Correlation of Morphological and Functional Characteristics of Growth Hormone-Producing Pituitary Adenomas

Abstract

Introduction. Previous studies demonstrated a relationship between T1- and T2-weighted signal intensity and tumor growth patterns and potential as well as hormonal activity in somatotropinomas. Further investigation of these findings could serve to define predictive diagnostic and treatment factors based on MRI characteristics.The aimof this retrospective study was to analyze the MRI characteristics of growth hormone-producing pituitary adenomas in newly diagnosed patients with acromegaly and to compare them with the corresponding morphological and biochemical characteristics.Methods. Seventy five patients with newly acromegaly were included in the study. Pre-treatment T1- and T2-weighted MR-images of all patients were analyzed, taking into account the intensity of the signals produced by the tumors, as well as their dimensions and growth direction. Growth hormone and IGF-1 levels were also recorded.Results. Out of 75 patients, 74.7% were macroadenomas. T1-weighted adenoma signal was hypointense in 45.3% of patients, hyperintense in 18.7% of patients and isointense in all other cases. T2-weighted adenoma signal was hypointense in 32.3% and hyperintense in 40.5% of patients. No statistically significant differences were found between GH and IGF1 levels as well as signal intensity in relation to patient age. Inferior tumor extension was present in 60.0% of patients overall and 33.3% more prevalent in patients with hyperintense T2 signal and 24.5% and 11.7% more prevalent in patients with hypointense and hyperintense T1 signal respectively. Superior extension was observed in 46.7% of patients and did not differ significantly from inferior extension in patients with hypointense T2 signal. The highest levels of IGF1 were associated with superior extension, while the highest levels of GH were associated with inferior extension. Mean adenoma volume was 8.45 times higher and GH levels were 3.8 times higher in patients with hyperintense T2-weighted signal and 2.3 and 1.3 times higher respectively in patients with hyperintense T1-weighted signal.Conclusion. Hyperintense T1- and T2-weighted MRI signal was associated with larger tumor dimensions, increased GH levels and more frequent inferior extension, all of which indicate higher proliferative potential of the adenomas.