White matter microstructural changes in tuberous sclerosis: Evaluation by neurite orientation dispersion and density imaging (NODDI) and diffusion tensor images

Toshiaki Taoka,Yuta Fujii,Noriko Aida,Hisashi Kawai,Kazushi Ichikawa,Rintaro Ito,Shinji Naganawa,Toshiki Nakane

doi:10.1038/s41598-019-57306-w

Abstract

Neurite orientation dispersion and density imaging (NODDI) is a novel diffusion method for evaluating tissue microstructure, and may provide additional information over conventional diffusion tensor imaging (DTI). We evaluated NODDI and DTI parameters in cases of tuberous sclerosis (TS) to assess microstructural changes in the white matter. Eleven cases of tuberous sclerosis and eight age-matched controls underwent NODDI and DTI. We performed qualitative analysis and tract-based spatial statistics (TBSS) analysis of the NODDI parameters (Ficv: intracellular volume fraction, Fiso: isotropic fraction, ODI: orientation dispersion index) as well as DTI parameters (MD: mean diffusivity, FA: fractional anisotropy). We also performed a correlation analysis between clinical symptoms and parameters. The qualitative analysis indicated that the Ficv had a lower value in TS cases particularly in the tubers adjacent to the white matter. The TBSS analysis showed that the TS cases had decreased Ficv in a greater area compared to the other parameters including MD. In particular, the Ficv was decreased in deep white matter, such as the superior longitudinal fascicles (SLF). The application of NODDI to TS cases revealed tissue microstructural changes, and particularly the Ficv could detect more widespread abnormalities in white matter structure compared to DTI parameters.

Highlights

Neurite orientation dispersion and density imaging (NODDI) is a novel diffusion method for evaluating tissue microstructure, and may provide additional information over conventional diffusion tensor imaging (DTI)
There was a trend to indicate that the Ficv, which is defined as the intra-neurite tissue volume fraction and represents the density of neurites, was reduced in the white matter of tuberous sclerosis (TS) cases
The tract-based spatial statistics (TBSS) analysis showed significant decreases of Ficv in widespread regions within the brain, and the Ficv delineated the white matter changes more sensitively compared to the other parameters (Fiso, orientation dispersion index (ODI), fractional anisotropy (FA) and mean diffusivity (MD)) investigated in this study

Summary

Introduction

Neurite orientation dispersion and density imaging (NODDI) is a novel diffusion method for evaluating tissue microstructure, and may provide additional information over conventional diffusion tensor imaging (DTI). We evaluated NODDI and DTI parameters in cases of tuberous sclerosis (TS) to assess microstructural changes in the white matter. The application of NODDI to TS cases revealed tissue microstructural changes, and the Ficv could detect more widespread abnormalities in white matter structure compared to DTI parameters. Other reports indicate no significant differences in either MD or fractional anisotropy (FA) in normal-appearing white matter of patients with TS compared to controls[10,11] Aside from these examples, findings for DTI in TS remain unclear[12]. The key advantage of NODDI is that it models the biophysical properties of the tissue and provides indices that are more directly related to the microstructure This non-Gaussian diffusion model can quantitatively evaluate specific microstructural changes in terms of neurite density and the orientation distribution of neurites, which are axons and dendrites. The resultant parameters include maps of the intra-cellular volume fraction (Ficv) or neurite density, which is based on intracellular diffusion, the isotropic volume fraction (Fiso), which represents the free water compartment within the tissue, and the orientation dispersion index (ODI), which reflects the dispersion of neurites

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