title: A validation study of multicenter diffusion tensor imaging: reliability of fractional anisotropy and diffusivity values.
abstract: OBJECTIVE
  DTI is increasingly being used as a measure to study tissue damage in several neurologic diseases. Our aim was to investigate the comparability of DTI measures between different MR imaging magnets and platforms.
  
  
  METHODS
  Two healthy volunteers underwent DTI on five 3T MR imaging scanners (3 Trios and 2 Signas) by using a matched 33 noncollinear diffusion-direction pulse sequence. Within each subject, a total of 16 white matter (corpus callosum, periventricular, and deep white matter) and gray matter (cortical and deep gray) ROIs were drawn on a single image set and then were coregistered to the other images. Mean FA, ADC, and longitudinal and transverse diffusivities were calculated within each ROI. Concordance correlations were derived by comparing ROI DTI values among each of the 5 magnets.
  
  
  RESULTS
  Mean concordance for FA was 0.96; for both longitudinal and transverse diffusivities, it was 0.93; and for ADC, it was 0.88. Mean scan-rescan concordance was 0.96-0.97 for all DTI measures. Concordance correlations within platforms were, in general, better than those between platforms for all DTI measures (mean concordance of 0.96).
  
  
  CONCLUSIONS
  We found that a 3T magnet and high-angular-resolution pulse sequence yielded comparable DTI measurements across different MR imaging magnets and platforms. Our results indicate that FA is the most comparable measure across magnets, followed by individual diffusivities. The comparability of DTI measures between different magnets supports the feasibility of multicentered clinical trials by using DTI as an outcome measure.
authors.affiliation: Mellen Center for Multiple Sclerosis, Cleveland Clinic, Cleveland, Ohio, USA. foxr@ccf.org
authors.forename: R J
authors.initials: RJ
authors.lastname: Fox
authors.forename: K
authors.initials: K
authors.lastname: Sakaie
authors.forename: J-C
authors.initials: JC
authors.lastname: Lee
authors.forename: J P
authors.initials: JP
authors.lastname: Debbins
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: D L
authors.initials: DL
authors.lastname: Arnold
authors.forename: E R
authors.initials: ER
authors.lastname: Melhem
authors.forename: C H
authors.initials: CH
authors.lastname: Smith
authors.forename: M D
authors.initials: MD
authors.lastname: Philips
authors.forename: M
authors.initials: M
authors.lastname: Lowe
authors.forename: E
authors.initials: E
authors.lastname: Fisher
mesh_terms: D000328:Adult; D016880:Anisotropy; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008297:Male; D009820:Ohio; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity