Brain injury and neurometabolic abnormalities in systemic lupus erythematosus.

Abstract

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. 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 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). Cerebrovascular abnormalities underlie diffuse cerebral injury in SLE, with small vessel injury (i.e., small focal lesions) primarily associated with a decreased NAA/Cr ratio and medium vessel injury (i.e., 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.