Semi-automatic brain region extraction (SABRE) reveals superior cortical and deep gray matter atrophy in MS

Brain Parenchymal Fraction in Healthy Adults-A Systematic Review of the Literature

Brain atrophy is an important feature of many neurodegenerative disorders. It can be described in terms of change in the brain parenchymal fraction (BPF). In order to interpret the BPF in disease, knowledge on the BPF in healthy individuals is required. The aim of this study was to establish a normal range of values for the BPF of healthy individuals via a systematic review of the literature. The databases PubMed and Scopus were searched and 95 articles, including a total of 9269 individuals, were identified including the required data. We present values of BPF from healthy individuals stratified by age and post-processing method. The mean BPF correlated with mean age and there were significant differences in age-adjusted mean BPF between methods. This study contributes to increased knowledge about BPF in healthy individuals, which may assist in the interpretation of BPF in the setting of disease. We highlight the differences between post-processing methods and the need for a consensus gold standard.

Gray Matter Correlates of Cognitive Performance Differ between Relapsing-Remitting and Primary-Progressive Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory/demyelinating and neurodegenerative disease of the central nervous system (CNS). Most patients experience a relapsing-remitting (RR) course, while about 15–20% of patients experience a primary progressive (PP) course. Cognitive impairment affects approximately 40–70% of all MS patients and differences in cognitive impairment between RR-MS and PP-MS have been found. We aimed to compare RR-MS and PP-MS patients in terms of cognitive performance, and to investigate the MRI correlates of cognitive impairment in the two groups using measures of brain volumes and cortical thickness. Fifty-seven patients (42 RR-MS, 15 PP-MS) and thirty-eight matched controls underwent neuropsychological (NP) testing and MRI. PP-MS patients scored lower than RR-MS patients on most of the NP tests in absence of any specific pattern. PP-MS patients showed significantly lower caudate volume. There was no significant difference in MRI correlates of cognitive impairment between the two groups except for a prevalent association with MRI measures of cortical GM injury in RR-MS patients and with MRI measures of subcortical GM injury in PP-MS patients. This suggests that although cognitive impairment results from several factors, cortical and subcortical GM injury may play a different role depending on the disease course.

Regional cortical thinning in multiple sclerosis and its relation with cognitive impairment: A multicenter study

Objectives:

The objectives of this paper are to compare in a multicenter setting patterns of regional cortical thickness in patients with relapsing–remitting multiple sclerosis (RRMS) and cognitive impairment (CI) and those cognitively preserved (CP), and explore the relationship between cortical thinning and cognitive performance.

Methods:

T1-weighted isotropic brain scans were collected at 3T from seven European centers in 60 RRMS patients and 65 healthy controls (HCs). Patients underwent clinical and neuropsychological examinations. Cortical thickness (CTh) measures were calculated using FreeSurfer (failing in four) and both lobar and vertex-based general linear model (GLM) analyses were compared between study groups.

Results:

Twenty (36%) MS patients were classified as CI. Mean global CTh was smaller in RRMS patients compared to HCs (left 2.43 vs. 2.53 mm, right 2.44 vs. 2.54 mm, p < 0.001). Multivariate GLM regional analysis showed significantly more temporal thinning in CI compared to CP patients. Verbal memory scores correlated to regional cortical thinning in the insula whereas visual memory scores correlated to parietal thinning.

Conclusions:

This multicenter study showed mild global cortical thinning in RRMS. The extent of thinning is less pronounced than previously reported. Only subtle regional differences between CI and CP patients were observed, some of which related to specific cognitive domains.

Corpus callosum thickness on mid-sagittal MRI as a marker of brain volume: a pilot study in children with HIV-related brain disease and controls

BACKGROUND

Corpus callosum thickness measurement on mid-sagittal MRI may be a surrogate marker of brain volume. This is important for evaluation of diseases causing brain volume gain or loss, such as HIV-related brain disease and HIV encephalopathy.

OBJECTIVE

To determine if thickness of the corpus callosum on mid-sagittal MRI is a surrogate marker of brain volume in children with HIV-related brain disease and in controls without HIV.

MATERIALS AND METHODS

A retrospective MRI analysis in children (<5 years old) with HIV-related brain disease and controls used a custom-developed semi-automated tool, which divided the midline corpus callosum and measured its thickness in multiple locations. Brain volume was determined using volumetric analysis. Overall corpus callosum thickness and thickness of segments of the corpus callosum were correlated with overall and segmented (grey and white matter) brain volume.

RESULTS

Forty-four children (33 HIV-infected patients and 11 controls) were included. Significant correlations included overall corpus callosum (mean) and total brain volume (P = 0.05); prefrontal corpus callosum maximum with white matter volume (P = 0.02); premotor corpus callosum mean with total brain volume (P = 0.04) and white matter volume (P = 0.02), premotor corpus callosum maximum with white matter volume (P = 0.02) and sensory corpus callosum mean with total brain volume (P = 0.02).

CONCLUSION

Corpus callosum thickness correlates with brain volume both in HIV-infected patients and controls.

Correlating brain volume and callosal thickness with clinical and laboratory indicators of disease severity in children with HIV-related brain disease

BACKGROUND

Objective MRI markers of central nervous system disease severity may precede subjective features of HIV encephalopathy in children. Previous work in HIV-infected adults shows that brain atrophy was associated with low CD4 and with neuropsychological impairment. Significant thinning of the corpus callosum (CC), predominantly anteriorly, was also found in HIV-infected adults and correlated with CD4 levels. These findings have not been tested in children.

PURPOSE

The aim of this study was to determine if brain volume and midsagittal CC linear measurements (thickness and length) on MRI in children with HIV-related brain disease correlate with clinical and laboratory parameters of disease severity.

METHODS

Retrospective MRI analysis in children with HIV-related brain disease used a volumetric analysis software and a semi-automated tool to measure brain volume and callosal thickness/length, respectively. Each measure was correlated with clinical parameters of disease severity including Griffiths Mental Development scores (GMDS), absolute CD4 counts (cells/mm(3)), nadir CD4 (the lowest CD4 recorded, excluding baseline), duration of HAART, and decreased brain growth.

