The role of MRI as a surrogate outcome measure in multiple sclerosis

The need for more specific and more sensitive outcome measures for use in testing new therapies in multiple sclerosis (MS) is generally accepted. This need has been accentuated by the realization that the ability to conduct large placebo-controlled trials will be limited in the future. From the first use of magnetic resonance imaging (MRI) to study MS, the ability of this imaging technique to identify areas of the central nervous system damage by the disease process in MS has been impressive. Thus, the possibility that MRI could serve as a surrogate outcome measure in clinical trials in MS has been attractive. The use of MRI as a surrogate outcome measure has been examined by an international group of investigators with expertise in clinical aspects of MS, the use of MRI in MS, and in experimental therapeutics. The group agreed that MRI does not represent a validated surrogate in any clinical form of MS. It was also agreed, however, that MRI does provide a reflection of the underlying pathology in the disease, but no single MRI measurement in isolation was seen as sufficient to monitor disease. The use for multiple imaging techniques, especially new, emerging techniques that may better reflect the underlying pathology, was seen as particularly important in monitoring studies of patients with either secondary or primary progressive MS. The choice of MRI techniques used to monitor new therapies needs to be consistent with the proposed mechanisms of the new therapy and phase of the disease. It was also noted, however, that additional validation is required for nonconventional imaging techniques. Finally, the participants noted that clinical trials using MRI as a primary outcome measure may fail to fully identify the effects of the therapy on clinical measures and that the risk and cost-benefit ratio of the treatment might be unresolved. Thus, before MRI is used as a primary outcome measure, new approaches to trial design must be given careful consideration. Multiple Sclerosis (2002)8, 40-51

On the horizon: possible neuroprotective role for glatiramer acetate

Inflammation and neurodegeneration characterize the pathogenesis of multiple sclerosis (MS). Slow axonal degeneration, rather than acute inflammation, is considered the cause of chronic disability in MS. The signs of acute axonal damage and loss have been shown to occur early in the lesion development of patients with chronic MS and often correlate with demyelination and inflammation. While immune activity in the central nervous system has traditionally been considered to be a detrimental event in MS, recent studies have found that autoimmune T cells may play an important role in protecting neurons from the ongoing spreading damage. Neuroprotectio n in MS is a new and evolving concept, and many questions remain with regard to potential targets for therapeutic intervention. Preliminary studies, both in animals and in humans, have suggested that glatiramer acetate (GA) may confer neuroprotective activity in addition to bystander suppression. Additional research is needed to determine if these promising neuroprotective effects correlate with the long-term effect of G A in MS.

Multiple sclerosis

Due to its sensitivity to the different multiple sclerosis (MS)-related abnormalities, magnetic resonance imaging (MRI) has become an established tool to diagnose MS and to monitor its evolution. MRI has been included in the diagnostic workup of patients with clinically isolated syndromes suggestive of MS, and ad hoc criteria have been proposed and are regularly updated. In patients with definite MS, the ability of conventional MRI techniques to explain patients' clinical status and progression of disability is still suboptimal. Several advanced MRI-based technologies have been applied to estimate overall MS burden in the different phases of the disease. Their use has allowed the heterogeneity of MS pathology in focal lesions, normal-appearing white matter and gray matter to be graded in vivo. Recently, additional features of MS pathology, including macrophage infiltration and abnormal iron deposition, have become quantifiable. All of this, combined with functional imaging techniques, is improving our understanding of the mechanisms associated with MS evolution. In the near future, the use of ultrahigh-field systems is likely to provide additional insight into disease pathophysiology. However, the utility of advanced MRI techniques in clinical trial monitoring and in assessing individual patients' response to treatment still needs to be assessed.

The current state-of-the-art of spinal cord imaging: applications

A first-ever spinal cord imaging meeting was sponsored by the International Spinal Research Trust and the Wings for Life Foundation with the aim of identifying the current state-of-the-art of spinal cord imaging, the current greatest challenges, and greatest needs for future development. This meeting was attended by a small group of invited experts spanning all aspects of spinal cord imaging from basic research to clinical practice. The greatest current challenges for spinal cord imaging were identified as arising from the imaging environment itself; difficult imaging environment created by the bone surrounding the spinal canal, physiological motion of the cord and adjacent tissues, and small crosssectional dimensions of the spinal cord, exacerbated by metallic implants often present in injured patients. Challenges were also identified as a result of a lack of "critical mass" of researchers taking on the development of spinal cord imaging, affecting both the rate of progress in the field, and the demand for equipment and software to manufacturers to produce the necessary tools. Here we define the current state-of-the-art of spinal cord imaging, discuss the underlying theory and challenges, and present the evidence for the current and potential power of these methods. In two review papers (part I and part II), we propose that the challenges can be overcome with advances in methods, improving availability and effectiveness of methods, and linking existing researchers to create the necessary scientific and clinical network to advance the rate of progress and impact of the research.

Modifications of longitudinally extensive transverse myelitis and brainstem lesions in the course of neuromyelitis optica (NMO): a population-based, descriptive study

BACKGROUND

Neuromyelitis optica (NMO) includes transverse myelitis, optic neuritis and brain lesions. Recent studies have indicated that the brainstem is an important site of attack in NMO. Longitudinally extensive transverse myelitis (LETM) is an important component of the clinical diagnosis of NMO. The frequency of brainstem and LETM lesions, changes over time of LETM and the clinical consequences in the course of NMO have only been sparsely studied.

