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Endocrine Abstracts (2016) 41 GP161 | DOI: 10.1530/endoabs.41.GP161

ECE2016 Guided Posters Pituitary - Clinical (1) (10 abstracts)

Evaluation of MRI T2-signal intensities of GH-secreting pituitary macroadenoma in treatment-naïve acromegalic patients receiving primary treatment with lanreotide autogel (LAN-ATG) 120 mg

Philippe Caron 1 , Louis-David Riviere 2 , Aude Houchard 3 , Caroline Sert 3 & Fabrice Bonneville 2

1Department of Endocrinology and Metabolic Diseases, CHU Larrey, Toulouse, France; 2Department of Neuroradiology, CHU Purpan, Toulouse, France; 3Ipsen, Boulogne-Billancourt, France.

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 (1435–2647); isointense, 3280 (2120–4441); hyperintense, 8533 (0–23843)).

Table 1 Hormonal control (GH ≤2.5 ng/ml and IGF-1<ULN) and tumour response (TVR ≥20%) at last visit according to baseline MRI T2-signal intensity.
Qualitative methodQuantitative first methodQuantitative second method
T2-signal intensityOverall (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.

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