Simultaneous brain and cervical spinal cord MP2RAGE for T1 measurement: robustness and sensitivity for tissue modification assessment in multiple sclerosis in a multicenter context

International audienceIntroductionRecent optimisations of T1 quantification through magnetization‐prepared two rapidacquisition gradient echoes (MP2RAGE; Marques et al. 2010) allow to perform both brainand cervical spinal cord acquisitions simultaneously with good trade-off between acquisitiontime, robustness and accuracy (Rasoanandrianina et al. 2019; Forodighasemabadi et al.2021). This sequence is of particular interest to investigate tissue microstructuralmodifications in pathologies such as multiple sclerosis (MS) (Demortière et al. 2020;Mchinda et al, 2021). In order to spread out the use of the MP2RAGE sequence, weevaluated the reproducibility and variability in two different centres.MethodsThe data included in this work were collected in the context of the multicentric MSTRACTS(NCT04220814), OSV-IRM (NCT05107232) and T1-M3C-SEP (FLI-RE2) studies. Sixhealthy controls (HC; F/M: 4/2, mean age 38.9 years) were scanned 3 times each(separated sessions), in two different centres both equipped with 3T Siemens scanners(Prisma with 20 channels in centre 1, Vida with 64 channels in centre 2 ). Additionally 26 HC(centre 1/2: 20/6) were scanned one time (F/M: 19/7, mean age 39.2 years). The sameacquisition protocol was performed in both centres and included MP2RAGE and B1 mapacquisitions covering both brain and cervical spinal cord (cSC). The acquisition parameterswere previously described in (Rasoanandrianina et al. 2019; 4000ms TR, 243×300mm² FOV,176 slabs, 6/8 partial Fourier (PF) factor 0.9×0.9×1mm 3 voxel size, TI1/TI2 = 650/2000ms,ɑ1/ɑ2=4/5°, GRAPPA 2). After B1 correction (Massire et al. 2016), mean T1 values wereextracted in different regions including brain white matter (bWM), deep grey matter (dGM)and cortical grey matter (cGM; all computed using CAT12 [(Ashburner and Friston 2000)])and all cSC segments (computed using the SCT toolbox [(De Leener et al. 2017)]). Weevaluated the variability between centres and subjects using linear mixed-effects modelswith subject as random effect and centre as fixed effect. The coefficients of variation (CV)and the intraclass correlations (ICC) of between-session and between-participant variabilitieswere computed according to Combès et al. (2019). In order to interpret these results withrespect to potential application in MS pathology, we also reported exploratory analysesbased on the extraction of T1 values in the same regions for 5 MS patients (centre 1/2: 3/2,same acquisition protocol and image processing) without cSC lesions.ResultsFor the whole dataset collected in HC, the mean (and standard deviation) T1 values in thebrain were 1281.5 (28.8), 1176.5 (20) and 823.9 (21.1) ms for cGM,dGM, and bWM,respectively and were ranging from 921 (22.6) to 954 (30.5) ms over the 7 cSC segments(see Fig. 1)For the brain, we observed evidence of centre differences for the three regions (all p<.01).Nevertheless, the estimated differences between centres were low, ranging from 4.71 (bWM)to 25.31 (dGM) ms (ie. 0.57 to 1.98% of the mean). Between-participant CV were 2.1, 1.7and 1.8%, and between-session CV were 0.2, 2.2 and 0.5% for bWM cGM and dGM,respectively. Between-session ICC were .01, .61 and .06 for the same regions.For the SC, we observed evidence of centre differences for all vertebrae (all p<.05), exceptC4, C5 and C7 (p=.149, .163, .062, resp.). The estimated mean differences were also low,ranging from 9.6 (C5) to 20.2 (C1) ms (ie. 1.03 to 2.15%). To simplify the results, T1 valuesfrom C3 to C5 levels were averaged. In this region, between-participant andbetween-session CV were 1.5 and 1.6%, while between-session ICC was .53.MS patients showed a mean T1 value increase ranging from 19.5 (cGM) to 44.2 (dGM) msfor the brain, and from 14 (C7) to 122.7 (C3) ms for the cSC compared to the mean in allHC. Fig. 2 shows that, for each region, the majority of patients (coloured triangles) havehigher T1 values than the third quartile of HC.DiscussionOur results showed that, even if differences exist between the two centres, the variability islow, especially for bWM (0.57 %) and central cSC segments (1.03 %). Moreover, the T1variability is primarily explained by between-participant variability for the brain and by bothsession- and participant-variabilities for cSC. The differences between scanners were foundto be less important than the differences observed between HC and MS patients with nocSC lesions. Overall, our results highlight the multicenter robustness of simultaneous brainand cervical spinal cord acquisition and its potential for further applications in multicenter MSstudies to assess regional tissue impairment

