Imaging modalities in central nervous system systemic lupus erythematosus

Combining multimodal magnetic resonance brain imaging and machine learning to unravel neurocognitive function in non-neuropsychiatric systemic lupus erythematosus

OBJECTIVE

To study whether multimodal brain MRI comprising permeability and perfusion measures coupled with machine learning can predict neurocognitive function in young patients with SLE without neuropsychiatric manifestations.

METHODS

SLE patients and healthy controls (HCs) (≤40 years of age) underwent multimodal structural brain MRI that comprised voxel-based morphometry (VBM), magnetization transfer ratio (MTR) and dynamic contrast-enhanced (DCE) MRI in this cross-sectional study. Neurocognitive function assessed by Automated Neuropsychological Assessment Metrics was reported as the total throughput score (TTS). Olfactory function was assessed. A machine learning-based model (i.e. glmnet) was constructed to predict TTS.

RESULTS

Thirty SLE patients and 10 HCs were studied. Both groups had comparable VBM, MTR, olfactory bulb volume (OBV), olfactory function and TTS. While after correction for multiple comparisons the uncorrected increase in the blood-brain barrier (BBB) permeability parameters compared with HCs did not remain evident in SLE patients, DCE-MRI perfusion parameters, notably an increase in right amygdala perfusion, was positively correlated with TTS in SLE patients (r = 0.636, false discovery rate P < 0.05). A machine learning-trained multimodal MRI model comprising alterations of VBM, MTR, OBV and DCE-MRI parameters mainly in the limbic system regions predicted TTS in SLE patients (r = 0.644, P < 0.0005).

CONCLUSION

Multimodal brain MRI demonstrated increased right amygdala perfusion that was associated with better neurocognitive performance in young SLE patients without statistically significant BBB leakage and microstructural abnormalities. A machine learning-constructed multimodal model comprising microstructural, perfusion and permeability parameters accurately predicted neurocognitive performance in SLE patients.

Hippocampal Atrophy in Systemic Lupus Erythematosus Patients without Major Neuropsychiatric Manifestations

This study was conducted to explore hippocampal structural changes and their possible associations with clinical characteristics, emotional status, and treatment regimens in patients with systemic lupus erythematosus (SLE) without major neuropsychiatric manifestations (non-NPSLE). Eighty-five non-NPSLE patients with normal conventional magnetic resonance imaging (MRI) and seventy-seven matched healthy control (HC) subjects were recruited. All participants underwent the standard high-resolution volumetric MRI. The bilateral hippocampal volume (HIPV) and hippocampal density (HIPD) were calculated, respectively, for each participant. We found that the bilateral HIPV and HIPD of the SLE patient group were significantly less than those of the HC group. The bilateral HIPV of female patients were significantly less than those of male patients. The SLE disease activity index (SLEDAI) was negatively correlated with the bilateral HIPV and the right HIPD. Urine protein quantity was negatively correlated with the bilateral HIPV and HIPD. Hydroxychloroquine (HCQ) showed a protective effect on right HIPV. In conclusion, we found that the early hippocampal atrophy could occur before obvious neuropsychiatric manifestations and might be associated with SLE disease activity and organ damages. Early detection and intervention of hippocampal damage might prevent the progression to NPSLE. More studies are needed to fully understand the underlying mechanisms of hippocampal atrophy in SLE.

Clinical Factors Associated with Brain Volume Reduction in Systemic Lupus Erythematosus Patients without Major Neuropsychiatric Manifestations

The aim of the study was to find structural brain changes in systemic lupus erythematosus patients without major neuropsychiatric manifestations [non-neuropsychiatric systemic lupus erythematosus (non-NPSLE)] using quantitative magnetic resonance imaging (MRI) and possible associations with clinical characteristics. 89 non-NPSLE patients with normal conventional MRI and 84 healthy controls (HCs) were recruited. The whole brain gray matter volume (GMV) and white matter volume (WMV) were calculated for each individual. We found obvious GMV and WMV reduction in the systemic lupus erythematosus (SLE) group compared with HCs. Female patients showed significant reduction of GMV and WMV compared with male patients. Patients treated with immunosuppressive agents (ISA) showed less WMV reduction than those without. Cognitive impairment was the most common subclinical neuropsychiatric manifestation and had a prevalence of 46.1%. Association between WMV reduction with cognitive impairment was found. Thus, we concluded that structural brain atrophy could happen even before occurrence of obvious neuropsychiatric signs and symptoms and was associated with subclinical symptoms such as cognitive impairment. ISA treatment might have a protective effect on the brain atrophy. Early treatment might prevent the progressive damage to the brain. More studies are needed to fully understand the complicated underlying mechanisms of brain atrophy in SLE.

