APPLICATION OF A NOVEL QUANTITATIVE TRACTOGRAPHY-BASED ANALYSIS OF DIFFUSION TENSOR IMAGING TO EXAMINE FIBER BUNDLE LENGTH IN HUMAN CEREBRAL WHITE MATTER
TECHNOLOGY AND INNOVATION
Authors: Baker, Laurie M.; Cabeen, Ryan P.; Cooley, Sarah; Laidlaw, David H.; Paul, Robert H.
Abstract
This paper reviews basic methods and recent applications of length-based fiber bundle analysis of cerebral white matter using diffusion magnetic resonance imaging (dMRI). Diffusion weighted imaging (DWI) is a dMRI technique that uses the random motion of water to probe tissue microstructure in the brain. Diffusion tensor imaging (DTI) is an extension of DWI that measures the magnitude and direction of water diffusion in cerebral white matter, using either voxel-based scalar metrics or tractography-based analyses. More recently, quantitative tractography based on diffusion tensor imaging (qtDTI) technology has been developed to help quantify aggregate structural anatomical properties of white matter fiber bundles, including both scalar metrics of bundle diffusion and more complex morphometric properties, such as fiber bundle length (FBL). Unlike traditional scalar diffusion metrics, FBL reflects the direction and curvature of white matter pathways coursing through the brain and is sensitive to changes within the entire tractography model. In this paper, we discuss applications of this approach to date that have provided new insights into brain organization and function. We also discuss opportunities for improving the methodology through more complex anatomical models and potential areas of new application for qtDTI.
Association of C-MYC amplification with progression from the in situ to the invasive stage in C-MYC-amplified breast carcinomas
JOURNAL OF PATHOLOGY
Authors: Robanus-Maandag, EC; Bosch, CAJ; Kristel, PM; Hart, AAM; Faneyte, IF; Nededof, PM; Peterse, JL; van de Vijver, MJ
Abstract
Human carcinoma in situ of the breast already demonstrates genomic changes found in invasive lesions. However, no specific genetic alterations have previously been identified that are associated with progression from the in situ to the invasive stage. By comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH) analysis of an invasive breast carcinoma with a large associated in situ component, high-level amplification of C-MYC was found in the invasive component only. To determine the frequency of this correlation in a panel of 188 invasive breast carcinomas, 18 additional cases with C-MYC amplification were identified. Nine of these cases had a detectable adjacent in situ component. FISH analysis demonstrated increased (>5) C-MYC signals per nucleus in seven invasive components and increased (>4) C-MYC/centromere 8 signal ratios in five of these. None of the associated in situ components demonstrated these increases. The minimal amplified region was defined at 8q24.13-8qter. C-MYC amplification was correlated with overexpression of C-MYC and two of its target genes, TERT and FBL. Thus, C-MYC amplification is the first identified genetic alteration that is associated with progression from the in situ to the invasive stage of breast carcinoma. Copyright (C) 2003 John Wiley Sons, Ltd.