Simultaneous brain and cervical spinal cord MP2RAGE for T1 measurement: robustness and sensitivity for tissue modification assessment in multiple sclerosis in a multicenter context

International audienceIntroductionRecent optimisations of T1 quantification through magnetization‐prepared two rapidacquisition gradient echoes (MP2RAGE; Marques et al. 2010) allow to perform both brainand cervical spinal cord acquisitions simultaneously with good trade-off between acquisitiontime, robustness and accuracy (Rasoanandrianina et al. 2019; Forodighasemabadi et al.2021). This sequence is of particular interest to investigate tissue microstructuralmodifications in pathologies such as multiple sclerosis (MS) (Demortière et al. 2020;Mchinda et al, 2021). In order to spread out the use of the MP2RAGE sequence, weevaluated the reproducibility and variability in two different centres.MethodsThe data included in this work were collected in the context of the multicentric MSTRACTS(NCT04220814), OSV-IRM (NCT05107232) and T1-M3C-SEP (FLI-RE2) studies. Sixhealthy controls (HC; F/M: 4/2, mean age 38.9 years) were scanned 3 times each(separated sessions), in two different centres both equipped with 3T Siemens scanners(Prisma with 20 channels in centre 1, Vida with 64 channels in centre 2 ). Additionally 26 HC(centre 1/2: 20/6) were scanned one time (F/M: 19/7, mean age 39.2 years). The sameacquisition protocol was performed in both centres and included MP2RAGE and B1 mapacquisitions covering both brain and cervical spinal cord (cSC). The acquisition parameterswere previously described in (Rasoanandrianina et al. 2019; 4000ms TR, 243×300mm² FOV,176 slabs, 6/8 partial Fourier (PF) factor 0.9×0.9×1mm 3 voxel size, TI1/TI2 = 650/2000ms,ɑ1/ɑ2=4/5°, GRAPPA 2). After B1 correction (Massire et al. 2016), mean T1 values wereextracted in different regions including brain white matter (bWM), deep grey matter (dGM)and cortical grey matter (cGM; all computed using CAT12 [(Ashburner and Friston 2000)])and all cSC segments (computed using the SCT toolbox [(De Leener et al. 2017)]). Weevaluated the variability between centres and subjects using linear mixed-effects modelswith subject as random effect and centre as fixed effect. The coefficients of variation (CV)and the intraclass correlations (ICC) of between-session and between-participant variabilitieswere computed according to Combès et al. (2019). In order to interpret these results withrespect to potential application in MS pathology, we also reported exploratory analysesbased on the extraction of T1 values in the same regions for 5 MS patients (centre 1/2: 3/2,same acquisition protocol and image processing) without cSC lesions.ResultsFor the whole dataset collected in HC, the mean (and standard deviation) T1 values in thebrain were 1281.5 (28.8), 1176.5 (20) and 823.9 (21.1) ms for cGM,dGM, and bWM,respectively and were ranging from 921 (22.6) to 954 (30.5) ms over the 7 cSC segments(see Fig. 1)For the brain, we observed evidence of centre differences for the three regions (all p<.01).Nevertheless, the estimated differences between centres were low, ranging from 4.71 (bWM)to 25.31 (dGM) ms (ie. 0.57 to 1.98% of the mean). Between-participant CV were 2.1, 1.7and 1.8%, and between-session CV were 0.2, 2.2 and 0.5% for bWM cGM and dGM,respectively. Between-session ICC were .01, .61 and .06 for the same regions.For the SC, we observed evidence of centre differences for all vertebrae (all p<.05), exceptC4, C5 and C7 (p=.149, .163, .062, resp.). The estimated mean differences were also low,ranging from 9.6 (C5) to 20.2 (C1) ms (ie. 1.03 to 2.15%). To simplify the results, T1 valuesfrom C3 to C5 levels were averaged. In this region, between-participant andbetween-session CV were 1.5 and 1.6%, while between-session ICC was .53.MS patients showed a mean T1 value increase ranging from 19.5 (cGM) to 44.2 (dGM) msfor the brain, and from 14 (C7) to 122.7 (C3) ms for the cSC compared to the mean in allHC. Fig. 2 shows that, for each region, the majority of patients (coloured triangles) havehigher T1 values than the third quartile of HC.DiscussionOur results showed that, even if differences exist between the two centres, the variability islow, especially for bWM (0.57 %) and central cSC segments (1.03 %). Moreover, the T1variability is primarily explained by between-participant variability for the brain and by bothsession- and participant-variabilities for cSC. The differences between scanners were foundto be less important than the differences observed between HC and MS patients with nocSC lesions. Overall, our results highlight the multicenter robustness of simultaneous brainand cervical spinal cord acquisition and its potential for further applications in multicenter MSstudies to assess regional tissue impairment

