title: 111Indium-octreotide brain scintigraphy: a prognostic factor in skull base meningiomas treated with gamma knife radiosurgery.
abstract: OBJECTIVE
  The purpose of this study is to prospectively investigate the prognostic role of somatostatin receptor scintigraphy (SRS) using an 111Indium-labelled somatostatin analogue, Octreotide, in skull base meningiomas (SBMs) treated with gamma knife (GK) radiosurgery.
  
  
  METHODS
  From December 1997 to March 2000, SRS was performed both before and within 1 year of radiosurgery on 12 patients. Semi-quantitative data were calculated as SRS index; the index decrease was arbitrarily considered significant above 10%. A potential correlation between the decrease in post/pre-GK SRS index and radiosurgical outcome was evaluated.
  
  
  RESULTS
  The follow-up period was at least 30 months in the whole series (median, 43 months). In all 12 patients, the pre-GK SRS index was always >1, averaging 3.73+/-2.9. A decrease in the post-GK average SRS index (2.35+/-1.5) was observed. The difference between the pre- and post-GK average values was statistically significant (p<0.03). At the 1st high-resolution magnetic resonance imaging (MRI) follow-up within 1 year of GK, there was no tumor shrinkage in any of the 12 patients of our series. A post/pre-GK SRS index decrease >10% was observed in 9 patients and <10% in 3. Delayed MRI follow-up documented tumor reduction in all 9 cases having an 111In uptake decrease >10%, with stable imaging in the others (p=0.00024).
  
  
  CONCLUSIONS
  Our preliminary findings suggest a prognostic correlation between a decrease in concentration of somatostatin receptors on meningioma cells within 1 year of radiosurgery and delayed meningioma shrinkage.
authors.affiliation: Department of Neurosurgery, University Hospital, Verona, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Nicolato
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007205:Indium Radioisotopes; D008297:Male; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D008579:Meningioma / Q000000981:diagnostic imaging* / Q000601:surgery; D008875:Middle Aged; D011379:Prognosis; D019275:Radiopharmaceuticals; D016634:Radiosurgery; D019292:Skull Base Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D013004:Somatostatin / Q000031:analogs & derivatives*; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D013004:Somatostatin; C081788:pentetreotide