METHODS

The study was a population-based retrospective case series with clinical and magnetic resonance imaging (MRI) follow-up of 35 patients with definite NMO and a relapsing-remitting course.

RESULTS

Brainstem lesions were observed in 25 patients, 18 in medulla oblongata (11 in area postrema). Lesions in the pons, mesencephalon and diencephalon occurred in 10, 7 and 7 patients, respectively. Lesions were symptomatic in medulla oblongata and pons, asymptomatic in mesencephalon and diencephalon. Brainstem lesions were observed significantly more often in anti-aquaporin-4 (AQP-4) antibody positive than in seronegative patients (p < 0.002).LETM was demonstrated by MRI of the spinal cord in 30/36 patients, 23/30 of whom had follow-up MRI of the spinal cord. Recurrent LETM was observed in five patients. In nine patients the LETM changed into multiple lesions during remission or treatment. Spinal cord atrophy was observed in 12/23 (52%) patients, correlating to Expanded Disability Status Scale (r = 0.88, p < 0.001).

CONCLUSIONS

NMO patients had frequent occurrence of brainstem lesions and LETM. Brainstem lesions were associated with anti-AQP4 antibody positivity. LETM lesions differentiated over time and the outcome included relapses, fragmentation and atrophy. Correlation was observed between spinal cord atrophy and neurological disability.

Overcoming the clinical-MR imaging paradox of multiple sclerosis: MR imaging data assessed with a random forest approach

BACKGROUND AND PURPOSE

In MS, the relation between clinical and MR imaging measures is still suboptimal. We assessed the correlation of disability and specific impairment of the clinical functional system with overall and regional CNS damage in a large cohort of patients with MS with different clinical phenotypes by using a random forest approach.

MATERIALS AND METHODS

Brain conventional MR imaging and DTI were performed in 172 patients with MS and 46 controls. Cervical cord MR imaging was performed in a subgroup of subjects. To evaluate whether MR imaging measures were able to correctly classify impairment in specific clinical domains, we performed a random forest analysis.

RESULTS

Between-group differences were found for most of the MR imaging variables, which correlated significantly with clinical measures (r ranging from -0.57 to 0.55). The random forest analysis showed a high performance in identifying impaired versus unimpaired patients, with a global error between 7% (pyramidal functional system) and 31% (Ambulation Index) in the different outcomes considered. When considering the performance in the unimpaired and impaired groups, the random forest analysis showed a high performance in identifying patients with impaired sensory, cerebellar, and brain stem functions (error below 10%), while it performed poorly in defining impairment of visual and mental systems (error of 91% and 70%, respectively). In analyses with a good level of classification, for most functional systems, damage of the WM fiber bundles subserving their function, measured by using DTI tractography, had the highest classification power.

CONCLUSIONS

Random forest analysis, especially if applied to DTI tractography data, is a valuable approach, which might contribute to overcoming the MS clinical-MR imaging paradox.

MR imaging of multiple sclerosis

Owing to its ability to depict the pathologic features of multiple sclerosis (MS) in exquisite detail, conventional magnetic resonance (MR) imaging has become an established tool in the diagnosis of this disease and in monitoring its evolution. MR imaging has been formally included in the diagnostic work-up of patients who present with a clinically isolated syndrome suggestive of MS, and ad hoc diagnostic criteria have been proposed and are updated on a regular basis. In patients with established MS and in those participating in treatment trials, examinations performed with conventional MR pulse sequences provide objective measures to monitor disease activity and progression; however, they have a limited prognostic role. This has driven the application of newer MR imaging technologies, including higher-field-strength MR units, to estimate overall MS burden and mechanisms of recovery in patients at different stages of the disease. These techniques have allowed in vivo assessment of the heterogeneity of MS pathologic features in focal lesions and in normal-appearing tissues. More recently, some of the finer details of MS, including macrophage infiltration and abnormal iron deposition, have become quantifiable with MR imaging. The utility of these modern MR techniques in clinical trial monitoring and in the assessment of the individual patient's response to treatment still need to be evaluated.

Ingested Type I Interferon-State of the Art as Treatment for Autoimmunity Part 2

We have proposed a unifying hypothesis of the etiopathogenesis of autoimmunity that defines autoimmunity as a type I interferon (IFN) immunodeficiency syndrome. We have examined toxicity and potential efficacy in two phase I (type 1 diabetes [T1D], multiple sclerosis [MS]) and phase II clinical trials in T1D and MS. In a phase I open label trial in T1D, ingested IFN-alpha preserved residual beta-cell function in recent onset patients. In a second phase I trial in MS, there was a significant decrease in peripheral blood mononuclear cell IL-2 and IFN-gamma production after ingesting IFN-alpha. In a phase II randomized, placebo-controlled, double-blind trial in MS, 10,000 IU ingested IFN-alpha significantly decreased gadolinium enhancements compared to the placebo group at month 5. TNF-alpha and IFN-gamma cytokine secretion in the 10,000 IU group at month 5 showed a significant decrease that corresponded with the effect of ingested IFN-alpha on decreasing gadolinium enhancements. In a phase II randomized, placebo-controlled, double-blind trial in T1D, patients in the 5,000 unit hrIFN-alpha treatment group maintained more beta-cell function one year after study enrollment compared to individuals in the placebo group. Ingested IFN-alpha was not toxic in these clinical trials. These studies suggest that ingested IFN-alpha may have a potential role in the treatment of autoimmunity.

