Tract-based spatial statistics on diffusion tensor imaging in systemic lupus erythematosus reveals localized involvement of white matter tracts.

OBJECTIVE The aim of this study was to determine whether there are differences in white matter integrity between systemic lupus erythematosus (SLE) patients and healthy controls, as determined using tract-based spatial statistics (TBSS) analysis of diffusion tensor imaging data. METHODS Twelve patients with SLE (mean age 42 years [range 15-61 years]) diagnosed according to the American College of Rheumatology 1982 revised criteria for SLE and 28 healthy controls (mean age 46 years [range 21-61 years]) were included in the study. Magnetic resonance imaging was performed on a 3.0T scanner. Fractional anisotropy (FA) maps were calculated for each patient. TBSS analysis was used to compare the FA maps. The TBSS technique projects the FA data into a common space through the use of an initial approximate nonlinear registration, followed by projection onto an alignment-invariant tract representation (mean FA skeleton). The cluster results were corrected for multiple comparisons across space, and a threshold of significance of 0.05 was used. RESULTS The white matter of tracts in the inferior fronto-occipital fasciculus, the fasciculus uncinatus, as well as the fornix, the posterior limb of the internal capsule (corticospinal tract), and the anterior limb of the internal capsule (anterior thalamic radiation) of patients with SLE showed reduced integrity as compared with normal subjects. CONCLUSION In this preliminary study, the integrity of white matter tracts in areas around limbic structures and in the internal capsule was found to be reduced. Larger studies could improve our understanding of the pathologic mechanisms behind the reduced white matter tract integrity in SLE.