High field MR imaging and 1H-MR spectroscopy in clinically isolated syndromes suggestive of multiple sclerosis: correlation between metabolic alterations and diagnostic MR imaging criteria

Early metabolic alterations in the normal‑appearing grey and white matter of patients with clinically isolated syndrome suggestive of multiple sclerosis: A proton MR spectroscopic study

Proton magnetic resonance spectroscopy (¹H-MRS) is an advanced method of examining metabolic profiles. The present study aimed to assess in vivo metabolite levels in areas of normal-appearing grey (thalamus) and white matter (centrum semiovale) using ¹H-MRS in patients with clinically isolated syndrome (CIS) suggestive of multiple sclerosis and compare them to healthy controls (HCs). Data from 35 patients with CIS (CIS group), of which 23 were untreated (CIS-untreated group) and 12 were treated (CIS-treated group) with disease-modifying-therapies (DMTs) at the time of ¹H-MRS, and from 28 age- and sex-matched HCs were collected using a 3.0 T MRI and single-voxel ¹H-MRS (point resolved spectroscopy sequence; repetition time, 2,000 msec; time to echo, 35 msec). Concentrations and ratios of total N-acetyl aspartate (tNAA), total creatine (tCr), total choline (tCho), myoinositol, glutamate (Glu), glutamine (Gln), Glu + Gln (Glx) and glutathione (Glth) were estimated in the thalamic-voxel (th) and centrum semiovale-voxel (cs). For the CIS group, the median duration from the first clinical attack to ¹H-MRS was 102 days (interquartile range, 89.5.-131.5). Compared with HCs, significantly lower Glx(cs) (P=0.014) and ratios of tCho/tCr(th) (P=0.026), Glu/tCr(cs) (P=0.040), Glx/tCr(cs) (P=0.004), Glx/tNAA(th) (P=0.043) and Glx/tNAA(cs) (P=0.015) were observed in the CIS group. No differences in tNAA levels were observed between the CIS and the HC groups; however, tNAA(cs) was higher in the CIS-treated than in the CIS-untreated group (P=0.028). Compared with those in HC group, decreased Glu(cs) (P=0.019) and Glx(cs) levels (P=0.014) and lower ratios for tCho/tCr(th) (P=0.015), Gln/tCr(th) (P=0.004), Glu/tCr(cs) (P=0.021), Glx/tCr(th) (P=0.041), Glx/tCr(cs) (P=0.003), Glx/tNAA(th) (P=0.030) and Glx/tNAA(cs) (P=0.015) were found in the CIS-untreated group. The present findings showed alterations in the normal-appearing grey and white matter of patients with CIS; moreover, the present results suggested an early indirect treatment effect of DMTs on the brain metabolic profile of these patients.

Longitudinal Assessment of Multiple Sclerosis Lesion Load With Synthetic Magnetic Resonance Imaging-A Multicenter Validation Study

INTRODUCTION

Double inversion recovery (DIR) has been validated as a sensitive magnetic resonance imaging (MRI) contrast in multiple sclerosis (MS). Deep learning techniques can use basic input data to generate synthetic DIR (synthDIR) images that are on par with their acquired counterparts. As assessment of longitudinal MRI data is paramount in MS diagnostics, our study's purpose is to evaluate the utility of synthDIR longitudinal subtraction imaging for detection of disease progression in a multicenter data set of MS patients.

METHODS

We implemented a previously established generative adversarial network to synthesize DIR from input T1-weighted and fluid-attenuated inversion recovery (FLAIR) sequences for 214 MRI data sets from 74 patients and 5 different centers. One hundred and forty longitudinal subtraction maps of consecutive scans (follow-up scan-preceding scan) were generated for both acquired FLAIR and synthDIR. Two readers, blinded to the image origin, independently quantified newly formed lesions on the FLAIR and synthDIR subtraction maps, grouped into specific locations as outlined in the McDonald criteria.

RESULTS

Both readers detected significantly more newly formed MS-specific lesions in the longitudinal subtractions of synthDIR compared with acquired FLAIR (R1: 3.27 ± 0.60 vs 2.50 ± 0.69 [ P = 0.0016]; R2: 3.31 ± 0.81 vs 2.53 ± 0.72 [ P < 0.0001]). Relative gains in detectability were most pronounced in juxtacortical lesions (36% relative gain in lesion counts-pooled for both readers). In 5% of the scans, synthDIR subtraction maps helped to identify a disease progression missed on FLAIR subtraction maps.

CONCLUSIONS

Generative adversarial networks can generate high-contrast DIR images that may improve the longitudinal follow-up assessment in MS patients compared with standard sequences. By detecting more newly formed MS lesions and increasing the rates of detected disease activity, our methodology promises to improve clinical decision-making.

