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2017

Journal Article

  • BESSON P., BANDT S. K., PROIX T., LAGARDE S., JIRSA V. K., RANJEVA J. - P., BARTOLOMEI F., GUYE M. “Anatomic consistencies across epilepsies: a stereotactic-EEG informed high-resolution structural connectivity study.”. Brain: A Journal of Neurology [En ligne]. 1 October 2017. Vol. 140, n°10, p. 2639-2652. Disponible sur : < http://dx.doi.org/10.1093/brain/awx181 > (consulté le no date)
    Mots-clés : brain networks, crmbm, diffusion weighted imaging, epilepsy, SEEG, snc, structural connectivity.

  • BYDDER M., RAPACCHI S., GIRARD O., GUYE M., RANJEVA J. - P. “Trimmed autocalibrating k-space estimation based on structured matrix completion.”. Magnetic Resonance Imaging [En ligne]. 15 July 2017. Vol. 43, p. 88-94. Disponible sur : < http://dx.doi.org/10.1016/j.mri.2017.07.015 > (consulté le no date)
    Résumé : PURPOSE: Parallel imaging allows the reconstruction of undersampled data from multiple coils. This provides a means to reject and regenerate corrupt data (e.g. from motion artefact). The purpose of this work is to approach this problem using the SAKE parallel imaging method. THEORY AND METHODS: Parallel imaging methods typically require calibration by fully sampling the center of k-space. This is a challenge in the presence of corrupted data, since the calibration data may be corrupted which leads to an errors-in-variables problem that cannot be solved by least squares or even iteratively reweighted least squares. The SAKE method, based on matrix completion and structured low rank approximation, was modified to detect and trim these errors from the data. RESULTS: Simulated and actual corrupted datasets were reconstructed with SAKE, the proposed approach and a more standard reconstruction method (based on solving a linear equation) with a data rejection criterion. The proposed approach was found to reduce artefacts considerably in comparison to the other two methods. CONCLUSION: SAKE with data trimming improves on previous methods for reconstructing images from grossly corrupted data.
    Mots-clés : Artefacts, crmbm, IRLS, Parallel imaging, Robust, snc, Structured low rank approximation.

  • CHATEL B., HOURDé C., GONDIN J., FOURé A., LE FUR Y., VILMEN C., BERNARD M., MESSONNIER L. A., BENDAHAN D. “Impaired muscle force production and higher fatigability in a mouse model of sickle cell disease.”. Blood Cells, Molecules & Diseases [En ligne]. 11 January 2017. Vol. 63, p. 37-44. Disponible sur : < http://dx.doi.org/10.1016/j.bcmd.2017.01.004 > (consulté le no date)
    Résumé : Skeletal muscle function has been scarcely investigated in sickle cell disease (SCD) so that the corresponding impact of sickle hemoglobin is still a matter of debate. The purpose of this study was to investigate muscle force production and fatigability in SCD and to identify whether exercise intensity could have a modulatory effect. Ten homozygous sickle cell (HbSS), ten control (HbAA) and ten heterozygous (HbAS) mice were submitted to two stimulation protocols (moderate and intense) to assess force production and fatigability. We showed that specific maximal tetanic force was lower in HbSS mice as compared to other groups. At the onset of the stimulation period, peak force was reduced in HbSS and HbAS mice as compared to HbAA mice. Contrary to the moderate protocol, the intense stimulation protocol was associated with a larger decrease in peak force and rate of force development in HbSS mice as compared to HbAA and HbAS mice. These findings provide in vivo evidence of impaired muscle force production and resistance to fatigue in SCD. These changes are independent of muscle mass. Moreover, SCD is associated with muscle fatigability when exercise intensity is high.
    Mots-clés : crmbm, Exercise intensity, msk, Muscle mass, Muscle volume, Rate of force development.


  • CHATEL B., MESSONNIER L. A., BENDAHAN D. “Exacerbated in vivo metabolic changes suggestive of a spontaneous muscular vaso-occlusive crisis in exercising muscle of a sickle cell mouse.”. Blood Cells, Molecules, and Diseases [En ligne]. 1 June 2017. Vol. 65, p. 56-59. Disponible sur : < http://dx.doi.org/10.1016/j.bcmd.2017.05.006 > (consulté le 18 August 2017)
    Résumé : While sickle cell disease (SCD) is characterized by frequent vaso-occlusive crisis (VOC), no direct observation of such an event in skeletal muscle has been performed in vivo. The present study reported exacerbated in vivo metabolic changes suggestive of a spontaneous muscular VOC in exercising muscle of a sickle cell mouse. Using magnetic resonance spectroscopy of phosphorus 31, phosphocreatine and inorganic phosphate concentrations and intramuscular pH were measured throughout two standardized protocols of rest – exercise – recovery at two different intensities in ten SCD mice. Among these mice, one single mouse presented divergent responses. A statistical analysis (based on confidence intervals) revealed that this single mouse presented slower phosphocreatine resynthesis and inorganic phosphate disappearance during the post-stimulation recovery of one of the protocols, what could suggest an ischemia. This study described, for the first time in a sickle cell mouse in vivo, exacerbated metabolic changes triggered by an exercise session that would be suggestive of a live observation of a muscular VOC. However, no evidence of a direct cause-effect relationship between exercise and VOC has been put forth.
    Mots-clés : crmbm, HbS polymerization, Magnetic resonance spectroscopy of phosphorus 31, msk, Physical activity, Red blood cell sickling.

  • DESROIS M., LAN C., MOVASSAT J., BERNARD M. “Reduced up-regulation of the nitric oxide pathway and impaired endothelial and smooth muscle functions in the female type 2 diabetic goto-kakizaki rat heart.”. Nutrition & Metabolism [En ligne]. 2017. Vol. 14, p. 6. Disponible sur : < http://dx.doi.org/10.1186/s12986-016-0157-z > (consulté le no date)
    Résumé : BACKGROUND: Type 2 diabetes is associated with greater relative risk of cardiovascular diseases in women than in men, which is not well understood. Consequently, we have investigated if male and female displayed differences in cardiac function, energy metabolism, and endothelial function which could contribute to increased cardiovascular complications in type 2 diabetic female. METHODS: Male and female Control and type 2 diabetic Goto-Kakizaki (GK) isolated rat hearts were perfused during 28 min with a physiological buffer before freeze-clamping for biochemical assays. High energy phosphate compounds and intracellular pH were followed using (31)P magnetic resonance spectroscopy with simultaneous measurement of contractile function. Nitric oxide (NO) pathway and endothelium-dependent and independent vasodilatations were measured as indexes of endothelial function. Results were analyzed via two-way ANOVA, p < 0.05 was considered as statistically significant. RESULTS: Myocardial function was impaired in male and female diabetic versus Control groups (p < 0.05) without modification of energy metabolism. Coronary flow was decreased in both diabetic versus Control groups but to a higher extent in female GK versus male GK rat hearts (p < 0.05). NO production was up-regulated in diabetic groups but to a less extent in female GK rat hearts (p < 0.05). Endothelium-dependent and independent vasodilatations were impaired in female GK rat compared with male GK (p < 0.05) and female Control (p < 0.05) rat hearts. CONCLUSIONS: We reported here an endothelial damage characterized by a reduced up-regulation of the NO pathway and impaired endothelial and smooth muscle functions, and coronary flow rates in the female GK rat hearts while energy metabolism was normal. Whether these results are related to the higher risk of cardiovascular complications among type 2 diabetic female needs to be further elicited in the future.
    Mots-clés : Cardiac function, crmbm, cvs, Endothelial function, Energy Metabolism, Gender differences, Type 2 diabetic heart.
  • DONADIEU M., LE FUR Y., MAAROUF A., GHERIB S., RIDLEY B., PINI L., RAPACCHI S., CONFORT-GOUNY S., GUYE M., SCHAD L. R. “Metabolic counterparts of sodium accumulation in multiple sclerosis: A whole brain 23Na-MRI and fast 1H-MRSI study.”. Multiple Sclerosis Journal. 2017. p. 1352458517736146.

