Abnormality of the myocardial sympathetic nervous system in a patient withbecker muscular dystrophy detected with iodine-123 metaiodobenzylguanidinescintigraphy

Purpose: This study was performed to determine whether I-123 metaiodobenzyl guanidine (MIBG) scintigraphy can depict myocardial sympathetic nerve abnor malities in Becker muscular dystrophy. Materials and Methods: A 34-year-old man with Becker muscular dystrophy und erwent TI-201 and I-123 MIBG scintigraphy sequentially before and 4 months after the beginning of oral administration of enalapril maleate, an angiote nsin-converting enzyme inhibitor. Results: Before and during treatment, stress TI-201 scintigraphy revealed n onreversible myocardial perfusion defects in the anterior, inferoposterior, and apical walls, and I-123 MIBG scintigraphy depicted a region with decre ased sympathetic nerve function or innervation. Before treatment, the I-123 MIBG heart count-mediastinum count (H:M) ratio was 2.1 and the washout rat e was 21 % on delayed images obtained 4 hours after the injection of I-123 MIBG, indicating hyperactivity of the sympathetic nervous system in the myo cardium. During treatment, the H:M ratio was 3.0 and the washout rate was 1 5%. Conclusion: With I-123 MIBG scintigraphy it is possible to evaluate an abno rmality of the myocardial sympathetic nervous system and the efficacy of ad ministration of an angiotensin-converting enzyme inhibitor in this disease.