title: Objective image analysis of real-time three-dimensional intraoperative ultrasound for intrinsic brain tumour surgery.
abstract: BACKGROUND
  There is growing evidence that maximal surgical resection of primary intrinsic brain tumours is beneficial, both by improving progression free and overall survival and also by facilitating postoperative chemotherapy and radiotherapy. Hence, there has been an increase in the popularity of real-time intraoperative imaging in brain tumour surgery. The complex theatre arrangements, prohibitive cost and prolonged theatre time of intraoperative MRI have restricted its application. By comparison, intraoperative three-dimensional ultrasound (i3DUS) is user friendly, cost-effective and portable and adds little to surgical time. However, operator-dependent image quality and image interpretation remain limiting factors to the wider application of this technique. The aim of this study was to explore objective i3DUS image analysis and its potential therapeutic role in brain tumour surgery.
  
  
  METHODS
  A prospective, observational study was undertaken (approved by the local Research and Ethics Committee prior to recruitment). Biopsies were taken from the solid, necrotic, periphery and brain/tumour interface of intrinsic primary brain tumours. Digital i3DUS images were analysed to extract quantitative parameters from these regions of interest (ROI) in the i3DUS images. These were then correlated with the histology of the relevant specimens. The histopathologist was blinded to the imaging findings.
  
  
  RESULTS
  Ninety-seven patients (62 males; mean 54 years) with varying gliomas (84 high grade) were included. Two hundred and ninety regions of interest were analysed. Mean pixel brightness (MPB) and standard deviation (SD) were correlated with histological features. Close correlations were noted between MPB and cellularity, and SD and intrinsic cellular diversity.
  
  
  CONCLUSIONS
  MPB and SD are objective measures reflecting the sensitivity of i3DUS in detecting the presence and extent of intrinsic brain tumours. They indirectly suggest heterogeneity, cellularity and invasiveness, providing information of the nature of the tumour, and also reflect the sensitivity of intraoperative US to detect the presence of residual intrinsic brain tumours. Development of this paradigm will enhance i3DUS use as an adjunct in brain tumour surgery. Optimizing its intraoperative application will impact surgical resection and, hence, patient outcome.
authors.affiliation: Department of Neurosurgery, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Sophie J
authors.initials: SJ
authors.lastname: Camp
authors.affiliation: Department of Radiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Vasileios
authors.initials: V
authors.lastname: Apostolopoulos
authors.affiliation: Department of Radiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Vasileios
authors.initials: V
authors.lastname: Raptopoulos
authors.affiliation: Department of Histopathology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Amrish
authors.initials: A
authors.lastname: Mehta
authors.affiliation: Department of Radiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Kevin
authors.initials: K
authors.lastname: O'Neill
authors.affiliation: Department of Radiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Awad
authors.affiliation: Department of Radiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Babar
authors.initials: B
authors.lastname: Vaqas
authors.affiliation: Department of Radiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: David
authors.initials: D
authors.lastname: Peterson
authors.affiliation: Department of Histopathology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Federico
authors.initials: F
authors.lastname: Roncaroli
authors.affiliation: Department of Radiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Road, London, W6 8RF UK.
authors.forename: Dipankar
authors.initials: D
authors.lastname: Nandi
keywords: Brain tumours; Image analysis; Intraoperative ultrasound