Transfert d'aimantation (MTR) de l'ensemble de la moelle épinière chez des patients atteints de sclérose en plaques

International audienceObjectifs : Le ratio de transfert d’aimantation (MTR) s’est révélé prometteur pour évaluer la modification de la microstructure des tissus chez les patients atteints de sclérose en plaques (SEP). Cette exploration s’est limitée au cerveau et à la moelle épinière (ME) cervicale mais pas thoracique. L’étude des anomalies du MTR dans l’ensemble de la ME pourrait permettre une meilleure association avec le handicap chez les patients atteints de SEP. Les objectifs de cette étude sont : i) comparer les valeurs moyennes de MTR chez des patients SEP et des contrôles sains (CS) en fonction du niveau de la ME ; ii) décrire le lien entre les mesures de MTR cervical et thoracique de la ME ; iii) évaluer le lien entre lesmesures de MTR et le handicap (via le score EDSS) selon le niveau de la ME. Matériel et Méthodes : Vingt-et-un patients atteints de SEP rémittente(RRMS), 10 patients atteints de SEP progressive (PMS) et 13 CS ont eté scannés sur une IRM 3T Siemens. Le protocole d’imagerie comprenait 3 niveaux d’acquisition de transfert d’aimantation pour couvrir l’ensemble de la ME. Pour chaque sujet, les cartes MTR et la localisation des vertèbres ont été calculées à l’aide de l’outil SCT. Les moyennes de MTR ont été calculées pour les niveaux vertébraux cérébraux C4 à C6 et thoraciques T4 à T6 et T9 à T10. Les différences entre les groupes ainsi que les corrélations avec les lésions dans l’ensemble du SC et avec l’EDSS ont été évaluées, avec l’âge en covariable.Résultats : Une différence significative entre les groupes a été trouvée uniquement dans la ME cervicale (C4C6 ; MTR moyen=41.7pu, 39.4pu, 35.4pu pour CS, RRMS et PMS respectivement ; p<.001), pas dans la ME thoracique. Une association positive a été observée entre les MTR moyens dans la ME cervicale et thoracique (r=.45, p=.01 pour T4T6 ; r=.54, p=.002 pour T9T10) chez les patients atteints de SEP. Nous avons également observé des associations négatives entre le MTR moyen dans la ME cervicale et l’EDSS (r=-.51, p=.004) et entre le MTR moyen dans la ME cervicale et la charge lésionnelle au niveau de la ME (r=-.6, p<.001), alors qu’aucune corrélation claire n’a été trouvée entre la charge lésionnelle de la ME et l’EDSS (r=.35 ; p=.084). Aucune association n’a été trouvée entre le MTR moyen dans la ME thoracique et le score EDSS.Conclusion : Les dommages microstructuraux de la ME des patients atteintsde SEP semblent être prédominants dans la partie cervicale et sont liés à la charge lésionnelle et au handicap. Dans notre échantillon de données, la valeur ajoutée de l’exploration de la ME thoracique en plus de la ME cervicale en utilisant le MTR pour expliquer le handicap chez les patients atteints de SEP semble limitée. Une plus grande variabilité du MTR dans la ME thoracique et la localisation préférentielle des lésions au niveau cervicale de la ME pourraient expliquer ces résultats

Simultaneous brain and cervical spinal cord MP2RAGE for T1 measurement: robustness and sensitivity for tissue modification assessment in multiple sclerosis in a multicenter context