Novel therapeutic strategies for multiple sclerosis--a multifaceted adversary

Therapeutic strategies for multiple sclerosis have radically changed in the past 15 years. Five regulatory-approved immunomodulatory agents are reasonably effective in the treatment of relapsing-remitting multiple sclerosis, and appear to delay the time to progression to disabling stages. Inhibiting disease progression remains the central challenge for the development of improved therapies. As understanding of the immunopathogenesis of multiple sclerosis has advanced, a number of novel potential therapeutics have been identified, and are discussed here. It has also become apparent that traditional views of multiple sclerosis simply as a CD4+ T-cell-mediated disease of the central nervous system are incomplete. The pathogenic role of other immune components such as the innate immune system, regulatory T cells, T helper 17 cells and B cells is reaching centre stage, opening up exciting avenues and novel potential targets to affect the natural course of multiple sclerosis.

The value of chemical fat-saturation pulse added to T1-weighted spin-echo sequence in evaluating gadolinium-enhancing brain lesions in multiple sclerosis

PURPOSE

This study was undertaken to assess the value of a chemical (spectral) fat-saturation (fat-sat) pulse added to a T1-weighted spin-echo sequence after intravenous administration of paramagnetic contrast agent in detecting enhancing lesions in multiple sclerosis.

MATERIALS AND METHODS

Twenty patients with relapsing-remitting multiple sclerosis underwent a brain 1.0-Tesla magnetic resonance (MR) scan with T1-weighted spin-echo sequences (24 contiguous para-axial slices with a thickness of 5 mm, pixel size 0.96 mm(2), number of excitations 2, flip angle 90 degrees ) 5 min after intravenous injection of 0.1 mmol/kg of gadodiamide with and without fat-sat, acquired with randomised order of priority. Two readers counted by consensus the number of enhancing lesions and assigned a conspicuity score (low conspicuity=1; high conspicuity=2) to each enhancing lesion during a randomised reading without any visual comparison between the two corresponding images (with and without fat-sat) of the same patient. McNemar and Wilcoxon matched-pair signed-rank tests were used.

RESULTS

Seventy-two enhancing lesions without fat-sat and 94 with fat-sat were detected; 22 lesions were visible only with fat-sat, whereas no lesion was detected only without fat-sat (p<0.0001). The conspicuity score was 1.17+/-0.38 (mean+/-standard deviation) and 1.57+/-0.44, respectively (p<0.0001).

CONCLUSIONS

A fat-sat pulse added to a T1-weighted spin-echo sequence increases significantly the number and conspicuity of contrast-enhancing lesions in patients with relapsing-remitting multiple sclerosis.

Conventional MRI in Multiple Sclerosis

During the past 10 years, conventional magnetic resonance imaging (cMRI) has become an established tool for the assessment of patients with multiple sclerosis (MS) and to monitor treatment trials. This is mainly due to the sensitivity and reproducibility of cMRI in the detection of MS-related damage. A large effort has also been devoted to develop imaging strategies capable of providing accurate estimates of the extent of disease-related damage not only in the brain, but also in the spinal cord and optic nerve. Guidelines have been defined to integrate MR findings in the diagnostic evaluation of patients at presentation with clinically isolated syndromes suggestive of MS, and specific acquisition protocols have been offered for monitoring longitudinal changes in patients with established disease. Despite the fact that the role of cMRI in MS has been profoundly obviated by the advent of modern and quantitative MR techniques, several issues are still unresolved. Technical development in acquisition and postprocessing, as well as the introduction of high-field magnets in the clinical arena, are likely to increase our understanding of disease pathobiology, mainly through an increased ability to quantify the extent of gray matter damage.

EFNS guidelines on the use of neuroimaging in the management of multiple sclerosis

Magnetic resonance (MR)-based techniques are widely used for the assessment of patients with suspected and definite multiple sclerosis (MS). However, despite the publication of several position papers, which attempted to define the utility of MR techniques in the management of MS, their application in everyday clinical practice is still suboptimal. This is probably related, not only, to the fact that the majority of published guidelines focused on the optimization of MR technology in clinical trials, but also to the continuing development of modern, quantitative MR-based techniques, that have not as yet entered the clinical arena. The present report summarizes the conclusions of the 'EFNS Expert Panel of Neuroimaging of MS' on the application of conventional and non-conventional MR techniques to the clinical management of patients with MS. These guidelines are intended to assist in the use of conventional MRI for the diagnosis and longitudinal monitoring of patients with MS. In addition, they should provide a foundation for the development of more widespread but rational clinical applications of non-conventional MR-based techniques in studies of MS patients.

