title: Diffusion tensor imaging of tract involvement in children with pontine tumors.
abstract: OBJECTIVE
  Conventional MR imaging permits subcategorization of brain stem tumors by location and focality; however, assessment of white matter tract involvement by tumor is limited. Diffusion tensor imaging (DTI) is a promising method for visualizing white matter tract tumor involvement supratentorially. We investigated the ability of DTI to visualize and quantify white matter tract involvement in pontine tumors.
  
  
  METHODS
  DTI data (echo-planar, 1.5T) were retrospectively analyzed in 7 patients with pontine tumors (6 diffuse, 1 focal), 4 patient controls, and 5 normal volunteers. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from the diffusion tensor in 6 regions of interest: bilateral corticospinal tracts, transverse pontine fibers, and medial lemnisci. Relationships between FA and ADC values and results of the neurologic examinations were evaluated.
  
  
  RESULTS
  The corticospinal tracts and transverse pontine fibers were affected more often than the medial lemnisci. The DTI parameters (FA and ADC) were significantly altered in all tracts of patients with pontine tumors (P < .05), compared with those values in the control groups. A marginally significant (P = .057) association was seen between the severity of cranial nerve deficit and decreased FA.
  
  
  CONCLUSIONS
  DTI provided superior visualization and quantification of tumor involvement in motor, sensory, and transverse pontine tracts, compared with information provided by conventional MR imaging. Thus, DTI may be a sensitive measure of tract invasion. Further prospective studies are warranted to assess the ability of DTI to delineate tumor focality and improve risk stratification in children with pontine tumors.
authors.affiliation: Department of Radiological Sciences, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Helton
authors.forename: N S
authors.initials: NS
authors.lastname: Phillips
authors.forename: R B
authors.initials: RB
authors.lastname: Khan
authors.forename: F A
authors.initials: FA
authors.lastname: Boop
authors.forename: R A
authors.initials: RA
authors.lastname: Sanford
authors.forename: P
authors.initials: P
authors.lastname: Zou
authors.forename: C S
authors.initials: CS
authors.lastname: Li
authors.forename: J W
authors.initials: JW
authors.lastname: Langston
authors.forename: R J
authors.initials: RJ
authors.lastname: Ogg
mesh_terms: D000293:Adolescent; D000328:Adult; D020295:Brain Stem Neoplasms / Q000175:diagnosis*; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D007231:Infant, Newborn; D009361:Neoplasm Invasiveness; D012189:Retrospective Studies