11C-Hydroxyephedrine Positron Emission Tomography Imaging of Pheochromocytoma: A Single Center Experience over 11 Years

Localization of the primary tumor and detection of metastases are essential for preoperative planning and postoperative management of pheochromocytoma. When computed tomography (CT) and magnetic resonance imaging are inadequate, functional imaging adds important information in this respect.In this study the efficacy of positron emission tomography (PET) and PET/CT with (11)C-hydroxyephedrine (HED) was evaluated.HED-PET (n = 69) and PET/CT (n = 101) examinations of 134 patients were analyzed, of which 103 were performed before surgery and 67 postoperatively. Image findings were evaluated and tracer uptake in tumors measured as the maximum standardized uptake value (SUVmax), which was compared with histopathological and clinical data.Sixty HED-PET and PET/CT examinations were positive, with no false-positive and six false-negative examinations (sensitivity 91%, specificity 100%). Sensitivity of HED-PET in multiple endocrine neoplasia type II patients was lower (73%) with 100% specificity. The mean SUVmax was significantly higher when sympathetic symptoms were present and in metastases compared with primary tumors. The SUVmax correlated significantly with plasma normetanephrine and urinary norepinephrine. The mean SUVmax in HED-positive primary tumors was significantly higher than in normal adrenal glands.HED-PET and PET/CT demonstrated 91% sensitivity and maximum specificity but with lower sensitivity in multiple endocrine neoplasia type II patients. The degree of HED accumulation (SUVmax) in the tumors correlated to malignancy and biochemical data.