title: Histogram-based characterization of healthy and ischemic brain tissues using multiparametric MR imaging including apparent diffusion coefficient maps and relaxometry.
abstract: Decreased, renormalized, or increased values of the calculated apparent diffusion coefficient (ADC) are observed in stroke models. A quantitative description of corresponding tissue states using ADC values may be extended to include true relaxation times. A histogram-based segmentation is well suited for characterizing tissues according to specific parameter combinations irrespective of the heterogeneity found for human healthy and ischemic brain tissues. In a new approach, navigated diffusion-weighted images and ADC maps were incorporated into voxel-based parameter sets of relaxation times (T1, T2), and T1- or T2-weighted images, followed by a supervised histogram-based analysis. Healthy tissues were segmented by incorporating T1 relaxation into the data set, ischemic regions by combining T2- or diffusion-weighted images with ADC maps. Mean values of healthy and pathologic tissues were determined, spatial distributions of the parameter vectors were visualized using color-encoded overlays. One to six days after stroke, ischemic regions exhibited reduced relative mean ADC values.
authors.affiliation: Department of Medical Informatics, University Hospital Benjamin Franklin, Free University of Berlin, Germany. bernarding@ukbf.fu-berlin.de
authors.forename: J
authors.initials: J
authors.lastname: Bernarding
authors.forename: J
authors.initials: J
authors.lastname: Braun
authors.forename: J
authors.initials: J
authors.lastname: Hohmann
authors.forename: U
authors.initials: U
authors.lastname: Mansmann
authors.forename: M
authors.initials: M
authors.lastname: Hoehn-Berlage
authors.forename: C
authors.initials: C
authors.lastname: Stapf
authors.forename: K J
authors.initials: KJ
authors.lastname: Wolf
authors.forename: T
authors.initials: T
authors.lastname: Tolxdorff
mesh_terms: D000328:Adult; D002545:Brain Ischemia / Q000175:diagnosis*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012680:Sensitivity and Specificity