RT Journal Article
SR Electronic
T1 Imaging of Adrenal Incidentalomas with PET Using <sup>11</sup>C-Metomidate and <sup>18</sup>F-FDG
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 972
OP 979
VO 45
IS 6
A1 Minn, Heikki
A1 Salonen, Anna
A1 Friberg, Johan
A1 Roivainen, Anne
A1 Viljanen, Tapio
A1 Långsjö, Jaakko
A1 Salmi, Jorma
A1 Välimäki, Matti
A1 Någren, Kjell
A1 Nuutila, Pirjo
YR 2004
UL http://jnm.snmjournals.org/content/45/6/972.abstract
AB Our aim was to evaluate the use of PET with 11C-metomidate and 18F-FDG for the diagnosis of adrenal incidentalomas. Methods: Twenty-one patients underwent hormonal screening before dynamic imaging of the upper abdomen with 11C-metomidate, and for 19 of these 21 patients, static 18F-FDG imaging followed. Uptake of 11C-metomidate and 18F-FDG in incidentalomas was quantified and correlated with the hormonal work-up and the mass size on CT (median, 2.5 cm; range, 2–10 cm). Results: The final diagnoses were hormonally active adenoma (n = 7), nonsecretory adenoma (n = 5), adrenocortical carcinoma (n = 1), pheochromocytoma (n = 2), benign noncortical tumor (n = 2), normal adrenal (n = 1), and malignant noncortical tumor (n = 3). Diagnosis was established at surgery (n = 9), percutaneous biopsy (n = 4), or follow-up (n = 8). The highest uptake of 11C-metomidate, expressed as standardized uptake value (SUV), was found in adrenocortical carcinoma (SUV = 28.0), followed by active adenomas (median SUV = 12.7), nonsecretory adenomas (median SUV = 12.2), and noncortical tumors (median SUV = 5.7). Patients with adenomas had significantly higher tumor–to–normal-adrenal 11C-metomidate SUV ratios than did patients with noncortical tumors. 18F-FDG detected 2 of 3 noncortical malignancies but failed to detect adrenal metastases from renal cell carcinoma. All inactive and most active adenomas were difficult to detect with 18F-FDG against background activity, whereas both pheochromocytomas and adrenocortical carcinoma showed slightly increased uptake of 18F-FDG. There was no correlation between uptake of 11C-metomidate or 18F-FDG and mass size. Conclusion: 11C-Metomidate is a promising PET tracer to identify incidentalomas of adrenocortical origin. 18F-FDG should be reserved for patients with a moderate to high likelihood of neoplastic disease.