title: Intraoperative visualization of residual tumor: the role of perfusion-weighted imaging in a high-field intraoperative magnetic resonance scanner.
abstract: BACKGROUND
  High-field, intraoperative magnetic resonance imaging (iMRI) achieves free tumor margins in glioma surgery by involving anatomic neuronavigation and sophisticated functional imaging.
  
  
  OBJECTIVE
  To evaluate the role of perfusion-weighted iMRI as an aid to detect residual tumor and to guide its resection.
  
  
  METHODS
  Twenty-two patients undergoing intraoperative scanning (in a dual-room 1.5-T magnet setting) during the resection of high-grade gliomas were examined with perfusion-weighted iMRI. The generated relative cerebral blood volume (rCBV) maps were scrutinized for any hot spots indicative of tumor remnants, and region-of-interest analysis was performed. Differences among the rCBV region-of-interest estimates in residual tumor, free tumor margins, and normal white matter were analyzed. Histopathology of the tissue specimens and the neurosurgeon's intraoperative macroscopic estimations were considered the reference standards.
  
  
  RESULTS
  In all cases, diagnostic rCBV perfusion maps were generated. Interpretation of perfusion maps demonstrated that gross total resection of gliomas was achieved in 4 of 22 cases (18%), which was macroscopically and histopathologically verified, whereas in 18 of 22 cases (82%), the perfusion-weighted iMRI revealed hot spots indicating subtotal tumor removal. The latter proved to be true in all but 1 case. The receiver-operating characteristic curves of the qualitative visual and quantitative analyses showed excellent sensitivity and specificity rates. Statistical analysis demonstrated statistically significant differences for the mean rCBV and maximum rCBV between residual disease and tumor-free margins (P = .002 for both).
  
  
  CONCLUSIONS
  Perfusion-weighted iMRI may be implemented easily into imaging protocols and may assist the surgeon in detecting residual tumor volume.
authors.affiliation: Department of Neurosurgery, Eberhard Karls University, Hoppe-Seyler-Strasse 3, Tübingen, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Roder
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bender
authors.forename: Rainer
authors.initials: R
authors.lastname: Ritz
authors.forename: Jürgen
authors.initials: J
authors.lastname: Honegger
authors.forename: Günther
authors.initials: G
authors.lastname: Feigl
authors.forename: Thomas
authors.initials: T
authors.lastname: Naegele
authors.forename: Marcos Soares
authors.initials: MS
authors.lastname: Tatagiba
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ernemann
authors.forename: Sotirios
authors.initials: S
authors.lastname: Bisdas
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000601:surgery; D005260:Female; D005910:Glioma / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D018365:Neoplasm, Residual / Q000175:diagnosis* / Q000601:surgery; D038361:Neuronavigation / Q000379:methods*