title: Apparent diffusion coefficients in oligodendroglial tumors characterized by genotype.
abstract: OBJECTIVE
  To investigate whether oligodendroglial tumors with or without 1p/19q loss differ in their diffusion-weighted imaging characteristics. Oligodendroglial tumors with or without 1p/19q loss differ in their therapeutic responsiveness and prognosis, and recent reports also suggest that these tumors may differ in their magnetic resonance characteristics and blood volume.
  
  
  METHODS
  Apparent diffusion coefficients (ADCs) were assessed in three grade II oligodendrogliomas, nine grade II and five grade III oligoastrocytomas with known 1p/19q status. Regions of interest (ROIs) were placed on ADC maps: 1) around tumor margins to generate pixel histograms; 2) over minimum and maximum tumor ADC; 3) on areas comparable to the highest choline (Cho)/creatine (Cr) ratio determined from chemical shift imaging (CSI); and 4) across tumor margins to measure the ADC transition coefficient (ATC).
  
  
  RESULTS
  Tumor ADC was significantly different from normal brain (P < 0.001). ADC in regions of highest Cho/Cr was greater than minimum ADC and did not correlate with the Cho/Cr ratio. ADC and ATC were not significantly different between oligodendroglial subtypes or grades. Tumors with intact 1p/19q had higher maximum (P = 0.021) and histogram ADC (P = 0.015), and greater ATC (P = 0.001) compared to those with 1p/19q loss, which may reflect differences in edema and cellularity.
  
  
  CONCLUSIONS
  This preliminary study identified differences in ADC and ATC between oligodendroglial tumor genotypes that may reflect underlying biology. Confirmation in a larger series is warranted.
authors.affiliation: Department of Neurosurgery, The Walton Centre for Neurology and Neurosurgery, Liverpool, UK. michael.jenkinson@liv.ac.uk
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jenkinson
authors.forename: Trevor S
authors.initials: TS
authors.lastname: Smith
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Brodbelt
authors.forename: Kathy A
authors.initials: KA
authors.lastname: Joyce
authors.forename: Peter C
authors.initials: PC
authors.lastname: Warnke
authors.forename: Carol
authors.initials: C
authors.lastname: Walker
mesh_terms: D000328:Adult; D000368:Aged; D022981:Allelic Imbalance; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology*; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005838:Genotype; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009837:Oligodendroglioma / Q000235:genetics* / Q000473:pathology*; D018709:Statistics, Nonparametric