International audienceIntroductionRecent optimisations of T1 quantification through magnetization‐prepared two rapidacquisition gradient echoes (MP2RAGE; Marques et al. 2010) allow to perform both brainand cervical spinal cord acquisitions simultaneously with good trade-off between acquisitiontime, robustness and accuracy (Rasoanandrianina et al. 2019; Forodighasemabadi et al.2021). This sequence is of particular interest to investigate tissue microstructuralmodifications in pathologies such as multiple sclerosis (MS) (Demortière et al. 2020;Mchinda et al, 2021). In order to spread out the use of the MP2RAGE sequence, weevaluated the reproducibility and variability in two different centres.MethodsThe data included in this work were collected in the context of the multicentric MSTRACTS(NCT04220814), OSV-IRM (NCT05107232) and T1-M3C-SEP (FLI-RE2) studies. Sixhealthy controls (HC; F/M: 4/2, mean age 38.9 years) were scanned 3 times each(separated sessions), in two different centres both equipped with 3T Siemens scanners(Prisma with 20 channels in centre 1, Vida with 64 channels in centre 2 ). Additionally 26 HC(centre 1/2: 20/6) were scanned one time (F/M: 19/7, mean age 39.2 years). The sameacquisition protocol was performed in both centres and included MP2RAGE and B1 mapacquisitions covering both brain and cervical spinal cord (cSC). The acquisition parameterswere previously described in (Rasoanandrianina et al. 2019; 4000ms TR, 243×300mm² FOV,176 slabs, 6/8 partial Fourier (PF) factor 0.9×0.9×1mm 3 voxel size, TI1/TI2 = 650/2000ms,ɑ1/ɑ2=4/5°, GRAPPA 2). After B1 correction (Massire et al. 2016), mean T1 values wereextracted in different regions including brain white matter (bWM), deep grey matter (dGM)and cortical grey matter (cGM; all computed using CAT12 [(Ashburner and Friston 2000)])and all cSC segments (computed using the SCT toolbox [(De Leener et al. 2017)]). Weevaluated the variability between centres and subjects using linear mixed-effects modelswith subject as random effect and centre as fixed effect. The coefficients of variation (CV)and the intraclass correlations (ICC) of between-session and between-participant variabilitieswere computed according to Combès et al. (2019). In order to interpret these results withrespect to potential application in MS pathology, we also reported exploratory analysesbased on the extraction of T1 values in the same regions for 5 MS patients (centre 1/2: 3/2,same acquisition protocol and image processing) without cSC lesions.ResultsFor the whole dataset collected in HC, the mean (and standard deviation) T1 values in thebrain were 1281.5 (28.8), 1176.5 (20) and 823.9 (21.1) ms for cGM,dGM, and bWM,respectively and were ranging from 921 (22.6) to 954 (30.5) ms over the 7 cSC segments(see Fig. 1)For the brain, we observed evidence of centre differences for the three regions (all p<.01).Nevertheless, the estimated differences between centres were low, ranging from 4.71 (bWM)to 25.31 (dGM) ms (ie. 0.57 to 1.98% of the mean). Between-participant CV were 2.1, 1.7and 1.8%, and between-session CV were 0.2, 2.2 and 0.5% for bWM cGM and dGM,respectively. Between-session ICC were .01, .61 and .06 for the same regions.For the SC, we observed evidence of centre differences for all vertebrae (all p<.05), exceptC4, C5 and C7 (p=.149, .163, .062, resp.). The estimated mean differences were also low,ranging from 9.6 (C5) to 20.2 (C1) ms (ie. 1.03 to 2.15%). To simplify the results, T1 valuesfrom C3 to C5 levels were averaged. In this region, between-participant andbetween-session CV were 1.5 and 1.6%, while between-session ICC was .53.MS patients showed a mean T1 value increase ranging from 19.5 (cGM) to 44.2 (dGM) msfor the brain, and from 14 (C7) to 122.7 (C3) ms for the cSC compared to the mean in allHC. Fig. 2 shows that, for each region, the majority of patients (coloured triangles) havehigher T1 values than the third quartile of HC.DiscussionOur results showed that, even if differences exist between the two centres, the variability islow, especially for bWM (0.57 %) and central cSC segments (1.03 %). Moreover, the T1variability is primarily explained by between-participant variability for the brain and by bothsession- and participant-variabilities for cSC. The differences between scanners were foundto be less important than the differences observed between HC and MS patients with nocSC lesions. Overall, our results highlight the multicenter robustness of simultaneous brainand cervical spinal cord acquisition and its potential for further applications in multicenter MSstudies to assess regional tissue impairment

Simultaneous brain and cervical spinal cord MP2RAGE for T1 measurement: robustness and sensitivity for tissue modification assessment in multiple sclerosis in a multicenter context