RESULTS

Thirty-three children with HIV-related brain disease were included. Premotor segment of the CC mean thickness correlated with age (p = 0.394). Motor CC maximum thickness correlated significantly with general developmental quotient (p = 0.0277); CC length correlated with a diagnosis of acquired microcephaly (p = 0.0071) and to CD4 level closest to date of the MRI scan (p = 0.04).

CONCLUSIONS

Length of the CC and the "motor CC segment" may represent surrogate clinical biomarkers of central nervous system disease severity and with decreased level of immunity in HIV-infected patients that precede established HIV encephalopathy.

Update on the relationships between neuropsychological dysfunction and structural MRI in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the CNS, characterized by demyelination and neurodegeneration. Besides the sensory and motor deficits that are the hallmark of this disease, approximately 50% of MS patients are cognitively impaired. Over the years, structural neuroimaging has been used widely in MS patients for both diagnostic and research purposes. Various conventional and nonconventional magnetic resonance imaging (MRI) measures have provided important information about the degree and mechanisms of cerebral pathology, and these measures correlate with cognitive and affective disturbances. In this article, recent contributions to the literature regarding the correlation between MRI and neuropsychological function in MS are reviewed.

Clinical use of brain volumetry

Magnetic resonance imaging (MRI)-based brain volumetry is increasingly being used in the clinical setting to assess brain volume changes from structural MR images in a range of neurologic conditions. Measures of brain volumes have been shown to be valid biomarkers of the clinical state and progression by offering high reliability and robust inferences on the underlying disease-related mechanisms. This review critically examines the different scenarios of the application of MRI-based brain volumetry in neurology: 1) supporting disease diagnosis, 2) understanding mechanisms and tracking clinical progression of disease, and 3) monitoring treatment effect. These aspects will be discussed in a wide range of neurologic conditions, with particular emphasis on Alzheimer's disease and multiple sclerosis.

Gray matter imaging in multiple sclerosis: what have we learned?

At the early onset of the 20^th century, several studies already reported that the gray matter was implicated in the histopathology of multiple sclerosis (MS). However, as white matter pathology long received predominant attention in this disease, and histological staining techniques for detecting myelin in the gray matter were suboptimal, it was not until the beginning of the 21^st century that the true extent and importance of gray matter pathology in MS was finally recognized. Gray matter damage was shown to be frequent and extensive, and more pronounced in the progressive disease phases. Several studies subsequently demonstrated that the histopathology of gray matter lesions differs from that of white matter lesions. Unfortunately, imaging of pathology in gray matter structures proved to be difficult, especially when using conventional magnetic resonance imaging (MRI) techniques. However, with the recent introduction of several more advanced MRI techniques, the detection of cortical and subcortical damage in MS has considerably improved. This has important consequences for studying the clinical correlates of gray matter damage. In this review, we provide an overview of what has been learned about imaging of gray matter damage in MS, and offer a brief perspective with regards to future developments in this field.

Survey of protocols for the manual segmentation of the hippocampus: preparatory steps towards a joint EADC-ADNI harmonized protocol

Manual segmentation from magnetic resonance imaging (MR) is the gold standard for evaluating hippocampal atrophy in Alzheimer's disease (AD). Nonetheless, different segmentation protocols provide up to 2.5-fold volume differences. Here we surveyed the most frequently used segmentation protocols in the AD literature as a preliminary step for international harmonization. The anatomical landmarks (anteriormost and posteriormost slices, superior, inferior, medial, and lateral borders) were identified from 12 published protocols for hippocampal manual segmentation ([Abbreviation] first author, publication year: [B] Bartzokis, 1998; [C] Convit, 1997; [dTM] deToledo-Morrell, 2004; [H] Haller, 1997; [J] Jack, 1994; [K] Killiany, 1993; [L] Lehericy, 1994; [M] Malykhin, 2007; [Pa] Pantel, 2000; [Pr] Pruessner, 2000; [S] Soininen, 1994; [W] Watson, 1992). The hippocampi of one healthy control and one AD patient taken from the 1.5T MR ADNI database were segmented by a single rater according to each protocol. The accuracy of the protocols' interpretation and translation into practice was checked with lead authors of protocols through individual interactive web conferences. Semantically harmonized landmarks and differences were then extracted, regarding: (a) the posteriormost slice, protocol [B] being the most restrictive, and [H, M, Pa, Pr, S] the most inclusive; (b) inclusion [C, dTM, J, L, M, Pr, W] or exclusion [B, H, K, Pa, S] of alveus/fimbria; (c) separation from the parahippocampal gyrus, [C] being the most restrictive, [B, dTM, H, J, Pa, S] the most inclusive. There were no substantial differences in the definition of the anteriormost slice. This survey will allow us to operationalize differences among protocols into tracing units, measure their impact on the repeatability and diagnostic accuracy of manual hippocampal segmentation, and finally develop a harmonized protocol.

Lesion Explorer: a comprehensive segmentation and parcellation package to obtain regional volumetrics for subcortical hyperintensities and intracranial tissue

Subcortical hyperintensities (SH) are a commonly observed phenomenon on MRI of the aging brain (Kertesz et al., 1988). Conflicting behavioral, cognitive and pathological associations reported in the literature underline the need to develop an intracranial volumetric analysis technique to elucidate pathophysiological origins of SH in Alzheimer's disease (AD), vascular cognitive impairment (VCI) and normal aging (De Leeuw et al., 2001; Mayer and Kier, 1991; Pantoni and Garcia, 1997; Sachdev et al., 2008). The challenge is to develop processing tools that effectively and reliably quantify subcortical small vessel disease in the context of brain tissue compartments. Segmentation and brain region parcellation should account for SH subtypes which are often classified as: periventricular (pvSH) and deep white (dwSH), incidental white matter disease or lacunar infarcts and Virchow-Robin spaces. Lesion Explorer (LE) was developed as the final component of a comprehensive volumetric segmentation and parcellation image processing stream built upon previously published methods (Dade et al., 2004; Kovacevic et al., 2002). Inter-rater and inter-method reliability was accomplished both globally and regionally. Volumetric analysis showed high inter-rater reliability both globally (ICC=.99) and regionally (ICC=.98). Pixel-wise spatial congruence was also high (SI=.97). Whole brain pvSH volumes yielded high inter-rater reliability (ICC=.99). Volumetric analysis against an alternative kNN segmentation revealed high inter-method reliability (ICC=.97). Comparison with visual rating scales showed high significant correlations (ARWMC: r=.86; CHIPS: r=.87). The pipeline yields a comprehensive and reliable individualized volumetric profile for subcortical vasculopathy that includes regionalized (26 brain regions) measures for: GM, WM, sCSF, vCSF, lacunar and non-lacunar pvSH and dwSH.