  • DONADIEU M., LE FUR Y., MAAROUF A., GHERIB S., RIDLEY B., PINI L., RAPACCHI S., CONFORT-GOUNY S., GUYE M., SCHAD L. R., MAUDSLEY A. A., PELLETIER J., AUDOIN B., ZAARAOUI W., RANJEVA J. - P. “Metabolic counterparts of sodium accumulation in multiple sclerosis: A whole brain (23)Na-MRI and fast (1)H-MRSI study.”. Multiple Sclerosis (Houndmills, Basingstoke, England) [En ligne]. 1 October 2017. p. 1352458517736146. Disponible sur : < http://dx.doi.org/10.1177/1352458517736146 > (consulté le no date)
    Résumé : BACKGROUND: Increase of brain total sodium concentrations (TSC) is present in multiple sclerosis (MS), but its pathological involvement has not been assessed yet. OBJECTIVE: To determine in vivo the metabolic counterpart of brain sodium accumulation. MATERIALS/METHODS: Whole brain (23)Na-MR imaging and 3D-(1)H-EPSI data were collected in 21 relapsing-remitting multiple sclerosis (RRMS) patients and 20 volunteers. Metabolites and sodium levels were extracted from several regions of grey matter (GM), normal-appearing white matter (NAWM) and white matter (WM) T2 lesions. Metabolic and ionic levels expressed as Z-scores have been averaged over the different compartments and used to explain sodium accumulations through stepwise regression models. RESULTS: MS patients showed significant (23)Na accumulations with lower choline and glutamate-glutamine (Glx) levels in GM; (23)Na accumulations with lower N-acetyl aspartate (NAA), Glx levels and higher Myo-Inositol (m-Ins) in NAWM; and higher (23)Na, m-Ins levels with lower NAA in WM T2 lesions. Regression models showed associations of TSC increase with reduced NAA in GM, NAWM and T2 lesions, as well as higher total-creatine, and smaller decrease of m-Ins in T2 lesions. GM Glx levels were associated with clinical scores. CONCLUSION: Increase of TSC in RRMS is mainly related to neuronal mitochondrial dysfunction while dysfunction of neuro-glial interactions within GM is linked to clinical scores.
    Mots-clés : 23Na-MRI, crmbm, demyelination, MRSI, Multiple Sclerosis, neurodegeneration, snc, stepwise regression.

  • FATEHI F., SALORT-CAMPANA E., LE TROTER A., LAREAU-TRUDEL E., BYDDER M., FOURé A., GUYE M., BENDAHAN D., ATTARIAN S. “Long-term follow-up of MRI changes in thigh muscles of patients with Facioscapulohumeral dystrophy: A quantitative study.”. PloS One [En ligne]. 2017. Vol. 12, n°8, p. e0183825. Disponible sur : < http://dx.doi.org/10.1371/journal.pone.0183825 > (consulté le no date)
    Résumé : Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common hereditary muscular disorders. Currently FSHD has no known effective treatment and detailed data on the natural history are lacking. Determination of the efficacy of a given therapeutic approach might be difficult in FSHD given the slow and highly variable disease progression. Magnetic resonance imaging (MRI) has been widely used to qualitatively and quantitatively evaluate in vivo the muscle alterations in various neuromuscular disorders. The main aim of the present study was to investigate longitudinally the time-dependent changes occurring in thigh muscles of FSHD patients using quantitative MRI and to assess the potential relationships with the clinical findings. Thirty-five FSHD1 patients (17 females) were enrolled. Clinical assessment tools including manual muscle testing using medical research council score (MRC), and motor function measure (MFM) were recorded each year for a period ranging from 1 to 2 years. For the MRI measurements, we used a new quantitative index, i.e., the mean pixel intensity (MPI) calculated from the pixel-intensity distribution in T1 weighted images. The corresponding MPI scores were calculated for each thigh, for each compartment and for both thighs totally (MPItotal). The total mean pixel intensity (MPItotal) refers to the sum of each pixel signal intensity divided by the corresponding number of pixels. An increased MPItotal indicates both a raised fat infiltration together with a reduced muscle volume thereby illustrating disease progression. Clinical scores did not change significantly over time whereas MPItotal increased significantly from an initial averaged value of 39.6 to 41.1 with a corresponding rate of 0.62/year. While clinical scores and MPItotal measured at the start of the study were significantly related, no correlation was found between the rate of MPItotal and MRC sum score changes, MFMtotal and MFM subscores. The relative rate of MPItotal change was 2.3% (0.5-4.3)/year and was significantly higher than the corresponding rates measured for MRCS 0% (0-1.7) /year and MFMtotal 0% (0-2.0) /year (p = 0.000). On the basis of these results, we suggested that muscle MRI and more particularly the MPItotal index could be used as a reliable biomarker and outcome measure of disease progression. In slowly progressive myopathies such as FSHD, the MPItotal index might reveal subclinical changes, which could not be evidenced using clinical scales over a short period of time.
    Mots-clés : crmbm, Humans, Magnetic Resonance Imaging, msk, Muscle, Skeletal, Muscular Dystrophy, Facioscapulohumeral.

  • FOURé A., BENDAHAN D. “Is Branched-Chain Amino Acids Supplementation an Efficient Nutritional Strategy to Alleviate Skeletal Muscle Damage? A Systematic Review.”. Nutrients [En ligne]. 21 September 2017. Vol. 9, n°10,. Disponible sur : < http://dx.doi.org/10.3390/nu9101047 > (consulté le no date)
    Résumé : Amino acids and more precisely, branched-chain amino acids (BCAAs), are usually consumed as nutritional supplements by many athletes and people involved in regular and moderate physical activities regardless of their practice level. BCAAs have been initially shown to increase muscle mass and have also been implicated in the limitation of structural and metabolic alterations associated with exercise damage. This systematic review provides a comprehensive analysis of the literature regarding the beneficial effects of BCAAs supplementation within the context of exercise-induced muscle damage or muscle injury. The potential benefit of a BCAAs supplementation was also analyzed according to the supplementation strategy-amount of BCAAs, frequency and duration of the supplementation-and the extent of muscle damage. The review protocol was registered prospectively with Prospective Register for Systematic Reviews (registration number CRD42017073006) and followed Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Literature search was performed from the date of commencement until August 2017 using four online databases (Medline, Cochrane library, Web of science and ScienceDirect). Original research articles: (i) written in English; (ii) describing experiments performed in Humans who received at least one oral BCAAs supplementation composed of leucine, isoleucine and valine mixture only as a nutritional strategy and (iii) reporting a follow-up of at least one day after exercise-induced muscle damage, were included in the systematic review analysis. Quality assessment was undertaken independently using the Quality Criteria Checklist for Primary Research. Changes in indirect markers of muscle damage were considered as primary outcome measures. Secondary outcome measures were the extent of change in indirect markers of muscle damage. In total, 11 studies were included in the analysis. A high heterogeneity was found regarding the different outcomes of these studies. The risk of bias was moderate considering the quality ratings were positive for six and neutral for three. Although a small number of studies were included, BCAAs supplementation can be efficacious on outcomes of exercise-induced muscle damage, as long as the extent of muscle damage was low-to-moderate, the supplementation strategy combined a high daily BCAAs intake (>200 mg kg(-1) day(-1)) for a long period of time (>10 days); it was especially effective if taken prior to the damaging exercise.
    Mots-clés : branched-chain amino acids (BCAAs), crmbm, exercise-induced muscle damage, msk, nutritional strategy, skeletal muscle.