Macrophages and neurodegeneration

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Demyelination is a classical feature of MS lesions, and neurological deficits are often ascribed to the reduced signal conduction by demyelinated axons. However, recent studies emphasize that axonal loss is an important factor in MS pathogenesis and disease progression. Axonal loss is found in association with cellular infiltrates in MS lesions. In this review, we discuss the possible contribution of the innate immune system in this process. In particular, we describe how infiltrated macrophages may contribute to axonal loss in MS and in experimental autoimmune encephalomyelitis (EAE), the animal model for MS. An overview is given of the possible effects of mediators, which are produced by activated macrophages, such as such as pro-inflammatory cytokines, free radicals, glutamate and metalloproteases, on axonal integrity. We conclude that infiltrated macrophages, which are activated to produce pro-inflammatory mediators, may be interesting targets for therapeutic approaches aimed to prevent or reduce axonal loss during exacerbation of inflammation. Interference with the process of infiltration and migration of monocytes across the blood-brain barrier is one of the possibilities to reduce the damage by activated macrophages.

Magnetic resonance imaging predictors of disability in primary progressive multiple sclerosis: a 5-year study

Magnetic resonance imaging (MRI) has become an accepted tool for monitoring therapeutic trials in relapsing-remitting and secondary progressive multiple sclerosis (MS); it is however unclear whether such MRI markers are equally applicable to primary progressive MS (PPMS). Forty-two patients with PPMS were reviewed five years after commencing a two-year MRI and clinical study. Clinical measures recorded at baseline and five years included both the Expanded Disability Status Scale and the MS functional composite. MRI data collected at baseline and two years included T1 and T2 lesion loads, the number of new brain and cord lesions, and measures of both brain and cord atrophy. The study demonstrated that both the number of new T2 lesions and rate of increase in ventricular volume over two years were modestly predictive of subsequent disease progression and therefore may be useful tools in the testing of new therapeutic agents in PPMS.

Short-term accrual of gray matter pathology in patients with progressive multiple sclerosis: an in vivo study using diffusion tensor MRI

The mechanisms underlying the progressive course of multiple sclerosis (MS) are not fully understood yet. Since diffusion tensor (DT) MRI can provide quantitative estimates of both MRI-visible and MRI-occult brain damage related to MS, the present study investigated the value of DT MRI-derived measures for the assessment of the short-term accumulation of white and gray matter (GM) pathology in patients with primary progressive (PP) and secondary progressive (SP) MS. Fifty-four patients with PPMS and 22 with SPMS were studied at baseline and after a mean follow-up of 15 months. Dual-echo, T1-weighted, and DT MRI scans of the brain were acquired on both occasions. Total lesion volumes (TLV) and percentage brain volume changes (PBVC) were computed. Mean diffusivity (MD) and fractional anisotropy (FA) maps of the normal-appearing white (NAWM) and gray matter (NAGM) were produced, and histogram analysis was performed. In both patient groups, a significant increase of average lesion MD (P = 0.01) and of average NAGM MD (P = 0.007) was found at follow-up. No significant differences between PPMS and SPMS patient groups were found for the on-study changes of any MRI-derived measure. No significant correlations were found between the percentage changes of DT MRI-derived measures and those of TLV and PBVC. No significant changes of DT MRI-derived measures were observed in age-matched healthy controls over the same study period. Over a 1-year period of follow-up, DT MRI can detect tissue changes beyond the resolution of conventional MRI in the NAGM of patients with progressive MS. The accumulation of DT MRI-detectable gray matter damage does not seem to merely depend upon the concomitant increase of T2-visible lesion load and the reduction of brain volume. These observations suggest that progressive NAGM damage might yet be an additional factor leading to the accumulation of disability in progressive MS.

The pathology of primary progressive multiple sclerosis

The pathological hallmark of chronic multiple sclerosis includes focal demyelination, gliosis, inflammation and axonal injury. There is limited information on whether these pathological features differ across the clinical phenotypes of the disease (relapsing-remitting, secondary progressive, and primary progressive). This review will focus on the pathological aspects of PPMS and pathogenic implications. A better understanding of the differences in PPMS pathology and pathogenesis will lead to more effective treatment strategies.

Natural history of primary progressive multiple sclerosis

The relationship of primary progressive multiple sclerosis (PPMS) to relapsing-remitting MS (RRMS) and secondary progressive MS (SPMS) remains unclear. Natural history data from a population-based cohort of patients with PPMS followed for approximately 25 years demonstrate remarkable similarities in the progressive phases of PPMS and SPMS. Immunogenetic and magnetic resonance imaging studies in large numbers of patients also fail to differentiate between the two MS categories. PPMS thus resembles SPMS without the relapses, although the two forms do differ with respect to sex ratio. An unfavourable outcome in PPMS in predicted by rapid early progression of disability and involvement of three or more systems. Natural history studies provide information on likely long-term outcomes and can be used in the design and interpretation of clinical trials in PPMS. The evidence that PPMS is distinct remains weak.