The diagnosis and clinical management of the neuropsychiatric manifestations of lupus

Neuropsychiatric (NP) involvement in Systemic Lupus Erythematosus (SLE), can be a severe and troubling manifestation of the disease that heavily impacts patient's health, quality of life and disease outcome. It is one of the most complex expressions of SLE which can affect central, peripheral and autonomous nervous system. Complex interrelated pathogenetic mechanisms, including genetic factors, vasculopathy, vascular occlusion, neuroendocrine-immune imbalance, tissue and neuronal damage mediated by autoantibodies, inflammatory mediators, blood brain barrier dysfunction and direct neuronal cell death can be all involved. About NPSLE a number of issues are still matter of debate: from classification and burden of NPSLE to attribution and diagnosis. The role of neuroimaging and new methods of investigation still remain pivotal and rapidly evolving as well as is the increasing knowledge in the pathogenesis. Overall, two main pathogenetic pathways have been recognized yielding different clinical phenotypes: a predominant ischemic-vascular one involving large and small blood vessels, mediated by aPL, immune complexes and leuko-agglutination which it is manifested with more frequent focal NP clinical pictures and a predominantly inflammatory-neurotoxic one mediated by complement activation, increased permeability of the BBB, intrathecal migration of autoantibodies, local production of immune complexes and pro-inflammatory cytokines and other inflammatory mediators usually appearing as diffuse NP manifestations. In the attempt to depict a journey throughout NPSLE from diagnosis to a reasoned therapeutic approach, classification, epidemiology, attribution, risk factors, diagnostic challenges, neuroimaging techniques and pathogenesis will be considered in this narrative review based on the most relevant and recent published data.

Quantitative magnetic resonance imaging in neuropsychiatric systemic lupus erythematosus

Neuropsychiatric symptoms are common in systemic lupus erythematosus (SLE) but are poorly understood.Although there is a wide spectrum of clinical manifestations, brain histologyoften simply shows a bland vasculopathy. Magnetic resonance techniques such as magnetic resonance spectroscopy, magnetization transfer imaging and diffusion weighted imaging have been used to try to improve our understandingof the pathophysiologicalmechanisms involved in neuropsychiatric lupus (NPSLE). This article reviews the current literature on the use of these techniques and their possible future role as diagnostic tools in NPSLE.

Early cerebral volume reductions and their associations with reduced lupus disease activity in patients with newly-diagnosed systemic lupus erythematosus

We examined if cerebral volume reduction occurs very early during the course of systemic lupus erythematosus (SLE), and observed prospectively whether gray (GMV) and white matter volumes (WMV) of the brain would improve with lowered SLE disease activity. T1-weighted MRI brain images were obtained from 14 healthy controls (HC) and 14 newly-diagnosed SLE patients within 5 months of diagnosis (S1) and after achieving low disease activity (S2). Whole brain voxel-based morphometry was used to detect differences in the GMV and WMV between SLE patients and HC and those between SLE patients at S1 and S2. SLE patients were found to have lower GMV than HC in the middle cingulate cortex, middle frontal gyrus and right supplementary motor area, and lower WMV in the superior longitudinal fasciculus, cingulum cingulate gyrus and inferior fronto-occipital fasciculus at both S1 and S2. Whole-brain voxel-wise analysis revealed increased GMV chiefly in the prefrontal regions at S2 compared to S1 in SLE patients. The GMV increase in the left superior frontal gyrus was significantly associated with lowered SLE disease activity. In conclusion, GMV and WMV reduced very early in SLE patients. Reduction of SLE disease activity was accompanied by region-specific GMV improvement in the prefrontal regions.