Cognitive dysfunction in multiple sclerosis: the effect of pharmacological interventions

Research has recently focused on cognitive dysfunction in multiple sclerosis (MS). Cognitive deficits are frequently encountered in patients and account for important impairment in quality of life, therefore posing a major therapeutic challenge for the disease. We presently review studies on cognitive effects of pharmacological treatments in MS. There is evidence for a possible beneficial effect of immunomodulatory treatments, particularly of interferons, and also of acetylcholinesterase inhibitors on cognition in MS, which, however, requires evaluation in larger, multi-centre, longitudinal studies. Methodological issues and future prospects regarding the investigation of this issue are also discussed.

Evidence for retrochiasmatic tissue loss in Leber's hereditary optic neuropathy

Patients with Leber's hereditary optic neuropathy (LHON) have loss of central vision with severe damage of small-caliber fibers of the papillomacular bundle and optic nerve atrophy. The aim of this study was to define the presence and topographical distribution of brain grey matter (GM) and white matter (WM) injury in LHON patients using voxel-based morphometry (VBM). The correlation of such changes with neuro-ophthalmologic findings and measurements of peripapillary retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT) was also assessed. Dual-echo and fast-field echo scans were acquired from 12 LHON patients and 12 matched controls. VBM analysis was performed using SPM5 and an ANCOVA model. A complete neuro-ophthalmologic examination, including standardized automated Humphrey perimetry as well as average and temporal peripapillary RNFL thickness measurements were obtained in all the patients. Compared with controls, average peripapillary RNFL thickness was significantly decreased in LHON patients. LHON patients also had significant reduced GM volume in the bilateral primary visual cortex, and reduced WM volume in the optic chiasm, optic tract, and several areas located in the optic radiations (OR), bilaterally. Visual cortex and OR atrophy were significantly correlated with average and temporal peripapillary RNFL thickness (P < 0.001; r values ranging from 0.76 to 0.89). Brain damage in patients with LHON is not limited to the anterior visual pathways, but extends posteriorly to the OR and the primary visual cortex. Such a damage to the posterior parts of the visual pathways may be due either to trans-synaptic degeneration secondary to neuroaxonal damage in the retina and optic nerve or to local mitochondrial dysfunction.

Smoking is associated with increased lesion volumes and brain atrophy in multiple sclerosis

BACKGROUND

Cigarette smoking has been linked to higher susceptibility and increased risk of progressive multiple sclerosis (MS). The effects of smoking on MRI characteristics of patients with MS have not been evaluated.

OBJECTIVES

To compare the MRI characteristics in cigarette smoker and nonsmoker patients with MS.

METHODS

We studied 368 consecutive patients with MS (age 44.0 +/-SD 10.2 years, disease duration 12.1 +/- 9.1 years) comprising 240 never-smokers and 128 (34.8%) ever-smokers (currently active and former smokers). The average number of packs per day smoked (+/-SD) was 0.95 +/- 0.65, and the mean duration of smoking was 18.0 +/- 9.5 years. All patients obtained full clinical and quantitative MRI evaluation. MRI measures included T1, T2, and gadolinium contrast-enhancing (CE) lesion volumes (LVs) and measures of central, global, and tissue-specific brain atrophy. The associations between smoking status and MRI measurements were assessed in regression analysis.

RESULTS

Smoking was associated with increased Expanded Disability Status Scale (EDSS) scores (p = 0.004). The median EDSS scores (interquartile range) in the ever-smoker group and the active-smoker group were both 3.0 (2.0), compared with 2.5 (2.5) in never-smokers. There were adverse associations between smoking and the lesion measures including increased number of CE lesions (p < 0.001), T2 LV (p = 0.009), and T1 LV (p = 0.003). Smoking was associated with decreased brain parenchymal fraction (p = 0.047) and with increases in the lateral ventricle volume (p = 0.001) and third ventricle width (p = 0.023).

CONCLUSIONS

Smoking is associated with increased blood-brain barrier disruption, higher lesion volumes, and greater atrophy in multiple sclerosis.

MRI characteristics of patients with antiphospholipid syndrome and multiple sclerosis

MRI findings of primary anti-phospholipid antibody syndrome (PAPLS) are difficult to distinguish from those of multiple sclerosis (MS). Only a few previous studies have compared conventional and non-conventional MRI findings in MS and PAPLS patients. In addition, MRI differences between anti-phospholipid antibody (APLA) positive (+) and APLA negative (-) MS patients have not been reported. Therefore, the aim of this study was to investigate the differences in MRI measures among patients with PAPLS, MS and normal control (NC) subjects. We also explored non-conventional MRI measures in APLA+ and APLA- MS patients. Forty-nine (49) consecutive MS patients among whom 39 had relapsing-remitting (RR) and 10 secondary-progressive (SP) disease course, 30 patients with PAPLS and 49 NC were enrolled. Twenty-eight (28) MS patients were APLA+. MRI measures of T1- and T2-lesion volumes (LV) and brain atrophy, including fractions of whole brain (BPF), gray matter (GMF) and white matter (WMF), were evaluated. The magnetization transfer ratio (MTR) of T2- and T1-LVs and different normal-appearing brain tissue (NABT) compartments as well as diffusion-weighted imaging of whole brain mean parenchyma diffusivity (MPD) were obtained. MS patients differed significantly from NC in all MRI measures. PAPLS patients differed from NC in their T2-LV, in MTR measures and in MPD. When MS patients were compared to PAPLS patients, they showed significantly higher T2- and T1-LVs and T2-LV MTR, lower BPF and GMF and higher MPD. APLA+ RR and SPMS (all APLA+) patients showed significantly higher T2-LV, lower GMF, lower normal-appearing gray matter MTR and higher MPD when compared to APLA- patients. The results indicate that brain abnormalities can be detected in PAPLS patients with non-conventional MRI. MRI reveals more profound injury in patients with MS versus PAPLS. APLA mediates heterogeneous cerebral pathology that remains to be further investigated.

