Clinical usefulness of coregistered 11C-methionine positron emission tomography/3-T magnetic resonance imaging at the follow-up of acromegaly.

Objective This study sought to characterize the utility of coregistered 11C-methionine positron emission tomography (MET-PET) with 3-T magnetic resonance imaging (3T MRI) in the diagnosis and follow-up of pituitary adenomas in patients with acromegaly and to compare MET-PET and 18 F-fluorodeoxyglucose emission tomography (FDG-PET) for the evaluation of active or recurrent disease. Methods This is a prospective observational study. It included a total of 17 patients, 6 patients with a new diagnosis of acromegaly and 11 patients who had previously undergone resection of a confirmed growth hormone–secreting adenoma. The study protocol consisted of preoperative and postoperative evaluation with 3T MRI, and both MET-PET and FDG-PET. Coregistration of 3T MRI/MET-PET was accomplished. Results In all patients who underwent preoperative imaging, MET-PET demonstrated increased uptake coincident with location of the pituitary lesion on 3T MRI. In the postoperative group, the coregistered 3T MRI/MET-PET demonstrated evidence of residual tumor in all patients with active disease. MET-PET sensitivity was 86% and specificity was 86% for the diagnosis of recurrence. Conclusions MET-PET is a sensitive technique for diagnosing persistent acromegaly, and its coregistration with 3T MRI has demonstrated a better definition of the interface, extension, and location of the lesion in the management of active postoperative acromegaly.