Brown fat imaging with (18)F-6-fluorodopamine PET/CT, (18)F-FDG PET/CT, and (123)I-MIBG SPECT: a study of patients being evaluated for pheochromocytoma.
Academic Article
Overview
abstract
UNLABELLED: Several radiopharmaceuticals such as (18)F-FDG, (123)I-metaiodobenzylguanidine (MIBG), and (99m)Tc-tetrofosmin have demonstrated uptake in brown adipose tissue (BAT). It is important to recognize these normal variants so that they are not misinterpreted as a significant pathologic state. In addition, these radiopharmaceuticals may shed light on BAT physiology. (18)F-6-fluorodopamine (F-DA) is being used as a PET radiopharmaceutical to image adrenergic innervation and suspected pheochromocytoma. Past reports have suggested that BAT is increased in pheochromocytoma patients. METHODS: The images of 96 patients evaluated with (18)F-F-DA or (18)F-FDG PET/CT for known or suspected pheochromocytoma were reviewed retrospectively to determine whether localized uptake of a pattern typically associated with BAT was present. When available, contemporaneous images obtained using (123)I-MIBG were also reviewed for the presence of BAT. RESULTS: Of 67 patients imaged with (18)F-F-DA, BAT was found in 17.9%. Of 83 patients imaged with (18)F-FDG, 19.2% had BAT. Discordant findings related to uptake in BAT were often seen in patients studied with (18)F-FDG, (18)F-F-DA, or (123)I-MIBG. Overall, 26 (27.0%) of 96 patients showed BAT on at least 1 of the 3 imaging modalities. CONCLUSION: (18)F-F-DA can image BAT, most likely by localizing to sympathetic innervations in a manner similar to (123)I-MIBG. Patients with pheochromocytoma may have a greater BAT tissue mass or activation because of elevated levels of circulating catecholamines. Quantitative PET with (18)F-FDG and (18)F-F-DA may have a role in in vivo studies of BAT physiology in humans or animal models.
