title: Linear array ultrasound in low-grade glioma surgery: histology-based assessment of accuracy in comparison to conventional intraoperative ultrasound and intraoperative MRI.
abstract: BACKGROUND
  In low-grade glioma (LGG) surgery, intraoperative differentiation between tumor and most likely tumor-free brain tissue can be challenging. Intraoperative ultrasound can facilitate tumor resection. The aim of this study is to evaluate the accuracy of linear array ultrasound in comparison to conventional intraoperative ultrasound (cioUS) and intraoperative high-field MRI (iMRI).
  
  
  METHODS
  We prospectively enrolled 13 patients harboring a LGG of WHO Grade II. After assumed near total removal, a resection control was performed using navigated cioUS, navigated lioUS, and iMRI. We harvested 30 navigated biopsies from the resection cavity and compared the histopathological findings with the respective imaging results. Spearman's rho was calculated to test for significant correlations. Sensitivity and specificity as well as receiver operating characteristics (ROC) were calculated to assess test performance of each imaging modality.
  
  
  RESULTS
  Imaging results of lioUS correlated significantly (p < 0.009) with iMRI. Both iMRI and lioUS correlated significantly with final histopathological diagnosis (p < 0.006, p < 0.014). cioUS did not correlate with other imaging findings or with final diagnosis. The highest sensitivity for residual tumor detection was found in iMRI (83 %), followed by lioUS (79 %). The sensitivity of cioUS was only 21 %. Specificity was highest in cioUS (100 %), whereas iMRI and lioUS both achieved 67 %. ROC curves showed fair results for iMRI and lioUS and a poor result for cioUS.
  
  
  CONCLUSIONS
  Intraoperative resection control in LGGs using lioUS reaches a degree of accuracy close to iMRI. Test results of lioUS are superior to cioUS. cioUS often fails to discriminate solid tumors from "normal" brain tissue during resection control. Only in lesions <10 cc cioUS does show good accuracy.
authors.affiliation: Department of Neurosurgery, University of Ulm, Ludwig Heilmeyerstr. 2, 89312, Günzburg, Germany, jan.coburger@uni-ulm.de.
authors.forename: Jan
authors.initials: J
authors.lastname: Coburger
authors.forename: Angelika
authors.initials: A
authors.lastname: Scheuerle
authors.forename: Dietmar Rudolf
authors.initials: DR
authors.lastname: Thal
authors.forename: Jens
authors.initials: J
authors.lastname: Engelke
authors.forename: Michal
authors.initials: M
authors.lastname: Hlavac
authors.forename: Christian R
authors.initials: CR
authors.lastname: Wirtz
authors.forename: Ralph
authors.initials: R
authors.lastname: König
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods / Q000592:standards*; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods / Q000592:standards*; D055815:Young Adult