International audienceIntroductionRecent optimisations of T1 quantification through magnetization‐prepared two rapidacquisition gradient echoes (MP2RAGE; Marques et al. 2010) allow to perform both brainand cervical spinal cord acquisitions simultaneously with good trade-off between acquisitiontime, robustness and accuracy (Rasoanandrianina et al. 2019; Forodighasemabadi et al.2021). This sequence is of particular interest to investigate tissue microstructuralmodifications in pathologies such as multiple sclerosis (MS) (Demortière et al. 2020;Mchinda et al, 2021). In order to spread out the use of the MP2RAGE sequence, weevaluated the reproducibility and variability in two different centres.MethodsThe data included in this work were collected in the context of the multicentric MSTRACTS(NCT04220814), OSV-IRM (NCT05107232) and T1-M3C-SEP (FLI-RE2) studies. Sixhealthy controls (HC; F/M: 4/2, mean age 38.9 years) were scanned 3 times each(separated sessions), in two different centres both equipped with 3T Siemens scanners(Prisma with 20 channels in centre 1, Vida with 64 channels in centre 2 ). Additionally 26 HC(centre 1/2: 20/6) were scanned one time (F/M: 19/7, mean age 39.2 years). The sameacquisition protocol was performed in both centres and included MP2RAGE and B1 mapacquisitions covering both brain and cervical spinal cord (cSC). The acquisition parameterswere previously described in (Rasoanandrianina et al. 2019; 4000ms TR, 243×300mm² FOV,176 slabs, 6/8 partial Fourier (PF) factor 0.9×0.9×1mm 3 voxel size, TI1/TI2 = 650/2000ms,ɑ1/ɑ2=4/5°, GRAPPA 2). After B1 correction (Massire et al. 2016), mean T1 values wereextracted in different regions including brain white matter (bWM), deep grey matter (dGM)and cortical grey matter (cGM; all computed using CAT12 [(Ashburner and Friston 2000)])and all cSC segments (computed using the SCT toolbox [(De Leener et al. 2017)]). Weevaluated the variability between centres and subjects using linear mixed-effects modelswith subject as random effect and centre as fixed effect. The coefficients of variation (CV)and the intraclass correlations (ICC) of between-session and between-participant variabilitieswere computed according to Combès et al. (2019). In order to interpret these results withrespect to potential application in MS pathology, we also reported exploratory analysesbased on the extraction of T1 values in the same regions for 5 MS patients (centre 1/2: 3/2,same acquisition protocol and image processing) without cSC lesions.ResultsFor the whole dataset collected in HC, the mean (and standard deviation) T1 values in thebrain were 1281.5 (28.8), 1176.5 (20) and 823.9 (21.1) ms for cGM,dGM, and bWM,respectively and were ranging from 921 (22.6) to 954 (30.5) ms over the 7 cSC segments(see Fig. 1)For the brain, we observed evidence of centre differences for the three regions (all p<.01).Nevertheless, the estimated differences between centres were low, ranging from 4.71 (bWM)to 25.31 (dGM) ms (ie. 0.57 to 1.98% of the mean). Between-participant CV were 2.1, 1.7and 1.8%, and between-session CV were 0.2, 2.2 and 0.5% for bWM cGM and dGM,respectively. Between-session ICC were .01, .61 and .06 for the same regions.For the SC, we observed evidence of centre differences for all vertebrae (all p<.05), exceptC4, C5 and C7 (p=.149, .163, .062, resp.). The estimated mean differences were also low,ranging from 9.6 (C5) to 20.2 (C1) ms (ie. 1.03 to 2.15%). To simplify the results, T1 valuesfrom C3 to C5 levels were averaged. In this region, between-participant andbetween-session CV were 1.5 and 1.6%, while between-session ICC was .53.MS patients showed a mean T1 value increase ranging from 19.5 (cGM) to 44.2 (dGM) msfor the brain, and from 14 (C7) to 122.7 (C3) ms for the cSC compared to the mean in allHC. Fig. 2 shows that, for each region, the majority of patients (coloured triangles) havehigher T1 values than the third quartile of HC.DiscussionOur results showed that, even if differences exist between the two centres, the variability islow, especially for bWM (0.57 %) and central cSC segments (1.03 %). Moreover, the T1variability is primarily explained by between-participant variability for the brain and by bothsession- and participant-variabilities for cSC. The differences between scanners were foundto be less important than the differences observed between HC and MS patients with nocSC lesions. Overall, our results highlight the multicenter robustness of simultaneous brainand cervical spinal cord acquisition and its potential for further applications in multicenter MSstudies to assess regional tissue impairment

Transfert d'aimantation (MTR) de l'ensemble de la moelle épinière chez des patients atteints de sclérose en plaques