Brain microstructural and metabolic alterations detected in vivo at onset of the first demyelinating event

In early multiple sclerosis, a clearer understanding of normal-brain tissue microstructural and metabolic abnormalities will provide valuable insights into its pathophysiology. We used multi-parametric quantitative MRI to detect alterations in brain tissues of patients with their first demyelinating episode. We acquired neurite orientation dispersion and density imaging [to investigate morphology of neurites (dendrites and axons)] and ²³Na MRI (to estimate total sodium concentration, a reflection of underlying changes in metabolic function). In this cross-sectional study, we enrolled 42 patients diagnosed with clinically isolated syndrome or multiple sclerosis within 3 months of their first demyelinating event and 16 healthy controls. Physical and cognitive scales were assessed. At 3 T, we acquired brain and spinal cord structural scans, and neurite orientation dispersion and density imaging. Thirty-two patients and 13 healthy controls also underwent brain ²³Na MRI. We measured neurite density and orientation dispersion indices and total sodium concentration in brain normal-appearing white matter, white matter lesions, and grey matter. We used linear regression models (adjusting for brain parenchymal fraction and lesion load) and Spearman correlation tests (significance level P ≤ 0.01). Patients showed higher orientation dispersion index in normal-appearing white matter, including the corpus callosum, where they also showed lower neurite density index and higher total sodium concentration, compared with healthy controls. In grey matter, compared with healthy controls, patients demonstrated: lower orientation dispersion index in frontal, parietal and temporal cortices; lower neurite density index in parietal, temporal and occipital cortices; and higher total sodium concentration in limbic and frontal cortices. Brain volumes did not differ between patients and controls. In patients, higher orientation dispersion index in corpus callosum was associated with worse performance on timed walk test (P = 0.009, B = 0.01, 99% confidence interval = 0.0001 to 0.02), independent of brain and lesion volumes. Higher total sodium concentration in left frontal middle gyrus was associated with higher disability on Expanded Disability Status Scale (r_s = 0.5, P = 0.005). Increased axonal dispersion was found in normal-appearing white matter, particularly corpus callosum, where there was also axonal degeneration and total sodium accumulation. The association between increased axonal dispersion in the corpus callosum and worse walking performance implies that morphological and metabolic alterations in this structure could mechanistically contribute to disability in multiple sclerosis. As brain volumes were neither altered nor related to disability in patients, our findings suggest that these two advanced MRI techniques are more sensitive at detecting clinically relevant pathology in early multiple sclerosis.

Neuroimaging Correlates of Cognitive Dysfunction in Adults with Multiple Sclerosis

Cognitive impairment is a frequent and meaningful symptom in multiple sclerosis (MS), caused by the accrual of brain structural damage only partially counteracted by effective functional reorganization. As both these aspects can be successfully investigated through the application of advanced neuroimaging, here, we offer an up-to-date overview of the latest findings on structural, functional and metabolic correlates of cognitive impairment in adults with MS, focusing on the mechanisms sustaining damage accrual and on the identification of useful imaging markers of cognitive decline.

Neurochemical Changes in the Brain and Neuropsychiatric Symptoms in Clinically Isolated Syndrome

To assess cognitive impairment and affective symptoms and their association with damage to normal-appearing white matter (NAWM) in patients with clinically isolated syndrome (CIS), we compared neuropsychological test scores between patients with CIS and healthy controls and examined correlations between these and proton magnetic resonance spectroscopy (¹H-MRS) outcomes in patients with CIS. Forty patients with CIS and 40 healthy participants were tested with a set of neuropsychological tests, which included the Beck Depression Inventory (BDI) and the Hospital Anxiety and Depression Scale (HADS). Single-voxel ¹H-MRS was performed on frontal and parietal NAWM of patients with CIS to assess ratios of N-acetyl-aspartate (NAA) to creatine (Cr), myo-inositol (mI), and choline (Cho), as well as mI/Cr and Cho/Cr ratios. Patients with CIS had lower cognitive performance and higher scores for the BDI and anxiety subscale of HADS than healthy controls. There were significant correlations between the following neuropsychological tests and metabolic ratios in the frontal NAWM: Stroop Color-Word Test and Cho/Cr, Symbol Digit Modalities Test and mI/Cr, as well as NAA/mI, Go/no-go reaction time, and NAA/Cho, as well as NAA/mI, Californian Verbal Learning Test, and NAA/Cr. BDI scores were related to frontal NAA/mI and parietal NAA/Cr and Cho/Cr ratios, whereas HADS-depression scores were associated with frontal NAA/Cr and NAA/mI and parietal NAA/Cr and Cho/Cr ratios. HADS-anxiety correlated with parietal NAA/Cr ratio. This study suggests that neurochemical changes in the NAWM assessed with single-voxel ¹H-MRS are associated with cognitive performance and affective symptoms in patients with CIS.

Detecting neurodegenerative pathology in multiple sclerosis before irreversible brain tissue loss sets in

Background

Multiple sclerosis (MS) is a complex chronic inflammatory and degenerative disorder of the central nervous system. Accelerated brain volume loss, or also termed atrophy, is currently emerging as a popular imaging marker of neurodegeneration in affected patients, but, unfortunately, can only be reliably interpreted at the time when irreversible tissue damage likely has already occurred. Timing of treatment decisions based on brain atrophy may therefore be viewed as suboptimal.

Main body

This Narrative Review focuses on alternative techniques with the potential of detecting neurodegenerative events in the brain of subjects with MS prior to the atrophic stage. First, metabolic and molecular imaging provide the opportunity to identify early subcellular changes associated with energy dysfunction, which is an assumed core mechanism of axonal degeneration in MS. Second, cerebral hypoperfusion has been observed throughout the entire clinical spectrum of the disorder but it remains an open question whether this serves as an alternative marker of reduced metabolic activity, or exists as an independent contributing process, mediated by endothelin-1 hyperexpression. Third, both metabolic and perfusion alterations may lead to repercussions at the level of network performance and structural connectivity, respectively assessable by functional and diffusion tensor imaging. Fourth and finally, elevated body fluid levels of neurofilaments are gaining interest as a biochemical mirror of axonal damage in a wide range of neurological conditions, with early rises in patients with MS appearing to be predictive of future brain atrophy.