Serial MRI in multiple sclerosis: a prospective pilot study of lesion load, whole brain volume and thalamic atrophy

Using serial magnetic resonance imaging (MRI), we investigated the relationship between diffuse cerebral atrophy, T1 and T2 lesion volumes, mean thalamic volumes and clinical progression in patients with established multiple sclerosis (MS). Eleven patients were included in this prospective serial study. Cerebral volumes, T1 hypointense lesion volumes, and T2 hyperintense lesion volumes at baseline and at up to 3 years follow-up were assessed on MRI brain scans. As a putative measure of cerebral atrophy mean thalamic volumes were also obtained. The outcome measures were the MRI parameters and disability on Kurtzke's expanded disability status scale (EDSS). Of the 11 patients 6 worsened clinically as measured by an increase of 0.5 or more on the EDSS. Cerebral atrophy occurred in 91% of patients and was independent of changes in lesion volumes and was not associated with disease progression as determined by the EDSS.

Ingested type I interferon: a potential treatment for autoimmunity

We have proposed a unifying hypothesis of the etiopathogenesis of autoimmunity that defines autoimmunity as a type I interferon (IFN) immunodeficiency syndrome. We have examined toxicity and potential efficacy in three phase I (type 1 diabetes, rheumatoid arthritis, multiple sclerosis) and one phase II clinical trials in multiple sclerosis (MS). In a phase I open-label trial in type 1 diabetes, ingested IFN-alpha preserved residual beta cell function in recent onset patients. In a second phase I trial, treatment of rheumatoid arthritis (RA) with ingested IFN-alpha reduced the secretion of interleukin-1 (IL-1), a proinflammatory cytokine. In a third phase I trial in MS, there was a significant decrease in peripheral blood mononuclear cell (PBMC) IL-2 and IFN-gamma production after ingesting IFN-alpha. In a phase II randomized, placebo-controlled, double-blind trial in MS, 10,000 IU ingested IFN-alpha significantly decreased gadolinium enhancements compared with the placebo group at month 5. Tumor necrosis factor-alpha (TNF-alpha) and IFN-gamma cytokine secretion in the 10,000 IU group at month 5 showed a significant decrease that corresponded with the effect of ingested IFN-alpha on decreasing gadolinium enhancements. Ingested IFN-alpha was not toxic in any of these clinical trials. These studies suggest that ingested IFN-alpha may have a potential role in the treatment of autoimmunity.

Inflammation in multiple sclerosis: the good, the bad, and the complex

Inflammation has always been thought of as detrimental in the pathophysiology of multiple sclerosis (MS). However, emerging genetic data, magnetic-resonance-imaging studies, and immunopathological evidence challenge this simplistic view. The evidence leads to the conclusion that inflammation is tightly regulated, and that its net effect may be beneficial in MS, thus explaining some of the results from recent trials of anti-inflammatory agents. We argue that the use of anti-inflammatory drugs to treat MS may not be appropriate in all cases. Precise identification of the inflammatory pathways to be targeted in the different phases of the disease and the timing of such interventions are therefore crucial.

Ingested type I interferon: state of the art as treatment for autoimmunity

We have proposed a unifying hypothesis of the etiopathogenesis of autoimmunity that defines autoimmunity as a type I interferon (IFN) immunodeficiency syndrome. We have examined toxicity and potential efficacy in three phase I (type 1 diabetes, rheumatoid arthritis, multiple sclerosis) and one phase II clinical trials in multiple sclerosis. In a phase I open-label trial in type 1 diabetes, ingested IFN-alpha preserved residual beta-cell function in recent onset patients. In a second phase I trial, treatment of rheumatoid arthritis with ingested IFN-alpha reduced the secretion of interleukin (IL)-1, a pro-inflammatory cytokine. In a third phase I trial in multiple sclerosis, there was a significant decrease in peripheral blood mononuclear cell IL-2 and IFN-gamma production after ingesting IFN-alpha. In a phase II randomized, placebo-controlled, double-blind trial in multiple sclerosis, 10,000 IU ingested IFN-alpha significantly decreased gadolinium enhancements compared with the placebo group at month 5. Tumor necrosis factor-alpha and IFN-gamma cytokine secretion in the 10,000 IU group at month 5 showed a significant decrease that corresponded with the effect of ingested IFN-alpha on decreasing gadolinium enhancements. Ingested IFN-alpha was not toxic in any of these clinical trials. These studies suggest that ingested IFN-alpha may have a potential role in the treatment of autoimmunity.

The role of MRI as a surrogate outcome measure in multiple sclerosis

The need for more specific and more sensitive outcome measures for use in testing new therapies in multiple sderosis (MS) is generally accepted. This need has been accentuated by the realization that the ability to conduct large placebo-controlled trials will be limited in the future. From the first use of magnetic resonance imaging (MRI) to study MS, the ability of this imaging technique to identify areas of the central nervous system damage by the disease process in MS has been impressive. Thus, the possibility that MRI could serve as a surrogate outcome measure in clinical trials in MS has been attractive. The use of MRI as a surrogate outcome measure has been examined by an international group of investigators with expertise in clinical aspects of MS, the use of MRI in MS, and in experimental therapeutics. The group agreed that MRI does not represent a validated surrogate in any clinical form of MS. It was also agreed, however, that MRI does provide a reflection of the underlying pathology in the disease, but no single MRI measurement in isolation was seen as sufficient to monitor disease. The use for multiple imaging techniques, especially new, emerging techniques that may better reflect the underlying pathology, was seen as particularly important in monitoring studies of patients with either secondary or primary progressive MS. The choice of MRI techniques used to monitor new therapies needs to be consistent with the proposed mechanisms of the new therapy and phase of the disease. It was also noted, however, that additional validation is required for nonconventional imaging techniques. Finally, the participants noted that clinical trials using MRI as a primary outcome measure may fail to fully identify the effects of the therapy on dinical measures and that the risk and cost-benefit ratio of the treatment might be unresolved. Thus, before MRI is used as a primary outcome measure, new approaches to trial design must be given careful consideration.

