Brain injury and neurometabolic abnormalities in systemic lupus erythematosus

PURPOSE: To investigate with statistical analysis the relationship between brain injury measured with magnetic resonance (MR) imaging and that measured with proton (hydrogen-1) MR spectroscopy. MATERIALS AND METHODS: Forty-two patients (34 female, eight male; mean age +/- SD, 38.7 years +/- 13.1; age range, 6-60 years) with systemic lupus erythematosus (SLE) were examined with H-1 MR spectroscopy to measure N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels in normal-appearing white matter and with MR imaging to detect anatomic abnormalities. RESULTS: Results of linear regression analysis revealed an association between the NAA/Cr ratio and anatomic abnormalities (P = .03). However, only small focal lesions were independently related to NAA/Cr ratio changes (P = .04). Results of a similar analysis showed associations between the Cho/Cr ratio and anatomic abnormalities (P = .002). An elevated Cho/Cr ratio and cerebral infarction were independently associated (P = .02), as were a decreased Cho/Cr ratio and severe cortical atrophy P = .02). CONCLUSION: Cerebrovascular abnormalities underlie diffuse cerebral injury in SLE, with small vessel injury (ie, small focal lesions) primarily associated with a decreased NAA/Cr ratio and medium vessel injury (ie, infarct) primarily associated with an increased Cho/Cr ratio. Statistical integration of H-1 MR spectroscopic and MR imaging findings over large data sets provides insights into the relevance of individual MR imaging-visible brain abnormalities in SLE. This statistical approach may be applicable to other systemic diseases complicated by brain injury.