DIRECTIONALLY ENCODED COLORMAPS FOR ANALYZING HUMAN BRAIN DIFFUSION TENSOR MRI

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction. Diffusion tensor magnetic resonance imaging (DTMRI) is increasingly used to assess the white matter integrity of patients with a variety of pathologies. Trace and FA maps indicate the mean bulk diffusivity and the level of structural organization, but neither map indicates the kind of underlying anisotropy. Tensor mode (TM) characterizes the kind of anisotropy as it ranges from linear anisotropic to planar anisotropic and can be incorporated into novel directionally encoded colormaps (DEC). Methods. DTMRI images were acquired on a GE 1.5T scanner during a routine clinical exam. All patients provided signed statements of informed consent. A diffusion weighted, slice-interleaved, spin echo-planar imaging sequence was used to acquire images. DECs that incorporate mode (DECM) were generated by encoding the components of the primary eigenvector into the red, green, and blue channels of a color image, then devaluating the color intensity by the product of FA and mode. Results. The first patient presented with neoplastic infiltration and edema in the area of a previously resected GBM. DEC maps indicates that the posterior part of the external capsule is a continuous fiber track, but DECM maps indicates that this path is likely disrupted. The second patient presented with GBM and surrounding vasogenic edema. The tissue surrounding the external capsule a DEC map appears as a large fibrous mass, but the DECM map clearly delineates a smaller band of linear anisotropic structure.