In vivo assessment of white matter damage in neuromyelitis optica: A diffusion tensor and diffusion kurtosis MR imaging study

• DTI and DKI techniques were compared in the assessment of WM abnormalities in NMO.
• DTI results reinforced the hypothesis that NMO has diffuse brain involvement.
• DKI demonstrated limitation for the evaluation of WM integrity in NMO patients.

Background and purposeIn patients with neuromyelitis optica (NMO), damage to extensive regions of normal-appearing WM has been observed. To investigate the possibility that microstructural alterations are present in these WM tracts, DTI and diffusion kurtosis imaging (DKI) techniques were applied and compared.Material and methodsThirteen patients with NMO and 13 demographically and gender-matched controls underwent MRI using a 3T MR scanner, with DTI/DKI sequence acquired jointly fitted. Parametric fractional anisotropy maps were derived from diffusion tensor (FADTI) values using b-values of 0 s/mm2 and 1000 s/mm2. Parametric fractional anisotropy maps derived from diffusion kurtosis tensor (FADKI) values were also acquired using b-values of 0, 1000, and 2000 s/mm2. Mean FADTI and FADKI values were also calculated. A ROI analysis of the genu and splenium of the corpus callosum (CC), cerebral peduncle (CP), and optic radiation (OR) was also performed. Student's t-test and corrections for multiple comparisons were used to evaluate the data obtained.ResultsA significant decrease in the FADTI values obtained for NMO patients versus controls was observed for the splenium of the CC and the left OR (p < 0.05). However, just a positive trend was observed for the FADKI values associated with the same WM tracts.ConclusionsTo our knowledge, this is the first study to analyze WM tracts of NMO patients using DTI and DKI. These data indicate that DKI could have limitations in evaluating the WM integrity in NMO patients. Furthermore, the results obtained are consistent with the hypothesis that diffuse brain involvement characterizes NMO.