123I‐METAIODOBENZYLGUANIDINE SCANS IN PHAEOCHROMOCYTOMA DIAGNOSIS: CURRENT CLINICAL PRACTICE AND RELATIONSHIP TO BIOCHEMICAL SCREENING

Abstract

SUMMARYThe use in practice of 123I‐metaiodobenzylguanidine (MIBG) scans in phaeochromocytoma diagnosis in a teaching hospital over an eight‐year period is reported. MIBG scans were performed in 43 patients and the clinical context is reviewed and reported in 42 of these. A paraganglioma and five phaeochromocytomas were found in the MIBG series. There were no false negative MIBG scans. CT was performed in 61.9%, abdominal ultrasound in 45.3% and MRI in 7.1% of the patients. Urinary catecholamines and metanephrines are considered the best screening tests for phaeochromocytoma and false positive biochemistry values were associated with MIBG scans in 35% of the cases. Despite published limitations on its sensitivity, MIBG scans were the only modality used in 21.4%; 25% of the scans were performed for clinical reasons when the biochemical screen was within the reference range. MIBG is superior to CT and MRI for the localisation of suspected recurrence after surgery and is also useful for the detection of extra adrenal tumours and metastases.