Method for combining information from white matter fiber tracking and gray matter parcellation

Abstract

We introduce a method for combining fiber tracking from diffusion-tensor (DT) imaging with cortical gray matter parcellation from structural high-spatial-resolution 3D spoiled gradient-recalled acquisition in the steady state images. We applied this method to a tumor case to determine the impact of the tumor on white matter architecture. We conclude that this new method for combining structural and DT imaging data is useful for understanding cortical connectivity and the localization of fiber tracts and their relationship with cortical anatomy and brain abnormalities.

Fig 1.

Cortical parcellations derived from SPGR images obtained from a tumor patient. Labels are based on the lookup table provided by Freesurfer. PrG, precentral gyrus; PoG, postcentral gyrus; SFG, superior frontal gyrus.

Fig 2.

T2-weighted, FA, and mean ADC images from a healthy subject are displayed in coronal view.

Fig 3.

2D visualization of coronal sections of a DT imaging. The major eigenvector of each voxel is displayed with line (in-plane component of the eigenvector) and color (from green to red, out-of-plane component of the eigenvector) on the background image of FA. The authors manually labeled the major fiber bundles (ie, CC, corpus callosum; SLF, superior longitudinal fasciculus; ILF, inferior longitudinal fasciculus; CB, cingulum bundle; CST, corticospinal tract; UF, uncinate fasciculus; AF, arcuate fasciculus; Af, arcuate fibers; AL, anterior limb of internal capsule; PL, posterior limb of internal capsule; and Fx, fornix).

Fig 4.

Coronal section images (SPGR, T2-weighted, FA, and mean ADC images) of a brain tumor are displayed. The tumor is located in the right medial temporal lobe, adjacent to the right cerebral peduncle.

Fig 5.

Visualization of DT map of a brain tumor. Left panel shows whole brain DT imaging map overlaid on an FA map, and the right panel demonstrates the magnified DT map of the tumor with mean ADC map as background. Except for the medial tumor margin, the tumor area shows high diffusivity and low anisotropy.

Fig 6.

3D reconstruction of fiber structures (tractography) derived from DT imaging. Fiber tractography is constructed and visualized by using a DT toolbox, DoDTI. Shorter fibers less than 5 cm were not displayed, to reduce complexity.

Fig 7.

Fiber tractography combined with cortical parcellation. Coronal, sagittal, and axial cross-sectional views of white and gray matter surface combined with fiber tractography are visualized. Light yellow surface shows the gray-white matter boundary. CC, corpus callosum; CR, corona radiata; SLF, superior longitudinal fasciculus; OR, optic radiation; CB, cingulum bundle; SCP, superior cerebellar peduncle; CST, corticospinal tract; UF, uncinate fasciculus; and AC, anterior commissure.

Fig 8.

Tractography and cortical parcellation of tumor brain. Upper left panel shows the whole tractography with a cross-section of gray and white matter surface. The cortical parcellation of the gray matter surface is displayed in color. Upper right panel shows a cross-section view of white matter overlaid with the gray matter–white matter surface. The tumor is colored as white. Lower panels show the fibers (in blue) originating from the right precentral gyrus (blue color in cortex) and located closest to the tumor. CC, corpus callosum; SLF, superior longitudinal fasciculus; CB, cingulum bundle; AF, arcuate fibers; IC, internal capsule; PL, posterior limb; CST, corticospinal tract; SCP, superior cerebellar peduncle; STG, superior temporal gyrus; MTG, middle temporal gyrus; PrG, precentral gyrus; and LV, lateral ventricle.