Assessment of cortical damage in early multiple sclerosis with quantitative T2 relaxometry.

T2 relaxation time is a quantitative MRI in vivo surrogate of cerebral tissue damage in multiple sclerosis (MS) patients. Cortical T2 prolongation is a known feature in later disease stages, but has not been demonstrated in the cortical normal appearing gray matter (NAGM) in early MS. This study centers on the quantitative evaluation of the tissue parameter T2 in cortical NAGM in a collective of early MS and clinically isolated syndrome (CIS) patients, hypothesizing that T2 prolongation is already present at early disease stages and variable over space, in line with global and focal inflammatory processes in MS. Additionally, magnetization transfer ratio (MTR) mapping was performed for further characterization of the expected cortical T2 alteration. Quantitative T2 and MTR maps were acquired from 12 patients with CIS and early MS, and 12 matched healthy controls. The lesion-free part of the cortical volume was identified, and the mean T2 and MTR values and their standard deviations within the cortical volume were determined. For evaluation of spatial specificity, cortical lobar subregions were tested separately for differences of mean T2 and T2 standard deviation. We detected significantly prolonged T2 in cortical NAGM in patients. T2 prolongation was found across the whole cerebral cortex and in all individual lobar subregions. Significantly higher standard deviations across the respective region of interest were found for the whole cerebral cortex and all subregions, suggesting the occurrence of spatially inhomogeneous cortical damage in all regions studied. A trend was observed for MTR reduction and increased MTR variability across the whole cortex in the MS group, suggesting demyelination. In conclusion, our results suggest that cortical damage in early MS is evidenced by spatially inhomogeneous T2 prolongation which goes beyond demyelination. Iron deposition, which is known to decrease T2, seems less prominent.

Quantitative T1 and proton density mapping with direct calculation of radiofrequency coil transmit and receive profiles from two-point variable flip angle data.

Quantitative T1 mapping of brain tissue is frequently based on the variable flip angle (VFA) method, acquiring spoiled gradient echo (GE) datasets at different excitation angles. However, accurate T1 calculation requires a knowledge of the sensitivity profile B1 of the radiofrequency (RF) transmit coil. For an additional derivation of proton density (PD) maps, the receive coil sensitivity profile (RP) must also be known. Mapping of B1 and RP increases the experiment duration, which may be critical when investigating patients. In this work, a method is presented for the direct calculation of B1 and RP from VFA data. Thus, quantitative maps of T1 , PD, B1 and RP can be obtained from only two spoiled GE datasets. The method is based on: (1) the exploitation of the linear relationship between 1/PD and 1/T1 in brain tissue and (2) the assumption of smoothly varying B1 and RP, so that a large number of data points can be fitted across small volume elements where B1 and RP are approximately constant. The method is tested and optimized on healthy subjects. Copyright © 2016 John Wiley & Sons, Ltd.

Structural correlates for fatigue in early relapsing remitting multiple sclerosis.

OBJECTIVES: Fatigue is a common symptom in multiple sclerosis (MS) patients, even early in the disease, but the pathophysiology remains unclear. We aimed to determine morphologic and microstructural correlates and neuropsychological parameters of cognitive fatigue in early relapsing-remitting MS patients. METHODS: Seventy-nine early relapsing-remitting MS patients (38 with fatigue and 41 without), none of whom suffered from depression, underwent neuropsychological testing. Magnetic resonance imaging was performed using anatomical and diffusion tensor imaging sequences on all patients and 40 controls. Voxel-based morphologic analysis and tract-based spatial statistics were performed. RESULTS: Only patients with cognitive fatigue, but not those without, exhibited alterations in the thalamic region, showing reduced thalamic fractional anisotropy and increased mean diffusivity values. No differences in lesion volume and lesion distribution were observed between patient groups. In cognitive tests, no significant differences were found between the two groups in the number of patients with pathologic scores; however, subjective cognitive impairment differed. CONCLUSION: Morphological alterations and distinct microstructural changes (mainly in the thalamus) but not typical MS lesions were found to be related to cognitive fatigue in early MS. We suggest that compensatory processes adapting to these changes could initially facilitate normal cognitive performance, but also result in a feeling of fatigue. KEY POINTS: • Morphological alterations and microstructural changes are related to fatigue in multiple sclerosis • Thalamic alterations in particular were related to fatigue in early MS • Fatigued patients exhibited subjective but not measurable cognitive impairment • Compensatory processes help preserve or maintain cognitive performance but also contribute to fatigue.

Flow cytometric analysis of T cell/monocyte ratio in clinically isolated syndrome identifies patients at risk of rapid disease progression.

