[123I-metaiodobenzylguanidine myocardial scintigraphy in a case of pheochromocytoma before and after resection of it].

A 55-year-old man with pheochromocytoma was examined by 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy before and after resection of the tumor. MIBG images showed decreased uptake in infero-posterior wall before operation. The heart to upper mediastinum uptake ratio was low at the delayed anterior planar image, and mean MIBG clearance from the left ventricle was increased. These abnormal scintigraphic findings improved after resection of the tumor. We thought that these abnormal MIBG findings were not due to abnormal cardiac sympathetic nerve function, because ECG, chest X-ray, UCG and 201Tl myocardial scintigram did not reveal any abnormality. It may be presumed that these abnormal MIBG findings were caused by high plasma catecholamines concentration. The mechanism of abnormal MIBG findings of the heart remains uncertain in various heart diseases. MIBG findings in this case with pheochromocytoma before and after resection may contribute to interpretation of the kinetics of MIBG in heart.