Three-dimensional architecture characteristics and diffusion properties of masticatory muscles assessed with diffusion tensor imaging and diffusion spectrum imaging: a pilot study of differences, reproducibility and sensitivity to microenvironment changes

Abstract

Background

Diffusion spectral imaging (DSI) could overcome the inherent limitation of diffusion tensor imaging (DTI), but its outcomes in masticatory muscle fiber-tracking have not been well-established. Therefore, the objective of this prospective study conducted in China was to evaluate and compare the performance of DTI and DSI in human masticatory muscles.

Methods

The differences and reproducibility of architecture characteristics and diffusion properties derived from DTI and DSI were evaluated in the masticatory muscles of healthy volunteers (n = 25). The quality of tracked fiber was analyzed based on anatomical information. To assess the sensitivity of DTI and DSI to muscular microenvironment changes, the architecture characteristics and diffusion properties of the masticatory muscles in patients with temporomandibular joint disorders (TMDs) (n = 25) between different subgroups according to the course of diseases were explored. The paired-samples t-test or Wilcoxon signed-rank test, Student’s t-test or Mann-Whitney U test, one-way ANOVA or the Kruskal-Wallis test, and the post-hoc multiple comparisons with false discovery rate adjustment were performed. Bland-Altman plots, within-subject coefficient of variation (CV), and relative absolute difference (RAD) were used to evaluate the reproducibility.

Results

In the healthy group, DSI generated significantly more fibers in all masticatory muscles (all P < 0.001) and fewer low-quality fibers in most masticatory muscles (P < 0.050) than DTI did. Moreover, higher values of mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were found in DSI (all P < 0.001). Satisfactory coefficient of variation (< 10%), relative absolute difference (< 10%), and agreement exhibited by the Bland-Altman analysis were found between two scans in both DTI and DSI. Compared with DTI, DSI found additional significant changes in the masticatory muscles of TMDs patients.

Conclusions

Although both DTI and DSI allowed reproducible assessment of masticatory muscles, significant differences existed between them. DSI was more sensitive to the microenvironment changes of the masticatory muscles in TMDs patients.