Does iodine-131 meta-iodobenzylguanidine (MIBG) scintigraphy have an impact on the management of sporadic and familial phaeochromocytoma?

OBJECTIVES: To assess the impact of [(131)I]meta-iodobenzylguanidine ((131)MIBG) scintigraphy on the management of phaeochromocytoma.

DESIGN AND PATIENTS: Between 1982 and 2002, 83 patients with histologically proven phaeochromocytoma or paraganglioma were investigated using (131)MIBG scintigraphy. Seventeen of these patients, with a hereditary form of the disease, presented with 23 phaeochromocytomas [three neurofibromatosis type 1 (NF1), five von Hippel-Lindau disease (VHL), eight multiple endocrine neoplasia type 2A (MEN2A) and one type 2B (MEN2B)].

RESULTS: MIBG uptake was observed in 44/54 sporadic phaeochromocytomas (sensitivity 81.5%), 14/23 familial phaeochromocytomas (60.9%), 3/6 paragangliomas and 4/6 malignant phaeochromocytomas. No significant correlations were found between the degree of tracer uptake, tumour size and urinary metanephrine levels. No patients undergoing surgery for sporadic phaeochromocytoma had a second tumour located. Nine of 54 sporadic phaeochromocytomas had normal or mildly elevated urinary metanephrine levels (< 1.5 greater than normal). In eight of these patients, (131)MIBG was positive and confirmed the diagnosis of phaeochromocytoma. In malignant phaeochromocytomas (n = 6), MIBG demonstrated additional lesions not detected with computed tomography (CT) and/or magnetic resonance imaging (MRI) in three cases. The MIBG findings in the group with apparently sporadic paragangliomas (n = 6) were negative in four cases and failed to detect a cervical lesion in one multifocal paraganglioma.

CONCLUSION: (131)MIBG was useful in confirming the diagnosis in phaeochromocytomas with low levels of catecholamine secretion. It contributed little to the management of patients when used as a means of screening for multifocality in sporadic phaeochromocytoma, or the management of patients with familial phaeochromocytoma. However, MIBG can be an informative method of investigation when dealing with malignant/ectopic forms, although the sensitivity of MIBG is lower in this group of patients.