30-second PCT scans were performed. The results were summarized as follows: The first scan exhibiting cardiac blood pool images revealed a reduced left ventricular cavity in the HCM subjects. After clearance of N-13 from the cardiopulmonary vasculature, the left ventricular myocardium was clearly visualized and an increased myocardial mass with characteristic morphology was demonstrated in the HCM subjects. Detailed analysis of the time-activity curves of the blood pool and myocardium derived from these serial scan images disclosed two uptake phases in the uptake mode of N-13 ammonia. In the initial phase within three minutes, the myocardial uptake of N-13 was rapid in the normal and OMI subjects, whereas its significant delay was observed in the HCM subjects. This may reflect an abnormal initial extraction of N-13 ammonia in the HCM patients compared with the other subjects. Subsequently, in the second phase, which was characterized by a gradual increase of N-13 in the myocardium, the HCM subjects revealed higher uptake ratios than did the others. This may indicate an increased extraction of metabolites of N-13 ammonia during the second phase. These preliminary results underscore the usefulness of dynamic PCT with N-13 ammonia for the assessment of HCM.
mesh_terms: D000328:Adult; D000641:Ammonia; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging*; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging; D009590:Nitrogen Radioisotopes; D014055:Tomography, Emission-Computed
chemical_list: D009590:Nitrogen Radioisotopes; D000641:Ammonia