Composite MET-PET Fusion 3.0 Tesla MRI is a New Sensitive Method for the Detection of GH Secreting Adenomas with Abnormal GH Secretary Dynamics

Abstract

Objective: To evaluate the usefulness of methionine (MET)-Positron Emission Tomography (PET) for the early diagnosis of Growth Hormone (GH) secreting adenomas, we retrospectively analyzed patients with abnormal GH dynamics and a histologically confirmed GH secreting pituitary adenoma who underwent pre-operative fluorodeoxyglucose-/MET-PET. Materials and methods:Thirty-two patients with abnormal GH dynamics were included in this study. 3 Tesla (3T) -MRI, [18 F]-flurodeoxyglucose (FDG) -/[ 11 C]-MET-PET, and transsphenoidal surgery were performed in all the patients. We determined correlations among FDG-/MET-PET (maximum standardized uptake value (SUVmax)), serum GH and IGF-1 levels, the GH response to a 75 g Oral Glucose Tolerance Test (OGTT), Thyrotropin-Releasing Hormone (TRH) /Luteinizing Hormone-Releasing Hormone (LHRH) loading tests, tumor volume, and proliferative activity. Results:The diagnostic sensitivity for early GH secreting adenoma was highest for MET-PET (100%), followed by TRH/LHRH (80%), 75 g OGTT (67%), and FDG-PET (47%). Significant correlations were observed between: MET-PET SUVmax and FDG-PET SUVmax (p<0.01), MET-/FDG-PET SUVmax and tumor volume (MET: p<0.01; FDG: p<0.01) ; MET-/FDG PET SUVmax and MIB-1 labeling index (MET: p<0.01; FDG: p=0.01) ; GH/insulin-like growth factor (IGF)-1 levels and tumor volume (GH: p=0.01; IGF-1: p<0.01) ; and GH and IGF-1 levels (p<0.01).