  • FOURé A., DUHAMEL G., VILMEN C., BENDAHAN D., JUBEAU M., GONDIN J. “Fast measurement of the quadriceps femoris muscle transverse relaxation time at high magnetic field using segmented echo-planar imaging.”. Journal of magnetic resonance imaging: JMRI [En ligne]. February 2017. Vol. 45, n°2, p. 356-368. Disponible sur : < http://dx.doi.org/10.1002/jmri.25355 > (consulté le no date)
    Résumé : PURPOSE: To assess and validate a technique for transverse relaxation time (T2 ) measurements of resting and recovering skeletal muscle following exercise with a high temporal resolution and large volume coverage using segmented spin-echo echo-planar imaging (sSE-EPI). MATERIALS AND METHODS: Experiments were performed on a 3T magnetic resonance imaging (MRI) scanner using a multislice sSE-EPI technique applied at different echo times (TEs). T2 measurements were first validated in vitro in calibrated T2 phantoms (range: 25-152 ms) by comparing sSE-EPI, standard spin-echo (SE), and multislice multiecho (MSME) techniques (using a fitting procedure or a 2-TEs calculation). In vivo measurements of resting T2 quadriceps femoris (QF) muscle were performed with both sSE-EPI and MSME sequences. Finally, sSE-EPI was used to quantify T2 changes in recovering muscle after an exercise. RESULTS: T2 values measured in vitro with sSE-EPI were similar to those assessed with SE (P > 0.05). In vitro and in vivo T2 measurements obtained with sSE-EPI were independent of the T2 determination procedure (P > 0.05). In contrast, both in vitro and in vivo T2 values derived from MSME were significantly different when using 2-TEs calculation as compared to the fitting procedure (P < 0.05). sSE-EPI allowed the detection of increased T2 values in the QF muscle immediately after exercise (+14 ± 9%), while lower T2 values were recorded less than 2 min afterwards (P < 0.05). CONCLUSION: sSE-EPI sequence is a relevant method to monitor exercise-induced T2 changes of skeletal muscles over large volume coverage and to detect abnormal patterns of muscle activation. LEVEL OF EVIDENCE: 1 J. Magn. Reson. Imaging 2017;45:356-368.
    Mots-clés : crmbm, Exercise, MRI, msk, skeletal muscle, spin-echo sequence, T2.

  • FOURNELY M., PETIT Y., WAGNAC É., LAURIN J., CALLOT V., ARNOUX P. - J. “High-speed video analysis improves the accuracy of spinal cord compression measurement in a mouse contusion model.”. Journal of Neuroscience Methods [En ligne]. 15 September 2017. Disponible sur : < http://dx.doi.org/10.1016/j.jneumeth.2017.09.007 > (consulté le no date)
    Résumé : BACKGROUND: Animal models of spinal cord injuries aim to utilize controlled and reproducible conditions. However, a literature review reveals that mouse contusion studies using equivalent protocols may show large disparities in the observed impact force vs. cord compression relationship. The overall purpose of this study was to investigate possible sources of bias in these measurements. The specific objective was to improve spinal cord compression measurements using a video-based setup to detect the impactor-spinal cord time-to-contact. NEW METHOD: A force-controlled 30kDyn unilateral contusion at C4 vertebral level was performed in six mice with the Infinite Horizon impactor (IH). High-speed video was used to determine the time-to-contact between the impactor tip and the spinal cord and to compute the related displacement of the tip into the tissue: the spinal cord compression and the compression ratio. RESULTS & COMPARISON WITH EXISTING METHOD(S): Delayed time-to-contact detection with the IH device led to an underestimation of the cord compression. Compression values indicated by the IH were 64% lower than those based on video analysis (0.33mm vs. 0.88mm). Consequently, the mean compression ratio derived from the device was underestimated when compared to the value derived from video analysis (22% vs. 61%). CONCLUSIONS: Default time-to-contact detection from the IH led to significant errors in spinal cord compression assessment. Accordingly, this may explain some of the reported data discrepancies in the literature. The proposed setup could be implemented by users of contusion devices to improve the quantative description of the primary injury inflicted to the spinal cord.
    Mots-clés : Compression ratio, Contusion device, crmbm, High-speed video analysis, Mouse model, snc, Spinal cord injury.


  • GIRARD O. M., CALLOT V., PREVOST V. H., ROBERT B., TASO M., RIBEIRO G., VARMA G., RANGWALA N., ALSOP D. C., DUHAMEL G. “Magnetization transfer from inhomogeneously broadened lines (ihMT): Improved imaging strategy for spinal cord applications.”. Magnetic Resonance in Medicine [En ligne]. January 2017. Vol. 77, p. 581-591. Disponible sur : < http://dx.doi.org/10.1002/mrm.26134 > (consulté le 10 March 2016)
    Résumé : Purpose Inhomogeneous magnetization transfer (ihMT) shows great promise for specific imaging of myelinated tissues. Whereas the ihMT technique has been previously applied in brain applications, the current report presents a strategy for cervical spinal cord (SC) imaging free of cerebrospinal fluid (CSF) pulsatility artifacts. Methods A pulsed ihMT preparation was combined with a single-shot HASTE readout. Electrocardiogram (ECG) synchronization was used to acquire all images during the quiescent phase of SC motion. However ihMT signal quantification errors may occur when a variable recovery delay is introduced in the sequence as a consequence of variable cardiac cycle. A semiautomatic retrospective correction algorithm, based on repetition time (TR) -matching, is proposed to correct for signal variations of long T1-components (e.g., CSF). Results The proposed strategy combining ECG synchronization and retrospective data pairing led to clean SC images free of CSF artifacts. Lower variability of the ihMT metrics were obtained with the correction algorithm, and allowed for shorter TR to be used, hence improving signal-to-noise ratio efficiency. Conclusion The proposed methodology enabled faster acquisitions, while offering robust ihMT quantification and exquisite SC image quality. This opens great perspectives for widening the in vivo characterization of SC physiopathology using MRI, such as studying white matter tracts microstructure or impairment in degenerative pathologies. Magn Reson Med, 2016. © 2016 Wiley Periodicals, Inc.
    Mots-clés : crmbm, CSF pulsatility, ECG synchronization, ihMT, Inhomogeneous magnetization transfer, motion correction, myelin, snc, Spinal Cord, white matter.

  • GUENOUN D., FOURé A., PITHIOUX M., GUIS S., LE CORROLLER T., MATTEI J. - P., PAULY V., GUYE M., BERNARD M., CHABRAND P., CHAMPSAUR P., BENDAHAN D. “Correlative Analysis of Vertebral Trabecular Bone Microarchitecture and Mechanical Properties: A Combined Ultra-high Field (7 Tesla) MRI and Biomechanical Investigation.”. Spine [En ligne]. 15 October 2017. Vol. 42, n°20, p. E1165-E1172. Disponible sur : < http://dx.doi.org/10.1097/BRS.0000000000002163 > (consulté le no date)
    Résumé : STUDY DESIGN: High-resolution imaging and biomechanical investigation of ex-vivo vertebrae. OBJECTIVE: The aim of this study was to assess bone microarchitecture of cadaveric vertebrae using ultra-high field (UHF) 7 Tesla magnetic resonance imaging (MRI) and to determine whether the corresponding microarchitecture parameters were related to bone mineral density (BMD) and bone strength assessed by dual-energy x-ray absorptiometry (DXA) and mechanical compression tests. SUMMARY OF BACKGROUND DATA: Limitations of DXA for the assessment of bone fragility and osteoporosis have been recognized and criteria of microarchitecture alteration have been included in the definition of osteoporosis. Although vertebral fracture is the most common osteoporotic fracture, no study has assessed directly vertebral trabecular bone microarchitecture. METHODS: BMD of 24 vertebrae (L2, L3, L4) from eight cadavers was investigated using DXA. The bone volume fraction (BVF), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp) of each vertebra were quantified using UHF MRI. Measurements were performed by two operators to characterize the inter-rater reliability. The whole set of specimens underwent mechanical compression tests to failure and the corresponding failure stress was calculated. RESULTS: The inter-rater reliability for bone microarchitecture parameters was good with intraclass correlation coefficients ranging from 0.82 to 0.94. Failure load and stress were significantly correlated with BVF, Tb.Sp, and BMD (P < 0.05). Tb.Th was only correlated with the failure stress (P < 0.05). Multiple regression analysis demonstrated that the combination of BVF and BMD improved the prediction of the failure stress from an adjusted R = 0.384 for BMD alone to an adjusted R = 0.414. CONCLUSION: We demonstrated for the first time that the vertebral bone microarchitecture assessed with UHF MRI was significantly correlated with biomechanical parameters. Our data suggest that the multimodal assessment of BMD and trabecular bone microarchitecture with UHF MRI provides additional information on the risk of vertebral bone fracture and might be of interest for the future investigation of selected osteoporotic patients. LEVEL OF EVIDENCE: N /A.
    Mots-clés : crmbm, msk.