International audienceObjectifs : Le ratio de transfert d’aimantation (MTR) s’est révélé prometteur pour évaluer la modification de la microstructure des tissus chez les patients atteints de sclérose en plaques (SEP). Cette exploration s’est limitée au cerveau et à la moelle épinière (ME) cervicale mais pas thoracique. L’étude des anomalies du MTR dans l’ensemble de la ME pourrait permettre une meilleure association avec le handicap chez les patients atteints de SEP. Les objectifs de cette étude sont : i) comparer les valeurs moyennes de MTR chez des patients SEP et des contrôles sains (CS) en fonction du niveau de la ME ; ii) décrire le lien entre les mesures de MTR cervical et thoracique de la ME ; iii) évaluer le lien entre lesmesures de MTR et le handicap (via le score EDSS) selon le niveau de la ME. Matériel et Méthodes : Vingt-et-un patients atteints de SEP rémittente(RRMS), 10 patients atteints de SEP progressive (PMS) et 13 CS ont eté scannés sur une IRM 3T Siemens. Le protocole d’imagerie comprenait 3 niveaux d’acquisition de transfert d’aimantation pour couvrir l’ensemble de la ME. Pour chaque sujet, les cartes MTR et la localisation des vertèbres ont été calculées à l’aide de l’outil SCT. Les moyennes de MTR ont été calculées pour les niveaux vertébraux cérébraux C4 à C6 et thoraciques T4 à T6 et T9 à T10. Les différences entre les groupes ainsi que les corrélations avec les lésions dans l’ensemble du SC et avec l’EDSS ont été évaluées, avec l’âge en covariable.Résultats : Une différence significative entre les groupes a été trouvée uniquement dans la ME cervicale (C4C6 ; MTR moyen=41.7pu, 39.4pu, 35.4pu pour CS, RRMS et PMS respectivement ; p<.001), pas dans la ME thoracique. Une association positive a été observée entre les MTR moyens dans la ME cervicale et thoracique (r=.45, p=.01 pour T4T6 ; r=.54, p=.002 pour T9T10) chez les patients atteints de SEP. Nous avons également observé des associations négatives entre le MTR moyen dans la ME cervicale et l’EDSS (r=-.51, p=.004) et entre le MTR moyen dans la ME cervicale et la charge lésionnelle au niveau de la ME (r=-.6, p<.001), alors qu’aucune corrélation claire n’a été trouvée entre la charge lésionnelle de la ME et l’EDSS (r=.35 ; p=.084). Aucune association n’a été trouvée entre le MTR moyen dans la ME thoracique et le score EDSS.Conclusion : Les dommages microstructuraux de la ME des patients atteintsde SEP semblent être prédominants dans la partie cervicale et sont liés à la charge lésionnelle et au handicap. Dans notre échantillon de données, la valeur ajoutée de l’exploration de la ME thoracique en plus de la ME cervicale en utilisant le MTR pour expliquer le handicap chez les patients atteints de SEP semble limitée. Une plus grande variabilité du MTR dans la ME thoracique et la localisation préférentielle des lésions au niveau cervicale de la ME pourraient expliquer ces résultats

Transfert d'aimantation (MTR) de l'ensemble de la moelle épinière chez des patients atteints de sclérose en plaques