The relationship between subjective reports of fatigue and executive control in multiple sclerosis

Previous studies failed to show a relationship between fatigue and cognitive performance. We used a theory-based Delayed Item Recognition (DIR) paradigm to examine the hypothesis that subjective reports of fatigue and executive control processes were related in MS. Participants were 20 individuals diagnosed with definite diagnosis of MS with Relapsing-Remitting course and 20 controls case matched for age, sex, education and IQ. The DIR paradigm manipulated executive demands in three conditions: Alone, Partial Interference (PI), and Complete Interference (CI). Fatigue was assessed using the Fatigue Severity Scale (FSS).

RESULTS

ANOVA Repeated measures analyses showed that DIR performance was slower and less accurate as a function of MS and increased executive demands across the three task conditions. Separate linear regressions revealed that fatigue was related to DIR reaction time and accuracy performance only in the CI condition where executive demands are maximized, and only in the MS group. The present study provided first behavioral evidence that fatigue and executive control are uniquely related in MS.

Gene-environment interactions between HLA B7/A2, EBV antibodies are associated with MRI injury in multiple sclerosis

PURPOSE

To determine the role of gene-environmental interactions between the Class I and Class II HLA alleles and the humoral anti-Epstein-Barr Virus (EBV) responses in the development of brain injury and clinical disability in multiple sclerosis (MS) patients.

METHODS

A total of 93 MS patients (62 females; 31 males) and 122 healthy controls underwent HLA typing and testing for antibodies against EBV. The MS patients underwent brain MRI and quantitative measurements of T1- and T2-lesion volumes (LVs) and brain parenchymal fraction (BPF) were obtained. There were 54 MS cases that underwent MRI and EBV-antibody assessments at the 3-year follow-up. The anti-EBV panel included measurements of the levels of anti-EBV early antigen (EA) IgG, anti-EBV nuclear antigen (EBNA) IgG and anti-EBV viral capsid antigen (VCA) IgM and anti-EBV VCA IgG. The relationships between HLA alleles, anti-EBV antibody levels, MRI and clinical parameters were assessed in regression analysis.

RESULTS

The presence of HLA B7 was associated with increased T1-LV and trends indicating increased anti-EBV VCA IgG levels, higher disability (EDSS) and more destructive MRI parameters (increased T2-LV and decreased BPF). The presence of HLA A2 was associated with lower EDSS and a trend toward decreased anti-EBV VCA IgG levels; the associations with MRI variables were not significant. The HLA B7-A2 haplotype was significantly associated with higher T2-LV and T1-LV and a trend toward lower BPF was observed.

CONCLUSIONS

Our data suggest that gene-environment interactions between specific HLA Class I loci and EBV exposure are associated with MRI markers of lesion injury and brain atrophy in MS patients.

Extent of cerebellum, subcortical and cortical atrophy in patients with MS: a case-control study

Cortical and subcortical atrophy occurs in multiple sclerosis (MS) and relates to clinical outcomes. FreeSurfer, a voxel-based automated software for brain reconstruction was used to investigate the extent of subcortical and cortical atrophy in 71 MS and 17 clinically isolated syndrome (CIS) patients, and 38 normal controls (NC), and to relate group differences to disease type and severity. Segmentation was performed on 3D SPGR T1-weighted MRI 1.5T images. Region-specific subcortical tissue volumes were calculated in mm(3) and cortical thickness in mm. Logistic regression and general linear model analyses, adjusted for age and intracranial volume, examined differences between NC, MS and CIS patients and disease subtypes. The MS group was characterized by significantly lower volumes of thalamus (left and right p<0.0001), left inferior lateral ventricle, third ventricle (p<0.0001), ventral diencephalon, pallidum and putamen bilaterally, as well as of right accumbens and brainstem with corresponding bilateral increase in volumes of lateral ventricles (p<0.01). Focal cortical atrophy areas in the thalamus, inferior parietal lobule of left hemisphere and in right precuneus were also significant in the MS sample. Versus CIS patients, RR or progressive MS patients showed significantly lower volumes of subcortical regions and cortical thinning. Hippocampal atrophy appeared only in advanced disease stages. Cerebellum WM volumes were significantly lower in MS and CIS patients vs. NC. Subcortical and cortical atrophy correlated with higher disability as measured by EDSS. This study confirmed selective deep gray matter atrophy (mostly thalamic), revealed cerebellum WM atrophy from the earliest clinical stages, and showed that cortical thinning advances with disease progression.

Gray matter atrophy is related to long-term disability in multiple sclerosis

OBJECTIVE

To determine the relation of gray matter (GM) and white matter (WM) brain volumes, and WM lesion load, with clinical outcomes 20 years after first presentation with clinically isolated syndrome suggestive of multiple sclerosis (MS).

METHODS

Seventy-three patients were studied a mean of 20 years from first presentation with a clinically isolated syndrome (33 of whom developed relapsing-remitting MS and 11 secondary-progressive MS, with the rest experiencing no further definite neurological events), together with 25 healthy control subjects. GM and WM volumetric measures were obtained from three-dimensional T1-weighted brain magnetic resonance images using Statistical Parametric Mapping 2.

