IMT Institutional Repository: No conditions. Results ordered -Date Deposited.
2024-03-28T09:51:14Z
EPrints
http://eprints.imtlucca.it/images/logowhite.png
http://eprints.imtlucca.it/
2016-03-21T08:41:12Z
2016-03-21T08:41:12Z
http://eprints.imtlucca.it/id/eprint/3240
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3240
2016-03-21T08:41:12Z
Parcellation-based connectome assessment by using structural and functional connectivity
Connectome analysis of the human brain structural and functional architecture provides a unique opportunity to understand the organization of brain networks. In this work, we investigate a novel large scale parcellation-based connectome, merging together information coming from resting state fMRI (rs-fMRI) data and diffusion tensor imaging (DTI) measurements.
Ying-Chia Lin
yingchia.lin@imtlucca.it
Tommaso Gili
Sotirios A. Tsaftaris
Andrea Gabrielli
Mariangela Iorio
Gianfranco Spalletta
Guido Caldarelli
guido.caldarelli@imtlucca.it
2016-03-21T08:41:04Z
2016-03-21T08:41:04Z
http://eprints.imtlucca.it/id/eprint/3239
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3239
2016-03-21T08:41:04Z
A cortical and sub-cortical parcellation clustering by intrinsic functional connectivity
Network analysis of resting-state fMRI (rsfMRI) has been widely utilized to investigate the functional architecture of the whole brain. Here we propose a robust parcellation method that first divides cortical and sub-cortical regions into sub-regions by clustering the rsfMRI data for each subject independently, and then merges those individual parcellations to obtain a global whole brain parcellation. To do so our method relies on majority voting (to merge parcellations of multiple subjects) and enforces spatial constraints within a hierarchical agglomerative clustering framework to define parcels that are spatially homogeneous.
Ying-Chia Lin
yingchia.lin@imtlucca.it
Tommaso Gili
Sotirios A. Tsaftaris
Andrea Gabrielli
Mariangela Iorio
Gianfranco Spalletta
Guido Caldarelli
guido.caldarelli@imtlucca.it
2016-03-14T13:02:02Z
2016-04-06T10:06:19Z
http://eprints.imtlucca.it/id/eprint/3223
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/3223
2016-03-14T13:02:02Z
A Cortical and Sub-cortical Parcellation Clustering by Intrinsic Functional Connectivity
Network analysis of resting-state fMRI (rsfMRI) has been widely utilized to investigate the functional architecture of the whole brain. Such analysis can divide the brain into several discrete elements (nodes) connected by links (edges) representing the relation between two elements. The brain cortical and subcortical areas can be segmented or parcelled into several functional and/or structural regions. The connectome analysis of human-brain structure and functional connectivity provides a unique opportunity to understand the organisation of brain networks. However, such analyses require an appropriate definition of functional or structural nodes to efficiently represent cortical regions. In order to address this issue, here we propose a robust parcellation method based on resting-state fMRI, which can be generalized from the single-subject level to the multi-group one. Considering the input data of a single subject and constructing multi-resolution graph elements. We combined voting-based measurements to divide the cortical region into sub-regions in order to obtain the whole brain parcellation. Our parcellation relies on majority vote and poses spatial constraints within a hierarchical agglomerative clustering framework to define parcels that are spatially homogeneous. We used rsfMRI data collected from 40 healthy subjects and we showed that our purposed algorithm is able to compute stable and reproducible parcellations across the group of subjects at multi-resolution level. We find that, even though previous methods ensure on average larger overlap between parcels and regions in AAL atlas, the method proposed herein reduces inter-subject variability, especially when the number of parcels increases. Our high-resolution parcels seem to be functionally more consistent and reliable and can be a useful tool for future analysis that will aim to match functional and structural architecture of the brain.
