Aim: The aim of this study was to assess the utility of combined 11C-methionine and 18F-FDG PET/CT imaging in hyperparathyroidism.
Patients and Methods: We reviewed all scans performed for hyperparathyroidism with both 11C-methionine and 18F-FDG PET/CT or PET in our institution since 1993. Forty-three patients (47 pairs of scans) were included (13 men and 30 women) with a mean age of 63 years. 11C-methionine and 18F-FDG PET/CT scans were classified as positive or negative for localization of abnormal parathyroid tissue, and the site of uptake was noted in the positive scans. Other concurrent imaging (99mTc-MIBI scintigraphy, ultrasonography, CT, or MRI) findings were also noted when performed. Clinical follow-up information was available in 27 patients (30 episodes).
Results: Of the 47 PET scan episodes, 23 (49%) were positive. Twenty-two 11C-methionine scans showed abnormal focal localization of which 10 also showed concordant abnormal 18F-FDG uptake. One patient was positive with 18F-FDG and negative with 11C-methionine.
Of the 16 patients who underwent subsequent surgery, 6 had concordant 11C-methionine, 18F-FDG, and surgical findings; 6 had concordant 11C-methionine and surgical findings; 1 had concordant 18F-FDG and surgical findings; and 3 had both PET scans negative but had adenomas excised during surgery.
Of the 3 with both PET scans negative and discordant surgical findings, 1 had mediastinal parathyroid lipoadenoma excised and 2 had normally sited parathyroid adenoma excised.
Conclusions: 18F-FDG PET/CT rarely provides additional information and could be saved for patients in whom 11C-methionine PET/CT is negative.