Conclusions

Recent findings from the fields of advanced neuroradiology and neurochemistry provide the promising prospect of demonstrating degenerative brain pathology in patients with MS before atrophy has installed. Although the overall level of evidence on the presented topic is still preliminary, this Review may pave the way for further longitudinal and multimodal studies exploring the relationships between the abovementioned measures, possibly leading to novel insights in early disease mechanisms and therapeutic intervention strategies.

Quantifying the Metabolic Signature of Multiple Sclerosis by in vivo Proton Magnetic Resonance Spectroscopy: Current Challenges and Future Outlook in the Translation From Proton Signal to Diagnostic Biomarker

Proton magnetic resonance spectroscopy (¹H-MRS) offers a growing variety of methods for querying potential diagnostic biomarkers of multiple sclerosis in living central nervous system tissue. For the past three decades, ¹H-MRS has enabled the acquisition of a rich dataset suggestive of numerous metabolic alterations in lesions, normal-appearing white matter, gray matter, and spinal cord of individuals with multiple sclerosis, but this body of information is not free of seeming internal contradiction. The use of ¹H-MRS signals as diagnostic biomarkers depends on reproducible and generalizable sensitivity and specificity to disease state that can be confounded by a multitude of influences, including experiment group classification and demographics; acquisition sequence; spectral quality and quantifiability; the contribution of macromolecules and lipids to the spectroscopic baseline; spectral quantification pipeline; voxel tissue and lesion composition; T₁ and T₂ relaxation; B₁ field characteristics; and other features of study design, spectral acquisition and processing, and metabolite quantification about which the experimenter may possess imperfect or incomplete information. The direct comparison of ¹H-MRS data from individuals with and without multiple sclerosis poses a special challenge in this regard, as several lines of evidence suggest that experimental cohorts may differ significantly in some of these parameters. We review the existing findings of in vivo¹H-MRS on central nervous system metabolic abnormalities in multiple sclerosis and its subtypes within the context of study design, spectral acquisition and processing, and metabolite quantification and offer an outlook on technical considerations, including the growing use of machine learning, by future investigations into diagnostic biomarkers of multiple sclerosis measurable by ¹H-MRS.

Magnetic Resonance Imaging in Multiple Sclerosis

Since its technical development in the early 1980s, magnetic resonance imaging (MRI) has quickly been adopted as an essential tool in supporting the diagnosis, longitudinal monitoring, evaluation of therapeutic response, and scientific investigations in multiple sclerosis (MS). The clinical usage of MRI has increased in parallel with technical innovations in the technique itself; the widespread adoption of clinically routine MRI at 1.5T has allowed sensitive qualitative and quantitative assessments of macroscopic central nervous system (CNS) inflammatory demyelinating lesions and tissue atrophy. However, conventional MRI lesion measures lack specificity for the underlying MS pathology and only weakly correlate with clinical status. Higher field strength units and newer, advanced MRI techniques offer increased sensitivity and specificity in the detection of disease activity and disease severity. This review summarizes the current status and future prospects regarding the role of MRI in the characterization of MS-related brain and spinal cord involvement.

Machine Learning Approach for Classifying Multiple Sclerosis Courses by Combining Clinical Data with Lesion Loads and Magnetic Resonance Metabolic Features

Purpose: The purpose of this study is classifying multiple sclerosis (MS) patients in the four clinical forms as defined by the McDonald criteria using machine learning algorithms trained on clinical data combined with lesion loads and magnetic resonance metabolic features.

Materials and Methods: Eighty-seven MS patients [12 Clinically Isolated Syndrome (CIS), 30 Relapse Remitting (RR), 17 Primary Progressive (PP), and 28 Secondary Progressive (SP)] and 18 healthy controls were included in this study. Longitudinal data available for each MS patient included clinical (e.g., age, disease duration, Expanded Disability Status Scale), conventional magnetic resonance imaging and spectroscopic imaging. We extract N-acetyl-aspartate (NAA), Choline (Cho), and Creatine (Cre) concentrations, and we compute three features for each spectroscopic grid by averaging metabolite ratios (NAA/Cho, NAA/Cre, Cho/Cre) over good quality voxels. We built linear mixed-effects models to test for statistically significant differences between MS forms. We test nine binary classification tasks on clinical data, lesion loads, and metabolic features, using a leave-one-patient-out cross-validation method based on 100 random patient-based bootstrap selections. We compute F1-scores and BAR values after tuning Linear Discriminant Analysis (LDA), Support Vector Machines with gaussian kernel (SVM-rbf), and Random Forests.

Results: Statistically significant differences were found between the disease starting points of each MS form using four different response variables: Lesion Load, NAA/Cre, NAA/Cho, and Cho/Cre ratios. Training SVM-rbf on clinical and lesion loads yields F1-scores of 71–72% for CIS vs. RR and CIS vs. RR+SP, respectively. For RR vs. PP we obtained good classification results (maximum F1-score of 85%) after training LDA on clinical and metabolic features, while for RR vs. SP we obtained slightly higher classification results (maximum F1-score of 87%) after training LDA and SVM-rbf on clinical, lesion loads and metabolic features.

Conclusions: Our results suggest that metabolic features are better at differentiating between relapsing-remitting and primary progressive forms, while lesion loads are better at differentiating between relapsing-remitting and secondary progressive forms. Therefore, combining clinical data with magnetic resonance lesion loads and metabolic features can improve the discrimination between relapsing-remitting and progressive forms.