Evoked potentials for evaluation of multiple sclerosis

The role of evoked potentials (EP) in the assessment of multiple sclerosis (MS) has changed over the last decade. This is largely due to progress in imaging techniques. But while MRI has a greater diagnostic sensitivity, EP remain a useful diagnostic tool in many clinical situations. Moreover, recent studies demonstrate the utility of EP for monitoring and predicting the course of the disease in patient groups, although not yet in individuals. For these purposes, EP show better results than conventional MRI. In the near future, new developments in electrophysiology, immunology and imaging may allow to differentiate between different subtypes of MS early in the course, and consequently to tailor therapeutic measures more precisely to the individual patients.

Magnetic resonance imaging of multiple sclerosis: new insights linking pathology to clinical evolution

Magnetic resonance imaging methods allow observation of pathological changes in vivo. Magnetic resonance-based studies have provided a number of important insights into the spatio-temporal evolution of the pathology of multiple sclerosis in vivo, particularly with respect to the relation between pathology and progression of disability. Magnetic resonance techniques have shown that this pathology is not restricted to the plaques that are evident at autopsy, but also involve the so-called normal-appearing white matter. Nonconventional magnetic resonance imaging strategies such as magnetization transfer imaging and spectroscopic imaging provide measures with higher pathological specificity for myelin and axonal injury. These and other advanced magnetic resonance techniques (such as the measurement of atrophy, lesion relaxation spectra, and lesion dynamics) are affording opportunities to use observations of patients to test biologically specific hypotheses. This should help us to better define new targets for drug therapy and to assess responses to new therapeutic agents.

The predictive value of gadolinium enhancement for long term disability in relapsing-remitting multiple sclerosis--preliminary results

As short-term MRI studies are increasingly being used to monitor disease activity in multiple sclerosis (MS) it is vital to establish if short-term MRI activity is predictive of long term clinical outcome. We followed up after 5 years a group of 10 benign (relapsing-remitting MS with a disease duration > 10 years and EDSS < or = 3) and 10 early relapsing-remitting patients who previously had monthly serial MRI scans for 6 months. In the early relapsing-remitting group median EDSS at entry to the initial serial study was three and in the benign group 2.5. At 5-year follow up, five of these 20 patients had developed a definite deterioration in EDSS. The median number of new enhancing lesions detected originally in the group that had deteriorated was 11 (7-17) compared to 0 (0-5) new enhancing lesions, for those who had not deteriorated (P < 0.05). There was a trend towards a higher baseline T2 lesion load in the group with a definite change in EDSS but this was not significant This study suggests that short-term measurement of the number of gadolinium enhancing lesions may predict long term outcome in relapsing-remitting MS.

Nuclear magnetic resonance monitoring of treatment and prediction of outcome in multiple sclerosis

Magnetic resonance (MR) techniques provide an objective, sensitive and quantitative assessment of the evolving pathology in multiple sclerosis. There is an increasing definition of the pathological specificity of newer techniques, and more robust correlations with clinical evolution are emerging. As the pathophysiological basis of in vivo nuclear MR signal abnormalities is further elucidated, it is likely that the importance of MR as a tool to monitor new therapies will increase.

Quantitative MRI in patients with secondary progressive MS treated with monoclonal antibody Campath 1H

BACKGROUND

To assess the long-term effect of the lymphocyte-depleting humanized monoclonal antibody Campath 1H on MR markers of disease activity and progression in secondary progressive MS patients.

METHODS

Twenty-five patients participated in a crossover treatment trial with monthly run-in MR scans for 3 months, followed (after a single pulse of Campath 1H) by monthly MR scans from months 1 to 6 and again from months 12 to 18. MR analysis was performed to provide measurements of the number and volume of gadolinium (Gd)-enhancing lesions as well as the hypointense lesion volume on a T1-weighted sequence. In addition, serial measurements of T2 brain lesion volume, brain volume, and spinal cord cross-sectional area were made over the duration of the study. The relationship between clinical and MR measures of disease evolution was also assessed.

RESULTS

Treatment was associated with a reduction in the number and volume of Gd-enhancing lesions (p < 0.01). Despite this, a decrease in brain volume was seen in 13 patients during the 18 months post-treatment. The mean pretreatment Gd-enhancing lesion volume was predictive of subsequent reduction in brain volume (r = 0.77, p = 0.002). Reduction in brain volume also correlated with the change in T1 hypointense lesion volume after treatment (r = 0.53, p < 0.01). A reduction in spinal cord area was also seen throughout the study duration, and this correlated with an increase in disability (r = 0.65, p = 0.01).

