Quantitative Diffusion Tensor Magnetic Resonance Imaging Signal Characteristics in the Human Brain: A Hemispheres Analysis

Recently, gray and white matter volumetric studies of the brain have been adjusted with measured brain diffusion scalar values, such as fractional anisotropy (FA). This is carried out mainly to determine the existence of manifested abnormal water diffusivity. This paper developed a method to quantify the diffusion tensor changes among right and left hemispheres. Morphological differences between the hemorrhagic brain injury and healthy subjects are investigated. Specifically, the diffusion orientation and the integrity of the white matter are expressed by the FA. Diffusion characteristics along the axial and radial directions and the mean diffusivity are assessed. The associated diffusivities are related to the diffusion tensor shape for each hemisphere and for the entire brain, based on linear, planar, and spherical measurements in a three-phase plot. This procedure is used to map and to compare changes in the anisotropy from healthy to hemorrhagic brain injury. These measures are combined and acted as a filtering technique. Only those possible macro structural diffusion measures, which are important in the assessment of fiber-tract organization or fiber-tract degradation, are retained. The results indicate that the proposed approach provides some anisotropy measures to efficiently and to accurately discriminate between the brain injuries. Furthermore, it is an established fact that the FA performs better to separate between healthy and temporal intracerebral hemorrhage (ICH) and ischemic stroke (IS)-induced brain injury subjects, whereas the radial diffusivity was more appropriate to discriminate between the left and right hemispheres versus the whole brain for ICH and IS subjects.