  • KERBRAT A., COMBèS B., COMMOWICK O., MAAROUF A., BANNIER E., FERRé J. C., TOURBAH A., RANJEVA J. - P., BARILLOT C., EDAN G. “USPIO-positive MS lesions are associated with greater tissue damage than gadolinium-positive-only lesions during 3-year follow-up.”. Multiple Sclerosis (Houndmills, Basingstoke, England) [En ligne]. 1 October 2017. p. 1352458517736148. Disponible sur : < http://dx.doi.org/10.1177/1352458517736148 > (consulté le no date)
    Résumé : BACKGROUND: Identifying in vivo the processes that determine lesion severity in multiple sclerosis (MS) remains a challenge. OBJECTIVES: To describe the dynamics of ultrasmall superparamagnetic iron oxide (USPIO) enhancement in MS lesions and the relationship between USPIO enhancement and microstructural changes over 3 years. METHODS: Lesion development was assessed at baseline, Months 3, 6, and 9, using magnetic resonance imaging (MRI) with gadolinium and USPIO. Microstructural changes were assessed at baseline, Months 3, 6, 9, 12, 18, 24, and 36, using relaxometry, magnetization transfer, and diffusion-weighted imaging. RESULTS: We included 15 patients with clinically isolated syndrome. In the 52 MRI scans acquired with USPIO, 22 lesions were USPIO and gadolinium positive, and 44 were USPIO negative but gadolinium positive. Lesions no longer exhibited sustained USPIO enhancement 3 months later. At baseline, lesions that were both USPIO and gadolinium positive had lower magnetization transfer ratio values (common language effect size = 0.84, p = 0.0005) and lower fractional anisotropy values (0.83, p = 0.001) than gadolinium-positive-only lesions. USPIO-positive lesions remained associated with greater damage than gadolinium-positive-only lesions throughout the 3-year follow-up. CONCLUSION: USPIO enhancement, mainly reflecting monocyte infiltration, is transient and is associated with persistent tissue damage after 3 years.
    Mots-clés : clinically isolated syndrome, crmbm, diffusion tensor imaging, Gadolinium, Magnetic Resonance Imaging, magnetization transfer imaging, Multiple Sclerosis, snc, USPIO.

  • LAROCHE M., ALMERAS L., PECCHI E., BECHAH Y., RAOULT D., VIOLA A., PAROLA P. “MALDI-TOF MS as an innovative tool for detection of Plasmodium parasites in Anopheles mosquitoes.”. Malaria Journal [En ligne]. 3 January 2017. Vol. 16, n°1, p. 5. Disponible sur : < http://dx.doi.org/10.1186/s12936-016-1657-z > (consulté le no date)
    Résumé : BACKGROUND: Malaria is still a major public health issue worldwide, and one of the best approaches to fight the disease remains vector control. The current methods for mosquito identification include morphological methods that are generally time-consuming and require expertise, and molecular methods that require laboratory facilities with relatively expensive running costs. Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) technology, routinely used for bacterial identification, has recently emerged in the field of entomology. The aim of the present study was to assess whether MALDI-TOF MS could successfully distinguish Anopheles stephensi mosquitoes according to their Plasmodium infection status. METHODS: C57BL/6 mice experimentally infected with Plasmodium berghei were exposed to An. stephensi bites. For the determination of An. stephensi infection status, mosquito cephalothoraxes were dissected and submitted to mass spectrometry analyses and DNA amplification for molecular analysis. Spectra were grouped according to mosquitoes' infection status and spectra quality was validated based on intensity and reproducibility within each group. The in-lab MALDI-TOF MS arthropod reference spectra database, upgraded with representative spectra from both groups (infected/non-infected), was subsequently queried blindly with cephalothorax spectra from specimens of both groups. RESULTS: The MALDI TOF MS profiles generated from protein extracts prepared from the cephalothorax of An. stephensi allowed distinction between infected and uninfected mosquitoes. Correct classification was obtained in blind test analysis for (79/80) 98.75% of all mosquitoes tested. Only one of 80 specimens, an infected mosquito, was misclassified in the blind test analysis. CONCLUSIONS: Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry appears to be a promising, rapid and reliable tool for the epidemiological surveillance of Anopheles vectors, including their identification and their infection status.
    Mots-clés : crmbm, sasnc.


  • LEPORQ B., TROTER A. L., FUR Y. L., SALORT-CAMPANA E., GUYE M., BEUF O., ATTARIAN S., BENDAHAN D. “Combined quantification of fatty infiltration, T1-relaxation times and T2*-relaxation times in normal-appearing skeletal muscle of controls and dystrophic patients.”. Magnetic Resonance Materials in Physics, Biology and Medicine [En ligne]. 1 August 2017. Vol. 30, n°4, p. 407-415. Disponible sur : < http://dx.doi.org/10.1007/s10334-017-0616-1 > (consulté le 18 August 2017)
    Résumé : ObjectivesTo evaluate the combination of a fat–water separation method with an automated segmentation algorithm to quantify the intermuscular fatty-infiltrated fraction, the relaxation times, and the microscopic fatty infiltration in the normal-appearing muscle.Materials and methodsMR acquisitions were performed at 1.5T in seven patients with facio-scapulo-humeral dystrophy and eight controls. Disease severity was assessed using commonly used scales for the upper and lower limbs. The fat–water separation method provided proton density fat fraction (PDFF) and relaxation times maps (T2* and T1). The segmentation algorithm distinguished adipose tissue and normal-appearing muscle from the T2* map and combined active contours, a clustering analysis, and a morphological closing process to calculate the index of fatty infiltration (IFI) in the muscle compartment defined as the relative amount of pixels with the ratio between the number of pixels within IMAT and the total number of pixels (IMAT + normal appearing muscle).ResultsIn patients, relaxation times were longer and a larger fatty infiltration has been quantified in the normal-appearing muscle. T2* and PDFF distributions were broader. The relaxation times were correlated to the Vignos scale whereas the microscopic fatty infiltration was linked to the Medwin-Gardner-Walton scale. The IFI was linked to a composite clinical severity scale gathering the whole set of scales.ConclusionThe MRI indices quantified within the normal-appearing muscle could be considered as potential biomarkers of dystrophies and quantitatively illustrate tissue alterations such as inflammation and fatty infiltration.
    Mots-clés : crmbm, Magnetic Resonance Imaging, msk, Muscle dystrophies, Segmentation.