RESULTS

Significant GM (p < 0.001) and WM atrophy (p = 0.001) was seen in MS patients compared with control subjects. There was significantly more GM, but not WM atrophy, in secondary-progressive MS versus relapsing-remitting MS (p = 0.003), and relapsing-remitting MS versus clinically isolated syndrome (p < 0.001). GM, but not WM, fraction correlated with expanded disability status scale (r(s) = -0.48; p < 0.001) and MS Functional Composite scores (r(s) = 0.59; p < 0.001). WM lesion load correlated with GM (r(s) = -0.63; p < 0.001), but not with WM fraction. Regression modeling indicated that the GM fraction explained more of the variability in clinical measures than did WM lesion load.

INTERPRETATION

In MS patients with a relatively long and homogeneous disease duration, GM atrophy is more marked than WM atrophy, and reflects disease subtype and disability to a greater extent than WM atrophy or lesions.

MRI in multiple sclerosis: current status and future prospects

Many promising MRI approaches for research or clinical management of multiple sclerosis (MS) have recently emerged, or are under development or refinement. Advanced MRI methods need to be assessed to determine whether they allow earlier diagnosis or better identification of phenotypes. Improved post-processing should allow more efficient and complete extraction of information from images. Magnetic resonance spectroscopy should improve in sensitivity and specificity with higher field strengths and should enable the detection of a wider array of metabolites. Diffusion imaging is moving closer to the goal of defining structural connectivity and, thereby, determining the functional significance of lesions at specific locations. Cell-specific imaging now seems feasible with new magnetic resonance contrast agents. The imaging of myelin water fraction brings the hope of providing a specific measure of myelin content. Ultra-high-field MRI increases sensitivity, but also presents new technical challenges. Here, we review these recent developments in MRI for MS, and also look forward to refinements in spinal-cord imaging, optic-nerve imaging, perfusion MRI, and functional MRI. Advances in MRI should improve our ability to diagnose, monitor, and understand the pathophysiology of MS.

Regional specificity of magnetization transfer imaging in multiple sclerosis

BACKGROUND

The goal of this study was to develop and validate a method for generation of regional magnetization transfer ratio (MTR). We also studied the topography of MTR changes in multiple sclerosis (MS) and in normal controls (NC), and preliminarily examined the clinical usefulness of this method.

METHODS

We examined 45 patients with MS (relapsing remitting [RR] = 28 and secondary progressive[SP] = 17] and 19 NC. Mean disease duration was 14.3 years and median Expanded Disability Status Scale was 3.0. Regions of the brain were determined using semiautomated brain region extraction (SABRE). Twenty-six regional masks were automatically applied to MTR maps that were further split into gray matter (GM) and white matter (WM)compartments.

RESULTS

Mean MTR from 12 SABRE regions differed significantly between MS patients and NC. For WM, all regional mean MTRs differed significantly between RR, SP, and NC participants(P < .001). In regression analysis, only 3 regions remained significantly different when corrected for total T2-LV. The regression model predicting disability selected GM mean MTR of the right medial inferior frontal region (P = .031).

CONCLUSIONS

The study results showed that this regional MTR approach is reproducible, reliable and clinically relevant. MTI changes occur selectively in specific sub-regions.

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.

A voxel-based morphometry study of grey matter loss in MS patients with different clinical phenotypes

To assess regional grey matter (GM) changes in a large cohort of multiple sclerosis (MS) patients with different clinical phenotypes, using voxel-based morphometry (VBM) and their correlation with the extent of global and regional T2 lesion volumes (LV), we acquired conventional MRI scans from 71 MS patients with different clinical phenotypes (26 with relapsing-remitting [RR] MS, 27 with secondary progressive [SP] MS and 18 with primary progressive [PP] MS), 28 patients with a clinically isolated syndrome (CIS) suggestive of MS, and 21 controls. No GM loss was found in CIS patients. Compared to CIS patients, those with RRMS had a significant GM loss in the right pre and postcentral gyri. Compared to RRMS, SPMS patients had a significant GM loss in several regions of the fronto-parieto-temporo-occipital lobes, the cerebellum and superior and inferior colliculus, bilaterally, and deep GM structures. Compared to PPMS, SPMS patients had a significant GM loss in the postcentral gyrus, the cuneus, the middle occipital gyrus, the thalamus, the cerebellum, and the superior and inferior colliculus. In all MS groups, regional GM loss was strongly/moderately correlated with brain T2 LV. In SPMS and PPMS patients, a correlation was found between cortical regional GM loss and T2 LV of the corresponding or adjacent lobes. In MS patients, GM volume loss follows different patterns of regional distribution according to the clinical phenotype of the disease, is likely secondary to the presence and topography of focal WM inflammatory-demyelinating lesions, and is more evident in the progressive forms of the disease.

Ventral frontal cortex functions and quantified MRI in traumatic brain injury

Ventral frontal cortex is commonly involved in traumatic brain injury (TBI). The smell identification test (SIT), object alternation (OA), and the Iowa gambling task (IGT) are associated with this brain region in experimental and neuropsychological research. We examined the relationship of performance on these tests to residual structural brain integrity quantified from MRI in 58 TBI patients, including 18 patients with focal cortical contusions and 40 patients with diffuse injury only. Image analysis yielded regional volumetric measures of gray matter, white matter and cerebrospinal fluid. Multivariate analyses identified distributed patterns of regional volume loss associated with test performance across all three behavioral measures. The tasks were sensitive to effects of TBI. In multivariate analyses, performance in all three tasks was related to gray matter loss including ventral frontal cortex, but the SIT was most sensitive to ventral frontal cortex damage, even in patients without focal lesions. The SIT was further related to temporal lobe and posterior cingulate/retrosplenial volumes. OA and the IGT were associated with superior medial frontal volumes. Complex tasks, such as OA and the IGT, do not consistently localize to a single cortical region. The SIT is associated with the integrity of ventral frontal regions, but it is also affected by distributed damage, although the contribution of undetected olfactory tract or bulb damage could not be ruled out. This study illustrates the scope and limitations of functional localization in human ventral frontal cortex.

MRI in multiple sclerosis: what's inside the toolbox?

