[Estimation of regional myocardial sympathetic neuronal function with I-123 metaiodobenzylguanidine (MIBG) myocardial images in patients with cardiomyopathy].

I-123 Metaiodobenzylguanidine (MIBG) is taken up by myocardial sympathetic neuronal endings. Sympathetic neuronal function in 10 patients with cardiomyopathy under stable state were studied by using MIBG and Tl-201 (Tl) SPECT images with 50% cut off level. For myocardial imaging MIBG and Tl were simultaneously injected and collected (dual injection and dual collection mode; Dd mode). Four hours delayed images were also collected. Three types of abnormal findings were noted in MIBG images in combination with Tl images. 1) Enhancement of regional MIBG washout with otherwise normal MIBG and Tl uptake in infero-lateral wall were noted in 5 patients with history of congestive heart failure (Pathophysiologically acceleration of regional sympathetic neuronal function was suspected. Mean washout ratio is 63 +/- 7% vs. 45 +/- 10% in normal region). 2) In 3 patients with dilated cardiomyopathy increase of MIBG/Tl (M/T) ratio was noted in basal septal wall (Sympathetic neuronal function is abnormally accelerated in the region with depressed coronary perfusion. Exaltation of regional sympathetic neuronal function was suspected. Mean M/T ratio is 1.6. Tentative normal range is from 0.8 to 1.20). 3) In 2 patients with dilated cardiomyopathy under severe congestive heart failure defects of MIBG uptake with normal Tl uptake were noted (Sympathetic neuronal function was depleted in spite of normal coronary perfusion. Depletion of myocardial catecolamine was suspected. M/T ratio is 0.75 and 0.7 respectively). Heterogeneous abnormality of sympathetic neuronal function was noted in MIBG images. This findings corresponded to report about heterogeneous myocardial catecholamine concentrations in hearts of recipients of transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)