Amiloride Clinical Trial In Optic Neuritis (ACTION) protocol: a randomised, double blind, placebo controlled trial

INTRODUCTION

Neurodegeneration is a widely accepted contributor to the development of long-term disability in multiple sclerosis (MS). While current therapies in MS predominantly target inflammation and reduce relapse rate they have been less effective at preventing long-term disability. The identification and evaluation of effective neuroprotective therapies within a trial paradigm are key unmet needs. Emerging evidence supports amiloride, a licenced diuretic, as a neuroprotective agent in MS through acid sensing ion channel blockade. Optic neuritis (ON) is a common manifestation of MS with correlates of inflammation and neurodegeneration measurable within the visual pathways. Amiloride Clinical Trial In Optic Neuritis (ACTION) will utilise a multimodal approach to assess the neuroprotective efficacy of amiloride in acute ON.

METHODS AND ANALYSIS

46 patients will be recruited within 28 days from onset of ON visual symptoms and randomised on a 1:1 basis to placebo or amiloride 10 mg daily. Double-blinded treatment groups will be balanced for age, sex and visual loss severity by a random-deterministic minimisation algorithm. The primary objective is to demonstrate that amiloride is neuroprotective in ON as assessed by scanning laser polarimetry of the peripapillary retinal nerve fibre layer (RNFL) thickness at 6 months in the affected eye compared to the unaffected eye at baseline. RNFL in combination with further retinal measures will also be assessed by optical coherence tomography. Secondary outcome measures on brain MRI will include cortical volume, diffusion-weighted imaging, resting state functional MRI, MR spectroscopy and magnetisation transfer ratio. In addition, high and low contrast visual acuity, visual fields, colour vision and electrophysiology will be assessed alongside quality of life measures.

ETHICS AND DISSEMINATION

Ethical approval was given by the south central Oxford B research ethics committee (REC reference: 13/SC/0022). The findings from ACTION will be disseminated through peer-reviewed publications and at scientific conferences.

TRIAL REGISTRATION NUMBER

EudraCT2012-004980-39, ClinicalTrials.gov Identifier: NCT01802489.

Histogram analysis of quantitative T1 and MT maps from ultrahigh field MRI in clinically isolated syndrome and relapsing-remitting multiple sclerosis

This study used quantitative MRI to study normal appearing white matter (NAWM) in patients with clinically isolated syndromes suggestive of multiple sclerosis and relapsing-remitting multiple sclerosis (RRMS). This was done at ultrahigh field (7 T) for greater spatial resolution and sensitivity. 17 CIS patients, 11 RRMS patients, and 20 age-matched healthy controls were recruited. They were scanned using a 3D inversion recovery turbo field echo sequence to measure the longitudinal relaxation time (T1). A 3D magnetization transfer prepared turbo field echo (MT-TFE) sequence was also acquired, first without a presaturation pulse and then with the MT presaturation pulse applied at -1.05 kHz and +1.05 kHz off resonance from water to produce two magnetization transfer ratio maps (MTR(-) and MTR(+)). Histogram analysis was performed on the signal from the voxels in the NAWM mask. The upper quartile cut-off of the T1 histogram was significantly higher in RRMS patients than in controls (p < 0.05), but there was no difference in CIS. In contrast, MTR was significantly different between CIS or RRMS patients and controls (p < 0.05) for most histogram measures considered. The difference between MTR(+) and MTR(-) signals showed that NOE contributions dominated the changes found. There was a weak negative correlation (r = -0.46, p < 0.05) between the mode of T1 distributions and healthy controls' age; this was not significant for MTR(+) (r = -0.34, p > 0.05) or MTR(-) (r = 0.13, p > 0.05). There was no significant correlation between the median of T1, MTR(-), or MTR(+) and the age of healthy controls. Furthermore, no significant correlation was observed between EDSS or disease duration and T1, MTR(-), or MTR(+) for either CIS or RRMS patients. In conclusion, MTR was found to be more sensitive to early changes in MS disease than T1.

Brain MRI lesions and atrophy are associated with employment status in patients with multiple sclerosis

Multiple sclerosis (MS) commonly affects occupational function. We investigated the link between brain MRI and employment status. Patients with MS (n = 100) completed a Work Productivity and Activity Impairment (WPAI) (general health version) survey measuring employment status, absenteeism, presenteeism, and overall work and daily activity impairment. Patients “working for pay” were considered employed; “temporarily not working but looking for work,” “not working or looking for work due to age,” and “not working or looking for work due to disability” were considered not employed. Brain MRI T1 hypointense (T1LV) and T2 hyperintense (T2LV) lesion volumes were quantified. To assess lesional destructive capability, we calculated each subject’s ratio of T1LV to T2LV (T1/T2). Normalized brain parenchymal volume (BPV) assessed brain atrophy. The mean (SD) age was 45.5 (9.7) years; disease duration was 12.1 (8.1) years; 75 % were women, 76 % were relapsing-remitting, and 76 % were employed. T1LV, T1/T2, Expanded Disability Status Scale (EDSS) scores, and activity impairment were lower and BPV was higher in the employed vs. not employed group (Wilcoxon tests, p < 0.05). Age, disease duration, MS clinical subtype, and T2LV did not differ between groups (p > 0.05). In multivariable logistic regression modeling, adjusting for age, sex, and disease duration, higher T1LV predicted a lower chance of employment (p < 0.05). Pearson correlations showed that EDSS was associated with activity impairment (p < 0.05). Disease duration, age, and MRI measures were not correlated with activity impairment or other WPAI outcomes (p > 0.05). We report a link between brain atrophy and lesions, particularly lesions with destructive potential, to MS employment status.

