Pituitary MRI characteristics in 297 acromegaly patients based on T2-weighted sequences.

Context: Responses of GH-secreting adenomas to multimodal management of acromegaly varies widely between patients. Understanding the behavioral patterns of GH-secreting adenomas by identifying predictive factors of their evolution is a research priority. Objective: To clarify the relationship between adenoma T2-weighted signal on diagnostic MRI in acromegaly and clinical and biological features at diagnosis. Design: International, multicenter, retrospective analysis. Setting: 10 endocrine tertiary referral centers. Patients: 297 acromegalic recently diagnosed patients with available diagnostic MRI evaluations were included in the study. Main outcome measure: Clinical, biochemical characteristics and MRI signal findings. Results: T2-hypointense adenomas represented 52.9% of the series, were smaller than their T2-hyper- and isointense counterparts (p<0.0001), were associated with higher IGF1 levels (p=0.0001), invaded the cavernous sinus less frequently (p=0.0002) and rarely caused optic chiasm compression (p<0.0001). Acromegalic men tended to be younger at diagnosis than women (p=0.067) and presented higher IGF1 values (p=0.01). Although in total, adenomas had a predominantly inferior extension in 45.8% of cases, in men this was more frequent (p<0.0001), whereas in women optic chiasm compression of macroadenomas occurred more often (p=0.0067). Most adenomas (45.1%) measured between 11-20mm in maximal diameter and bigger adenomas were diagnosed at younger ages (p=0.0001). Conclusions: T2-weighted signal differentiates GH-secreting adenomas into subgroups with particular behaviors. This raises the question of whether T2-weighted signal could represent a factor in the classification of acromegalic patients in future studies.