NEUROCHEMISTRY OF BRAIN-LESIONS DETERMINED BY SPECTROSCOPIC IMAGING IN SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective. The significance and etiology of focal brain lesions in sys temic lupus erythematosus (SLE) are unknown. Our purpose was to determ ine whether the neurochemistry of focal lesions and normal appearing b rain tissues in SLE were consistent with neuronal loss, demyelination, or ischemia. Methods. Patients with SLE (n = 14) and controls (n = 13 ) were studied using magnetic resonance imaging (MRI) and spectroscopi c imaging (SI) at 1.5 Tesla. Results. MRI detected fixed focal brain l esions (n = 16) and SI measured brain metabolites, including N-acetyla spartate (NAA), creatine (Cre), choline (Cho), and lactate (Lac). NAA/ Cre of normal appearing brain was decreased in patients with SLE compa red to controls: grey matter (1.74 +/- 0.16 vs 1.92 +/- 0.18; p = 0.01 ), occipital white matter (1.98 +/- 0.22 vs 2.23 +/- 0.16; p = 0.004), and periventricular white matter (2.00 +/- 0.23 vs 2.33 +/- 0.23; p = 0.001). Lesions were characterized by markedly decreased NAA/Cre rela tive to normal appearing tissues in the same patient (1.67 +/- 0.22 vs 1.88 +/- 0.14; p = 0.0002). Elevated Cho/Cre was observed in 25% of f ocal lesions and 21% of normal appearing tissues. No elevation of lact ate was observed in lesions or normal appearing tissues. Conclusion. S I detects focal and generalized brain abnormalities in SLE characteriz ed by decreased NAA, elevated choline, and normal lactate. These findi ngs are consistent with widespread neuronal injury and demyelination, but are not consistent with anaerobic metabolism.