title: Apparent diffusion coefficient mapping in medulloblastoma predicts non-infiltrative surgical planes.
abstract: BACKGROUND
  An appropriate surgical approach for posterior fossa lesions is to start tumor removal from areas with a defined plane to where tumor is infiltrating the brainstem or peduncles. This surgical approach minimizes risk of damage to eloquent areas. Although magnetic resonance imaging (MRI) is the current standard preoperative imaging obtained for diagnosis and surgical planning of pediatric posterior fossa tumors, it offers limited information on the infiltrative planes between tumor and normal structures in patients with medulloblastomas. Because medulloblastomas demonstrate diffusion restriction on apparent diffusion coefficient map (ADC map) sequences, we investigated the role of ADC map in predicting infiltrative and non-infiltrative planes along the brain stem and/or cerebellar peduncles by medulloblastomas prior to surgery.
  
  
  METHODS
  Thirty-four pediatric patients with pathologically confirmed medulloblastomas underwent surgical resection at our facility from 2004 to 2012. An experienced pediatric neuroradiologist reviewed the brain MRIs/ADC map, assessing the planes between the tumor and cerebellar peduncles/brain stem. An independent evaluator documented surgical findings from operative reports for comparison to the radiographic findings. The radiographic findings were statistically compared to the documented intraoperative findings to determine predictive value of the test in identifying tumor infiltration of the brain stem cerebellar peduncles.
  
  
  RESULTS
  Twenty-six patients had preoperative ADC mapping completed and thereby, met inclusion criteria. Mean age at time of surgery was 8.3 ± 4.6 years. Positive predictive value of ADC maps to predict tumor invasion of the brain stem and cerebellar peduncles ranged from 69 to 88 %; negative predictive values ranged from 70 to 89 %. Sensitivity approached 93 % while specificity approached 78 %.
  
  
  CONCLUSIONS
  ADC maps are valuable in predicting the infiltrative and non-infiltrative planes along the tumor and brain stem interface in medulloblastomas. Inclusion and evaluation of ADC maps in preoperative evaluation can assist in surgical resection planning in patients with medulloblastoma.
authors.affiliation: Department of Neurosurgery, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA.
authors.forename: Neena I
authors.initials: NI
authors.lastname: Marupudi
authors.affiliation: Department of Pediatric Radiology, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA.
authors.forename: Deniz
authors.initials: D
authors.lastname: Altinok
authors.affiliation: Department of Pediatric Radiology, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Goncalves
authors.affiliation: Department of Neurosurgery, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Ham
authors.affiliation: Department of Neurosurgery, Wayne State University, Children's Hospital of Michigan, Detroit, MI, USA. ssood@med.wayne.edu.|Pediatric Neurosurgery, Children's Hospital of Michigan, 3901 Beaubien St., 2nd Floor, Detroit, MI, 48201, USA. ssood@med.wayne.edu.
authors.forename: Sandeep
authors.identifier: http://orcid.org/0000-0001-9305-446X
authors.initials: S
authors.lastname: Sood
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D002528:Cerebellar Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008527:Medulloblastoma / Q000000981:diagnostic imaging* / Q000601:surgery; D011237:Predictive Value of Tests
keywords: ADC map; Apparent diffusion coefficient map; Diffusion-weighted imaging; Medulloblastoma; Surgical planes