Autoantibodies Affect Brain Density Reduction in Nonneuropsychiatric Systemic Lupus Erythematosus Patients

This study explores the relationship between autoantibodies and brain density reduction in SLE patients without major neuropsychiatric manifestation (NPSLE). Ninety-five NPSLE patients without obvious cerebral deficits, as determined by conventional MRI, as well as 89 control subjects, underwent high-resolution structural MRI. Whole-brain density of grey matter (GMD) and white matter (WMD) were calculated for each individual, and correlations between the brain density, symptom severity, immunosuppressive agent (ISA), and autoantibody levels were assessed. The GMD and WMD of the SLE group decreased compared to controls. GMD was negatively associated with SLE activity. The WMD of patients who received ISA treatment were higher than that in the patients who did not. The WMD of patients with anticardiolipin (ACL) or anti-SSB/La antibodies was lower than in patients without these antibodies, while the GMD was lower in patients with anti-SM or anti-U1RNP antibodies. Thus, obvious brain atrophy can occur very early even before the development of significant symptoms and specific autoantibodies might contribute to the reduction of GMD or WMD in NPSLE patients. However, ISAs showed protective effects in minimizing GMD and WMD reduction. The presence of these specific autoantibodies might help identify early brain damage in NPSLE patients.

Repeated brain conventional MRI and SPECT evaluation in systemic lupus erythematosus patients with and without neuropsychiatric involvement: a follow up study

Objectives: To assess the utility of a combined neuroimaging approach in the follow up of patients affected by systemic lupus erythematosus (SLE) with and without neuropsychiatric (NP) involvement. Methods: Patients who underwent a first combined brain conventional magnetic resonance imaging (cMRI) and single photon emission computed tomography (SPECT) and later repeated the same examinations between 2001 and 2008 were retrieved from a large database. Clinical and neuroimaging data were analysed and their relationships evaluated at baseline and at follow up. Results: Fifty SLE patients (38 with and 12 without NP involvement, mean age 36.8 yrs and mean disease duration at first instrumental evaluation 5.5 yrs) were enrolled. At baseline, the majority of them had a diffuse pattern of NP involvement. After a mean follow up period of 4 years all patients repeated neuroimaging and clinical evaluation. In 23 patients (22 with and 1 without NP manifestations at baseline) a new NP event occurred. Overall, neuroimaging remained unchanged or improved, but in some cases it worsened. No correlations were found between instrumental findings and clinical picture. Conclusions: In this study, the clinical features at baseline appeared to be a better predictor of future NP events than morphological and functional neuroimaging. Therefore the utility of repeating a combined instrumental evaluation (cMRI and SPECT) may be debatable especially for patients with diffuse NP involvement where the decision to perform serial combined neuroimaging examinations should be carefully assessed and based mainly on clinical judgement. Lupus (2011) 20, 1387–1395.

[Imaging of non-traumatic and non-tumoral cord lesions]

There is a wide range of spinal cord pathologies (vascular, inflammatory, infectious, metabolic, degenerative). They present clinically as acute partial or complete cord syndromes, or chronic myelopathies (more than 4 weeks in duration). MRI examination should be undertaken with a very strict protocol. Spinal cord lesions should be evaluated with regards to their T1W and T2W signal characteristics, involvement of grey and/or white matter, axial and sagittal extension, cord volume changes, contrast uptake and associated lesions (perimedullary, radicular or brain). The correlation of MR imaging features with clinical and biological data (blood and CSF) should suggest a differential diagnosis.

White-matter volume reduction and the protective effect of immunosuppressive therapy in systemic lupus erythematosus patients with normal appearance by conventional magnetic resonance imaging

OBJECTIVE

The central nervous system (CNS) is often affected by systemic lupus erythematosus (SLE), but assessment of CNS outcomes using noninvasive cerebral structural measures remains in its infancy. Magnetic resonance imaging (MRI) with expert visual interpretation is critical to diagnosis, but does not permit quantitative measurements. Our pilot study investigated whether quantitative brain volumetric analyses could be used to detect white-matter (WM) abnormalities and responses to treatment in SLE (ClinicalTrials.gov: NCT00703742).

METHODS

Forty-two pairs of SLE patients and healthy controls underwent high-resolution 3-dimensional structural MRI scans. Combining voxel-based morphometry and region of interest analyses, subtle WM volume abnormalities in whole brains from SLE patients were identified, and regional WM volume was calculated. Associations between WM volume and symptom severity, as well as the effects of immunosuppressive therapy, were then investigated.

RESULTS

The WM volume of the SLE group was significantly decreased in the bilateral posterior and anterior crus of the internal capsule (PIC and AIC, respectively), the subgyral right frontal lobe, and left temporal lobe (p < 0.001). Regional WM volume (left PIC and right AIC) was correlated with SLEDAI scores. The WM volume of patients treated with immunosuppressive therapy was greater than that of patients who were never treated with immunosuppressive therapy.

CONCLUSION

Quantitative brain volumetric analyses detect brain injuries in WM for SLE that are not obvious by conventional MRI, and may be adequately sensitive and quantitative to measure the effect of therapeutic interventions in preventing brain injury and outcomes in SLE.

