Mapping the Orientation of White Matter Fiber Bundles: A Comparative Study of Diffusion Tensor Imaging, Diffusional Kurtosis Imaging, and Diffusion Spectrum Imaging

Editor’s Choice

The authors evaluated fiber bundle orientations from DTI and diffusional kurtosis compared with diffusion spectrum imaging as a criterion standard to assess the performance of each technique. DTI, diffusional kurtosis imaging, and diffusion spectrum imaging datasets were acquired during 2 independent sessions in 3 volunteers. While orientation estimates from all 3 techniques had comparable angular reproducibility, diffusional kurtosis imaging decreased angular error throughout the white matter compared with DTI. Diffusion spectrum imaging and diffusional kurtosis imaging enabled the detection of crossing-fiber bundles. They conclude that fiber bundle orientation estimates from diffusional kurtosis imaging have less systematic error than those from DTI.

Abstract

BACKGROUND AND PURPOSE

White matter fiber tractography relies on fiber bundle orientation estimates from diffusion MR imaging. However, clinically feasible techniques such as DTI and diffusional kurtosis imaging use assumptions, which may introduce error into in vivo orientation estimates. In this study, fiber bundle orientations from DTI and diffusional kurtosis imaging are compared with diffusion spectrum imaging as a criterion standard to assess the performance of each technique.

MATERIALS AND METHODS

For each subject, full DTI, diffusional kurtosis imaging, and diffusion spectrum imaging datasets were acquired during 2 independent sessions, and fiber bundle orientations were estimated by using the specific theoretic assumptions of each technique. Angular variability and angular error measures were assessed by comparing the orientation estimates. Tractography generated with each of the 3 reconstructions was also examined and contrasted.

RESULTS

Orientation estimates from all 3 techniques had comparable angular reproducibility, but diffusional kurtosis imaging decreased angular error throughout the white matter compared with DTI. Diffusion spectrum imaging and diffusional kurtosis imaging enabled the detection of crossing-fiber bundles, which had pronounced effects on tractography relative to DTI. Diffusion spectrum imaging had the highest sensitivity for detecting crossing fibers; however, the diffusion spectrum imaging and diffusional kurtosis imaging tracts were qualitatively similar.

CONCLUSIONS

Fiber bundle orientation estimates from diffusional kurtosis imaging have less systematic error than those from DTI, which can noticeably affect tractography. Moreover, tractography obtained with diffusional kurtosis imaging is qualitatively comparable with that of diffusion spectrum imaging. Because diffusional kurtosis imaging has a shorter typical scan time than diffusion spectrum imaging, diffusional kurtosis imaging is potentially more suitable for a variety of clinical and research applications.

Figure 4 from paper
Effects of dODF reconstructions on WM tractography. Column A shows a coronal cross-section through the fiber tracts identified with DSI, DKI, and DTI, respectively, overlaid on the corresponding section from the MPRAGE image for anatomic reference. The color encoding is used to represent the overall displacement of the end points of each tract with 1 color being applied per tract, where red represents an overall left-right orientation, blue represents an overall inferior-superior orientation, and green represents an overall anterior-posterior orientation. DSI is the most sensitive technique for detecting fibers (white arrows); however, DSI and DKI are fairly similar in both the color, which illustrates the overall trajectory, and distribution of fibers identified. Column B shows selected dODFs with the same coloring scheme as the fibers in column A, overlaid on the corresponding FA image from the DTI scan. The region shown in column B is demarcated by the white box in the corresponding images in column A. DTI fibers are conspicuously affected in this region because the dODFs cannot detect crossing fibers; this feature causes fibers to prematurely terminate or meld anatomically distinct tracts. This cross-section was chosen to demonstrate interactions that occur among the corpus callosum, corona radiata, superior longitudinal fasciculus, and cingulum bundle and their effect on dODFs and subsequent tractography.

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Mapping the Orientation of White Matter Fiber Bundles: A Comparative Study of Diffusion Tensor Imaging, Diffusional Kurtosis Imaging, and Diffusion Spectrum Imaging
Jeffrey Ross
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