Evidence-based guidelines: MAGNIMS consensus guidelines on the use of MRI in multiple sclerosis-clinical implementation in the diagnostic process

The clinical use of MRI in patients with multiple sclerosis (MS) has advanced markedly over the past few years. Technical improvements and continuously emerging data from clinical trials and observational studies have contributed to the enhanced performance of this tool for achieving a prompt diagnosis in patients with MS. The aim of this article is to provide guidelines for the implementation of MRI of the brain and spinal cord in the diagnosis of patients who are suspected of having MS. These guidelines are based on an extensive review of the recent literature, as well as on the personal experience of the members of the MAGNIMS (Magnetic Resonance Imaging in MS) network. We address the indications, timing, coverage, reporting and interpretation of MRI studies in patients with suspected MS. Our recommendations are intended to help radiologists and neurologists standardize and optimize the use of MRI in clinical practice for the diagnosis of MS.

Visual pathway neurodegeneration winged by mitochondrial dysfunction

Objectives

To test for structural and functional contribution of mitochondrial dysfunction to neurodegeneration in multiple sclerosis (MS). A visual pathway model void of MS lesions was chosen in order to exclude neurodegeneration secondary to lesion related axonotmesis.

Methods

A single-centre cohort study (230 MS patients, 63 controls). Spectral domain optical coherence tomography of the retina, 3T magnetic resonance imaging of the brain, spectrophotometric assessment of serum lactate levels. Postmortem immunohistochemistry.

Results

The visual pathway was void of MS lesions in 31 patients and 31 age-matched controls. Serum lactate was higher in MS compared to controls (P = 0.029). High serum lactate was structurally related to atrophy of the retinal nerve fiber layer at the optic disc (P = 0.041), macula (P = 0.025), and the macular ganglion cell complex (P = 0.041). High serum lactate was functionally related to poor color vision (P < 0.01), Expanded Disability Status Scale score (R = 0.37, P = 0.041), Guy's Neurological disability score (R = 0.38, P = 0.037), MS walking scale (R = 0.50, P = 0.009), upper limb motor function (R = 0.53, P = 0.002). Immunohistochemistry demonstrated increased astrocytic expression of a key lactate generating enzyme in MS lesions as well as profound vascular expression of monocarboxylate transporter-1, which is involved in lactate transport.

Interpretation

This study provides structural, functional, and translational evidence for visual pathway neurodegeneration in MS related to mitochondrial dysfunction.

Increased PK11195-PET binding in normal-appearing white matter in clinically isolated syndrome

The most accurate predictor of the subsequent development of multiple sclerosis in clinically isolated syndrome is the presence of lesions at magnetic resonance imaging. We used in vivo positron emission tomography with (11)C-(R)-PK11195, a biomarker of activated microglia, to investigate the normal-appearing white matter and grey matter of subjects with clinically isolated syndrome to explore its role in the development of multiple sclerosis. Eighteen clinically isolated syndrome and eight healthy control subjects were recruited. Baseline assessment included: history, neurological examination, expanded disability status scale, magnetic resonance imaging and PK11195-positron emission tomography scans. All assessments except the PK11195-positron emission tomography scan were repeated over 2 years. SUPERPK methodology was used to measure the binding potential relative to the non-specific volume, BPND. We show a global increase of normal-appearing white matter PK11195 BPND in clinically isolated syndrome subjects compared with healthy controls (P = 0.014). Clinically isolated syndrome subjects with T2 magnetic resonance imaging lesions had higher PK11195 BPND in normal-appearing white matter (P = 0.009) and their normal-appearing white matter PK11195 BPND correlated with the Expanded Disability Status Scale (P = 0.007; r = 0.672). At 2 years those who developed dissemination in space or multiple sclerosis, had higher PK11195 BPND in normal-appearing white matter at baseline (P = 0.007 and P = 0.048, respectively). Central grey matter PK11195 BPND was increased in subjects with clinically isolated syndrome compared to healthy controls but no difference was found in cortical grey matter PK11195 BPND. Microglial activation in clinically isolated syndrome normal-appearing white matter is diffusely increased compared with healthy control subjects and is further increased in those who have magnetic resonance imaging lesions. Furthermore microglial activation in clinically isolated syndrome normal-appearing white matter is also higher in those subjects who developed multiple sclerosis at 2 years. Our finding, if replicated in a larger study, could be of prognostic value and aid early treatment decisions in clinically isolated syndrome.

Short-term cuprizone feeding verifies N-acetylaspartate quantification as a marker of neurodegeneration

Proton magnetic resonance spectroscopy (1H-MRS) is a quantitative MR imaging technique often used to complement conventional MR imaging with specific metabolic information. A key metabolite is the amino acid derivative N-Acetylaspartate (NAA) which is an accepted marker to measure the extent of neurodegeneration in multiple sclerosis (MS) patients. NAA is catabolized by the enzyme aspartoacylase (ASPA) which is predominantly expressed in oligodendrocytes. Since the formation of MS lesions is paralleled by oligodendrocyte loss, NAA might accumulate in the brain, and therefore, the extent of neurodegeneration might be underestimated. In the present study, we used the well-characterized cuprizone model. There, the loss of oligodendrocytes is paralleled by a reduction in ASPA expression and activity as demonstrated by genome-wide gene expression analysis and enzymatic activity assays. Notably, brain levels of NAA were not increased as determined by gas chromatography-mass spectrometry and 1H-MRS. These important findings underpin the reliability of NAA quantification as a valid marker for the paraclinical determination of the extent of neurodegeneration, even under conditions of oligodendrocyte loss in which impaired metabolization of NAA is expected. Future studies have to reveal whether other enzymes are able to metabolize NAA or whether an excess of NAA is cleared by other mechanisms rather than enzymatic metabolism.