Neurocognitive deficits and neuroimaging abnormalities are prevalent in children with lupus: clinical and research experiences at a US pediatric institution

Neurocognitive impairments and neuroimaging abnormalities are frequently observed in adults with systemic lupus erythematosus. There is a paucity of similar data in childhood-onset disease. We hypothesized that neurocognitive and neuroimaging abnormalities would be prevalent in children undergoing neuropsychological evaluations. We reviewed patient neurocognitive evaluations performed at a large United States pediatric institution during the period 2001 to 2008. Records were retrieved from 24 children referred to neuropsychology due to clinical indications. Data from 15 children enrolled in a prospective structure-function association study were also analyzed. Subjects were predominantly African-American and Hispanic adolescent girls of average intelligence. aPL positivity and aspirin use was prevalent. Neurocognitive impairment was designated in 70.8% of retrospective, and 46.7% of prospective cohort patients. Deficits were seen at times of wellness, without previous neuropsychiatric lupus, and early in disease courses. Scores >1.5 standard deviations below published age-matched norms were common in tests of executive functioning, visual memory and visual-spatial planning. Features of depression were seen in 33.3% of the children in the retrospective cohort (clinical referrals). Cerebral and cerebellar volume loss was observed in a majority of blinded prospective cohort research magnetic resonance images (73.3% and 67.7% respectively). White matter hyperintensities were observed in retrospective and prospective cohort magnetic resonance images (36.6% and 46.7% respectively). Larger prospective studies that elucidate structure-function associations in children with systemic lupus erythematosus are planned.

Diagnostic reliability of magnetic resonance imaging for central nervous system syndromes in systemic lupus erythematosus: a prospective cohort study

Background

Previous studies of magnetic resonance imaging (MRI) as a diagnostic tool for central nervous system (CNS) syndromes in systemic lupus erythematosus (SLE) contained several limitations such as study design, number of enrolled patients, and definition of CNS syndromes. We overcame these problems and statistically evaluated the diagnostic values of abnormal MRI signals and their chronological changes in CNS syndromes of SLE.

Methods

We prospectively studied 191 patients with SLE, comparing those with (n = 57) and without (n = 134) CNS syndrome. CNS syndromes were characterized using the American College of Rheumatology case definitions.

Results

Any abnormal MRI signals were more frequently observed in subjects in the CNS group (n = 25) than in the non-CNS group (n = 32) [relative risk (RR), 1.7; 95% confidence interval (CI), 1.1-2.7; p = 0.016] and the positive and negative predictive values for the diagnosis of CNS syndrome were 42% and 76%, respectively. Large abnormal MRI signals (ø ≥ 10 mm) were seen only in the CNS group (n = 7; RR, 3.7; CI, 2.9-4.7; p = 0.0002), whereas small abnormal MRI signals (ø < 10 mm) were seen in both groups with no statistical difference. Large signals always paralleled clinical outcome (p = 0.029), whereas small signals did not (p = 1.000).

Conclusions

Abnormal MRI signals, which showed statistical associations with CNS syndrome, had insufficient diagnostic values. A large MRI signal was, however, useful as a diagnostic and surrogate marker for CNS syndrome of SLE, although it was less common.

Immunity and acquired alterations in cognition and emotion: lessons from SLE

Classic immunologic teaching describes the brain as an immunologically privileged site. Studies of neuroimmunology have focused for many years almost exclusively on multiple sclerosis, a disease in which inflammatory cells actually infiltrate brain tissue, and the rodent model of this disease, experimental allergic encephalitis. Over the past decade, however, increasingly, brain-reactive antibodies have been demonstrated in the serum of patients with numerous neurological diseases. The contribution these antibodies make to neuronal dysfunction has, in general, not been determined. Here, we describe recent studies showing that serum antibodies to the N-methyl-D-aspartate receptor occur frequently in patients with systemic lupus erythematosus and can cause alterations in cognition and behavior following a breach in the blood-brain barrier.

Quantifying subclinical central nervous lesions in primary antiphospholipid syndrome: the role of magnetization transfer imaging

PURPOSE

To define the role of magnetization transfer imaging (MTI) in detecting subclinical central nervous system (CNS) lesions in primary antiphospholipid syndrome (PAPS).

