title: Intensity of pituitary adenoma on T2-weighted magnetic resonance imaging predicts the response to octreotide treatment in newly diagnosed acromegaly.
abstract: BACKGROUND
  Primary, preoperative medical treatment is an option in selected patients with acromegaly, but a subset of patients respond poorly. Valid prediction of response to somatostatin analogues (SA) might thus alter treatment stratification. The aims of this study were to assess whether T2 signal intensity could determine long-term response to first-line SA treatment and to assess clinical and biochemical baseline characteristics, as well as histological subtype in relation to the magnetic resonance imaging (MRI) appearances.
  
  
  METHODS
  In 45 newly diagnosed patients, T2-weighted signal intensity of the tumour was classified into hypo-, iso- or hyperintense. Biochemical and clinical baseline variables for the three groups were compared. In 25 patients primarily treated with long-acting SA for a median of 6 months [interquartile range (IQR):155-180 days], GH and IGF-1 reduction was assessed, and in 34 cases, immunohistochemical granulation pattern was evaluated.
  
  
  RESULTS
  The results showed that 12 (27%) adenomas were hypointense, 15 (33%) isointense and 18 (40%) hyperintense. Median IGF-1 [ratio IGF-1/ULN; (upper limit of normal)] was 3·5 (2·3-4·9), 2·9 (2·6-3·8) and 1·9 (1·3-2·6), respectively (P = 0·006 for difference between groups). Median GH values (μg/l) of a 3- to 5-point profile were 17·5 (6·1-35), 9·3 (6·0-32·5) and 4·1 (1·5-8·3), (P = 0·025). Median IGF-1 reduction (% of baseline) after first-line SA treatment was 51 (49-70), 36 (19-74) and 13 (5-42) (P = 0·03); median reduction in GH (% of baseline) was 86 (72-94), 78 (62-85) and 46 (1-70) (P = 0·02). T2 hyperintensity was associated with sparse granulation pattern on immunohistochemistry.
  
  
  CONCLUSIONS
  In patients with acromegaly, T2 signal intensity at diagnosis correlates with histological features and predicts biochemical outcome of first-line SA treatment.
authors: Section of Specialized Endocrinology, Oslo University Hospital, Rikshospitalet, Norway. ansgar.heck@medisin.uio.no
authors: Ansgar
authors: A
authors: Heck
authors: Geir
authors: G
authors: Ringstad
authors: Stine L
authors: SL
authors: Fougner
authors: Olivera
authors: O
authors: Casar-Borota
authors: Terje
authors: T
authors: Nome
authors: Jon
authors: J
authors: Ramm-Pettersen
authors: Jens
authors: J
authors: Bollerslev
mesh_terms: D000172:Acromegaly / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology / Q000209:etiology; D000236:Adenoma / Q000150:complications / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D000328:Adult; D017668:Age of Onset; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*; D010911:Pituitary Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D011859:Radiography; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted
chemical_list: D018931:Antineoplastic Agents, Hormonal; D015282:Octreotide