Detection of pheochromocytoma using F-18 FDG PET: Comparison with I-131 MIBG scintigraphy

Abstract

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Objectives: The purpose of this study was to assess the sensitivity of F-18 FDG PET for the detection of pheochromocytoma, in comparison with I-131 metaiodobenzylguanidine (MIBG) scintigraphy.

Methods: A total of 12 tumors in 10 patients with known or subsequently proved pheochromocytomas were examined with both F-18 FDG PET and I-131 MIBG scintigraphy. Tumors were identified as areas of focally increased uptake, exceeding that of surrounding background. For tumors visualized on F-18 FDG PET, the maximal standardized uptake value (SUV) was calculated for semi-quantitative analysis.

Results: Three tumors were found to be malignant pheochromocytomas; and 9 benign pheochromocytomas. The overall sensitivity of F-18 FDG PET for detection of pheochromocytoma was 92% (11/12), compared with 67% (8/12) for I-131 MIBG scintigraphy. For malignant pheochromocytoma, F-18 FDG PET showed a sensitivity of 100% (3/3), compared with 67% (2/3) for I-131 MIBG scintigraphy. One benign pheochromocytoma failed to accumulate neither F-18 FDG nor I-131 MIBG. The mean F-18 FDG SUV in all visualized pheochromocytoma was 9.40 (SD 8.77, range 2.86-30.27). The mean (±SD) F-18 FDG SUV in malignant pheochromocytoma (19.25±12.12) was higher than that in benign pheochromocytoma (5.71±3.25).

Conclusions: F-18 FDG PET showed higher sensitivity than I-131 MIBG scintigraphy for detection of pheochromocytoma. F-18 FDG PET may help define the distribution of pheochromocytoma that fail to accumulate I-131 MIBG and warrants further investigation.