MATERIALS AND METHODS

Ten non-CNS PAPS patients were compared to 10 CNS PAPS patients and 10 age- and sex-matched controls. All PAPS patients met Sapporo criteria. All subjects underwent conventional MRI and complementary MTI analysis to compose histograms. CNS viability was determined according to the magnetization transfer ratio (MTR) by mean pixel intensity (MPI) and the mean peak height (MPH). Volumetric cerebral measurements were assessed by brain parenchyma factor (BPF) and total/cerebral volume.

RESULTS

MTR histograms analysis revealed that MPI was significantly different among groups (P < 0.0001). Non-CNS PAPS had a higher MPI than CNS PAPS (30.5 +/- 1.01 vs. 25.1 +/- 3.17 percent unit (pu); P < 0.05) although lower than controls (30.5 +/- 1.01 vs. 31.20 +/- 0.50 pu; P < 0.05). MPH in non-CNS PAPS (5.57 +/- 0.20% (1/pu)) was similar to controls (5.63 +/- 0.20% (1/pu), P > 0.05) and higher than CNS PAPS (4.71 +/- 0.30% (1/pu), P < 0.05). A higher peak location (PL) was also observed in the CNS PAPS group in comparison with the other groups (P < 0.0001). In addition, a lower BPF was found in non-CNS PAPS compared to controls (0.80 +/- 0.03 vs. 0.84 +/- 0.02 units; P < 0.05) but similar to CNS PAPS (0.80 +/- 0.03 vs. 0.79 +/- 0.05 units; P > 0.05).

CONCLUSION

Our findings suggest that non-CNS PAPS patients have subclinical cerebral damage. The long-termclinical relevance of MTI analysis in these patients needs to be defined by prospective studies.

Neuropsychological impairment in systemic lupus erythematosus: a comparison with multiple sclerosis

In this manuscript, we review literature describing the neuropsychological and brain imaging characteristics of systemic lupus erythematosus (SLE) patients. The findings are compared and contrasted with multiple sclerosis (MS) studies, revealing similarities and differences of interest to clinicians and researchers. While cognitive impairment is somewhat less common in SLE than MS, the diseases share a similar cognitive profile with deficits most prominent on tests emphasizing the speed of information processing, working memory, and visual/spatial learning, and memory. In early or more mildly affected patients, diffuse white matter damage, which may not be apparent on conventional brain imaging, plays a major role in clinical presentation and cognitive testing. The causes of white matter damage are very different, however, and in later stages of the disease MS and SLE appear to give rise to different forms of cerebral pathology. MS may be characterized by increasing brain atrophy affecting especially the cortical and deep gray matter, at least after conversion to secondary progressive course. There is less evidence for neurodegenerative changes in SLE, but patients are increasingly at risk for cerebrovascular disease. We conclude by offering some suggestions for future clinical and imaging research.

Detection of change in CNS involvement in neuropsychiatric SLE: a magnetization transfer study

PURPOSE

To assess whether magnetization transfer imaging (MTI) parameters change in correspondence with clinical changes in NPSLE patients.

MATERIALS AND METHODS

Nineteen female patients (mean age=37.5 years, range=19-64) underwent MTI on at least two separate occasions (mean time between scans=25.4 months, range=5.4-52.3 months). Twenty-four pairs of scans of 19 patients were available. Each patient's clinical course was classified as improved, stable, or deteriorated. Whole-brain magnetization transfer ratio (MTR) histograms were generated. The peak height of these histograms was used as an estimate of parenchymal integrity. Based on the change in clinical status, paired examinations were grouped and tested for significant differences between the first and second examinations using paired-samples t-tests.

RESULTS

Four patients clinically deteriorated, all patients showed a significant peak height decrease (mean decrease=8.6%, P=0.02), and in 14 patients with stable disease the peak height did not change significantly (mean increase=0.4%). Six patients clinically improved, and all showed a significant relative peak height increase (mean increase=12.0%, P=0.02).

CONCLUSION

The peak height of whole-brain MTR histograms corresponds to changes in the clinical status of individual NPSLE patients. This suggests that MTI can be a valuable tool in the clinical assessment of such patients.

