Ya-Ou Liu, Presenter: Nothing to Disclose

Shu Ni, Abstract Co-Author: Nothing to Disclose

Jun Wang, Abstract Co-Author: Nothing to Disclose

Yong He, Abstract Co-Author: Nothing to Disclose

Kuncheng Li MD, Abstract Co-Author: Nothing to Disclose

To investigate whether normal-appearing white matter (NAWM) abnormalities occur in patients with neuromyelitis optica (NMO) by Tract-Based Spatial Statistics (TBSS).

Twenty-seven NMO patients (2 males, 25 females; mean age 35.7 years, SD 11.9 years) and 27 age- and gender-matched normal controls (NC) were included in this study. Diffusion weighted images were acquired employing a single-shot echo planar imaging (EPI) sequence on a 1.5T MR scanner (Sonata Siemens, Germany). DT images were obtained in 6 non-linear directions (b = 1000s/mm2), together with an acquisition without diffusion weighting (b = 0 s/mm2), average = 10. The imaging parameters were 30 continuous axial slices with a slice thickness of 4 mm and slice gap of 0.4 mm, FOV = 240 × 240 mm, TR/TE = 5000/100 ms, acquisition matrix = 128 × 128. The reconstruction matrix was 256 × 256, resulting in an in-plane resolution of 0.9375 × 0.9375 mm. Voxelwise DTI analyses were performed with Tract-Based Spatial Statistics (TBSS).

First, the mean diffusion measures (FA, MD, λ1 and λ23) in the white matter skeleton were extracted for each subject. Statistic analysis revealed significant group differences in MD, λ1 and λ23 in the skeleton (MD: P = 0.00005; λ1: P < 10-4; λ23: P = 0.0007). From the results, NMO patients have significantly increased MD (3.6%), λ1 (2.6%) and λ23 (4.6%) in the white matter skeleton. Second, TBSS analyses revealed the white matter regions with abnormal diffusion changes in NMO patients, which are shown in Figure 2. No regions with FA changes were revealed at P < 0.05 (corrected for multiple comparisons). At uncorrected P < 0.05, some regions with reduced FA in NMO group were identified.  

Using TBSS to minimize preprocessing and analytic inaccuracies, this study investigated changes in both FA and non-fractional measures of diffusivity (MD, λ1 and λ23). The results indicated that the latter are more sensitive which suggested absolute diffusivities should be investigated in the future studies to capture the full extent of pathological changes in NMO and other neurological diseases. Widespread NAWM abnormalities were found in NMO imply complex pathological changes may occur which challenging the classic notion that brain WM is relatively spared in NMO.

This study provides evidences for NAWM damage in NMO,and may give clues to the pathophysiological basis of NMO.

Liu, Y, Ni, S, Wang, J, He, Y, Li, K, Widespread Abnormalities of the Normal-appearing White Matter in Patients with Neuromyelitis Optica: A TBSS Study.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008272.html