Deep grey matter T2 hypo-intensity in patients with paediatric multiple sclerosis

Functional correlates of cognitive abilities vary with age in pediatric multiple sclerosis

BACKGROUND

Pediatric multiple sclerosis (PedMS) can hamper brain maturation. Aim of this study was to assess the neuropsychological profile of PedMS patients and their resting-state functional connectivity (RS FC).

METHODS

We assessed intelligence quotient (IQ), executive speed, and language in 76 PedMS patients. On a 3.0T scanner RS FC of brain networks was estimated with a seed-based analysis (subset of 58 right-handed PedMS patients and 22 matched healthy controls). Comparisons were run between controls and PedMS (whole cohort and by age).

RESULTS

Ninety-five% of patients had normal IQ. The highest rate of failure was observed in executive speed. PedMS showed reduced RS FC in all networks than controls, especially in the basal ganglia. In younger patients (<16-year-old, n = 32) reduced RS FC in the basal ganglia, language, and sensorimotor networks associated with poorer cognitive performance (p < 0.05; r range: 0.39; 0.56). Older patients (≥16-year-old, n = 26) showed increased RS FC in the basal ganglia, default-mode, sensorimotor, executive, and language networks, associated with poorer performance in executive speed and language abilities (p < 0.05; r range: -0.40; -0.59). In both groups, lower RS FC of the caudate nucleus associated with poorer executive speed.

CONCLUSIONS

The effect of PedMS on RS FC is clinically relevant and differs according to patients' age.

Magnetic resonance imaging detection of deep gray matter iron deposition in multiple sclerosis: A systematic review

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease involving immune-mediated damage. Iron deposition in deep gray matter (DGM) structures like the thalamus and basal ganglia have been suggested to play a role in MS pathogenesis. Magnetic Resonance Imaging (MRI) imaging methods like T2 and T2* imaging, susceptibility-weighted imaging, and quantitative susceptibility mapping can track iron deposition storage in the brain primarily from ferritin and hemosiderin (paramagnetic iron storage proteins) with varying levels of tissue contrast and sensitivity. In this systematic review, we evaluated the role of DGM iron deposition as detected by MRI techniques in relation to MS-related neuroinflammation and its potential as a novel therapeutic target. We searched through PubMed, Embase, and Web of Science databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, against predetermined inclusion and exclusion criteria. We included 89 articles (n = 6630 patients), and then grouped them into different categories: i) methodological techniques to measure DGM iron, ii) cross-sectional and group comparison of DGM iron content, iii) longitudinal comparisons of DGM iron, iv) associations between DGM iron and other imaging and neurobiological markers, v) associations with disability, and vi) associations with cognitive impairment. The review revealed that iron deposition in DGM is independent yet concurrent with demyelination, and that these iron deposits contribute to MS-related cognitive impairment and disability. Variability in iron distributions appears to rely on a positive feedback loop between inflammation, and release of iron by oligodendrocytes. DGM iron seems to be a promising prognostic biomarker for MS pathophysiology.

Brain atrophy in multiple sclerosis: mechanisms, clinical relevance and treatment options

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system characterized by focal or diffuse inflammation, demyelination, axonal loss and neurodegeneration. Brain atrophy can be seen in the earliest stages of MS, progresses faster compared to healthy adults, and is a reliable predictor of future physical and cognitive disability. In addition, it is widely accepted to be a valid, sensitive and reproducible measure of neurodegeneration in MS. Reducing the rate of brain atrophy has only recently been incorporated as a critical endpoint into the clinical trials of new or emerging disease modifying drugs (DMDs) in MS. With the advent of easily accessible neuroimaging softwares along with the accumulating evidence, clinicians may be able to use brain atrophy measures in their everyday clinical practice to monitor disease course and response to DMDs. In this review, we will describe the different mechanisms contributing to brain atrophy, their clinical relevance on disease presentation and course and the effect of current or emergent DMDs on brain atrophy and neuroprotection.

[Anemia and dysregulation of iron metabolism in multiple sclerosis]

Anemia is one of the common diseases comorbid with multiple sclerosis (MS). This article reviews the prevalence and types of anemia in MS patients. It has been shown that anemia is often accompanied by a decrease in serum iron level. The authors present the data on iron metabolism in patients with MS and MRI findings concerning deposits of iron in the gray matter of the brain. The causal relationship between abnormalities in iron metabolism and MS remains unclear; this study allows to approach the understanding of the MS pathogenesis and to increase the efficacy of therapy for this disease.