International audienceObjectifs : Le ratio de transfert d’aimantation (MTR) s’est révélé prometteur pour évaluer la modification de la microstructure des tissus chez les patients atteints de sclérose en plaques (SEP). Cette exploration s’est limitée au cerveau et à la moelle épinière (ME) cervicale mais pas thoracique. L’étude des anomalies du MTR dans l’ensemble de la ME pourrait permettre une meilleure association avec le handicap chez les patients atteints de SEP. Les objectifs de cette étude sont : i) comparer les valeurs moyennes de MTR chez des patients SEP et des contrôles sains (CS) en fonction du niveau de la ME ; ii) décrire le lien entre les mesures de MTR cervical et thoracique de la ME ; iii) évaluer le lien entre lesmesures de MTR et le handicap (via le score EDSS) selon le niveau de la ME. Matériel et Méthodes : Vingt-et-un patients atteints de SEP rémittente(RRMS), 10 patients atteints de SEP progressive (PMS) et 13 CS ont eté scannés sur une IRM 3T Siemens. Le protocole d’imagerie comprenait 3 niveaux d’acquisition de transfert d’aimantation pour couvrir l’ensemble de la ME. Pour chaque sujet, les cartes MTR et la localisation des vertèbres ont été calculées à l’aide de l’outil SCT. Les moyennes de MTR ont été calculées pour les niveaux vertébraux cérébraux C4 à C6 et thoraciques T4 à T6 et T9 à T10. Les différences entre les groupes ainsi que les corrélations avec les lésions dans l’ensemble du SC et avec l’EDSS ont été évaluées, avec l’âge en covariable.Résultats : Une différence significative entre les groupes a été trouvée uniquement dans la ME cervicale (C4C6 ; MTR moyen=41.7pu, 39.4pu, 35.4pu pour CS, RRMS et PMS respectivement ; p<.001), pas dans la ME thoracique. Une association positive a été observée entre les MTR moyens dans la ME cervicale et thoracique (r=.45, p=.01 pour T4T6 ; r=.54, p=.002 pour T9T10) chez les patients atteints de SEP. Nous avons également observé des associations négatives entre le MTR moyen dans la ME cervicale et l’EDSS (r=-.51, p=.004) et entre le MTR moyen dans la ME cervicale et la charge lésionnelle au niveau de la ME (r=-.6, p<.001), alors qu’aucune corrélation claire n’a été trouvée entre la charge lésionnelle de la ME et l’EDSS (r=.35 ; p=.084). Aucune association n’a été trouvée entre le MTR moyen dans la ME thoracique et le score EDSS.Conclusion : Les dommages microstructuraux de la ME des patients atteintsde SEP semblent être prédominants dans la partie cervicale et sont liés à la charge lésionnelle et au handicap. Dans notre échantillon de données, la valeur ajoutée de l’exploration de la ME thoracique en plus de la ME cervicale en utilisant le MTR pour expliquer le handicap chez les patients atteints de SEP semble limitée. Une plus grande variabilité du MTR dans la ME thoracique et la localisation préférentielle des lésions au niveau cervicale de la ME pourraient expliquer ces résultats

Transfert d'aimantation (MTR) de l'ensemble de la moelle épinière chez des patients atteints de sclérose en plaques

International audienceObjectifs : Le ratio de transfert d’aimantation (MTR) s’est révélé prometteur pour évaluer la modification de la microstructure des tissus chez les patients atteints de sclérose en plaques (SEP). Cette exploration s’est limitée au cerveau et à la moelle épinière (ME) cervicale mais pas thoracique. L’étude des anomalies du MTR dans l’ensemble de la ME pourrait permettre une meilleure association avec le handicap chez les patients atteints de SEP. Les objectifs de cette étude sont : i) comparer les valeurs moyennes de MTR chez des patients SEP et des contrôles sains (CS) en fonction du niveau de la ME ; ii) décrire le lien entre les mesures de MTR cervical et thoracique de la ME ; iii) évaluer le lien entre lesmesures de MTR et le handicap (via le score EDSS) selon le niveau de la ME. Matériel et Méthodes : Vingt-et-un patients atteints de SEP rémittente(RRMS), 10 patients atteints de SEP progressive (PMS) et 13 CS ont eté scannés sur une IRM 3T Siemens. Le protocole d’imagerie comprenait 3 niveaux d’acquisition de transfert d’aimantation pour couvrir l’ensemble de la ME. Pour chaque sujet, les cartes MTR et la localisation des vertèbres ont été calculées à l’aide de l’outil SCT. Les moyennes de MTR ont été calculées pour les niveaux vertébraux cérébraux C4 à C6 et thoraciques T4 à T6 et T9 à T10. Les différences entre les groupes ainsi que les corrélations avec les lésions dans l’ensemble du SC et avec l’EDSS ont été évaluées, avec l’âge en covariable.Résultats : Une différence significative entre les groupes a été trouvée uniquement dans la ME cervicale (C4C6 ; MTR moyen=41.7pu, 39.4pu, 35.4pu pour CS, RRMS et PMS respectivement ; p<.001), pas dans la ME thoracique. Une association positive a été observée entre les MTR moyens dans la ME cervicale et thoracique (r=.45, p=.01 pour T4T6 ; r=.54, p=.002 pour T9T10) chez les patients atteints de SEP. Nous avons également observé des associations négatives entre le MTR moyen dans la ME cervicale et l’EDSS (r=-.51, p=.004) et entre le MTR moyen dans la ME cervicale et la charge lésionnelle au niveau de la ME (r=-.6, p<.001), alors qu’aucune corrélation claire n’a été trouvée entre la charge lésionnelle de la ME et l’EDSS (r=.35 ; p=.084). Aucune association n’a été trouvée entre le MTR moyen dans la ME thoracique et le score EDSS.Conclusion : Les dommages microstructuraux de la ME des patients atteintsde SEP semblent être prédominants dans la partie cervicale et sont liés à la charge lésionnelle et au handicap. Dans notre échantillon de données, la valeur ajoutée de l’exploration de la ME thoracique en plus de la ME cervicale en utilisant le MTR pour expliquer le handicap chez les patients atteints de SEP semble limitée. Une plus grande variabilité du MTR dans la ME thoracique et la localisation préférentielle des lésions au niveau cervicale de la ME pourraient expliquer ces résultats

