title: Optimizing intracranial metastasis detection for stereotactic radiosurgery.
abstract: OBJECTIVE
  The authors characterize the detection of additional intracranial metastases in cancer patients at the time of stereotactic radiosurgery (SRS) using a specialized high-resolution magnetic resonance imaging (MRI) protocol.
  
  
  METHODS
  A retrospective review of 150 consecutive radiosurgical procedures for patients with < or =5 known metastatic intracranial tumors diagnosed using MRI was undertaken at a single center. On the day of SRS, all patients underwent rigid head fixation in a stereotactic frame followed by a specialized MRI using a 3-dimensional fast spoiled-gradient sequence on a 1.5-tesla magnet with double-dose gadolinium. Axial imaging was performed using 2-mm cuts and no gap.
  
  
  RESULTS
  Additional metastases were detected in 29.3% of patients. The number of known tumors before SRS was predictive of additional metastases being found (p = 0.014). In multivariate analysis, we more frequently found additional metastases at radiosurgery in patients with 3-5 previously known metastases (p = 0.005), in patients with non-small cell lung cancer (p = 0.012) and in patients with a longer time interval between their diagnostic MRI and their stereotactic MRI (p = 0.030). Age, sex and prior fractionated radiation therapy were not predictive factors.
  
  
  CONCLUSIONS
  Our specialized protocol of high-resolution, double-dose contrast-enhanced MRI is a reliable method to evaluate the extent of intracranial disease in patients with known brain metastasis. Treatment planning for radiosurgery, radiation therapy and open surgical therapy are all impacted by improved metastasis detection.
authors.affiliation: Department of Neurological Surgery, University of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA.
authors.forename: Johnathan A
authors.initials: JA
authors.lastname: Engh
authors.forename: John C
authors.initials: JC
authors.lastname: Flickinger
authors.forename: Ajay
authors.initials: A
authors.lastname: Niranjan
authors.forename: Devin V
authors.initials: DV
authors.lastname: Amin
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Kondziolka
authors.forename: L Dade
authors.initials: LD
authors.lastname: Lunsford
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D002289:Carcinoma, Non-Small-Cell Lung / Q000556:secondary / Q000601:surgery; D018288:Carcinoma, Small Cell / Q000556:secondary / Q000601:surgery; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008545:Melanoma / Q000556:secondary / Q000601:surgery; D008875:Middle Aged; D015999:Multivariate Analysis; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000473:pathology