CONCLUSION

Campath 1H treatment was associated with a sustained and marked reduction in the volume of Gd enhancement, indicating suppression of active inflammation. Nevertheless, many patients developed increasing brain and spinal cord atrophy, T1 hypointensity, and disability. This study highlights the potential role for novel MR techniques in monitoring the effect of treatment on the pathologic process in MS.

MRI in multiple sclerosis: correlation with expanded disability status scale (EDSS)

Magnetic resonance (MR) imaging is very sensitive in showing disseminated MS lesions. Subclinical MR progression occurs frequently, explaining why MR is now used to monitor treatment, even without measurable consequences, of new MR lesions to the patient at this moment. In the light of this clinico-radiological paradox, the significance of MR in MS is discussed, particularly in relation with the expanded disability status scale (EDSS). Gadolinium-enhancing lesions correlate with the occurrence of relapses, CSF myelin breakdown products and, in patients with relapsing-remitting disease, with higher EDSS. However, the predictive value of the frequency of enhancement for changes in EDSS is only weak. For conventional T2-weighted MR imaging, the cross-sectional correlation with EDSS varies between 0.15 and 0.60, and is limited mainly by the inherent lack of tissues specificity of T2-weighted images. Both T1 black holes and magnetisation transfer (MT) parameters show a better correlation with EDSS; it should be noted that lesions in which those abnormalities are found go through an initial phase of enhancement as well. For T1 black holes, a correlation up to 0.81 has been reported for SP patients. Post-mortem studies show that black holes and low MT ratios are in vivo markers of axonal loss. Preliminary data indicate that progressive atrophy also correlates with progression on the EDSS scale. More should be learned about the fate of new MR lesion with regards to development of axonal loss, which at present is difficult to predict in the enhancing stage. The existence of escape mechanisms, including remyelination, make a simple correlation with EDSS extremely unlikely, and perhaps not even desirable. Nevertheless, while the clinical effect of a given new lesion may be difficult to ascertain, the absence of (new) MR lesions is prognostically favourable, as will be the degree to which new lesions are prevented by treatment.

Magnetic resonance imaging in the monitoring of disease progression in multiple sclerosis

Disease progression and irreversible disability in multiple sclerosis results from incomplete recovery from relapses, but most importantly from insidious disease progression. Although magnetic resonance imaging parameters, such as new lesion rate and gadolinium enhancement, reflect inflammation and disease activity they have no bearing on disease progression. Until now the T2 lesion load or disease burden has been relied upon for this, despite its poor relationship with disability measures. This paper looks at the mechanisms responsible for disease progression and discusses the MR techniques now available to reflect these pathological processes.

Predictive value of gadolinium-enhanced magnetic resonance imaging for relapse rate and changes in disability or impairment in multiple sclerosis: a meta-analysis. Gadolinium MRI Meta-analysis Group

BACKGROUND

Reliable prognostic factors are lacking for multiple sclerosis (MS). Gadolinium enhancement in magnetic resonance imaging (MRI) of the brain detects with high sensitivity disturbance of the blood-brain barrier, an early event in the development of inflammatory lesions in MS. To investigate the prognostic value of gadolinium-enhanced MRI, we did a meta-analysis of longitudinal MRI studies.

METHODS

From the members of MAGNIMS (European Magnetic Resonance Network in Multiple Sclerosis) and additional centres in the USA, we collected data from five natural-course studies and four placebo groups of clinical trials completed between 1992 and 1995. We included a total of 307 patients, 237 with relapsing disease course and 70 with secondary progressive disease course. We investigated by regression analysis the relation between initial count of gadolinium-enhancing lesions and subsequent worsening of disability or impairment as measured by the expanded disability status scale (EDSS) and relapse rate.

FINDINGS

The relapse rate in the first year was predicted with moderate ability by the mean number of gadolinium-enhancing lesions in monthly scans during the first 6 months (relative risk per five lesions 1.13, p=0.023). The predictive value of the number of gadolinium-enhancing lesions in one baseline scan was less strong. The best predictor for relapse rate was the variation (SD) of lesion counts in the first six monthly scans which allowed an estimate of relapse in the first year (relative risk 1.2, p=0.020) and in the second year (risk ratio=1.59, p=0.010). Neither the initial scan nor monthly scans over six months were predictive of change in the EDSS in the subsequent 12 months or 24 months. The mean of gadolinium-enhancing-lesion counts in the first six monthly scans was weakly predictive of EDSS change after 1 year (odds ratio=1.34, p=0.082) and 2 years (odds ratio=1.65, p=0.049).

INTERPRETATION

Although disturbance of the blood-brain barrier as shown by gadolinium enhancement in MRI is a predictor of the occurrence of relapses, it is not a strong predictor of the development of cumulative impairment or disability. This discrepancy supports the idea that variant pathogenetic mechanisms are operative in the occurrence of relapses and in the development of long-term disability in MS.