Ying-Chia Lin
yingchia.lin@imtlucca.it
Tommaso Gili
Sotirios A. Tsaftaris
sotirios.tsaftaris@imtlucca.it
Andrea Gabrielli
Mariangela Iorio
Gianfranco Spalletta
Guido Caldarelli
guido.caldarelli@imtlucca.it
2014-12-18T12:15:05Z
2015-11-02T11:27:17Z
http://eprints.imtlucca.it/id/eprint/2425
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2425
2014-12-18T12:15:05Z
Multicontrast MRI quantification of focal inflammation and degeneration in multiple sclerosis
Local microstructural pathology in multiple sclerosis patients might influence their clinical performance. This study applied multicontrast MRI to quantify inflammation and neurodegeneration in MS lesions. We explored the impact of MRI-based lesion pathology in cognition and disability. Methods. 36 relapsing-remitting MS subjects and 18 healthy controls underwent neurological, cognitive, behavioural examinations and 3 T MRI including (i) fluid attenuated inversion recovery, double inversion recovery, and magnetization-prepared gradient echo for lesion count; (ii) T1, T2, and T2* relaxometry and magnetisation transfer imaging for lesion tissue characterization. Lesions were classified according to the extent of inflammation/neurodegeneration. A generalized linear model assessed the contribution of lesion groups to clinical performances. Results. Four lesion groups were identified and characterized by (1) absence of significant alterations, (2) prevalent inflammation, (3) concomitant inflammation and microdegeneration, and (4) prevalent tissue loss. Groups 1, 3, 4 correlated with general disability (Adj-; ), executive function (Adj-; ), verbal memory (Adj-; ), and attention (Adj-; ). Conclusion. Multicontrast MRI provides a new approach to infer in vivo histopathology of plaques. Our results support evidence that neurodegeneration is the major determinant of patients’ disability and cognitive dysfunction
Guillaume Bonnier
Alexis Roche
David Romascano
Samanta Simioni
Djalel-Eddine Meskaldji
David Rotzinger
Ying-Chia Lin
yingchia.lin@imtlucca.it
Gloria Menegaz
Myriam Schluep
Renaud Du Pasquier
Tilman Johannes Sumpf
Jens Frahm
Jean-Philippe Thiran
Gunnar Krueger
Cristina Granziera
2014-12-18T11:34:55Z
2016-04-06T09:03:15Z
http://eprints.imtlucca.it/id/eprint/2424
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2424
2014-12-18T11:34:55Z
Quantitative analysis of myelin and axonal remodeling in the uninjured motor network after stroke
Objectives: Contralesional brain connectivity plasticity was previously reported after stroke. This study aims at disentangling the biological mechanisms underlying connectivity plasticity in the uninjured motor network after an ischemic lesion. In particular, we measured generalized fractional anisotropy (GFA) and magnetization transfer ratio (MTR) to assess whether post-stroke connectivity remodeling depend on axonal and/or myelin changes. Materials and Methods: Diffusion Spectrum Imaging (DSI) and Magnetization Transfer MRI at 3T were performed in 10 patients in acute phase, at one and six months after stroke, which was affecting motor cortical and/or subcortical areas. Ten age- and gender- matched healthy volunteers were scanned one month apart for longitudinal comparison. Clinical assessment was also performed in patients prior to MRI. In the contra-lesional hemisphere, average measures and tract-based quantitative analysis of GFA and MTR was performed to assess axonal integrity and myelination along motor connections as well as their variations in time. Results and Conclusions: Mean and tract-based measures of MTR and GFA showed significant changes in a number of contralesional motor connections, confirming both axonal and myelin plasticity in our cohort of patients. Moreover, density-derived features (peak height, standard deviation-SD and skewness) of GFA and MTR along the tracts showed additional correlation with clinical scores than mean values. These findings reveal the interplay between contralateral myelin and axonal remodeling after stroke.
Ying-Chia Lin
yingchia.lin@imtlucca.it
Alessandro Daducci
Djalel-Eddine Meskaldji
Jean-Philippe Thiran
Patrik Michel
Reto A Meuli
Gunnar Krueger
Gloria Menegaz
Cristina Granziera
2014-12-18T11:19:20Z
2016-04-06T09:02:53Z
http://eprints.imtlucca.it/id/eprint/2423
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2423
2014-12-18T11:19:20Z
Advanced MRI unravels the nature of tissue alterations in early multiple sclerosis
Introduction In patients with multiple sclerosis (MS), conventional magnetic resonance imaging (MRI) provides only limited insights into the nature of brain damage with modest clinic-radiological correlation. In this study, we applied recent advances in MRI techniques to study brain microstructural alterations in early relapsing-remitting MS (RRMS) patients with minor deficits. Further, we investigated the potential use of advanced MRI to predict functional performances in these patients. Methods Brain relaxometry (T1, T2, T2*) and magnetization transfer MRI were performed at 3T in 36 RRMS patients and 18 healthy controls (HC). Multicontrast analysis was used to assess for microstructural alterations in normal-appearing (NA) tissue and lesions. A generalized linear model was computed to predict clinical performance in patients using multicontrast MRI data, conventional MRI measures as well as demographic and behavioral data as covariates. Results Quantitative T2 and T2* relaxometry were significantly increased in temporal normal-appearing white matter (NAWM) of patients compared to HC, indicating subtle microedema (P = 0.03 and 0.004). Furthermore, significant T1 and magnetization transfer ratio (MTR) variations in lesions (mean T1 z-score: 4.42 and mean MTR z-score: −4.09) suggested substantial tissue loss. Combinations of multicontrast and conventional MRI data significantly predicted cognitive fatigue (P = 0.01, Adj-R2 = 0.4), attention (P = 0.0005, Adj-R2 = 0.6), and disability (P = 0.03, Adj-R2 = 0.4). Conclusion Advanced MRI techniques at 3T, unraveled the nature of brain tissue damage in early MS and substantially improved clinical–radiological correlations in patients with minor deficits, as compared to conventional measures of disease.
