title: Quantitative analyses of T2-weighted MRI as a potential marker for response to somatostatin analogs in newly diagnosed acromegaly.
abstract: In growth hormone (GH)-producing adenomas, T2-weighted MRI signal intensity is a marker for granulation pattern and response to somatostatin analogs (SSA). Prediction of treatment response is necessary for individualized treatment, and T2 intensity assessment might improve preoperative classification of somatotropinomas. The objectives of this study are (I) to explore the feasibility of quantitative T2-weighted MRI histogram analyses in newly diagnosed somatotroph adenomas and their relation to clinical and histological parameters and (II) to compare the quantitative method to conventional, visual assessment of T2 intensity. The study was a retrospective cohort study of 58 newly diagnosed patients. In 34 of these, response to primary SSA treatment after median 6 months was evaluated. Parameters from the T2 histogram analyses (T2 intensity ratio and T2 homogeneity ratio) were correlated to visually assessed T2 intensity (hypo-, iso-, hyperintense), baseline characteristics, response to SSA treatment, and histological granulation pattern (anti-Cam5.2). T2 intensity ratio was lowest in the hypointense tumors and highest in the hyperintense tumors (0.66 ± 0.10 vs. 1.07 ± 0.11; p < 0.001). T2 intensity at baseline correlated with reduction in GH (r = -0.67; p < 0.001) and IGF-1 (r = -0.36; p = 0.037) after primary SSA treatment (n = 34). The T2 homogeneity ratio correlated with adenoma size reduction (r = -0.45; p = 0.008). Sparsely granulated adenomas had a higher T2 intensity than densely or intermediately granulated adenomas. T2 histogram analyses are an applicable tool to assess T2 intensity in somatotroph adenomas. Quantitatively assessed T2 intensity ratio in GH-producing adenomas correlates with conventional assessment of T2 intensity, baseline characteristics, response to SSA treatment, and histological granulation pattern.
authors.affiliation: Section of Specialized Endocrinology, Department of Endocrinology, Oslo University Hospital, Rikshospitalet, P.b 4950, Nydalen, 0424, Oslo, Norway. ansgar.heck@medisin.uio.no.|Faculty of Medicine, University of Oslo, Oslo, Norway. ansgar.heck@medisin.uio.no.
authors.forename: Ansgar
authors.initials: A
authors.lastname: Heck
authors.affiliation: The Intervention Centre, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Kyrre E
authors.initials: KE
authors.lastname: Emblem
authors.affiliation: Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.|Department of Pathology, Oslo University Hospital, Oslo, Norway.
authors.forename: Olivera
authors.initials: O
authors.lastname: Casar-Borota
authors.affiliation: Section of Specialized Endocrinology, Department of Endocrinology, Oslo University Hospital, Rikshospitalet, P.b 4950, Nydalen, 0424, Oslo, Norway.|Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Jens
authors.initials: J
authors.lastname: Bollerslev
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Geir
authors.initials: G
authors.lastname: Ringstad
mesh_terms: D000172:Acromegaly / Q000000981:diagnostic imaging* / Q000188:drug therapy; D000236:Adenoma / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D000368:Aged; D005240:Feasibility Studies; D005260:Female; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013004:Somatostatin / Q000031:analogs & derivatives / Q000378:metabolism; D055815:Young Adult
chemical_list: D013004:Somatostatin
keywords: Acromegaly; Granulation; MRI; Somatostatin analog; T2