  • LUTZ N. W., BERNARD M. “Multiparametric quantification of thermal heterogeneity within aqueous materials by water 1H NMR spectroscopy: Paradigms and algorithms.”. PLOS ONE [En ligne]. 2017. Vol. 12, n°5, p. e0178431. Disponible sur : < http://dx.doi.org/10.1371/journal.pone.0178431 > (consulté le 18 August 2017)
    Résumé : Processes involving heat generation and dissipation play an important role in the performance of numerous materials. The behavior of (semi-)aqueous materials such as hydrogels during production and application, but also properties of biological tissue in disease and therapy (e.g., hyperthermia) critically depend on heat regulation. However, currently available thermometry methods do not provide quantitative parameters characterizing the overall temperature distribution within a volume of soft matter. To this end, we present here a new paradigm enabling accurate, contactless quantification of thermal heterogeneity based on the line shape of a water proton nuclear magnetic resonance (1H NMR) spectrum. First, the 1H NMR resonance from water serving as a "temperature probe" is transformed into a temperature curve. Then, the digital points of this temperature profile are used to construct a histogram by way of specifically developed algorithms. We demonstrate that from this histogram, at least eight quantitative parameters describing the underlying statistical temperature distribution can be computed: weighted median, weighted mean, standard deviation, range, mode(s), kurtosis, skewness, and entropy. All mathematical transformations and calculations are performed using specifically programmed EXCEL spreadsheets. Our new paradigm is helpful in detailed investigations of thermal heterogeneity, including dynamic characteristics of heat exchange at sub-second temporal resolution.
    Mots-clés : Algorithms, crmbm, cvs, Distribution curves, Entropy, Gels, NMR spectroscopy, Nuclear magnetic resonance, Skewness, Statistical distributions.


  • MAAROUF A., AUDOIN B., PARIOLLAUD F., GHERIB S., RICO A., SOULIER E., CONFORT-GOUNY S., GUYE M., SCHAD L., PELLETIER J., RANJEVA J. - P., ZAARAOUI W. “Increased total sodium concentration in gray matter better explains cognition than atrophy in MS.”. Neurology [En ligne]. 17 January 2017. Vol. 88, n°3, p. 289-295. Disponible sur : < http://dx.doi.org/10.1212/WNL.0000000000003511 > (consulté le 18 August 2017)
    Résumé : Objective: To investigate whether brain total sodium accumulation assessed by 23Na MRI is associated with cognitive deficit in relapsing-remitting multiple sclerosis (RRMS). Methods: Eighty-nine participants were enrolled in the study (58 patients with RRMS with a disease duration ≤10 years and 31 matched healthy controls). Patients were classified as cognitively impaired if they failed at least 2 tasks on the Brief Repeatable Battery. MRI was performed at 3T using 23Na MRI to obtain total sodium concentration (TSC) in the different brain compartments (lesions, normal-appearing white matter [NAWM], gray matter [GM]) and 1H- magnetization-prepared rapid gradient echo to assess GM atrophy (GM fraction). Results: The mean disease duration was 3.1 years and the median Expanded Disability Status Scale score was 1 (range 0–4.5). Thirty-seven patients were classified as cognitively preserved and 21 as cognitively impaired. TSC was increased in GM and NAWM in cognitively impaired patients compared to cognitively preserved patients and healthy controls. Voxel-wise analysis demonstrated that sodium accumulation was mainly located in the neocortex in cognitively impaired patients. Regression analysis evidenced than the 2 best independent predictors of cognitive impairment were GM TSC and age. Receiver operating characteristic analyses demonstrated that sensitivity and specificity of the GM TSC to classify patients according to their cognitive status were 76% and 71%, respectively. Conclusions: This study provides 2 main findings. (1) In RRMS, total sodium accumulation in the GM is better associated with cognitive impairment than GM atrophy; and (2) total sodium accumulation in patients with cognitive impairment is mainly located in the neocortex.
    Mots-clés : crmbm, snc.

  • MCHINDA S., VARMA G., PREVOST V. H., LE TROTER A., RAPACCHI S., GUYE M., PELLETIER J., RANJEVA J. - P., ALSOP D. C., DUHAMEL G., GIRARD O. M. “Whole brain inhomogeneous magnetization transfer (ihMT) imaging: Sensitivity enhancement within a steady-state gradient echo sequence.”. Magnetic Resonance in Medicine [En ligne]. 23 September 2017. Disponible sur : < http://dx.doi.org/10.1002/mrm.26907 > (consulté le no date)
    Résumé : PURPOSE: To implement, characterize, and optimize an interleaved inhomogeneous magnetization transfer (ihMT) gradient echo sequence allowing for whole-brain imaging within a clinically compatible scan time. THEORY AND METHODS: A general framework for ihMT modelling was developed based on the Provotorov theory of radiofrequency saturation, which accounts for the dipolar order underpinning the ihMT effect. Experimental studies and numerical simulations were performed to characterize and optimize the ihMT-gradient echo dependency with sequence timings, saturation power, and offset frequency. The protocol was optimized in terms of maximum signal intensity and the reproducibility assessed for a nominal resolution of 1.5 mm isotropic. All experiments were performed on healthy volunteers at 1.5T. RESULTS: An important mechanism driving signal optimization and leading to strong ihMT signal enhancement that relies on the dynamics of radiofrequency energy deposition has been identified. By taking advantage of the delay allowed for readout between ihMT pulse bursts, it was possible to boost the ihMT signal by almost 2-fold compared to previous implementation. Reproducibility of the optimal protocol was very good, with an intra-individual error < 2%. CONCLUSION: The proposed sensitivity-boosted and time-efficient steady-state ihMT-gradient echo sequence, implemented and optimized at 1.5T, allowed robust high-resolution 3D ihMT imaging of the whole brain within a clinically compatible scan time. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
    Mots-clés : crmbm, dipolar order, dual frequency RF saturation, ihMT, Inhomogeneous magnetization transfer, magnetization transfer model, myelin, Provotorov theory of radiofrequency saturation, snc.

  • OGIER A., SDIKA M., FOURE A., LE TROTER A., BENDAHAN D. “Individual muscle segmentation in MR images: A 3D propagation through 2D non-linear registration approaches.”. Conference proceedings: .. Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference [En ligne]. July 2017. Vol. 2017, p. 317-320. Disponible sur : < http://dx.doi.org/10.1109/EMBC.2017.8036826 > (consulté le no date)
    Résumé : Manual and automated segmentation of individual muscles in magnetic resonance images have been recognized as challenging given the high variability of shapes between muscles and subjects and the discontinuity or lack of visible boundaries between muscles. In the present study, we proposed an original algorithm allowing a semi-automatic transversal propagation of manually-drawn masks. Our strategy was based on several ascending and descending non-linear registration approaches which is similar to the estimation of a Lagrangian trajectory applied to manual masks. Using several manually-segmented slices, we have evaluated our algorithm on the four muscles of the quadriceps femoris group. We mainly showed that our 3D propagated segmentation was very accurate with an averaged Dice similarity coefficient value higher than 0.91 for the minimal manual input of only two manually-segmented slices.
    Mots-clés : crmbm, msk.


  • PREVOST V. H., GIRARD O. M., MCHINDA S., VARMA G., ALSOP D. C., DUHAMEL G. “Optimization of inhomogeneous magnetization transfer (ihMT) MRI contrast for preclinical studies using dipolar relaxation time (T1D) filtering.”. NMR in Biomedicine [En ligne]. 1 June 2017. Vol. 30, n°6,. Disponible sur : < http://dx.doi.org/10.1002/nbm.3706 > (consulté le 18 August 2017)

