title: The role of early intra-operative MRI in partial resection of optic pathway/hypothalamic gliomas in children.
abstract: BACKGROUND
  Optic pathway/hypothalamic gliomas (OPHGs) are generally benign but situated in an exquisitely sensitive brain region. They follow an unpredictable course and are usually impossible to resect completely. We present a case series of 10 patients who underwent surgery for OPHGs with the aid of intra-operative MRI (ioMRI). The impact of ioMRI on OPHG resection is presented, and a role for ioMRI in partial resection is discussed.
  
  
  METHODS
  Ten patients with OPHGs managed surgically utilising ioMRI at Alder Hey Children's Hospital between 2010 and 2013 were retrospectively identified. Demographic and relevant clinical data were obtained. MRI was used to estimate tumour volume pre-operatively and post-resection. If ioMRI demonstrated that further resection was possible, second-look surgery, at the discretion of the operating surgeon, was performed, followed by post-operative imaging to establish the final status of resection. Tumour volume was estimated for each MR image using the MRIcron software package.
  
  
  RESULTS
  Control of tumour progression was achieved in all patients. Seven patients had, on table, second-look surgery with significant further tumour resection following ioMRI without any surgically related mortality or morbidity. The median additional quantity of tumour removed following second-look surgery, as a percentage of the initial total volume, was 27.79% (range 11.2-59.2%). The final tumour volume remaining with second-look surgery was 23.96 vs. 33.21% without (p = 0.1).
  
  
  CONCLUSIONS
  OPHGs are technically difficult to resect due to their eloquent location, making them suitable for debulking resection only. IoMRI allows surgical goals to be reassessed intra-operatively following primary resection. Second-look surgery can be performed if possible and necessary and allows significant quantities of extra tumour to be resected safely. Although the clinical significance of additional tumour resection is not yet clear, we suggest that ioMRI is a safe and useful additional tool, to be combined with advanced neuronavigation techniques for partial tumour resection.
authors.affiliation: Neurosurgery Department, Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, UK. christopherpaulmillward@gmail.com.
authors.forename: Christopher Paul
authors.initials: CP
authors.lastname: Millward
authors.affiliation: Neurosurgery Department, Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, UK.|Pediatric Neurosurgery Department, Carlos Haya Hospital, University of Málaga, Avenida Carlos Haya, 29010, Málaga, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Perez Da Rosa
authors.affiliation: Neurosurgery Department, Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, UK.
authors.forename: Shivaram
authors.initials: S
authors.lastname: Avula
authors.affiliation: Neurosurgery Department, Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, UK.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Ellenbogen
authors.affiliation: Centre for Vision Speech and Signal Processing, Department of Electronic Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
authors.forename: Michaela
authors.initials: M
authors.lastname: Spiteri
authors.affiliation: Centre for Vision Speech and Signal Processing, Department of Electronic Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Lewis
authors.affiliation: Neurosurgery Department, Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, UK.
authors.forename: Mo
authors.initials: M
authors.lastname: Didi
authors.affiliation: Neurosurgery Department, Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, UK.
authors.forename: Conor
authors.initials: C
authors.lastname: Mallucci
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D005910:Glioma / Q000601:surgery*; D006801:Humans; D007029:Hypothalamic Neoplasms / Q000601:surgery*; D007091:Image Processing, Computer-Assisted; D007223:Infant; D064795:Intraoperative Neurophysiological Monitoring; D008279:Magnetic Resonance Imaging; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data; D019635:Neurosurgical Procedures / Q000379:methods*; D020339:Optic Nerve Glioma / Q000601:surgery*; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: Glioma; Hypothalamic; Intra-operative MRI; Optic pathway