Imaging in Pediatric Demyelinating and Inflammatory Diseases of the Brain- Part 1

Imaging plays an important role in the diagnosis, management, prognostication and follow up of pediatric demyelinating and inflammatory diseases of the brain and forms an integral part of the diagnostic criteria. Conventional and advanced MR imaging is the first and only reliable imaging modality. This article reviews the typical and atypical imaging features of common and some uncommon demyelinating and inflammatory diseases with emphasis on the criteria for categorization. Imaging protocols and the role of advanced imaging techniques are also covered appropriately.

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.

Abnormal cerebellar functional MRI connectivity in patients with paediatric multiple sclerosis

Objectives:

We investigated resting state functional connectivity (RSFC) of the cerebellar dentate nuclei in paediatric MS patients and its correlations with clinical, neuropsychological and structural MRI measures.

Methods:

RSFC analysis was performed using a seed-region correlation approach and SPM8 from 48 paediatric MS patients and 27 matched healthy controls.

Results:

In both groups, dentate nuclei RSFC was significantly correlated with RSFC of several cerebellar and extra-cerebellar brain regions. Compared with healthy controls, paediatric MS patients had reduced RSFC between the right dentate nuclei and the bilateral caudate nuclei and left thalamus as well as increased RSFC between the right dentate nuclei and the left precentral and postcentral gyri. Cognitively impaired patients showed a reduced RSFC between the dentate nuclei and bilateral regions located in the parietal, frontal and temporal lobes. Decreased RSFC was correlated with longer disease duration and higher T2 lesion volumes, whereas increased RSFC correlated with shorter disease duration, lower T2 lesion volume and a better motor performance.

Conclusions:

Modifications of cerebellar RSFC occur in paediatric MS and are influenced by the duration of the disease and brain focal lesions. Decreased RSFC may reflect early maladaptive plasticity contributing to cognitive impairment.

Quantification of Nonenhancing Tumor Burden in Gliomas Using Effective T2 Maps Derived from Dual-Echo Turbo Spin-Echo MRI

PURPOSE

Evaluation of nonenhancing tumor (NET) burden is an important yet challenging part of brain tumor response assessment. This study focuses on using dual-echo turbo spin-echo MRI as a means of quickly estimating tissue T2, which can be used to objectively define NET burden.

EXPERIMENTAL DESIGN

A series of experiments were performed to establish the use of T2 maps for defining NET burden. First, variation in T2 was determined using the American College of Radiology (ACR) water phantoms in 16 scanners evaluated over 3 years. Next, the sensitivity and specificity of T2 maps for delineating NET from other tissues were examined. Then, T2-defined NET was used to predict survival in separate subsets of patients with glioblastoma treated with radiotherapy, concurrent radiation, and chemotherapy, or bevacizumab at recurrence.

RESULTS

Variability in T2 in the ACR phantom was 3% to 5%. In training data, ROC analysis suggested that 125 ms < T2 < 250 ms could delineate NET with a sensitivity of >90% and specificity of >65%. Using this criterion, NET burden after completion of radiotherapy alone, or concurrent radiotherapy, and chemotherapy was shown to be predictive of survival (Cox, P < 0.05), and the change in NET volume before and after bevacizumab therapy in recurrent glioblastoma was also a predictive of survival (P < 0.05).

CONCLUSIONS

T2 maps using dual-echo data are feasible, stable, and can be used to objectively define NET burden for use in brain tumor characterization, prognosis, and response assessment. The use of effective T2 maps for defining NET burden should be validated in a randomized, clinical trial.

A pilot, longitudinal, 24-week study to evaluate the effect of interferon beta-1a subcutaneous on changes in susceptibility-weighted imaging-filtered phase assessment of lesions and subcortical deep-gray matter in relapsing-remitting multiple sclerosis

BACKGROUND

Studies have shown a relationship between increased iron content and clinical progression, cognitive impairment, and brain atrophy in patients with multiple sclerosis. Altered phase, as determined by susceptibility-weighted imaging (SWI), can potentially capture iron content changes.

OBJECTIVE

The objective of this study was to investigate phase changes in white matter (WM) lesions and subcortical deep-gray matter (SDGM) of patients with relapsing-remitting (RR) MS treated with interferon beta-1a administered subcutaneously versus untreated healthy controls (HCs).

METHODS

We conducted a 24-week, nonrandomized, open-label pilot study of 23 patients with RRMS receiving interferon beta-1a administered subcutaneously and 15 HCs. Patients were imaged on a 3T scanner at baseline, 12, and 24 weeks; changes in phase behavior in WM lesions and regional SDGM [mean phase of low-phase voxels (MP-LPV)], and in SDGM volumes, were measured. Between- and within-group changes were tested using nonparametric statistics adjusted for multiple comparisons.

RESULTS

The number (p = 0.003) and volume (p < 0.001) of phase WM lesions both significantly decreased among RRMS patients over 24 weeks. At baseline, MP-LPV was lower (suggestive of greater iron content) in total SDGM among RRMS patients versus HCs (p = 0.002). Week 24 MP-LPV changes from baseline were not significantly different between groups in total SDGM or any region except the putamen (-0.0025 radians in RRMS patients versus 0.0035 radians in HCs; p = 0.041).