  • RASOANANDRIANINA H., GRAPPERON A. - M., TASO M., GIRARD O. M., DUHAMEL G., GUYE M., RANJEVA J. - P., ATTARIAN S., VERSCHUEREN A., CALLOT V. “Region-specific impairment of the cervical spinal cord (SC) in amyotrophic lateral sclerosis: A preliminary study using SC templates and quantitative MRI (diffusion tensor imaging/inhomogeneous magnetization transfer).”. NMR in biomedicine [En ligne]. 19 September 2017. Disponible sur : < http://dx.doi.org/10.1002/nbm.3801 > (consulté le no date)
    Résumé : In this preliminary study, our objective was to investigate the potential of high-resolution anatomical imaging, diffusion tensor imaging (DTI) and conventional/inhomogeneous magnetization transfer imaging [magnetization transfer (MT)/inhomogeneous magnetization transfer (ihMT)] at 3 T, analyzed with template-extracted regions of interest, to measure the atrophy and structural changes of white (WM) and gray (GM) matter spinal cord (SC) occurring in patients with amyotrophic lateral sclerosis (ALS). Ten patients with ALS and 20 age-matched healthy controls were recruited. SC GM and WM areas were automatically segmented using dedicated templates. Atrophy indices were evaluated from T2 *-weighted images at each vertebral level from cervical C1 to C6. DTI and ihMT metrics were quantified within the corticospinal tract (CST), posterior sensory tract (PST) and anterior GM (aGM) horns at the C2 and C5 levels. Clinical disabilities of patients with ALS were evaluated using the Revised ALS Functional Rating Scale, upper motor neuron (UMN) and Medical Research Council scorings, and correlated with MR metrics. Compared with healthy controls, GM and WM atrophy was observed in patients with ALS, especially at lower cervical levels, where a strong correlation was also observed between GM atrophy and the UMN score (R = -0.75, p = 0.05 at C6). Interestingly, a significant decrease in ihMT ratio was found in all regions of interest (p < 0.0008), fractional anisotropy (FA) and MT ratios decreased significantly in CST, especially at C5 (p < 0.005), and λ// (axial diffusivity) decreased significantly in CST (p = 0.0004) and PST (p = 0.003) at C2. Strong correlations between MRI metrics and clinical scores were also found (0.47 < |R| < 0.87, p < 0.05). Altogether, these preliminary results suggest that high-resolution anatomical imaging and ihMT imaging, in addition to DTI, are valuable for the characterization of SC tissue impairment in ALS. In this study, in addition to an important SC WM demyelination, we also observed, for the first time in ALS, impairments of cervical aGM.
    Mots-clés : ALS, crmbm, diffusion tensor imaging, GM atrophy, ihMT, Inhomogeneous magnetization transfer, motor neuron, snc, Spinal Cord, spinal cord templates.

  • RIDLEY B., MARCHI A., WIRSICH J., SOULIER E., CONFORT-GOUNY S., SCHAD L., BARTOLOMEI F., RANJEVA J. - P., GUYE M., ZAARAOUI W. “Brain sodium MRI in human epilepsy: Disturbances of ionic homeostasis reflect the organization of pathological regions.”. NeuroImage [En ligne]. 7 June 2017. Vol. 157, p. 173-183. Disponible sur : < http://dx.doi.org/10.1016/j.neuroimage.2017.06.011 > (consulté le no date)
    Résumé : In light of technical advancements supporting exploration of MR signals other than (1)H, sodium ((23)Na) has received attention as a marker of ionic homeostasis and cell viability. Here, we evaluate for the first time the possibility that (23)Na-MRI is sensitive to pathological processes occurring in human epilepsy. A normative sample of 27 controls was used to normalize regions of interest (ROIs) from 1424 unique brain locales on quantitative (23)Na-MRI and high-resolution (1)H-MPRAGE images. ROIs were based on intracerebral electrodes in ten patients undergoing epileptic network mapping. The stereo-EEG gold standard was used to define regions as belonging to primarily epileptogenic, secondarily irritative and to non-involved regions. Estimates of total sodium concentration (TSC) on (23)Na-MRI and cerebrospinal fluid (CSF) on (1)H imaging were extracted for each patient ROI, and normalized against the same region in controls. ROIs with disproportionate CSF contributions (ZCSF≥1.96) were excluded. TSC levels were found to be elevated in patients relative to controls except in one patient, who suffered non-convulsive seizures during the scan, in whom we found reduced TSC levels. In the remaining patients, an ANOVA (F1100= 12.37, p<0.0001) revealed a highly significant effect of clinically-defined zones (F1100= 11.13, p<0.0001), with higher normalized TSC in the epileptogenic zone relative to both secondarily irritative (F1100= 11, p=0.0009) and non-involved regions (F1100= 17.8, p<0.0001). We provide the first non-invasive, in vivo evidence of a chronic TSC elevation alongside ZCSF levels within the normative range, associated with the epileptogenic region even during the interictal period in human epilepsy, and the possibility of reduced TSC levels due to seizure. In line with modified homeostatic mechanisms in epilepsy - including altered mechanisms underlying ionic gating, clearance and exchange - we provide the first indication of (23)Na-MRI as an assay of altered sodium concentrations occurring in epilepsy associated with the organization of clinically relevant divisions of pathological cortex.
    Mots-clés : Cortical localisation, crmbm, epilepsy, Epilepsy surgery, Intracranial EEG, Ionic imaging, snc, Sodium MRI.

  • RIDLEY B., WIRSICH J., BETTUS G., RODIONOV R., MURTA T., CHAUDHARY U., CARMICHAEL D., THORNTON R., VULLIEMOZ S., MCEVOY A., WENDLING F., BARTOLOMEI F., RANJEVA J. - P., LEMIEUX L., GUYE M. “Simultaneous Intracranial EEG-fMRI Shows Inter-Modality Correlation in Time-Resolved Connectivity Within Normal Areas but Not Within Epileptic Regions.”. Brain Topography [En ligne]. 13 February 2017. Disponible sur : < http://dx.doi.org/10.1007/s10548-017-0551-5 > (consulté le no date)
    Résumé : For the first time in research in humans, we used simultaneous icEEG-fMRI to examine the link between connectivity in haemodynamic signals during the resting-state (rs) and connectivity derived from electrophysiological activity in terms of the inter-modal connectivity correlation (IMCC). We quantified IMCC in nine patients with drug-resistant epilepsy (i) within brain networks in 'healthy' non-involved cortical zones (NIZ) and (ii) within brain networks involved in generating seizures and interictal spikes (IZ1) or solely spikes (IZ2). Functional connectivity (h (2) ) estimates for 10 min of resting-state data were obtained between each pair of electrodes within each clinical zone for both icEEG and fMRI. A sliding window approach allowed us to quantify the variability over time of h (2) (vh (2)) as an indicator of connectivity dynamics. We observe significant positive IMCC for h (2) and vh (2), for multiple bands in the NIZ only, with the strongest effect in the lower icEEG frequencies. Similarly, intra-modal h (2) and vh (2) were found to be differently modified as a function of different epileptic processes: compared to NIZ, [Formula: see text] was higher in IZ1, but lower in IZ2, while [Formula: see text] showed the inverse pattern. This corroborates previous observations of inter-modal connectivity discrepancies in pathological cortices, while providing the first direct invasive and simultaneous comparison in humans. We also studied time-resolved FC variability multimodally for the first time, finding that IZ1 shows both elevated internal [Formula: see text] and less rich dynamical variability, suggesting that its chronic role in epileptogenesis may be linked to greater homogeneity in self-sustaining pathological oscillatory states.
    Mots-clés : connectivity, crmbm, Dynamic connectivity, Focal epilepsy, Multimodal imaging, Resting-state, snc.

  • WEGRZYK J., RANJEVA J. - P., FOURÉ A., KAVOUNOUDIAS A., VILMEN C., MATTEI J. - P., GUYE M., MAFFIULETTI N. A., PLACE N., BENDAHAN D., GONDIN J. “Specific brain activation patterns associated with two neuromuscular electrical stimulation protocols.”. Scientific Reports [En ligne]. 2 June 2017. Vol. 7, n°1, p. 2742. Disponible sur : < http://dx.doi.org/10.1038/s41598-017-03188-9 > (consulté le no date)
    Résumé : The influence of neuromuscular electrical stimulation (NMES) parameters on brain activation has been scarcely investigated. We aimed at comparing two frequently used NMES protocols - designed to vary in the extent of sensory input. Whole-brain functional magnetic resonance imaging was performed in sixteen healthy subjects during wide-pulse high-frequency (WPHF, 100 Hz-1 ms) and conventional (CONV, 25 Hz-0.05 ms) NMES applied over the triceps surae. Each protocol included 20 isometric contractions performed at 10% of maximal force. Voluntary plantar flexions (VOL) were performed as control trial. Mean force was not different among the three protocols, however, total current charge was higher for WPHF than for CONV. All protocols elicited significant activations of the sensorimotor network, cerebellum and thalamus. WPHF resulted in lower deactivation in the secondary somatosensory cortex and precuneus. Bilateral thalami and caudate nuclei were hyperactivated for CONV. The modulation of the NMES parameters resulted in differently activated/deactivated regions related to total current charge of the stimulation but not to mean force. By targeting different cerebral brain regions, the two NMES protocols might allow for individually-designed rehabilitation training in patients who can no longer execute voluntary movements.
    Mots-clés : crmbm, msk.