Risk of multiple sclerosis after optic neuritis in patients with normal baseline brain MRI

When assessing and managing a patient with optic neuritis (ON), the risk of future development of multiple sclerosis (MS) is an important issue, as this can be the first presentation of the disease. Although the presence of lesions on baseline brain MRI is the strongest predictor of MS conversion, some patients with normal imaging also develop MS. We aimed to estimate MS risk in patients with ON and a normal baseline MRI and identify individuals with higher risk of conversion. We performed a retrospective study including patients with idiopathic ON and normal baseline brain MRI who presented to our hospital over an 8 year period. Of a total of 42 patients, 10 converted to MS: five during the first follow-up year, seven during the first 2 years and all of the patients within the first 5 years, with a 5 year MS conversion rate of 23.8%. MS conversion rates were significantly higher in patients with history of previous symptoms suggestive of demyelination (p=0.002), cerebrospinal fluid oligoclonal bands unmatched in serum (p=0.004) and incomplete visual acuity recovery (≤6/12) after 1 year (p=0.002). Lower conversion rates were found in patients with optic disc edema (p=0.022). According to these results, a significant proportion of patients with idiopathic ON and a normal baseline brain MRI will develop MS, with a higher risk during the first 5 years. Therefore, in the presence of factors in favor of MS conversion, close follow-up, including semestral medical consultations and yearly brain MRI, can be recommended. Early immunomodulatory treatment may be individually considered as it can delay conversion and reduce new lesion development rate.

Metabolic profile of PML lesions in patients with and without IRIS: an observational study

OBJECTIVE

To characterize progressive multifocal leukoencephalopathy (PML) lesions by contrast-enhanced MRI and evaluate their metabolism using proton magnetic resonance spectroscopy ((1)H- MRS) in the setting of immune reconstitution inflammatory syndrome (IRIS).

METHODS

A total of 42 patients with PML underwent a clinical evaluation as well as brain MRI and (1)H-MRS at baseline and 3, 6, and 12 months later. The presence of IRIS was determined based on clinical and laboratory criteria. Ratios of N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), and lipid/lactate (Lip1 and Lip2) to creatine (Cr) were measured and correlated with the presence of contrast enhancement (CE) in PML lesions.

RESULTS

IRIS occurred in 16 of 28 (57.1%) PML survivors (PML-S) and 1 of 14 (7.1%) PML progressors (PML-P). Lesions of patients with PML-IRIS showed significantly higher Cho/Cr (p = 0.0001), mI/Cr (p = 0.02), Lip1/Cr (p < 0.0001), and Lip2/Cr (p = 0.002) ratios and lower NAA/Cr (p = 0.02) ratios than patients with PML who did not have IRIS. An elevated Cho/Cr ratio was associated with CE within the (1)H-MRS voxel, whereas lipid/Cr ratios were elevated in PML-IRIS lesions independently of CE. Follow-up until 33 months from PML onset showed persistent elevation of the mI/Cr ratio in lesions of patients with PML-IRIS. A Lip1/Cr ratio greater than 1.5 combined with the presence of CE yielded a 79% probability of IRIS compared with 13% in the absence of these criteria.

CONCLUSION

(1)H-MRS is a valuable tool to recognize and track IRIS in PML and may prove useful in the clinical management of these patients.

Clinically isolated syndromes suggestive of multiple sclerosis: an optical coherence tomography study

BACKGROUND

Optical coherence tomography (OCT) is a simple, high-resolution technique to quantify the thickness of retinal nerve fiber layer (RNFL), which provides an indirect measurement of axonal damage in multiple sclerosis (MS). This study aimed to evaluate RNFL thickness in patients at presentation with clinically isolated syndromes (CIS) suggestive of MS.

METHODOLOGY

This was a cross-sectional study. Twenty-four patients with CIS suggestive of MS (8 optic neuritis [ON], 6 spinal cord syndromes, 5 brainstem symptoms and 5 with sensory and other syndromes) were prospectively studied. The main outcome evaluated was RNFL thickness at CIS onset. Secondary objectives were to study the relationship between RNFL thickness and MRI criteria for disease dissemination in space (DIS) as well as the presence of oligoclonal bands in the cerebrospinal fluid.

PRINCIPAL FINDINGS

Thirteen patients had decreased RNFL thickness in at least one quadrant. Mean RNFL thickness was 101.67±10.72 µm in retrobulbar ON eyes and 96.93±10.54 in unaffected eyes. Three of the 6 patients with myelitis had at least one abnormal quadrant in one of the two eyes. Eight CIS patients fulfilled DIS MRI criteria. The presence of at least one quadrant of an optic nerve with a RNFL thickness at a P<5% cut-off value had a sensitivity of 75% and a specificity of 56% for predicting DIS MRI.

