showing 17 related works from this author
Multimodal quantitative MRI assessment of cortical damage in relapsing-remitting multiple sclerosis
2016
Purpose To investigate magnetization transfer ratio (MTR), T1 relaxation time, and proton density (PD) as indicators of gray matter damage in relapsing-remitting multiple sclerosis (RRMS), reflecting different aspects of microstructural damage and as imaging correlates of clinical disability. We aimed to determine which of these parameters may optimally quantify cortical damage, and serve as an imaging surrogate of clinical disability. In this study, cortical values of MTR, a surrogate for demyelination in MS, of PD, reflecting replacement of neural tissue by water, and of T1 , indicating a complex array of microstructural changes, were assessed in a group of RRMS patients in comparison to …
Longitudinal quantitative MRI assessment of cortical damage in multiple sclerosis: A pilot study
2017
PURPOSE Quantitative MRI (qMRI) allows assessing cortical pathology in multiple sclerosis (MS) on a microstructural level, where cortical damage has been shown to prolong T1 -relaxation time and increase proton density (PD) compared to controls. However, the evolution of these changes in MS over time has not been investigated so far. In this pilot study we used an advanced method for the longitudinal assessment of cortical tissue change in MS patients with qMRI in comparison to cortical atrophy, as derived from conventional MRI. MATERIALS AND METHODS Twelve patients with relapsing-remitting MS underwent 3T T1 /PD-mapping at two timepoints with a mean interval of 12 months. The respective co…
Supplement_TAND_050219 – Supplemental material for Longitudinal cortical network reorganization in early relapsing–remitting multiple sclerosis
2019
Supplemental material, Supplement_TAND_050219 for Longitudinal cortical network reorganization in early relapsing–remitting multiple sclerosis by Vinzenz Fleischer, Nabin Koirala, Amgad Droby, René-Maxime Gracien, Ralf Deichmann, Ulf Ziemann, Sven G. Meuth, Muthuraman Muthuraman, Frauke Zipp and Sergiu Groppa in Therapeutic Advances in Neurological Disorders
Testing different ICA algorithms and connectivity analyses on MS patients.
2015
Multiple sclerosis (MS) is a progressive neurological disorder that affects the central nervous system. Functional magnetic resonance imaging (fMRI) has been employed to track the course and disease progression in patients with MS. The two main aims of this study were to apply in a data-driven approach the independent component analysis (ICA) in the spatial domain to depict the active sources and to look at the effective connectivity between the identified spatial sources. Several ICA algorithms have been proposed for fMRI data analysis. In this study, we aimed to test two well characterized algorithms, namely, the fast ICA and the complex infomax algorithms, followed by two effective conne…
Characterizing microstructural tissue properties in multiple sclerosis with diffusion MRI at 7 T and 3 T: The impact of the experimental design
2019
The recent introduction of advanced magnetic resonance (MR) imaging techniques to characterize focal and global degeneration in multiple sclerosis (MS), like the Composite Hindered and Restricted Model of Diffusion, or CHARMED, diffusional kurtosis imaging (DKI) and Neurite Orientation Dispersion and Density Imaging (NODDI) made available new tools to image axonal pathology non-invasively in vivo. These methods already showed greater sensitivity and specificity compared to conventional diffusion tensor-based metrics (e.g., fractional anisotropy), overcoming some of its limitations. While previous studies uncovered global and focal axonal degeneration in MS patients compared to healthy contr…
A novel automated segmentation method for retinal layers in OCT images proves retinal degeneration after optic neuritis.
2015
Aim The evaluation of inner retinal layer thickness can serve as a direct biomarker for monitoring the course of inflammatory diseases of the central nervous system such as multiple sclerosis (MS). Using optical coherence tomography (OCT), thinning of the retinal nerve fibre layer and changes in deeper retinal layers have been observed in patients with MS. Here, we first compare a novel method for automated segmentation of OCT images with manual segmentation using two cohorts of patients with MS. Using this method, we also aimed to reproduce previous findings showing retinal degeneration following optic neuritis (ON) in MS. Methods Based on a 5×5 expansion of the Prewitt operator to efficie…
Increased structural white and grey matter network connectivity compensates for functional decline in early multiple sclerosis
2016
Background: The pathology of multiple sclerosis (MS) consists of demyelination and neuronal injury, which occur early in the disease; yet, remission phases indicate repair. Whether and how the central nervous system (CNS) maintains homeostasis to counteract clinical impairment is not known. Objective: We analyse the structural connectivity of white matter (WM) and grey matter (GM) networks to understand the absence of clinical decline as the disease progresses. Methods: A total of 138 relapsing–remitting MS patients (classified into six groups by disease duration) and 32 healthy controls were investigated using 3-Tesla magnetic resonance imaging (MRI). Networks were analysed using graph the…
An improved anatomical MRI technique with suppression of fixative fluid artifacts for the investigation of human postmortem brain phantoms
2016
PURPOSE Phantoms are often used to assess MR system stability in multicenter studies. Postmortem brain phantoms best replicate human brain anatomy, allowing for a combined assessment of the MR system and software chain for data analysis. However, a wash-out of fixative fluid affecting T1 values and thus T1-weighted sequences such as magnetization-prepared 180 degrees radiofrequency pulses and rapid gradient-echo (MP-RAGE) has been reported for brain phantoms, hampering their immediate use. The purpose of this study was the creation of anatomical data that provide the characteristics of conventional data while avoiding this artifact. THEORY AND METHODS Two brain phantoms were scanned at seve…
The impact of isolated lesions on white-matter fiber tracts in multiple sclerosis patients
2015
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/cm3) and peduncles (13.38/cm3) to be predilection sites for infratentorial lesions. Based on these results, 118 fiber bundles from 15 healthy controls and a subgroup of 23 …
Gray matter network reorganization in multiple sclerosis from 7‐Tesla and 3‐Tesla MRI data
2020
[Objective]: The objective of this study was to determine the ability of 7T‐MRI for characterizing brain tissue integrity in early relapsing‐remitting MS patients compared to conventional 3T‐MRI and to investigate whether 7T‐MRI improves the performance for detecting cortical gray matter neurodegeneration and its associated network reorganization dynamics.