  • WIRSICH J., RIDLEY B., BESSON P., JIRSA V., BÉNAR C., RANJEVA J. - P., GUYE M. “Complementary contributions of concurrent EEG and fMRI connectivity for predicting structural connectivity.”. NeuroImage [En ligne]. 22 August 2017. Disponible sur : < http://dx.doi.org/10.1016/j.neuroimage.2017.08.055 > (consulté le no date)
    Résumé : While averaged dynamics of brain function are known to estimate the underlying structure, the exact relationship between large-scale function and structure remains an unsolved issue in network neuroscience. These complex functional dynamics, measured by EEG and fMRI, are thought to arise from a shared underlying structural architecture, which can be measured by diffusion MRI (dMRI). While simulation and data transformation (e.g. graph theory measures) have been proposed to refine the understanding of the underlying function-structure relationship, the potential complementary and/or independent contribution of EEG and fMRI to this relationship is still poorly understood. As such, we explored this relationship by analyzing the function-structure correlation in fourteen healthy subjects with simultaneous resting-state EEG-fMRI and dMRI acquisitions. We show that the combination of EEG and fMRI connectivity better explains dMRI connectivity and that this represents a genuine model improvement over fMRI-only models for both group-averaged connectivity matrices and at the individual level. Furthermore, this model improves the prediction within each resting-state network. The best model fit to underlying structure is mediated by fMRI and EEG-δ connectivity in combination with Euclidean distance and interhemispheric connectivity with more local contributions of EEG-γ at the scale of resting state networks. This highlights that the factors mediating the relationship between functional and structural metrics of connectivity are context and scale dependent, influenced by topological, geometric and architectural features. It also suggests that fMRI studies employing simultaneous EEG measures may characterize additional and essential parts of the underlying neuronal activity of the resting-state, which might be of special interest for both clinical studies and the investigation of resting-state dynamics.
    Mots-clés : Brain connectivity, Connectome, crmbm, Multimodal, Network theory, snc.

  • WYBRECHT D., REUTER F., PARIOLLAUD F., ZAARAOUI W., LE TROTER A., RICO A., CONFORT-GOUNY S., SOULIER E., GUYE M., MAAROUF A., RANJEVA J. - P., PELLETIER J., AUDOIN B. “New brain lesions with no impact on physical disability can impact cognition in early multiple sclerosis: A ten-year longitudinal study.”. PloS One [En ligne]. 2017. Vol. 12, n°11, p. e0184650. Disponible sur : < http://dx.doi.org/10.1371/journal.pone.0184650 > (consulté le no date)
    Résumé : OBJECTIVE: In early multiple sclerosis, although brain T2 lesions accrual are hallmark of the disease, only weak correlations were found between T2 lesions accrual and EDSS progression, the disability scale commonly used in multiple sclerosis studies. This may be related to the very poor sensitivity of EDSS to cognitive dysfunctions that may occur and progress from the first stage of the disease. In the present study, we aimed to demonstrate that cognitive deficits progress during the first ten years of MS and are significantly impacted by new T2 lesions. METHODS: EDSS and extensive neuropsychological battery (22 measures) exploring memory, attention/speed of information processing and executive functions were assessed at baseline, Year 1 and Year 10 in 26 patients enrolled after their first clinical attack. To limit the bias of test-retest effect, only measures obtained at Year 1 and Year 10 were reported in the analysis. Raw scores of patients were transformed into z-scores using published normative data when available or scores of matched controls. Lesion probability mapping was used to assess the potential relationships between T2 lesions accumulation, cognitive decline and EDSS progression (P<0.05, FWE-corrected). RESULTS: At Year 1, 27% of patients showed attention/speed of information processing deficits, 11.5% executive dysfunction and 11.5% memory impairment. During the follow-up, frequency and severity of executive dysfunction increased (from 11.5% of patients at Year 1 to 42% at Year 10, p<0.01) while no significant changes were evidenced for the other cognitive domains. Median EDSS increased from 0.5 [range: 0-3] at Year 1 to 2.5 [range: 0-6.5] at Year 10 (p<0.001). During the ten-year follow-up, lesions accumulation in the left cerebellum and semi-ovale centers was associated with EDSS progression. In contrast, most lesions accumulation in the frontal, parietal and temporal lobes were associated with cognitive decline but had no effect on EDSS progression. CONCLUSION: The present study provides strong evidence that clinically silent T2 lesions impact cognition in early MS. In daily practice, early prevention of T2 lesions accrual may be useful to limit cognitive decline.
    Mots-clés : crmbm, snc.

2016

Journal Article

  • ABDESSELAM I., DUTOUR A., KOBER F., ANCEL P., BEGE T., DARMON P., LESAVRE N., BERNARD M., GABORIT B. “Time Course of Change in Ectopic Fat Stores After Bariatric Surgery.”. Journal of the American College of Cardiology [En ligne]. 5 January 2016. Vol. 67, n°1, p. 117-119. Disponible sur : < http://dx.doi.org/10.1016/j.jacc.2015.10.052 > (consulté le no date)

  • BAL-THEOLEYRE L., LALANDE A., KOBER F., GIORGI R., COLLART F., PIQUET P., HABIB G., AVIERINOS J. - F., BERNARD M., GUYE M., JACQUIER A. “Aortic Function's Adaptation in Response to Exercise-Induced Stress Assessing by 1.5T MRI: A Pilot Study in Healthy Volunteers.”. PloS One [En ligne]. 2016. Vol. 11, n°6, p. e0157704. Disponible sur : < http://dx.doi.org/10.1371/journal.pone.0157704 > (consulté le no date)
    Résumé : AIM: Evaluation of the aortic "elastic reserve" might be a relevant marker to assess the risk of aortic event. Our aim was to compare regional aortic elasticity at rest and during supine bicycle exercise at 1.5 T MRI in healthy individuals. METHODS: Fifteen volunteers (8 men), with a mean age of 29 (23-41) years, completed the entire protocol. Images were acquired immediately following maximal exercise. Retrospective cine sequences were acquired to assess compliance, distensibility, maximum rates of systolic distension and diastolic recoil at four different locations: ascending aorta, proximal descending aorta, distal descending aorta and aorta above the coeliac trunk level. Segmental aortic pulse wave velocity (PWV) was assessed by through plane velocity-encoded MRI. RESULTS: Exercise induced a significant decrease of aortic compliance and distensibility, and a significant increase of the absolute values of maximum rates of systolic distension and diastolic recoil at all sites (p<10-3). At rest and during stress, ascending aortic compliance was statistically higher compared to the whole descending aorta (p≤0.0007). We found a strong correlation between the rate pressure product and aortic distensibility at all sites (r = - 0.6 to -0.75 according to the site, p<10-4). PWV measured at the proximal and distal descending aorta increased significantly during stress (p = 0.02 and p = 0.008, respectively). CONCLUSION: Assessment of regional aortic function during exercise is feasible using MRI. During stress, aortic elasticity decreases significantly in correlation with an increase of the PWV. Further studies are required to create thresholds for ascending aorta dysfunction among patients with aneurysms, and to monitor the impact of medication on aortic remodeling.
    Mots-clés : Adaptation, Physiological, Adult, Aorta, Aorta, Thoracic, crmbm, cvs, Diastole, Elasticity, Exercise, Female, Healthy Volunteers, Humans, Magnetic Resonance Imaging, Male, Pilot Projects, Pulse Wave Analysis, Stress, Physiological, Supine Position, Systole, Vascular Stiffness.