CONCLUSIONS

The findings from this study show that axonal damage measured by OCT is present in any type of CIS; even in myelitis forms, not only in ON as seen up to now. OCT can detect axonal damage in very early stages of disease and seems to have high sensitivity and moderate specificity for predicting DIS MRI. Studies with prospective long-term follow-up would be needed to establish the prognostic value of baseline OCT findings.

Brain metabolite proton T2 mapping at 3.0 T in relapsing-remitting multiple sclerosis

PURPOSE

To test the hypothesis that T2 signals in lesions and normal-appearing tissue are sufficiently similar that signal variations represent true variations in metabolite concentration.

MATERIALS AND METHODS

The T2 distributions of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) at 3.0 T were mapped in the brain of 10 relapsing-remitting (RR) MS patients of 0.3-12 years disease duration with multivoxel (four sections of 80 1-cm(3) voxels) point-resolved proton spectroscopy imaging in a two-point protocol. Institutional review board approval and written informed consent were obtained; the study was Health Insurance Portability and Accountability-compliant. Mixed-model analysis of variance was performed to compare brain regions and lesion types for each metabolite; a Wilcoxon test was performed to compare observed T2 values with age-based predictions.

RESULTS

The T2 histograms from 320 voxels in each patient were similar in peak position for mean values (+/- standard error) for NAA (250 msec +/- 9), Cr (166 msec +/- 3), and Cho (221 msec +/- 6); shape was characterized by full width at half maximum values of 174 msec +/- 11, 98 msec +/- 3, and 143 msec +/- 5, respectively. Regional T2 values in white matter (WM; 298 msec +/- 6, 162 msec +/- 1, and 222 msec +/- 4 for NAA, Cr, and Cho, respectively) were all significantly longer than in gray matter (GM; 221 msec +/- 7, 143 msec +/- 4, and 205 msec +/- 8, respectively) but not different from isointense (313 msec +/- 24, 188 msec +/- 12, and 238 msec +/- 17, respectively) or hypointense (296 msec +/- 27, 163 msec +/- 12, and 199 msec +/- 12, respectively) lesions, except for the Cho value for hypointense lesion, which was significantly lower. When compared with corresponding values in healthy contemporaries, these T2 values were shorter by 18%, 8%, and 14% in GM and by 21%, 12%, and 13% in WM for NAA, Cr, and Cho, respectively.

CONCLUSION

For the purpose of metabolic quantification at 3.0 T and echo times of less than 100 msec, an average T2 value per metabolite should suffice for any brain region and lesion regardless of disease duration, age, or disability in any RR MS patient and their controls. (c) RSNA, 2010.

Early MRI in optic neuritis: the risk for clinically definite multiple sclerosis

MRI brain lesions at presentation with optic neuritis (ON) increase the risk for developing clinically definite (CD) multiple sclerosis (MS). More detailed early MRI findings may improve prediction of conversion.

The objectives of this study were to investigate the influence of number, location and activity of lesions at presentation, new lesions at early follow-up and non-lesion MRI measures on conversion from optic neuritis (ON) to CDMS.

142/143 ON patients, prospectively recruited into a serial MRI and clinical follow-up study, were followed-up at least once. Cox regression analysis determined independent early MRI predictors of time to CDMS from: (i) baseline lesion number, location and activity measures, (ii) three-month lesion activity measures and (iii) brain atrophy, magnetization transfer ratio and spectroscopy measures.

114/142 (80%) had abnormal baseline brain or cord MRI. 57 (40%) developed CDMS (median of 16 months from clinically isolated syndrome onset). Median follow-up of the non-converters was 62 months. Multivariate analysis of baseline parameters revealed gender, periventricular and gadolinium-enhancing lesions as independent predictors of CDMS. Considering both scans together, gender, baseline periventricular and new T2 lesions at follow-up remained significant (hazard ratios 2.1, 2.4 and 4.9, respectively). No non-conventional measure predicted CDMS.

It was concluded that new T2 lesions on an early follow-up scan were the strongest independent predictor of CDMS.

1H-MRS for the diagnosis of acute disseminated encephalomyelitis: insight into the acute-disease stage

BACKGROUND

Acute disseminated encephalomyelitis (ADEM) is a demyelinating disorder of the central nervous system (CNS). Differentiating ADEM from other inflammatory disorders, such as multiple sclerosis, is not always conclusive using conventional MRI.

OBJECTIVE

To evaluate longitudinal magnetic resonance spectroscopy (MRS) changes that distinguish ADEM from other inflammatory disorders.

MATERIALS AND METHODS

MRI/MRS scans were performed in seven patients with ADEM during the acute and chronic phases of the disease.

RESULTS

Partial recovery was detected between the acute and chronic phases in choline/creatine ratio. Major elevation of lipids and reduction in myo-inositol/creatine ratio was detected in all patients during the acute phase, followed by a reduction in lipids peak and elevation above normal in myo-inositol/creatine ratio during the chronic phase.

CONCLUSION

Consistent and unique MRS changes in metabolite ratios between the acute and chronic presentations of the disease were found. To the best of our knowledge, these patterns have not been described in other inflammatory disorders and might assist in the early diagnosis of ADEM.