BACKGROUND: Multiple sclerosis is a chronic inflammatory central nervous system disease diagnosed by clinical presentation and characteristic magnetic resonance imaging findings. The role of cerebrospinal fluid (CSF) analysis has been emphasized in particular in the context of differential diagnosis in patients with a first episode suggestive of multiple sclerosis. OBJECTIVE: We investigated here the potential additional value of analysis of CSF cellularity by fluorescence activated cell sorting (FACS) in the setting of a routine diagnostic work-up in our inpatient clinic. METHODS: CSF cells from back-up samples from patients with suspected chronic inflammatory central nervous system disorder were analyzed by FACS and correlated with clinical data, magnetic resonance imaging findings and oligoclonal band status. RESULTS: We found distinct changes of T cell/monocyte (CD4/CD14) and B cell/monocyte (CD20/CD14) ratios between clinically isolated syndrome (CIS)/multiple sclerosis and other neurologic diseases or other inflammatory neurologic diseases. In particular, patients with a rapid transition from CIS to multiple sclerosis had an elevated CD4/CD14 ratio. A subgroup analysis showed diagnostic value of CD4/CD8 ratio in the differential diagnosis of CIS/multiple sclerosis to neurosarcoidosis. CONCLUSION: The diagnostic and prognostic accuracy of autoimmune neuroinflammatory diseases can be improved by FACS analysis of CSF cells.

Changes and variability of proton density and T1 relaxation times in early multiple sclerosis: MRI markers of neuronal damage in the cerebral cortex.

OBJECTIVES: Proton density (PD) and T1 relaxation time are promising quantitative MRI (qMRI) markers of neuronal damage in multiple sclerosis (MS). However, it is unknown whether cortical differences of these parameters between patients and controls exist in the early stages of disease. This study investigates cortical T1 and PD in early MS stages, hypothesizing that these are altered and display a high spatial variability. METHODS: Quantitative T1 and PD mapping was performed on 11 patients with clinically isolated syndrome (CIS)/early MS in remission and 11 healthy controls. The normal appearing cortical gray matter was extracted, lobar regions were identified, and mean values and standard deviations of both parameters were calculated within each region. RESULTS: Increased PD was detected in MS/CIS patients in the cerebral cortex as a whole and all subregions, indicating an increase of water content. Increase of PD variability reached significance in the whole cortex and in the frontal and parietal regions. Longer T1 relaxation times and increased variability were found in the cerebral cortex in all regions studied, indicating a change of microstructural tissue composition that is spatially heterogeneous. CONCLUSIONS: The data show spatially heterogeneous cortical involvement in early MS is reflected in T1 and PD qMRI. KEY POINTS: • Cortical involvement in early MS is reflected in T1/PD quantitative MRI. • The changes are spatially heterogeneous. • Cortical damage goes beyond increased water content.

The impact of isolated lesions on white-matter fiber tracts in multiple sclerosis patients.

Infratentorial lesions have been assigned an equivalent weighting to supratentorial plaques in the new McDonald criteria for diagnosing multiple sclerosis. Moreover, their presence has been shown to have prognostic value for disability. However, their spatial distribution and impact on network damage is not well understood. As a preliminary step in this study, we mapped the overall infratentorial lesion pattern in relapsing-remitting multiple sclerosis patients (N = 317) using MRI, finding the pons (lesion density, 14.25/cm(3)) and peduncles (13.38/cm(3)) to be predilection sites for infratentorial lesions. Based on these results, 118 fiber bundles from 15 healthy controls and a subgroup of 23 patients showing lesions unilaterally at the predilection sites were compared using diffusion tensor imaging to analyze the impact of an isolated infratentorial lesion on the affected fiber tracts. Fractional anisotropy, mean diffusion as well as axial and radial diffusivity were investigated at the lesion site and along the entire fiber tract. Infratentorial lesions were found to have an impact on the fractional anisotropy and radial diffusivity not only at the lesion site itself but also along the entire affected fiber tract. As previously found in animal experiments, inflammatory attack in the posterior fossa in multiple sclerosis impacts the whole affected fiber tract. Here, this damaging effect, reflected by changes in diffusivity measures, was detected in vivo in multiple sclerosis patients in early stages of the disease, thus demonstrating the influence of a focal immune attack on more distant networks, and emphasizing the pathophysiological role of Wallerian degeneration in multiple sclerosis.

Putaminal alteration in multiple sclerosis patients with spinal cord lesions.

Typical multiple sclerosis (MS) lesions occur in the brain as well as in the spinal cord. However, two extreme magnetic resonance imaging phenotypes appear occasionally: those with predominantly spinal cord lesions (MS + SL) and those with cerebral lesions and no detectable spinal lesions (MS + CL). We assessed whether morphological differences can be found between these two extreme phenotypes. We examined 19 patients with MS + SL, 18 with MS + CL and 20 controls. All subjects were examined using magnetic resonance imaging, including anatomical and diffusion tensor imaging sequences. Voxel-based morphologic and regions of interest-based analyses and tract-based spatial statistics were performed. Patients also underwent neuropsychological testing. Demographic, clinical and neuropsychological characteristics did not differ between MS + SL and MS + CL patients. Patients with MS + SL showed significantly larger putamen volumes than those with MS + CL which correlated negatively with disability. Compared to controls, only MS + CL revealed clear cortical and deep gray matter atrophy, which correlated with cerebral lesion volume. Additionally, extensive white matter microstructural damage was found only in MS + CL compared to MS + SL and controls in the tract-based spatial statistics. Higher putamen volumes in MS + SL could suggest compensatory mechanisms in this area responsible for motor control. Widely reduced fractional anisotropy values in MS + CL were caused by higher cerebral lesion volume and thus presumably stronger demyelination, which subsequently leads to higher global gray matter atrophy.