Metaiodobenzylguanidine (MIBG) scintigraphy and computed tomography (CT) in clinical practice. Primary and secondary evaluation for localization of phaeochromocytomas.

Abstract

OBJECTIVE: To determine the diagnostic value of metaiodobenzylguanidine (MIBG) scintigraphy compared with computed tomography (CT) for the localization of phaeochromocytomas in clinical practice. DESIGN: Retrospective comparison between MIBG scintigrams and CT for localization of phaeochromocytomas in all patients successively examined with MIBG scintigraphy in Malmö from 1984 until January 1997. SETTING: Malmö University Hospital, Sweden. SUBJECTS: Sixty-four patients with clinically suspected phaeochromocytomas. MAIN OUTCOME MEASURES: MIBG scintigrams and CTs classified as positive or negative based on original interpretations (primary evaluation) and in a secondary evaluation by one blinded examiner are assessed through histological confirmation or clinical rule out of phaeochromocytomas. RESULTS: Twenty-five patients had surgically removed phaeochromocytomas. The remaining 39 patients had no proof of phaeochromocytomas. In the secondary evaluation, sensitivity for MIBG scintigraphy was 88% (22/25) and for CT was 100% (25/25). The specificity for MIBG scintigraphy was 89% (35/39) but only 50% for CT (18/36). Two out of a total of six extra-adrenal tumours were amongst the false-negative MIBG scintigrams. CONCLUSIONS: MIBG scintigraphy for the localization of phaeochromocytomas is superior to CT as far as specificity, whereas CT has a higher sensitivity. After biochemical diagnosis, CT will detect most phaeochromocytomas. MIBG scintigraphy can be of value in patients who show inconclusive results with biochemical testing and CT.