Alteration of myocardial metaiodobenzylguanidine uptake after treatment of phaeochromocytoma and neuroblastoma

The relationships between changes in myocardial uptake of metaiodobenzylguanidine (MIBG) and those in circulating catecholamines and cardiac function after treatment of phaeochromocytoma and neuroblastoma were evaluated. Iodine-123 or iodine-131 MIBG scintigraphy was performed before and after surgical resection and/or chemotherapy for primary tumours in nine patients with phaeochromocytoma and 13 patients with neuroblastoma. Changes in myocardial MIBG uptake after treatment were estimated by the heart-to-upper mediastinum (H/M) uptake ratios on the images obtained 24 h after MIBG injection, which were compared with serum levels of noradrenaline (NA) and adrenaline (A). Cardiac function was assessed by echocardiography, with measurements of the left ventricular ejection fraction (LVEF). Before treatment, eight patients with phaeochromocytoma and three with neuroblastoma showed poor myocardial MIBG uptake, with highly elevated circulating NA and A. Echocardiography, however, did not show cardiac dysfunction in these patients with the exception of two patients with phaeochromocytoma. With normalization of NA and A levels after treatment, all of these patients except for the two with persistent cardiac dysfunction showed restoration of myocardial MIBG uptake. The H/M ratios increased significantly after treatment in both patient groups, i.e. with phaeochromocytoma and with neuroblastoma (P