Objective: Damage of brain parenchyma in patients with primary diffuse neuropsychiatric systemic lupus erythematosus (NPSLE) has been indicated by magnetization transfer imaging (MTI). However, the location of MTI abnormalities is unknown. This study was undertaken to assess the distribution of MTI abnormalities over gray matter (GM) and white matter (WM) in SLE patients with a history of NP symptoms without explanatory magnetic resonance imaging (MRI) evidence of focal disease.
Methods: MTI was performed in 24 female SLE patients with a history of diffuse NP symptoms and 24 healthy female controls. Magnetization transfer ratio (MTR) maps were calculated for GM and WM separately, and GM and WM MTR histograms were generated. Univariate and multivariate analyses with age as an additional covariate were performed on the histogram parameters peak location (PL), peak height (PH), and mean MTR.
Results: Compared with controls, significantly reduced PH (mean +/- SD 136 +/- 22 arbitrary units versus 151 +/- 13 arbitrary units) and mean MTR (33.3 +/- 1.0 percent units versus 33.6 +/- 0.5 percent units) were found in the GM of NPSLE patients (P = 0.002 and P = 0.033, respectively, in multivariate analyses). No significant differences were observed for WM MTR parameters.
Conclusion: This is the first study to demonstrate, using MTI, that in SLE patients with a history of NP symptoms and without explanatory focal abnormalities on MRI, the GM is particularly affected. These findings support the hypothesis that neuronal injury may underlie central nervous system manifestations in NPSLE.