Volumetric and advanced functional MR imaging in neuropsychiatric systemic lupus erythematosus (NPSLE)

Abstract



Neuropsychiatric systemic erythematosus (NPSLE) is a complicated complication of systemic erythematosus (SLE). Asian patients are associated with high prevalence of systemic disease and mortality It increases patients’ morbidity and mortality (Samanta et al., 1991). But the detailed pathology and pathogenesis are still remained unclear. Our study’s purpose is to use advanced functional imaging method, including diffusion tensor imaging (DTI) and magnetic resonance spectroscopy imaging (MRSI) to detect intracranial volumetry, functional and other metabolite changes in NPSLE patients. We recruited 3 age-matched female groups, one patient group with NPSLE (20 patients), one patient group with SLE (20 patients) and one control group (15 normal controls). Each patient was applied to structural 3D-T1 and axial T2, DTI and MRSI. Whole brain volumetry and hippocampus volumetry were analyzed by FSL and MARINA software from T1 images. White matter hyperintensity was calculated manually. Whole brain FA and other indices were collected. Regional FA was also collected and was collected with MRS over corpus callosum slice. The result showed no significant whole brain atrophy in NPSLE patients and SLE patients compared with controls. But with segmentation of grey matter, white matter and CSF, NPSLE patients showed significant decrease volume from SLE patients in white matter. Left hippocampus showed significant decreased volume in white matter and grey matter compared with control, while right hippocampus showed significant decreased volume in white matter. No other significant difference was found between NPSLE vs SLE and SLE vs controls. Whole brain FA was significantly decreased in NPSLE compared to SLE and controls, but not significantly different between SLE and controls. MD, λ∥ and λ⊥ were significantly increased in NPSLE and SLE compared with controls, but not significantly different between SLE and controls. White matter hyperintensity score was consistent with MD, λ∥ and λ⊥ results, showed significantly higher scores in two patients groups compared to controls. Regional FA, involving frontal lobes and corpus callosum, periventricular regions adjacent to centrum semiovale and posterior lateral temporal lobe, confirmed the regional FA decrease showed in whole brain FA statistical color map and NPSLE patients’ regional FA decrease correlated with MRS metabolic changes. N-acetyl aspartate (NAA)/ Creatine (Cr), the marker of neurons, decreased significantly in NPSLE patients compared with SLE and controls. Choline (Cho)/Cr showed significant increase of tendency of significant increase in NPSLE and SLE patients in some ROIs compared with controls. Our finding suggested that, although the whole brain atrophy is not obvious in NPSLE, the hippocampus and white matter suffered atrophy in NPSLE patients. These atrophy in white matter of whole brain and hippocampus combined with functional imaging results of DTI and MRS, indicated that NPSLE endured more severe axonal damage than SLE, which might be due to a variety of lesions, such as demyelination, microangiopathy, large vessel thrombosis, cytokine, etc. Varying ratio of NAA/Cr and Cho/Cr may be associated with the severity of axonal damage, probably due to demyelination in the background of inflammatory/ischemic/vasculitic changes.