MR spectroscopy (MRS) and magnetisation transfer imaging (MTI), lesion load and clinical scores in early relapsing remitting multiple sclerosis: a combined cross-sectional and longitudinal study

The purpose of this study was to correlate magnetic resonance imaging (MRI)-based lesion load assessment with clinical disability in early relapsing remitting multiple sclerosis (RRMS). Seventeen untreated patients (ten women, seven men; mean age 33.0 +/- 7.9 years) with the initial diagnosis of RRMS were included for cross-sectional as well as longitudinal (24 months) clinical and MRI-based assessment in comparison with age-matched healthy controls. Conventional MR sequences, MR spectroscopy (MRS) and magnetisation transfer imaging (MTI) were performed at 1.5 T. Lesion number and volume, MRS and MTI measurements for lesions and normal appearing white matter (NAWM) were correlated to clinical scores [Expanded Disability Status Scale (EDSS), Multiple Sclerosis Functional Composite (MSFC)] for monitoring disease course after treatment initiation (interferon beta-1a). MTI and MRS detected changes [magnetisation transfer ratio (MTR), N-acetylaspartate (NAA)/creatine ratio] in NAWM over time. EDSS and lesional MTR increases correlated throughout the disease course. Average MTR of NAWM raised during the study (p < 0.05) and correlated to the MSFC score (r = 0.476, p < 0.001). At study termination, NAA/creatine ratio of NAWM correlated to the MSFC score (p < 0.05). MTI and MRS were useful for initial disease assessment in NAWM. MTI and MRS correlated with clinical scores, indicating potential for monitoring the disease course and gaining new insights into treatment-related effects.

High field MRI in the diagnosis of multiple sclerosis: high field-high yield?

Following the approval of the U.S. Food and Drug Administration (FDA), high field magnetic resonance imaging (MRI) has been increasingly incorporated into the clinical setting. Especially in the field of neuroimaging, the number of high field MRI applications has been increased dramatically. Taking advantage on increased signal-to-noise ratio (SNR) and chemical shift, higher magnetic field strengths offer new perspectives particularly in brain imaging and also challenges in terms of several technical and physical consequences. Over the past few years, many applications of high field MRI in patients with suspected and definite multiple sclerosis (MS) have been reported including conventional and quantitative MRI methods. Conventional pulse sequences at 3 T offers higher lesion detection rates when compared to 1.5 T, particularly in anatomic regions which are important for the diagnosis of patients with MS. MR spectroscopy at 3 T is characterized by an improved spectral resolution due to increased chemical shift allowing a better quantification of metabolites. It detects significant axonal damage already in patients presenting with clinically isolated syndromes and can quantify metabolites of special interest such as glutamate which is technically difficult to quantify at lower field strengths. Furthermore, the higher susceptibility and SNR offer advantages in the field of functional MRI and diffusion tensor imaging. The recently introduced new generation of ultra-high field systems beyond 3 T allows scanning in submillimeter resolution and gives new insights into in vivo MS pathology on MRI. The objectives of this article are to review the current knowledge and level of evidence concerning the application of high field MRI in MS and to give some ideas of research perspectives in the future.

24 month-treatment with miglustat of three patients with Niemann-Pick disease type C: follow up using brain spectroscopy

Niemann-Pick C (NPC) is a fatal progressive neurolipidosis. Miglustat, an inhibitor of glycosphingolipid synthesis, has been proposed to treat patients but questions remain regarding its efficacy. A major problem has been the lack of suitable objective efficacy endpoints. Three adults with NPC were treated with miglustat for 24 months. Efficacy of treatment was assessed clinically and using brain magnetic resonance spectroscopy. All patients reported mild clinical improvement or stabilization. Furthermore, a sustained decrease in the choline/creatine ratio was observed in all three patients over time. Although these preliminary results require confirmation on a larger cohort of patients, they suggest that miglustat has some beneficial effect on brain dysfunction in NPC and that MRS could be used routinely as a non invasive surrogate marker of treatment efficacy.

Proton magnetic resonance spectroscopy in multiple sclerosis

Proton magnetic resonance spectroscopy ((1)H-MRS) provides tissue metabolic information in vivo. This article reviews the role of MRS-determined metabolic alterations in lesions, normal-appearing white matter, gray matter, and spinal cord in advancing our knowledge of pathologic changes in multiple sclerosis (MS). In addition, the role of MRS in objectively evaluating therapeutic efficacy is reviewed. This potential metabolic information makes MRS a unique tool to follow MS disease evolution, understand its pathogenesis, evaluate the disease severity, establish a prognosis, and objectively evaluate the efficacy of therapeutic interventions.

A defect of sphingolipid metabolism modifies the properties of normal appearing white matter in multiple sclerosis

Maintaining the appropriate complement and content of lipids in cellular membranes is critical for normal neural function. Accumulating evidence suggests that even subtle perturbations in the lipid content of neurons and myelin can disrupt their function and may contribute to myelin and axonal degradation. In this study, we determined the composition and quantified the content of lipids and sterols in normal appearing white matter (NAWM) and normal appearing grey matter (NAGM) from control and multiple sclerosis brain tissues by electrospray ionization tandem mass spectrometry. Our results suggest that in active-multiple sclerosis, there is a shift in the lipid composition of NAWM and NAGM to a higher phospholipid and lower sphingolipid content. We found that this disturbance in lipid composition was reduced in NAGM but not in NAWM of inactive-multiple sclerosis. The pattern of disturbance in lipid composition suggests a metabolic defect that causes sphingolipids to be shuttled to phospholipid production. Modelling the biophysical consequence of this change in lipid composition of NAWM indicated an increase in the repulsive force between opposing bilayers that could explain decompaction and disruption of myelin structure.