Longitudinal analysis of gray and white matter loss in patients with systemic lupus erythematosus

Cerebral atrophy has been described to occur in systemic lupus erythematosus (SLE) with variable frequency. The aim of this study was to determine white and gray matter abnormalities in brain magnetic resonance imaging (MRI) of patients with SLE and to determine if these abnormalities progress over a one-year period. Seventy-five patients with SLE and 44 healthy age and sex-matched controls were enrolled in this study. T1-weighted volumetric images were used for voxel based morphometry (VBM) analyses. SLE patients exhibited a significant reduction in white matter and gray matter volume compared to controls (p=0.001). Follow-up images, after an average interval of 19 months, revealed a progressive white matter and gray matter atrophy (p=0.001). Reduced white and gray matter volume was associated with disease duration and the presence of antiphospholipid antibodies. Patients with severe cognitive impairment had a more pronounced white and gray matter reduction than patients with moderate cognitive impairment. Total corticosteroid dose was associated with gray matter reduction and not with white matter loss in SLE patients. We concluded that brain tissue loss associated with SLE is significant and progresses over a relatively short period of time. Disease duration, the presence of antiphospholipid antibodies and cognitive impairment were associated with white and gray matter loss. Corticosteroid was associated only with gray matter atrophy.

Diffusion changes in patients with systemic lupus erythematosus

BACKGROUND AND PURPOSE

Systemic lupus erythematosus (SLE) is an autoimmune disease in which almost all the organs are involved. Neuropsychiatric SLE is of one of the major concerns in the clinical evaluation of this disease. Routine magnetic resonance imaging (MRI) findings are often nonspecific or negative. In this study, we explored the use of diffusion tensor imaging in assisting with the diagnosis of SLE.

METHODS

Data from 34 SLE patients (age range, 18-73 years) and 29 age-matched volunteers (age range, 29-64 years) were analyzed. MRI was performed on a 1.5-T clinical MR scanner with a quadrature head coil. The average diffusion constant (D(av)) and diffusion anisotropy maps [fractional anisotropy (FA)] were determined on a pixel-by-pixel basis. Regional diffusion measurements were made by region of interest in the genu and splenium of the corpus callosum (CC), anterior and posterior limb of the internal capsule (IC) and frontal lobe and thalamus. The diffusion distribution was fitted to a triple-Gaussian model. The mean of the brain tissue distribution was determined as a mean diffusion constant for the whole brain (BD(av)). Student's t test was used to determine the diffusion difference between SLE patients and control subjects. The SLE patients were separated into two groups according to their MRI results. A P value lower than .05 was considered to be statistically significant.

RESULTS

Twenty of the 34 SLE patients with abnormal MRI results showed findings dominated by nonspecific white matter disease. The BD(av) and D(av) values of the frontal lobe, splenium CC and anterior IC were significantly higher in all SLE patients as compared with the control subjects. The SLE patients with normal MRI results also showed higher BD(av) and D(av) values in the frontal lobe, splenium and anterior and posterior limbs of the IC as compared with the control subjects. There was no significant difference in the D(av) values of the thalamus between the SLE patients and the control subjects. The BD(av) value in the SLE patient group was robustly correlated with the D(av) values of the frontal lobe, splenium and thalamus. These correlations were found to be similarly significant for the SLE patients with normal MRI findings. The diffusion anisotropy measurements showed that splenium CC had the highest FA value in both the control subjects and SLE patients. Overall, SLE patients had lower FA values in the genu and splenium CC as compared with the control subjects. In the group of patients with normal MRI findings, the FA values of the genu and splenium CC as well as the anterior IC were also lower than those in the control subjects. Pearson's correlation statistics revealed robust correlations between the measurements of D(av) and FA values in the SLE patient group.

CONCLUSION

Quantitative diffusion imaging and diffusion anisotropy showed early changes in the brains of the SLE patients. Increased BD(av) and D(av) values of the frontal lobe as well as decreased anisotropy in the genu CC and anterior IC may represent preclinical signs of central nervous system involvement of SLE even when the routine MRI findings are negative or nonspecific. Quantitative diffusion analysis may prove to be useful in detecting the initial brain involvement of SLE and may enable monitoring of early disease progression and treatment efficacy.

Association between microscopic brain damage as indicated by magnetization transfer imaging and anticardiolipin antibodies in neuropsychiatric lupus

The pathogenetic role of anticardiolipin antibodies (aCLs) in patients with neuropsychiatric systemic lupus erythematosus (NPSLE) without cerebral infarcts remains elusive. Magnetization transfer imaging (MTI) has proved to be a sensitive tool for detecting diffuse microscopic brain damage in NPSLE patients. In this study we examined the correlation between grey and white matter magnetization transfer ratio (MTR) parameters and the presence of IgM and IgG aCLs and lupus anticoagulant in 18 patients with systemic lupus erythematosus and a history of NPSLE but without cerebral infarcts on conventional magnetic resonance imaging. Lower grey matter mean MTR (P < 0.05), white matter mean MTR (P < 0.05), white matter peak location (P < 0.05) and grey matter peak location (trend toward statistical significance) were observed in IgM aCL-positive patients than in IgM aCL-negative patients. No significant differences were found in MTR histogram parameters with respect to IgG aCL and lupus anticoagulant status, nor with respect to anti-dsDNA or anti-ENA (extractable nuclear antigen) status. This is the first report of an association between the presence of aCLs and cerebral damage in grey and white matter in NPSLE. Our findings suggest that aCLs are associated with diffuse brain involvement in NPSLE patients.