Magnetic resonance imaging (MRI) has played a central role in the diagnosis and management of multiple sclerosis (MS). In addition, MRI metrics have become key supportive outcome measures to explore drug efficacy in clinical trials. Conventional MRI measures have contributed to the understanding of MS pathophysiology at the macroscopic level yet have failed to provide a complete picture of underlying MS pathology. They also show relatively weak relationships to clinical status such as predictive strength for clinical progression. Advanced quantitative MRI measures such as magnetization transfer, spectroscopy, diffusion imaging, and relaxometry techniques are somewhat more specific and sensitive for underlying pathology. These measures are particularly useful in revealing diffuse damage in cerebral white and gray matter and therefore may help resolve the dissociation between clinical and conventional MRI findings. In this article, we provide an overview of the array of tools available with brain and spinal cord MRI technology as it is applied to MS. We review the most recent data regarding the role of conventional and advanced MRI techniques in the assessment of MS. We focus on the most relevant pathologic and clinical correlation studies relevant to these measures.

Quantitative assessment of iron accumulation in the deep gray matter of multiple sclerosis by magnetic field correlation imaging

BACKGROUND AND PURPOSE

Deposition of iron has been recognized recently as an important factor of pathophysiologic change including neurodegenerative processes in multiple sclerosis (MS). We propose that there is an excess accumulation of iron in the deep gray matter in patients with MS that can be measured with a newly developed quantitative MR technique--magnetic field correlation (MFC) imaging.

MATERIALS AND METHODS

With a 3T MR system, we studied 17 patients with relapsing-remitting MS and 14 age-matched healthy control subjects. We acquired MFC imaging using an asymmetric single-shot echo-planar imaging sequence. Regions of interest were selected in both deep gray matter and white matter regions, and the mean MFC values were compared between patients and controls. We also correlated the MFC data with lesion load and neuropsychologic tests in the patients.

RESULTS

MFC measured in the deep gray matter in patients with MS was significantly higher than that in the healthy controls (P < or = .03), with an average increase of 24% in the globus pallidus, 39.5% in the putamen, and 30.6% in the thalamus. The increased iron deposition measured with MFC in the deep gray matter in the patients correlated positively with the total number of MS lesions (thalamus: r = 0.61, P = .01; globus pallidus: r = 0.52, P = .02). A moderate but significant correlation between the MFC value in the deep gray matter and the neuropsychologic tests was also found.

CONCLUSION

Quantitative measurements of iron content with MFC demonstrate increased accumulation of iron in the deep gray matter in patients with MS, which may be associated with the disrupted iron outflow pathway by lesions. Such abnormal accumulation of iron may contribute to neuropsychologic impairment and have implications for neurodegenerative processes in MS.

Independent contributions of cortical gray matter atrophy and ventricle enlargement for predicting neuropsychological impairment in multiple sclerosis

The primary goal of this study was to investigate associations between regional gray matter (GM) atrophy and neuropsychological function in multiple sclerosis (MS), while accounting for the influence of central brain atrophy (i.e. third ventricle enlargement). Using a cross-sectional design, we studied 59 MS patients with brain MRI and neuropsychological testing. Regional gray matter fractions (rGMFs) were calculated from MRI images for 11 homologous brain areas using the semiautomatic brain region extraction (SABRE) technique. Neuropsychological testing followed consensus panel guidelines and included tests emphasizing episodic memory, working memory and processing speed. The analytic approach was stepwise linear regression, with forward selection and p<0.05 threshold for significance. Consistent with previous research, there were significant correlations between third ventricle width and neuropsychological tests. Stepwise linear regression analyses controlling for third ventricle width retained rGMFs obtained from specific regions within the prefrontal cortex. Left frontal atrophy was associated with tests emphasizing auditory/verbal memory. Right frontal atrophy was associated with impairment in visual episodic and working memory. For the first time, we show an independent relationship between cortical atrophy and cognitive impairment after accounting for the effects of central atrophy.

Kinematic analysis of thalamic versus subthalamic neurostimulation in postural and intention tremor

Deep brain stimulation of the thalamus (thalamic DBS) is an established therapy for medically intractable essential tremor and tremor caused by multiple sclerosis. In both disorders, motor disability results from complex interaction between kinetic tremor and accompanying ataxia with voluntary movements. In clinical studies, the efficacy of thalamic DBS has been thoroughly assessed. However, the optimal anatomical target structure for neurostimulation is still debated and has never been analysed in conjunction with objective measurements of the different aspects of motor impairment. In 10 essential tremor and 11 multiple sclerosis patients, we analysed the effect of thalamic DBS through each contact of the quadripolar electrode on the contralateral tremor rating scale, accelerometry and kinematic measures of reach-to-grasp-movements. These measures were correlated with the anatomical position of the stimulating electrode in stereotactic space and in relation to nuclear boundaries derived from intraoperative microrecording. We found a significant impact of the stereotactic z-coordinate of stimulation contacts on the TRS, accelerometry total power and spatial deviation in the deceleration and target period of reach-to-grasp-movements. Most effective contacts clustered within the subthalamic area (STA) covering the posterior Zona incerta and prelemniscal radiation. Stimulation within this region led to a mean reduction of the lateralized tremor rating scale by 15.8 points which was significantly superior to stimulation within the thalamus (P < 0.05, student's t-test). STA stimulation resulted in reduction of the accelerometry total power by 99%, whereas stimulation at the ventral thalamic border (68%) or within the thalamus proper (2.5%) was significantly less effective (P < 0.01). Concomitantly, STA stimulation led to a significantly higher increase of tremor frequency and decrease in EMG synchronization compared to stimulation within the thalamus proper (P < 0.001). In reach-to-grasp movements, STA stimulation reduced the spatial variability of the movement path in the deceleration period by 28.9% and in the target period by 58.4%, whereas stimulation within the thalamus was again significantly less effective (P < 0.05), with a reduction in the deceleration period between 6.5 and 21.8% and in the target period between 1.2 and 11.3%. An analysis of the nuclear boundaries from intraoperative microrecording confirmed the anatomical impression that most effective electrodes were located within the STA. Our data demonstrate a profound effect of deep brain stimulation of the thalamic region on tremor and ataxia in essential tremor and tremor caused by multiple sclerosis. The better efficacy of stimulation within the STA compared to thalamus proper favours the concept of a modulation of cerebello-thalamic projections underlying the improvement of these symptoms.

