Zusammenfassung
Introduction:
Phase-sensitive inversion recovery (PSIR) magnetic resonance imaging (MRI) represent a promising approach to study gray and white matter (GM, WM) spinal cord (SC) atrophy. One study has reported that while GM atrophy can be detected in relapsing-remitting MS in absence of WM atrophy, both GM and WM SC atrophy are present in patients with progressive multiple sclerosis (MS). Therefore, it is not clear whether SC segmentation has clinical significance in progressive MS. The aim of our study was to compare progressive patients and controls in terms of GM, WM and SC cross sectional area (SCCA) and to investigate the association between measures of SC area and clinical disability.
Methods:
Nineteen patients with progressive MS (9 with primary-progressive (PP), 10 with secondary-progressive (SP) MS) and 19 healthy controls (HC) were prospectively enrolled. Mean±SD age was 54.4±8.2 years for patients and 49.3±8.1 years for HC. All patients underwent clinical examination with extended disability scale (EDSS), 9-hole peg test (9HPT), 25-foot walk test (25FWT).
All subjects underwent MRI at 3.0 Tesla (Siemens Skyra, Erlangen, Germany) using a 20-channel head-neck coil. The MRI protocol included a sagittal T2-weighted image of the SC (0.9x0.9 mm², slice thickness=0.9 mm, field of view=287x287 mm², repetition time (TR)=1000 ms, echo time (TE)=121.0 ms) and Axial 2D-PSIR (0.78x0.78 mm², slice thickness=5 mm, matrix 256x256, TR=930 ms, TE=3.22 ms, inversion time (TI) = 400 ms, angle=10°, 3 averages) acquired perpendicular to the spinal cord at the C2/C3 intervertebral disc level.
Two readers assessed the SCCA and GM area on the phase-sensitive reconstructed PSIR image using the software JIM7 (Xinapse Systems, www.xinapse.com). The SCCA measure was obtained using a semi-automated segmentation with edge detection. The GM SC area was obtained by manual segmentation and the WM SC area was calculated as difference between SCCA and GM area. Mann-Whitney test was used to compare MS patients and HC in terms of GM, WM and SCCA. Spearman correlation test was used to assess the association between GM, WM, SCCA and clinical metrics.
Results:
Patients' mean±SD disease duration was 16.3±12.7 years, median EDSS was 6, mean 9HPT was 47.7±34.3 seconds and mean 25FWT was 10.7±9.0 seconds.
GM, WM and SCCA were significantly smaller in progressive MS patients than in HC (p<0.001). In addition, SCCA was significantly reduced in SP patients compared with PP patients (p=0.028).
There was a statistically significant association between the SCCA and WM SC area and the 25FWT score (r=-0.59 and -0.54, p=0.007 and 0.017, respectively) and between the SCCA and the 9HPT score (r=-0.47, p=0.041).
Conclusions:
Our preliminary study shows that although there is a significant WM and GM SC atrophy in progressive MS patients, clinical disability is best explained by the measure of the whole SC area rather than by that of the segmented areas. Our results support previous findings about the utility of SCCA assessment in the evaluation of SC atrophy in progressive MS patients and suggest that, in this stage of the disease, GM and WM atrophy equally contribute to development of clinical disability.