Cerebral and corpus callosum atrophy in systemic lupus erythematosus

OBJECTIVE

To determine cerebral and corpus callosum volumes in patients with systemic lupus erythematosus (SLE), using semiautomatic magnetic resonance imaging (MRI) volumetric measurements, and to determine possible relationships between a reduction in cerebral volume and disease duration, total corticosteroid dose, neuropsychiatric manifestations, and the presence of antiphospholipid antibodies.

METHODS

We studied 115 consecutive patients with SLE and 44 healthy volunteers. A complete clinical, laboratory, and neurologic evaluation was performed. MRI scans were obtained through a standardized protocol. Sagittal T1-weighted images were used for semiautomatic volumetric measurements. We compared SLE patients with controls using the 2-sample t-test. Analysis of variance was used to test for differences between groups, followed by Tukey's post hoc test for pairwise comparisons, when necessary. Linear regression was used to analyze the association between cerebral atrophy and disease duration and total corticosteroid dose.

RESULTS

Cerebral and corpus callosum volumes were significantly smaller in patients with SLE compared with healthy volunteers (P < 0.001). Reduced cerebral and corpus callosum volumes were related to disease duration (P < 0.001). Patients with a history of central nervous system (CNS) involvement more frequently had a reduction in cerebral and corpus callosum volumes (P < 0.001). Patients with cognitive impairment had significantly reduced corpus callosum and cerebral volumes when compared with SLE patients without cognitive impairment (P = 0.001). Cerebral and corpus callosum volumes were not associated with the total corticosteroid dose or the presence of antiphospholipid antibodies.

CONCLUSION

In patients with SLE, a reduction in cerebral and corpus callosum volumes is associated with disease duration, a history of CNS involvement, and cognitive impairment. The total corticosteroid dose and the presence of antiphospholipid antibodies were not associated with more pronounced atrophy.

Elevated immunoglobulin levels in the cerebrospinal fluid from lupus-prone mice

The systemic autoimmune disease lupus erythematosus (SLE) is frequently accompanied by neuropsychiatric manifestations and brain lesions of unknown etiology. The MRL-lpr mice show behavioral dysfunction concurrent with progression of a lupus-like disease, thus providing a valuable model in understanding the pathogenesis of autoimmunity-induced CNS damage. Profound neurodegeneration in the limbic system of MRL-lpr mice is associated with cytotoxicity of their cerebrospinal fluid (CSF) to mature and immature neurons. We have recently shown that IgG-rich CSF fraction largely accounts for this effect. The present study examines IgG levels in serum and CSF, as well as the permeability of the blood-brain barrier in mice that differ in immune status, age, and brain morphology. In comparison to young MRL-lpr mice and age-matched congenic controls, a significant elevation of IgG and albumin levels were detected in the CSF of aged autoimmune MRL-lpr mice. Two-dimensional gel electrophoresis and MALDI-TOF MS confirmed elevation in IgG heavy and Ig light chain isoforms in the CSF. Increased permeability of the blood-brain barrier correlated with neurodegeneration (as revealed by Fluoro Jade B staining) in periventricular areas. Although the source and specificity of neuropathogenic antibodies remain to be determined, these results support the hypothesis that a breached blood-brain barrier and IgG molecules are involved in the etiology of CNS damage during SLE-like disease.

Proton magnetic resonance spectroscopy may predict future brain lesions in SLE patients: a functional multi-imaging approach and follow up

OBJECTIVE

To determine whether single photon emission tomography (SPECT) and magnetic resonance spectroscopy (1H-MRS) can predict the appearance of new lesions in systemic lupus erythematosus (SLE), detectable by magnetic resonance imaging (MRI).

