Introduction: Pituitary MRI T2-signal intensity may be associated with the response to somatostatin analogue therapy in acromegalic patients. Here, we explore how best to evaluate MRI T2-signal intensity of GH-secreting pituitary macroadenoma using data from the PRIMARYS study (NCT00690898; EudraCT2007-000155-34).
Methods: PRIMARYS assessed tumour volume reduction (TVR) on MRI in treatment-naïve acromegalic patients with GH-secreting pituitary macroadenoma receiving monthly LAN-ATG 120 mg primary therapy over 1 yr. In this additional post hoc analysis, pituitary MRI T2-signals from 85 acromegalic patients were evaluated at baseline and during treatment. T2-signal intensity was defined as hypo-/iso-/hyper-intense based on comparison of adenoma/normal cerebral parenchyma, according to a qualitative method (visually comparing tissues); and two quantitative methods using ratio of signal intensities of region-of-interests in either tissues (adenoma vs grey matter only (first method) or vs grey matter and white matters in adjacent lobes (second method)). Here, we present the results of baseline MRI evaluations according three methods.
Results: A greater proportion of patients macroadenoma were categorized as hypointense using the qualitative method (59%) than the quantitative methods (36 and 20%) (Table 1). In addition, more of the patients showing full hormonal control or tumoural response had hypointense macroadenoma using the qualitative than using the quantitative methods (Table 1). There were no notable differences in baseline demographics between groups. The exception was a trend towards smaller TV in the hypointense group observed with all three methods; this was most evident, albeit still non-significant, on the qualitative method (mean (95% CI) TV, mm3: hypointense, 2041 (14352647); isointense, 3280 (21204441); hyperintense, 8533 (023843)).
|Qualitative method||Quantitative first method||Quantitative second method|
|T2-signal intensity||Overall (n=85)||Hormonal control (n=30)||Tumoural response (n=53)||Overall (n=85)||Hormonal control (n=30)||Tumoural response (n=53)||Overall (n=85)||Hormonal control (n=30)||Tumoural response (n=53)|
|Hypointense, n (%)||50 (59)||20 (67)||38 (72)||31 (36)||14 (47)||25 (47)||17 (20)||8 (27)||14 (26)|
|Isointense, n (%)||31 (36)||8 (27)||13 (25)||44 (52)||13 (43)||25 (47)||40 (47)||14 (47)||26 (49)|
|Hyperintense, n (%)||4 (5)||2 (7)||2 (4)||10 (12)||3 (10)||3 (6)||28 (33)||8 (27)||13 (25)|
Conclusion: A simple qualitative method could be used to identify MRI T2-signal hypointensity in treatment-naïve acromegalic patients with GH-secreting pituitary macroadenoma, which could be associated with later favourable responses to LAN-ATG primary therapy. Regression analyses are ongoing to determine associations between T2-signal intensity and treatment response.