11C-Methionine PET/CT Imaging of 99mTc-MIBI-SPECT/CT-Negative Patients With Primary Hyperparathyroidism and Previous Neck Surgery

Context: Tc-99m-Methoxy-isobutyl-isonitrile (MIBI) scintigraphy is a standard preoperative localization imaging modality in patients with primary hyperparathyroidism (pHPT). Its accuracy in localizing a hyperactive parathyroid gland after previous cervical surgery is limited. Recently, C-11-methionine has been introduced as a promising radiotracer for pHPT imaging. Yet, few data exist for this technique in patients with persisting or recurrent pHPT before reoperation. Objectives: We aimed to investigate the ability of C-11-methionine positron emission tomography (PET)/computed tomography (CT) to localize a parathyroid disorder after cervical surgery and negative postsurgical Tc-99m-MIBI single-photon emission CT (SPECT)/CT. Design, Setting, and Participants: Fifteen patients (6 males, 9 females; age range, 36-85 years) with pHPT and negative Tc-99m-MIBI SPECT/CT who had undergone earlier neck surgery because of pHPT and/or thyroid disorder were recruited. Twelve of the 15 patients had thyroidectomy for goiter or differentiated thyroid carcinoma. Ten patients had previous parathyroid surgery for pHPT, and 2 patients had a history of parathyroid carcinoma. Thirteen of 15 patients showed elevated levels of intact PTH at the time of PET/CT imaging, whereas all patients had elevated serum calcium values. Main Outcome Measurements: Pathological results of contrast-enhanced C-11-methionine PET/CT and surgical results were evaluated. Results: In 6 of 15 patients C-11-methionine PET/CT showed a hypermetabolic focus in the upper mediastinum in 2 patients, in the thoracic outlet in 1 patient, and in the cervical region in 3 patients. In 9 of the 15 patients, no hyperactive parathyroid gland could be visualized. Reoperation was performed in 5 of 6 patients without surgical complications. One patient refused surgery. In 2 of the 5 patients, a transsternal procedure was performed. Correlating with the C-11-methionine PET/CT results, a single parathyroid adenoma was found in 4 patients and parathyroid carcinoma metastasis in 1 patient. Conclusion: C-11-Methionine PET/CT is a useful complementary imaging technique to localize parathyroid adenoma or carcinoma in Tc-99m-MIBI SPECT/CT-negative patients.