Diffusion kurtosis imaging in mild traumatic brain injury and postconcussional syndrome

Abstract

Aims of this study were to investigate white matter (WM) and thalamus microstructure 72 hr and 3 months after mild traumatic brain injury (TBI) with diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI), and to relate DKI and DTI findings to postconcussional syndrome (PCS). Twenty-five patients (72 hr = 24; 3 months = 23) and 22 healthy controls were recruited, and DKI and DTI data were analyzed with Tract-Based Spatial Statistics (TBSS) and a region-of-interest (ROI) approach. Patients were categorized into PCS or non-PCS 3 months after injury according to the ICD-10 research criteria for PCS. In TBSS analysis, significant differences between patients and controls were seen in WM, both in the acute stage and 3 months after injury. Fractional anisotropy (FA) reductions were more widespread than kurtosis fractional anisotropy (KFA) reductions in the acute stage, while KFA reductions were more widespread than the FA reductions at 3 months, indicating the complementary roles of DKI and DTI. When comparing patients with PCS (n = 9), without PCS (n = 16), and healthy controls, in the ROI analyses, no differences were found in the acute DKI and DTI metrics. However, near-significant differences were observed for several DKI metrics obtained in WM and thalamus concurrently with symptom assessment (3 months after injury). Our findings indicate a combined utility of DKI and DTI in detecting WM microstructural alterations after mild TBI. Moreover, PCS may be associated with evolving alterations in brain microstructure, and DKI may be a promising tool to detect such changes.

Keywords: brain concussion; diffusion tensor imaging; magnetic resonance imaging; postconcussion syndrome.

Figure 1

Flow chart of the patient evaluation process

Figure 2

Example of placement of the thalamus ROIs in three planes and the surrounding landmarks (internal capsule, splenium of corpus callosum, and the cerebral midline) on the FA image of one mild TBI patient

Figure 3

TBSS analyses comparing mild TBI (MTBI) patients and healthy controls (HC) corrected for differences in sex and age. Threshold‐free cluster enhancement was used to correct for multiple comparisons and the statistical threshold for all the analyses was set to p < 0.05. Statistically significant differences in KFA, FA, and RD between patients and healthy controls were found on the acute MRI, while differences in KFA and FA were found on the 3‐month MRI.