METHODS

(99)Tc(m)-HMPAO-SPECT, brain MRI, and (1)H-MRS were done in eight women with SLE (mean age 31.8 years; disease duration 5.5 years). NAA/Cho, NAA/Cre, and Cho/Cre ratios were assessed in hypoperfused and normoperfused areas detected by SPECT that were normal on MRI examination. Reference values were obtained in 20 normal healthy controls. In five patients, MRI was repeated four to six years after the first evaluation.

RESULTS

Mean NAA/Cho and Cho/Cre ratios in hypoperfused and normoperfused frontal areas were, respectively, lower and higher than control. There were no differences in NAA/Cre ratios. Mean Cho/Cre ratios were increased in hypoperfused v normoperfused brain areas (mean (SD): 1.43 (0.27) v 1.00 (0.07); p<0.023). NAA/Cre ratios were not altered (2.18 (0.30) v 1.99 (0.28); p = 0.381). Three of five patients who had a second MRI had new lesions in areas previously abnormal on MRS and SPECT but normal on first MRI. One patient with positive MRI, SPECT, and MRS showed an increase in the number of MRI lesions; one patient with negative MRI, SPECT, and MRS did not show any new lesions.

CONCLUSIONS

Abnormalities reflecting altered perfusion or neuronal-chemical changes can be demonstrated by functional imaging techniques even in the absence of morphological lesions detectable by MRI. The abnormal areas identified by SPECT and MRS may predict future parenchymal damage.

Selective gray matter damage in neuropsychiatric lupus

OBJECTIVE

Damage of brain parenchyma in patients with primary diffuse neuropsychiatric systemic lupus erythematosus (NPSLE) has been indicated by magnetization transfer imaging (MTI). However, the location of MTI abnormalities is unknown. This study was undertaken to assess the distribution of MTI abnormalities over gray matter (GM) and white matter (WM) in SLE patients with a history of NP symptoms without explanatory magnetic resonance imaging (MRI) evidence of focal disease.

METHODS

MTI was performed in 24 female SLE patients with a history of diffuse NP symptoms and 24 healthy female controls. Magnetization transfer ratio (MTR) maps were calculated for GM and WM separately, and GM and WM MTR histograms were generated. Univariate and multivariate analyses with age as an additional covariate were performed on the histogram parameters peak location (PL), peak height (PH), and mean MTR.

RESULTS

Compared with controls, significantly reduced PH (mean +/- SD 136 +/- 22 arbitrary units versus 151 +/- 13 arbitrary units) and mean MTR (33.3 +/- 1.0 percent units versus 33.6 +/- 0.5 percent units) were found in the GM of NPSLE patients (P = 0.002 and P = 0.033, respectively, in multivariate analyses). No significant differences were observed for WM MTR parameters.

CONCLUSION

This is the first study to demonstrate, using MTI, that in SLE patients with a history of NP symptoms and without explanatory focal abnormalities on MRI, the GM is particularly affected. These findings support the hypothesis that neuronal injury may underlie central nervous system manifestations in NPSLE.

Molecular imaging applications for immunology

The use of multimodality molecular imaging has recently facilitated the study of molecular and cellular events in living subjects in a noninvasive and repetitive manner to improve the diagnostic capability of traditional assays. The noninvasive imaging modalities utilized for both small animal and human imaging include positron emission tomography (PET), single photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), ultrasound, and computed tomography (CT). Techniques specific to small-animal imaging include bioluminescent imaging (BIm) and fluorescent imaging (FIm). Molecular imaging permits the study of events within cells, the examination of cell trafficking patterns that relate to inflammatory diseases and metastases, and the ability to rapidly screen new drug treatments for distribution and effectiveness. In this paper, we will review the current field of molecular imaging assays (especially those utilizing PET and BIm modalities) and examine how they might impact animal models and human disease in the field of clinical immunology.

Systemic lupus erythematosus in the intensive care unit

SLE causes significant morbidity and mortality by multisystem organ involvement. Infections are the leading cause of morbidity and mortality in patients with SLE. Meticulous exclusion of infection is mandatory in patients with SLE, because infections may masquerade as exacerbation of underlying disease; and the immunosuppression used to treat severe forms of exacerbation of lupus can have catastrophic consequences in patients with infections. Corticosteroids are the first-line therapy for most noninfectious complications of SLE, with various adjuvant immunosuppressive agents such as cyclophosphamide being increasingly used in combination with plasmapheresis. Some recent series have shown an improved survival rate, but this improvement needs to be confirmed by further studies. Controlled trials comparing various therapeutic options are lacking, and optimal therapy has not been defined.