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, [18F]-flurodeoxyglucose (FDG) -/[11C]-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). Conclusions: All the patients with abnormal GH dynamics detected by MET-PET had GH adenomas, indicating that MET-PET is useful for the early diagnosis of GH adenomas.
Highlights
Sustained Growth Hormone (GH) excess resulting from a GH secreting pituitary adenoma causes acromegaly, the diagnosis of which ranges from 2.5 to 10 years after the onset of symptoms [1,2,3,4,5,6]
The lesions detected by MET-Positron Emission Tomography (PET) fusion Magnetic Resonance Imaging (MRI), based on the high tracer uptake, were confirmed by the operative findings in all 32 patients, illustrating a high level of accuracy
We found significant correlations between MET-PET SUVmax and MIB-1 (p
Summary
Sustained Growth Hormone (GH) excess resulting from a GH secreting pituitary adenoma causes acromegaly, the diagnosis of which ranges from 2.5 to 10 years (mean 8 years) after the onset of symptoms [1,2,3,4,5,6]. Establishing guidelines for the early diagnosis or assessment of the disease activity of acromegaly is a major challenge [1,4,6,10]. Which sometimes shows a false-negative or false-positive reaction to various hormone-loading tests, does not always fulfill the established diagnostic criteria. Neuroradiological assessments, such as computed tomography (CT) or Magnetic Resonance Imaging (MRI), sometimes fail to detect GH secreting adenomas. We analyzed correlations among Fluorodeoxyglucose (FDG) -/MET-PET (maximum Standardized Uptake Value (SUVmax)), serum GH and IGF-1 levels, the GH response to a 75 g OGTT, TRH/LHRH loading tests, tumor volume, and proliferative activity. We sought to identify the factors that facilitated the early diagnosis of GH secreting adenoma
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