CONCLUSIONS

Over 24 weeks, phase lesions were reduced significantly in the RRMS group. These preliminary results suggest that SWI-filtered phase may become a useful tool for monitoring RRMS disease activity.

The prognostic utility of MRI in clinically isolated syndrome: a literature review

For patients presenting with clinically isolated syndrome, the treating clinician needs to advise the patient on the probability of conversion to clinically definite multiple sclerosis. MR imaging may give useful prognostic information, and there is large body of literature pertaining to the use of MR imaging in assessing patients presenting with clinically isolated syndrome. This literature review evaluates the accuracy of MR imaging in predicting which patients with clinically isolated syndrome will go on to develop long-term disease and/or disability. New and emerging MR imaging technologies and their applicability to patients with clinically isolated syndrome are also considered.

Iron chelation and multiple sclerosis

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

Insights from magnetic resonance imaging

Recent years have witnessed impressive advancements in the use of magnetic resonance imaging (MRI) for the assessment of patients with multiple sclerosis (MS). Complementary to the clinical evaluation, conventional MRI (cMRI) provides crucial pieces of information for the diagnosis of MS, the understanding of its natural history, and monitoring the efficacy of experimental treatments. Measures derived from cMRI present clear advantages over the clinical assessment, including their more objective nature and an increased sensitivity to MS-related changes. However, the correlation between these measures and the clinical manifestations of the disease remains weak, and this can be explained, at least partially, by the limited ability of cMRI to characterize and quantify the heterogeneous features of MS pathology. Quantitative MR-based techniques have the potential to overcome the limitations of cMRI. Magnetization transfer MRI, diffusion-weighted and diffusion tensor MRI with fiber tractography, proton magnetic resonance spectroscopy, T1 and T2 relaxation time measurement, and functional MRI are contributing to elucidate the mechanisms that underlie injury, repair, and functional adaptation in patients with MS. All conventional and nonconventional MR techniques will benefit from the use of high-field MR systems (3.0T or more).

Pediatric multiple sclerosis: pathobiological, clinical, and magnetic resonance imaging features

In this article, the pathobiological, clinical, and treatment aspects of pediatric-onset multiple sclerosis (MS) are summarized, and the conventional magnetic resonance (MR) imaging (ie, T1-weighted, proton-density, and T2-weighted imaging) features of MS in children are discussed, as well as the application of MR imaging in the diagnosis of pediatric-onset MS and in prediction of MS in children with an incident central nervous system demyelination. Insights gained from studies comparing MR imaging features of pediatric-onset and adult-onset MS are presented.

No regional gray matter atrophy differences between pediatric- and adult-onset relapsing-remitting multiple sclerosis

OBJECTIVE

To investigate differences in region-specific gray matter (GM) damage between adults with pediatric-onset (PO) multiple sclerosis (MS) and adult-onset (AO) MS.

METHODS

Twenty-four relapsing-remitting (RR) adults with POMS (mean age = 35 years, mean disease duration = 18.4 years) were compared to 23 age-matched (AOA, mean age = 33.9 years, mean disease duration = 2.4 years) and 24 disease-duration matched (AOD, mean age = 45.9 years, mean disease duration = 18.5 years) RRMS adults who developed MS after the age of 18. Three-dimensional-T1-weighted images were acquired on a 1.5 T MRI. Image analysis was conducted using voxel-based morphometry (Statistical Parametric Mapping 8).

RESULTS

There were no regional GM atrophy differences between POMS and AODMS groups. No regional GM atrophy differences were found between POMS and AOAMS patients when disease duration was included as a covariate.

CONCLUSIONS

Regional GM differences were not found between POMS adults and MS controls matched for age or disease duration. Although of limited sample size, these findings suggest that there are no regional GM atrophy differences between RR POMS and AOMS.

Iron content of the pulvinar nucleus of the thalamus is increased in adolescent multiple sclerosis

OBJECTIVE

The objective of this paper is to assess abnormal phase values, indicative of increased iron content, using susceptibility-weighted imaging (SWI)-filtered phase of the subcortical deep gray matter (SDGM) in adolescent multiple sclerosis (MS) and other neurological disorders (OND) patients, and in healthy controls (HC).

METHODS

Twenty adolescent MS and eight adolescent OND patients and 21 age- and sex-matched HC were scanned on a 3T GE scanner. Mean phase of abnormal phase tissue (MP-APT), MP-APT volume, normal phase tissue volume (NPTV) and normalized volume measurements were obtained for total SDGM, as well as specific structures separately.