Diffusion-weighted imaging predicts cognitive impairment in multiple sclerosis

Following a previous study with diffusion tensor imaging, we investigated the correlation between diffusion-weighted imaging (DWI) and cognitive dysfunction in multiple sclerosis (MS). We studied 60 MS patients (mean age 45.8+/-9.0 years) using 1.5-T MRI. Disease course was RR=40 and SP = 20. Mean disease duration was 12.8+/-8.7 years. Mean EDSS was 3.4+/-1.7. Whole brain, gray and white matter normalized volumes were calculated on 3D SPGR T1-WI using a fully automated Hybrid SIENAX method. Parenchymal mean diffusivity (PMD) maps were created after automated segmentation of the brain parenchyma and cerebrospinal fluid using T2-WI and DW images. Histogram analysis was performed and DWI indices of peak position (PP), peak height (PH), mean parenchymal diffusivity (MPD) and entropy were obtained. Neuropsychological (NP) evaluation emphasized auditory/verbal and visual/spatial memory, as well as processing speed and executive function. We found significant correlations between DWI and performance in all cognitive domains. Overall, stronger correlations emerged for MPD and entropy than other DWI measures, although all correlations were in the expected direction. The strongest association was between DWI entropy and performance on the Symbol Digit Modalities Test, which assesses processing speed and working memory (r = -0.54). Fisher r to z transformations revealed that DWI, gray matter (GMF) and whole brain (BPF) atrophy, T1-lesion volume (LV) and T2-LV all accounted for similar amounts of variance in NP testing. Stepwise regression models determined whether multiple MRI measures predicted unique additive variance in test performance. GMF (R2 = 0.35, F =30.82, P <0.01) and entropy (DeltaR2 =0.06, DeltaF=5.47, P <0.05) both accounted for unique variance in processing speed. Our data make a stronger case for the clinical validity of DWI in MS than heretofore reported. DWI has very short acquisition times, and the segmentation method applied in the present study is reliable and fully automated. Given its overall simplicity and moderate correlation with cognition, DWI may offer several logistic advantages over more traditional MRI measures when predicting the presence of NP impairment.

Magnetization transfer ratio measurement in multiple sclerosis normal-appearing brain tissue: limited differences with controls but relationships with clinical and MR measures of disease

We investigated the magnetization transfer ratio (MTR) of normal-appearing white (NAWM) and grey matter (NAGM) in a relatively large group of multiple sclerosis (MS) patients, and the relations of MTR changes with clinical disability. MTR was measured in 66 MS patients (12 PP, 35 RR, 19 SP) and 23 healthy controls, using a whole-brain 3D-FLASH technique corrected post-hoc for B1-induced variation. Histogram parameters of conservatively selected NAWM and cortical NAGM were analysed using Bonferroni-corrected ANOVA with age as covariate. Additionally, manually outlined regions of interest were analysed using a multilevel method. Lesions had low MTR (mean 22.7±6.9%), but NAWM exhibited limited changes: MTR histogram peak position was 32.8±1.0% in controls and 32.4±0.9% in MS patients, with a significant decrease compared to controls only in SPMS patients (31.9±1.1%, p=0.045). Cortical NAGM histograms did not differ significantly between patients and controls. In SPMS, regional mean MTR was significantly decreased in corpus callosum and hippocampus. MTR histogram parameters of NAGM and NAWM were correlated with EDSS and MSFC scores, with lesion volume and with normalized brain volume. We conclude that disease-induced MTR changes were small in MS NAWM and NAGM, but did correlate with clinical decline, lesion volume and overall cerebral atrophy. Multiple Sclerosis 2007; 13: 708-716. http://msj.sagepub.com

I nterferon beta-1a slows progression of brain atrophy in relapsing-remitting multiple sclerosis predominantly by reducing gray matter atrophy

Background Brain atrophy, as assessed by magnetic resonance imaging (MRI), has been correlated with disability in patients with multiple sclerosis (MS). Recent evidence indicates that both white matter (WM) and gray matter (GM) are subject to atrophy in patients with MS. Although neurological deficiencies in MS are primarily due to loss of WM, the clinical significance of GM atrophy has not been fully explored in MS.

Methods We have undertaken a three-year, open-label study, comparing 26 patients who elected to receive intramuscular interferon beta-1a (IFN β-1a) therapy, with 28 patients who elected not to receive therapy. Both groups had quantitative cranial MRI scans at study entry and after three years, and standardized clinical assessments every six months. Brain parenchymal fraction (BPF), GM fraction (GMF), and WM fraction (WMF) percent changes were calculated, and T2- and T1-lesion volumes (LVs) assessed.

Results After three years, mean percent (%) change in BPF favored the IFN β-1a treatment group (IFN β-1a —1.3% versus the control group —2.5%, P=0.009), as did the mean percent change in GMF (+0.2 versus —1.4%, P=0.014), and the mean percent change in T1-LV (—9.3 versus +91.6%, P=0.011). At the end of the study, there was a significant within-patient decrease in BPF for both groups (P=0.02 for the IFN β-1a treatment group, and P<0.001 for the control group), a significant within-patient decrease in WMF for the IFN β-1a treatment group (P=0.01), and a significant decrease in GMF for the control group (P=0.013) when compared with baseline.

