Objective: To determine the relationship between neurochemical markers of brain injury and brain dysfunction associated with systemic lupus erythematosus (SLE).
Methods: Patients with SLE (n = 12) were studied using magnetic resonance spectroscopic imaging at 1.5 Tesla to determine neurochemistry and a neurocognitive testing battery to determine brain dysfunction. N-acetylaspartate (NAA), creatine (Cre), and choline (Cho) concentrations were measured in white (WM) and gray (GM) matter and expressed as the ratios NAA/Cho, NAA/Cre, and Cho/Cre. Neurocognitive testing results were expressed as a composite z score. Disease activity was quantified by SLE Disease Activity Index (SLEDAI) and disease injury by Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology Damage Index.
Results: Neurochemical measures of brain injury were correlated with neurocognitive testing z scores: NAA/Cho in WM (r = 0.77, p = 0.003) and GM (r = 0.67, p = 0.017); WM Cho/Cre also correlated with total z score (r = -0.74, p = 0.006). Neurometabolite ratios and SLICC were correlated: GM NAA/Cho (r = -0.70, p = 0.011 ) and NAA/Cre (r = -0.71, p = 0.01) and WM Cho/Cre (r = 0.66, p = 0.02). Correlations between neurometabolite ratios and SLEDAI did not reach significance.
Conclusion: Brain function is closely correlated with brain injury assessed noninvasively by proton magnetic resonance spectroscopy. This important finding further supports the use of magnetic resonance spectroscopy to evaluate brain injury in SLE.