RESULTS

Significantly increased MP-APT (28.2%, p<.001) and MP-APT volume (82.7%, p<.001), and decreased NPTV (-23.3%, p<.001) and normalized volume (-15.5%, p<.001) in the pulvinar nucleus of the thalamus was found in MS patients compared to HC. MP-APT in MS patients was also increased in total SDGM (p=.012) and thalamus (p=.044). Compared to OND patients, MS patients had increased MP-APT volume in the pulvinar nucleus of the thalamus (p=.044) and caudate (p=.045). Increased MP-APT of the SDGM structures were associated with increased T2 and T1 lesion burden and brain atrophy in MS patients.

CONCLUSION

Adolescent MS patients showed increased iron content in the SDGM compared to OND patients and HC.

Iron deposition on SWI-filtered phase in the subcortical deep gray matter of patients with clinically isolated syndrome may precede structure-specific atrophy

BACKGROUND AND PURPOSE

Increasing evidence suggests that iron deposition is present in the later stages of MS. In this study we examined abnormal phase values, indicative of increased iron content on SWI-filtered phase images of the SDGM in CIS patients and HC. We also examined the association of abnormal phase with conventional MR imaging outcomes at first clinical onset.

MATERIALS AND METHODS

Forty-two patients with CIS (31 female, 11 male) and 65 age and sex-matched HC (41 female, 24 male) were scanned on a 3T scanner. Mean age was 40.1 (SD = 10.4) years in patients with CIS, and 42.8 (SD = 14) years in HC, while mean disease duration was 1.2 years (SD = 1.3) in patients with CIS. MP-APT, NPTV, and normalized volume measurements were derived for all SDGM structures. Parametric and nonparametric group-wise comparisons were performed, and associations were determined with other MR imaging metrics.

RESULTS

Patients with CIS had significantly increased MP-APT (P = .029) and MP-APT volume (P = .045) in the pulvinar nucleus of the thalamus compared with HC. Furthermore, the putamen (P = .004), caudate (P = .035), and total SDGM (P = .048) displayed significant increases in MP-APT volume, while MP-APT was also significantly increased in the putamen (P = .029). No global or regional volumetric MR imaging differences were found between the study groups. Significant correlations were observed between increased MP-APT volumes of total SDGM, caudate, thalamus, hippocampus, and substantia nigra with white matter atrophy and increased T2 lesion volume (P < .05).

CONCLUSION

Patients with CIS showed significantly increased content and volume of iron, as determined by abnormal SWI-phase measurement, in the various SDGM structures, suggesting that iron deposition may precede structure-specific atrophy.

Improved T2 mapping accuracy with dual-echo turbo spin echo: effect of phase encoding profile orders

Turbo spin echo (TSE) pulse sequences have been applied to estimate T(2) relaxation times in clinically feasible scan times. However, T(2) estimations using TSE pulse sequences has been shown to differ considerable from reference standard sequences due to several sources of error. The purpose of this work was to apply voxel-sensitivity formalism to correct for one such source of error introduced by differing phase encoding profile orders with dual-echo TSE pulse sequences. The American College of Radiology phantom and the brains of two healthy volunteers were imaged using dual-echo TSE as well as 32-echo spin-echo acquisitions and T(2) estimations from uncorrected and voxel-sensitivity formalism-corrected dual-echo TSE and 32-echo acquisitions were compared. In all regions of the brain and the majority of the analyses of the American College of Radiology phantom, voxel-sensitivity formalism correction resulted in considerable improvements in dual-echo TSE T(2) estimation compared with the 32-echo acquisition, with improvements in T(2) value accuracy ranging from 5.2% to 18.6%.

Pathogenic implications of iron accumulation in multiple sclerosis

Iron, an essential element used for a multitude of biochemical reactions, abnormally accumulates in the CNS of patients with multiple sclerosis (MS). The mechanisms of abnormal iron deposition in MS are not fully understood, nor do we know whether these deposits have adverse consequences, that is, contribute to pathogenesis. With some exceptions, excess levels of iron are represented concomitantly in multiple deep gray matter structures often with bilateral representation, whereas in white matter, pathological iron deposits are usually located at sites of inflammation that are associated with veins. These distinct spatial patterns suggest disparate mechanisms of iron accumulation between these regions. Iron has been postulated to promote disease activity in MS by various means: (i) iron can amplify the activated state of microglia resulting in the increased production of proinflammatory mediators; (ii) excess intracellular iron deposits could promote mitochondria dysfunction; and (iii) improperly managed iron could catalyze the production of damaging reactive oxygen species (ROS). The pathological consequences of abnormal iron deposits may be dependent on the affected brain region and/or accumulation process. Here, we review putative mechanisms of enhanced iron uptake in MS and address the likely roles of iron in the pathogenesis of this disease.