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

Abstract

Responses of GH-secreting adenomas to multimodal management of acromegaly vary widely between patients. Understanding the behavioral patterns of GH-secreting adenomas by identifying factors predictive of their evolution is a research priority. The aim of this study was to clarify the relationship between the T2-weighted adenoma signal on diagnostic magnetic resonance imaging (MRI) in acromegaly and clinical and biological features at diagnosis. An international, multicenter, retrospective analysis was performed using a large population of 297 acromegalic patients recently diagnosed with available diagnostic MRI evaluations. The study was conducted at ten endocrine tertiary referral centers. Clinical and biochemical characteristics, and MRI signal findings were evaluated. T2-hypointense adenomas represented 52.9% of the series, were smaller than their T2-hyperintense and isointense counterparts (P!0.0001), were associated with higher IGF1 levels (PZ0.0001), invaded the cavernous sinus less frequently (PZ0.0002), and rarely caused optic chiasm compression (P!0.0001). Acromegalic men tended to be younger at diagnosis than women (PZ0.067) and presented higher IGF1 values (PZ0.01). 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 (PZ0.0067). Most adenomas (45.1%) measured between 11 and 20 mm in maximal diameter and bigger adenomas were diagnosed at younger ages (PZ0.0001). The T2-weighted signal differentiates GH-secreting adenomas into subgroups with

T2-weighted MRI signal predicts hormone and tumor responses to somatostatin analogs in acromegaly

“…These results confirm and build upon previous studies on T2-weighted MRI signal intensity in acromegaly. As shown previously, T2-hypo-intensity is more frequent in smaller adenomas that are less invasive (Hagiwara et al 2003, Heck et al 2012, Potorac et al 2015. Also, T2-hyper-intensity is more frequent in sparsely granulated pituitary adenomas (Hagiwara et al 2003, Heck et al 2012.…”

“…It has been previously shown that lower baseline GH and IGF1 levels are associated with better hormonal responses to SSA treatment, expressed in terms of IGF1 normalization and achievement of a GH threshold concentration 23:11 (Mercado et al 2007, Melmed et al 2010. Here and previously we reported that T2-hypo-intense adenomas have higher baseline GH and IGF1 levels despite having smaller and less invasive tumors than non-T2 hypointense adenomas (Potorac et al 2015). Here we show that these patients have greater percentage decreases from baseline in hormones and tumor size during primary SSA therapy.…”

“…Only adenomas treated pre-operatively with SSA were included. Therefore, the proportions of T2-hypo/iso/hyper-intense adenomas are not identical to those in large, unselected populations like in our previous study (Potorac et al 2015). This point will require further studies to be performed on larger series of T2-iso-and hyper-intense adenomas, which could help to clarify the differences between T2 hypo-intense and non-hypo-intense tumors in acromegaly patients.…”

“…Apart from adenoma size and extension patterns, T2-weighted adenoma signal has recently been highlighted as a potential marker of disease behavior in acromegaly. In an international cohort of 297 patients with acromegaly, we showed that more than 50% of GH-secreting adenomas are T2-hypo-intense at diagnosis when compared to normal pituitary tissue (Potorac et al 2015). These T2-hypo-intense adenomas are generally smaller, less frequently invade the cavernous sinus and are associated with higher levels of IGF-1.…”

“…This was performed by two experienced neuroradiologists and by consensus in cases of discordant readings. The T2-weighted signal on the diagnostic MRI was visually assessed as compared with normal pituitary tissue and when this was not visible, to the gray matter of the temporal lobe, as described previously (Potorac et al 2015). Moreover, quantification of the T2-weighted signal by Region Of Interest (ROI) measurement of the adenoma, normal pituitary tissue and gray matter of the temporal lobe was performed and the calculated ROI-derived T2 intensity ratio of the adenoma vs gray matter was used for all further analyses.…”