A one year study of new lesions in multiple sclerosis using monthly gadolinium enhanced MRI: correlations with changes of T2 and magnetization transfer lesion loads

In this study, 14 patients with either relapsing-remitting or secondary progressive multiple sclerosis (MS) were scanned monthly using gadolinium enhanced magnetic resonance imaging (MRI). At the start of the study and at 1 year follow up, T2-weighted and magnetization transfer (MT) scans were also performed. The correlation between the frequency and extent of enhancement and changes of lesion load over a 1 year period on T2-weighted and MT images were assessed. For all patients, and for the relapsing-remitting patients only, the number and volume of enhancing lesions per month showed no significant correlation with the change between baseline and 1 year follow up of lesion volumes on T2 and MT images. However, strong correlations were found between the number and volume of gadolinium enhancing lesions with changes of T2 (r = 0.93, P = 0.02) and MT (r = 0.82, P = 0.04) lesion loads in patients with secondary progressive MS. Strong correlations were also found between the lesion loads on T2-weighted scans and on MT images both at baseline and at 1 year follow up (r = 0.83, P = 0.003). In addition, the changes in lesion load over 1 year, detected using the two techniques, were moderately correlated (r = 0.51, P = 0.05). This study provides further evidence that the pathological processes in MS are at different stages in relapsing-remitting and secondary progressive MS. It also suggests that the effectiveness of recovery mechanisms within lesions might be one of the major factors responsible for such a difference.

Guidelines for using quantitative measures of brain magnetic resonance imaging abnormalities in monitoring the treatment of multiple sclerosis

The change of brain lesion load, measured on T2-weighted magnetic resonance imaging (MRI) using computer-assisted techniques, is a widely used secondary endpoint for phase III clinical trials in multiple sclerosis (MS). Collection, transfer, and analysis of the electronic data across multiple centers have all proved challenging and give rise to potential errors. However, many new acquisition schemes and postprocessing techniques have been developed; these may reduce scan times and result in better lesion conspicuity or lessen the human interaction needed for data analysis. This review considers many aspects of the use of MRI in clinical trials for MS and provides international consensus guidelines, derived from a task force of the European Magnetic Resonance Networks in Multiple Sclerosis (MAGNIMS) together with a group of North American experts. The main points considered are the organization of correctly powered trials and selection of participating sites; the appropriate choice of pulse sequences and image acquisition protocol given the current state of technology; quality assurance for data acquisition and analysis; accuracy and reproducibility of lesion load assessments; and the potential for the application of quantitative methods to other MRI-derived measures of disease burden.

Correlations between monthly enhanced MRI lesion rate and changes in T2 lesion volume in multiple sclerosis

Magnetic resonance imaging (MRI) provides a powerful tool for assessing disease activity in multiple sclerosis (MS), and its role as a surrogate marker for monitoring treatment efficacy is now becoming established. The most commonly used MRI parameters in treatment trials are (1) monthly gadolinium-enhanced MRI, with the number of active lesions serving as the outcome measure, and (2) annual lesion load quantification, in which change in MS lesion volume provides the MRI endpoint. We evaluated clinical/MRI correlations and the relationship between these two markers of disease activity in 73 patients with clinically definite MS. Quantification of T2 lesion load was performed at study entry and exit, with a median study duration of 11 months (range, 9 to 14 months). Monthly postgadolinium T1-weighted images were acquired between these time points. Lesion load at study entry was significantly correlated with the baseline Expanded Disability Status Scale (EDSS) score, but no significant longitudinal correlation was demonstrated. The number of enhancing lesions on the entry scan was predictive of subsequent relapse rate over the study duration and also correlated with the subsequent enhancing lesion activity over the study period. A significant correlation was found between change in lesion load and disease activity on the monthly scans. Our results suggest that annual lesion load quantification provides an efficient measure of ongoing disease activity, and this supports its application as a surrogate marker of disease evolution in phase III treatment trials.

Gadolinium enhanced MRI predicts clinical and MRI disease activity in relapsing-remitting multiple sclerosis

The aim of the study was to evaluate the predictive power of baseline gadolinium (Gd) enhanced MRI in relation to subsequent clinical and MRI activity. Sixty eight patients with clinically definite relapsing-remitting multiple sclerosis had a baseline Gd enhanced MRI and were followed up clinically and by monthly Gd enhanced MRI for six months. The occurrence of relapses during the follow up period was predicted by the presence of at least one enhancing lesion on the baseline MRI (P < 0.05). The number and volume of enhancing lesions at baseline were significantly associated with both enhancing lesions observed during the follow up period (P < 0.0001) and the accumulation of abnormality on T2 weighted images (P < 0.0001). Moreover, the presence of three or more enhancing lesions at baseline scan was consistently associated with the development of permanent abnormalities on T2 weighted images six months later. The study suggests that the number and volume of Gd enhancing lesions at a single examination are strong short term predictors of subsequent clinical and MRI activity.

Magnetic resonance in monitoring the natural history of multiple sclerosis and the effects of treatment

In this review the main contributions of magnetic resonance (MR) techniques in the monitoring of multiple sclerosis (MS) course, both natural or modified by treatments, are presented. MR measures well correlate with short-term disease evolution and therefore their use is appropriate as primary end-points in preliminary clinical trials evaluating the effects of new treatments. In contrast, the correlation between MR measures and long-term clinical evolution in clinically definite MS is less clear, thus indicating that such measures can be used at present only as a secondary end-point in large scale definitive trials. The results coming from the clinical application of newer MR techniques with higher pathological specificity are also presented and their possible future roles in monitoring treatment aimed at preventing development of disability in MS are discussed.