Joint assessment of brain and spinal cord motor tract damage in patients with early RRMS: predominant impact of spinal cord lesions on motor function

International audienceBACKGROUND: In patients with MS, the effect of structural damage to the corticospinal tract (CST) has been separately evaluated in the brain and spinal cord (SC), even though a cumulative impact is suspected.OBJECTIVE: To evaluate CST damages on both the cortex and cervical SC, and examine their relative associations with motor function, measured both clinically and by electrophysiology.METHODS: We included 43 patients with early relapsing-remitting MS. Lesions were manually segmented on SC (axial T2*) and brain (3D FLAIR) scans. The CST was automatically segmented using an atlas (SC) or tractography (brain). Lesion volume fractions and diffusion parameters were calculated for SC, brain and CST. Central motor conduction time (CMCT) and triple stimulation technique amplitude ratio were measured for 42 upper limbs, from 22 patients.RESULTS: Mean lesion volume fractions were 5.2% in the SC portion of the CST and 0.9% in the brain portion. We did not find a significant correlation between brain and SC lesion volume fraction (r = 0.06, p = 0.68). The pyramidal EDSS score and CMCT were both significantly correlated with the lesion fraction in the SC CST (r = 0.39, p = 0.01 and r = 0.33, p = 0.03), but not in the brain CST.CONCLUSION: Our results highlight the major contribution of SC lesions to CST damage and motor function abnormalities

Multiple sclerosis lesions in motor tracts from brain to cervical cord: spatial distribution and correlation with disability

Despite important efforts to solve the clinico-radiological paradox, correlation between lesion load and physical disability in patients with multiple sclerosis remains modest. One hypothesis could be that lesion location in corticospinal tracts plays a key role in explaining motor impairment. In this study, we describe the distribution of lesions along the corticospinal tracts from the cortex to the cervical spinal cord in patients with various disease phenotypes and disability status. We also assess the link between lesion load and location within corticospinal tracts, and disability at baseline and 2-year follow-up. We retrospectively included 290 patients (22 clinically isolated syndrome, 198 relapsing remitting, 39 secondary progressive, 31 primary progressive multiple sclerosis) from eight sites. Lesions were segmented on both brain (T2-FLAIR or T2-weighted) and cervical (axial T2- or T2*-weighted) MRI scans. Data were processed using an automated and publicly available pipeline. Brain, brainstem and spinal cord portions of the corticospinal tracts were identified using probabilistic atlases to measure the lesion volume fraction. Lesion frequency maps were produced for each phenotype and disability scores assessed with Expanded Disability Status Scale score and pyramidal functional system score. Results show that lesions were not homogeneously distributed along the corticospinal tracts, with the highest lesion frequency in the corona radiata and between C2 and C4 vertebral levels. The lesion volume fraction in the corticospinal tracts was higher in secondary and primary progressive patients (mean = 3.6 ± 2.7% and 2.9 ± 2.4%), compared to relapsing-remitting patients (1.6 ± 2.1%, both P < 0.0001). Voxel-wise analyses confirmed that lesion frequency was higher in progressive compared to relapsing-remitting patients, with significant bilateral clusters in the spinal cord corticospinal tracts (P < 0.01). The baseline Expanded Disability Status Scale score was associated with lesion volume fraction within the brain (r = 0.31, P < 0.0001), brainstem (r = 0.45, P < 0.0001) and spinal cord (r = 0.57, P < 0.0001) corticospinal tracts. The spinal cord corticospinal tracts lesion volume fraction remained the strongest factor in the multiple linear regression model, independently from cord atrophy. Baseline spinal cord corticospinal tracts lesion volume fraction was also associated with disability progression at 2-year follow-up (P = 0.003). Our results suggest a cumulative effect of lesions within the corticospinal tracts along the brain, brainstem and spinal cord portions to explain physical disability in multiple sclerosis patients, with a predominant impact of intramedullary lesions