Conclusion Over a three-year period, treatment with IFN β-1a significantly slowed the progression of whole-brain and GM atrophy, and of T1-hypointense LV accumulation, when compared with the control group. Multiple Sclerosis 2007; 13: 490-501. http://msj.sagepub.com

Neuroimaging in multiple sclerosis

Conventional magnetic resonance imaging (MRI) has routinely been used to improve the accuracy of multiple sclerosis (MS) diagnosis and prognosis. Metrics derived from conventional MRI are now routinely used to detect therapeutic effects and extend clinical observations. However, conventional MRI measures, such as the use of lesion volume and count of gadolinium-enhancing and T2 lesions, have insufficient sensitivity and specificity to reveal the true degree of pathological changes occurring in MS. They cannot distinguish between inflammation, edema, demyelination, Wallerian degeneration, and axonal loss. In addition, they do not show a reliable correlation with clinical measures of disability and do not provide a complete assessment of therapeutic outcomes. Recent neuropathologic studies of typical chronic MS brains reveal macroscopic demyelination in cortical and deep gray matter (GM) that cannot be detected by currently available MRI techniques. Therefore, there is a pressing need for the development of newer MRI techniques to detect these lesions. Newer metrics of MRI analysis, including T1-weighted hypointense lesions, central nervous system atrophy measures, magnetization transfer imaging, magnetic resonance spectroscopy, and diffusion tensor imaging, are able to capture a more global picture of the range of tissue alterations caused by inflammation and neurodegeneration. At this time, they provide the only proof--albeit indirect--that important occult pathology is occurring in the GM. However, evidence is increasing that these nonconventional MRI measures correlate better with both existing and developing neurological impairment and disability when compared to conventional metrics.

HLA‐DRB1*1501, ‐DQB1*0301, ‐DQB1*0302, ‐DQB1*0602, and ‐DQB1*0603 Alleles are Associated With More Severe Disease Outcome on Mri in Patients With Multiple Sclerosis

The most important confirmed genetic factor of susceptibility to multiple sclerosis (MS) has been identified in the HLA class II region. The hypothesis that several genes, including HLA class II, may influence the prognosis of patients with MS has been proposed. In a recent study, using low intermediate resolution typing, we found that some HLA alleles may predict disease severity as assessed by magnetic resonance imaging (MRI) measures. The aim of this study was to examine the relationship between high-resolution typing of HLA alleles and disease severity as measured by brain MRI quantitative markers of demyelinating and destructive pathology in patients with MS. In 41 MS patients (27 relapsing-remitting, 7 secondary progressive, and 7 primary progressive), we performed high-resolution typing of alleles HLA-DRB1*04, -DQB1*03, -DRB1*15, -DQB1*06, and of haplotypes -DRB1*04-DQB1*03 and -DRB1*15-DQB1*06. These alleles and haplotypes were associated with higher susceptibility to MS in a recently published case-control study conducted in the Friuli-Venezia-Giulia region, Italy. Of 41 included patients, 13 were men and 28 were women. Mean age was 43.3 (SD 11.4) years, mean disease duration 10.3 (SD 7.8) years, and mean EDSS 2.3. DNA extraction and genomic typing were obtained with the sequence-specific primers method using primer pairs that amplified the HLA alleles. All patients underwent a 1.5-T MRI examination of the brain. Disease severity was assessed by clinical measures [Expanded Disability Status Scale (EDSS)] and MRI measures. T2- and T1-lesion volumes (LVs) and brain atrophy measures [fractions of brain parenchyma (BPF), gray matter (GMF), and white matter (WMF)] were calculated. We used general linear model analysis (GML), controlled for age, disease duration, and treatment status, to compare the MRI measures according to allele and haplotype status. The following significant results were found: HLA-DRB1*1501 positive patients had significantly lower GMF (0.493 vs 0.526, p < 0.001), lower BPF (0.784 vs 0.815, p = 0.018), and higher T1-LV (2.8 vs 0.7ml, p = 0.036); -DQB1*0301 positive patients had significantly higher T2-LV (34.1 vs 0.7 ml, p = 0.041), and showed a trend for lower BPF (0.790 vs 0.846, p = 0.064); -DQB1*0302 positive patients had significantly lower T1-LV (2.4 vs 0.9 ml, p = 0.016); and -DQB1*0602 positive patients had significantly lower GMF (0.492 vs 0.521, p = 0.007) and lower BPF (0.781 vs 0.811, p = 0.023). No differences were found in the indices of MRI disease severity according to HLA haplotype associations. Both in correlation and in regression analyses, we observed significant associations between HLA-DRB1*1501 and lower GMF and BPF and higher T1-LV, between -DQB1*0301 and higher T2-LV and disease duration, between -DQB1*0302 and lower GMF and higher T1- and T2-LV, between -DQB1*0602 and lower GMF and BPF, and between -DQB1*0603 and higher T1-LV and EDSS. High-resolution HLA genotyping analysis revealed a robust relationship between alleles HLA-DRB1*1501, -DQB1*0301, -DQB1*0302, -DQB1*0602, and -DQB1*0603, and more severe damage on inflammatory and neurodegenerative MRI measures.

Deep gray matter and fatigue in MS: a T1 relaxation time study

Fatigue in multiple sclerosis (MS) occurs commonly, sometimes as the earliest symptom. Some MS patients consider fatigue to be their most troublesome complaint, and it has been shown to be an independent predictor of impaired quality of life. Several reports have demonstrated that subcortical gray matter pathology is related to fatigue. We hypothesized that MRI detectable changes in the deep gray matter of MS patients may correlate with fatigue severity. Our objective was: to assess the relationship between fatigue severity and detectable changes on magnetic resonance imaging (MRI), quantified using the mean T1 relaxation time (T1), in deep gray matter structures in relapsing remitting multiple sclerosis (RRMS). Using region of interest analysis, T1 values were measured for the thalamus, putamen and caudate nucleus in 52 RRMS patients and 19 healthy volunteers. Fatigue was assessed using the Fatigue Severity Scale.

RESULTS

The median T1 in the thalamus and the putamen were significantly higher in the patient cohort than in the healthy controls; the median T1 in the caudate was also higher in the MS patients but did not reach statistical significance. There was a significant correlation between fatigue severity and the T1 of the thalamus (rho = 0.418; p = 0.014). Furthermore, the median T1 in the thalamus was significantly higher in patients with fatigue compared with those without (p = 0.018). Our results provide further evidence for the role of subcortical gray matter structures in the pathogenesis of multiple sclerosis (MS)-related fatigue. This study also demonstrates that T1 relaxation time measurement is a suitable technique for detecting abnormalities of the deep gray matter in RRMS and presents further support of gray matter involvement in MS.