Guillaume Bonnier
Alexis Roche
David Romascano
Samanta Simioni
Djalel-Eddine Meskaldji
David Rotzinger
Ying-Chia Lin
yingchia.lin@imtlucca.it
Gloria Menegaz
Myriam Schluep
Renaud Du Pasquier
Tilman Johannes Sumpf
Jens Frahm
Jean-Philippe Thiran
Gunnar Krueger
Cristina Granziera
2014-12-18T11:09:56Z
2016-04-06T09:56:55Z
http://eprints.imtlucca.it/id/eprint/2422
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2422
2014-12-18T11:09:56Z
Multicontrast connectometry: a new tool to assess cerebellum alterations in early relapsing-remitting multiple sclerosis
Background: Cerebellar pathology occurs in late multiple sclerosis (MS) but little is known about cerebellar changes during early disease stages. In this study, we propose a new multicontrast “connectometry” approach to assess the structural and functional integrity of cerebellar networks and connectivity in early MS. Methods: We used diffusion spectrum and resting-state functional MRI (rs-fMRI) to establish the structural and functional cerebellar connectomes in 28 early relapsing-remitting MS patients and 16 healthy controls (HC). We performed multicontrast “connectometry” by quantifying multiple MRI parameters along the structural tracts (generalized fractional anisotropy-GFA, T1/T2 relaxation times and magnetization transfer ratio) and functional connectivity measures. Subsequently, we assessed multivariate differences in local connections and network properties between MS and HC subjects; finally, we correlated detected alterations with lesion load, disease duration, and clinical scores. Results: In MS patients, a subset of structural connections showed quantitative MRI changes suggesting loss of axonal microstructure and integrity (increased T1 and decreased GFA, P < 0.05). These alterations highly correlated with motor, memory and attention in patients, but were independent of cerebellar lesion load and disease duration. Neither network organization nor rs-fMRI abnormalities were observed at this early stage. Conclusion: Multicontrast cerebellar connectometry revealed subtle cerebellar alterations in MS patients, which were independent of conventional disease markers and highly correlated with patient function. Future work should assess the prognostic value of the observed damage. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
David Romascano
Djalel-Eddine Meskaldji
Guillaume Bonnier
Samanta Simioni
David Rotzinger
Ying-Chia Lin
yingchia.lin@imtlucca.it
Gloria Menegaz
Alexis Roche
Myriam Schluep
Renaud Du Pasquier
Jonas Richiardi
Dimitri Van De Ville
Alessandro Daducci
Tilman Johannes Sumpf
Jens Fraham
Jean-Philippe Thiran
Gunnar Krueger
Cristina Granziera
2014-12-18T11:04:46Z
2014-12-18T11:04:46Z
http://eprints.imtlucca.it/id/eprint/2421
This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/2421
2014-12-18T11:04:46Z
Quantitative comparison of reconstruction methods for intra-voxel fiber recovery from diffusion MRI
Validation is arguably the bottleneck in the diffusion magnetic resonance imaging (MRI) community. This paper evaluates and compares 20 algorithms for recovering the local intra-voxel fiber structure from diffusion MRI data and is based on the results of the “HARDI reconstruction challenge” organized in the context of the “ISBI 2012” conference. Evaluated methods encompass a mixture of classical techniques well known in the literature such as diffusion tensor, Q-Ball and diffusion spectrum imaging, algorithms inspired by the recent theory of compressed sensing and also brand new approaches proposed for the first time at this contest. To quantitatively compare the methods under controlled conditions, two datasets with known ground-truth were synthetically generated and two main criteria were used to evaluate the quality of the reconstructions in every voxel: correct assessment of the number of fiber populations and angular accuracy in their orientation. This comparative study investigates the behavior of every algorithm with varying experimental conditions and highlights strengths and weaknesses of each approach. This information can be useful not only for enhancing current algorithms and develop the next generation of reconstruction methods, but also to assist physicians in the choice of the most adequate technique for their studies.
Alessandro Daducci
Erick Jorge Canales-Rodriguez
Maxime Descoteaux
Eleftherios Garyfallidis
Yaniv Gur
Ying-Chia Lin
yingchia.lin@imtlucca.it
Merry Mani
Sylvain Merlet
Michael Paquette
Alonso Ramirez-Manzanares
Marco Reisert
Paulo Reis Rodrigues
Farshid Sepehrband
Emmanuel Caruyer
Jeiran Choupan
Rachid Deriche
Matthew Jacob
Gloria Menegaz
Vesna Prckovska
Mariano Rivera
Yves Wiaux
Jean-Philippe Thiran