The Relationship between Gray Matter Quantitative MRI and Disability in Secondary Progressive Multiple Sclerosis
2016
Purpose: In secondary progressive Multiple Sclerosis (SPMS), global neurodegeneration as a driver of disability gains importance in comparison to focal inflammatory processes. However, clinical MRI does not visualize changes of tissue composition outside MS lesions. This quantitative MRI (qMRI) study investigated cortical and deep gray matter (GM) proton density (PD) values and T1 relaxation times to explore their potential to assess neuronal damage and its relationship to clinical disability in SPMS. Materials and Methods: 11 SPMS patients underwent quantitative T1 and PD mapping. Parameter values across the cerebral cortex and deep GM structures were compared with 11 healthy controls, and…
A "kissing lesion": In-vivo 7T evidence of meningeal inflammation in early multiple sclerosis
2017
Background: The role of cortical lesions (CLs) in disease progression and clinical deficits is increasingly recognized in multiple sclerosis (MS); however the origin of CLs in MS still remains unclear. Objective: Here, we report a para-sulcal CL detected two years after diagnosis in a relapsing-remitting MS (RRMS) patient without manifestation of clinical deficit. Methods: Ultra-high field (7T) MR imaging using magnetization-prepared 2 rapid acquisition gradient echoes (MP2RAGE) sequence was performed. Results: A para-sulcal CL was detected which showed hypointense rim and iso- to hyperintense core. This was detected in the proximity of the leptomeninges in the left precentral gyrus extendi…
A human post-mortem brain model for the standardization of multi-centre MRI studies
2015
Multi-centre MRI studies of the brain are essential for enrolling large and diverse patient cohorts, as required for the investigation of heterogeneous neurological and psychiatric diseases. However, the multi-site comparison of standard MRI data sets that are weighted with respect to tissue parameters such as the relaxation times (T1, T2) and proton density (PD) may be problematic, as signal intensities and image contrasts depend on site-specific details such as the sequences used, imaging parameters, and sensitivity profiles of the radiofrequency (RF) coils. Water or gel phantoms are frequently used for long-term and/or inter-site quality assessment. However, these phantoms hardly mimic t…
Assessment of cortical damage in early multiple sclerosis with quantitative T 2 relaxometry
2016
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 furt…
Functional connectivity analysis using whole brain and regional network metrics in MS patients
2016
In the present study we investigated brain network connectivity differences between patients with relapsing-remitting multiple sclerosis (RRMS) and healthy controls (HC) as derived from functional resonance magnetic imaging (fMRI) using graph theory. Resting state fMRI data of 18 RRMS patients (12 female, mean age ± SD: 42 ± 12.06 years) and 25 HC (8 female, 29.2 ± 5.38 years) were analyzed. In order to obtain information of differences in entire brain network, we focused on both, local and global network connectivity parameters. And the regional connectivity differences were assessed using regional network parameters. RRMS patients presented a significant increase of modularity in comparis…
Diagnosis of multiple sclerosis: a multicentre study to compare revised McDonald-2010 and Filippi-2010 criteria
2018
MRI has been formally included in the diagnostic work-up of patients with a suspicion of multiple sclerosis (MS) in 2001, to demonstrate disease dissemination in space (DIS) and time (DIT) and to exclude alternative diagnoses.1 Over time, these criteria have been modified to simplify their use and to clarify specific aspects (eg, spinal cord findings).2 One aspect marginally analysed in the diagnostic work-up of patients with clinically isolated syndrome (CIS) is the role of intracortical lesions (ICLs), which are a prominent feature of MS and contribute to disability and cognitive impairment.2 A single-centre study3 showed that inclusion of ICL for the evaluation of DIS in CIS increased th…
Quantitative T 1 and proton density mapping with direct calculation of radiofrequency coil transmit and receive profiles from two-point variable flip…
2016
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 …