  • BÉCHIR N., PECCHI E., VILMEN C., LE FUR Y., AMTHOR H., BERNARD M., BENDAHAN D., GIANNESINI B. “ActRIIB blockade increases force-generating capacity and preserves energy supply in exercising mdx mouse muscle in vivo.”. FASEB journal: official publication of the Federation of American Societies for Experimental Biology [En ligne]. October 2016. Vol. 30, n°10, p. 3551-3562. Disponible sur : < http://dx.doi.org/10.1096/fj.201600271RR > (consulté le no date)
    Résumé : Postnatal blockade of the activin type IIB receptor (ActRIIB) represents a promising therapeutic strategy for counteracting dystrophic muscle wasting. However, its impact on muscle function and bioenergetics remains poorly documented in physiologic conditions. We have investigated totally noninvasively the effect of 8-wk administration of either soluble ActRIIB signaling inhibitor (sActRIIB-Fc) or vehicle PBS (control) on gastrocnemius muscle force-generating capacity, energy metabolism, and anatomy in dystrophic mdx mice using magnetic resonance (MR) imaging and dynamic [(31)P]-MR spectroscopy ([(31)P]-MRS) in vivo ActRIIB inhibition increased muscle volume (+33%) without changing fiber-type distribution, and increased basal animal oxygen consumption (+22%) and energy expenditure (+23%). During an in vivo standardized fatiguing exercise, maximum and total absolute contractile forces were larger (+40 and 24%, respectively) in sActRIIB-Fc treated animals, whereas specific force-generating capacity and fatigue resistance remained unaffected. Furthermore, sActRIIB-Fc administration did not alter metabolic fluxes, ATP homeostasis, or contractile efficiency during the fatiguing bout of exercise, although it dramatically reduced the intrinsic mitochondrial capacity for producing ATP. Overall, sActRIIB-Fc treatment increased muscle mass and strength without altering the fundamental weakness characteristic of dystrophic mdx muscle. These data support the clinical interest of ActRIIB blockade for reversing dystrophic muscle wasting.-Béchir, N., Pecchi, E., Vilmen, C., Le Fur, Y., Amthor, H., Bernard, M., Bendahan, D., Giannesini, B. ActRIIB blockade increases force-generating capacity and preserves energy supply in exercising mdx mouse muscle in vivo.
    Mots-clés : crmbm, Duchenne muscular dystrophy, msk, Muscle Fatigue, myostatin inhibition, skeletal muscle hypertrophy.

  • BERNARD M., MAIXENT J. - M., GERBI A., LAN C., COZZONE P. J., PIERONI G., ARMAND M., COSTE T. C. “Dietary docosahexaenoic acid-enriched glycerophospholipids exert cardioprotective effects in ouabain-treated rats via physiological and metabolic changes.”. Food & Function [En ligne]. 17 February 2016. Vol. 7, n°2, p. 798-804. Disponible sur : < http://dx.doi.org/10.1039/c5fo01300c > (consulté le no date)
    Résumé : Docosahexaenoic acid (DHA) might prevent heart failure or optimise drug treatments by improving cardiac contraction. We investigated whether DHA-enriched avian glycerophospholipids (GPL-DHA) exert cardioprotection in ouabain-treated rats after 4 weeks of dietary supplementation with 10, 35 or 60 mg DHA per kg body weight versus none (DHA10, DHA35, DHA60 and control groups, respectively). The contractile responsiveness to different doses of ouabain (10(-7) to 10(-4) M), ouabain intoxication (at 3 × 10(-4) M), and relative variations in cardiac energy metabolism were determined using (31)P NMR in isolated perfused rat hearts. The fatty acid composition of cardiac membranes was analysed by gas chromatography. DHA accretion in the heart was dose-dependent (+8%, +30% and +45% for DHA10, DHA35 and DHA60, respectively). The cardiac phosphocreatine content significantly increased at the baseline in DHA35 (+45%) and DHA60 groups (+85%), and at the different doses of ouabain in the DHA60 group (+73% to 98%). The maximum positive inotropy achieved at 10(-4) M ouabain was significantly increased in all DHA groups versus control (+150%, +122.5% and +135% for DHA10, DHA35 and DHA60, respectively), and ouabain intoxication was delayed. The increase in myocardial phosphocreatine content and the improved efficacy of ouabain on myocardial contraction without toxicity suggest the potential of GPL-DHA as a dietary supplement or ingredient for functional food, and possibly as a co-treatment with digitalis drugs in humans.
    Mots-clés : crmbm, snc.

  • BOUTIÈRE C., REY C., ZAARAOUI W., LE TROTER A., RICO A., CRESPY L., ACHARD S., REUTER F., PARIOLLAUD F., WIRSICH J., ASQUINAZI P., CONFORT-GOUNY S., SOULIER E., GUYE M., PELLETIER J., RANJEVA J. - P., AUDOIN B. “Improvement of spasticity following intermittent theta burst stimulation in multiple sclerosis is associated with modulation of resting-state functional connectivity of the primary motor cortices.”. Multiple Sclerosis (Houndmills, Basingstoke, England) [En ligne]. 1 August 2016. Disponible sur : < http://dx.doi.org/10.1177/1352458516661640 > (consulté le no date)
    Résumé : BACKGROUND: Intermittent theta burst stimulation (iTBS) of the primary motor cortex improves transiently lower limbs spasticity in multiple sclerosis (MS). However, the cerebral mechanisms underlying this effect have never been investigated. OBJECTIVE: To assess whether modulation of spasticity induced by iTBS is underlined by functional reorganization of the primary motor cortices. METHODS: A total of 17 patients with MS suffering from lower limbs spasticity were randomized to receive real iTBS or sham iTBS during the first half of a 5-week indoor rehabilitation programme. Spasticity was assessed using the Modified Ashworth Scale and the Visual Analogue Scale at baseline, after the stimulation session and at the end of the rehabilitation programme. Resting-state functional magnetic resonance imaging (fMRI) was performed at the three time points, and brain functional networks topology was analysed using graph-theoretical approach. RESULTS: At the end of stimulation, improvement of spasticity was greater in real iTBS group than in sham iTBS group (p = 0.026). iTBS had a significant effect on the balance of the connectivity degree between the stimulated and the homologous primary motor cortex (p = 0.005). Changes in inter-hemispheric balance were correlated with improvement of spasticity (rho = 0.56, p = 0.015). CONCLUSION: This longitudinal resting-state fMRI study evidences that functional reorganization of the primary motor cortices may underlie the effect of iTBS on spasticity in MS.
    Mots-clés : connectivity, crmbm, intermittent theta burst stimulation, Multiple Sclerosis, primary motor cortex, resting state fMRI, snc, spasticity.

  • BRICQ S., FRANDON J., BERNARD M., GUYE M., FINAS M., MARCADET L., MIQUEROL L., KOBER F., HABIB G., FAGRET D., JACQUIER A., LALANDE A. “Semiautomatic detection of myocardial contours in order to investigate normal values of the left ventricular trabeculated mass using MRI.”. Journal of magnetic resonance imaging: JMRI [En ligne]. June 2016. Vol. 43, n°6, p. 1398-1406. Disponible sur : < http://dx.doi.org/10.1002/jmri.25113 > (consulté le no date)
    Résumé : PURPOSE: To propose, assess, and validate a semiautomatic method allowing rapid and reproducible measurement of trabeculated and compacted left ventricular (LV) masses from cardiac magnetic resonance imaging (MRI). MATERIALS AND METHODS: We developed a method to automatically detect noncompacted, endocardial, and epicardial contours. Papillary muscles were segmented using semiautomatic thresholding and were included in the compacted mass. Blood was removed from trabeculae using the same threshold tool. Trabeculated, compacted masses and ratio of noncompacted to compacted (NC:C) masses were computed. Preclinical validation was performed on four transgenic mice with hypertrabeculation of the LV (high-resolution cine imaging, 11.75T). Then analysis was performed on normal cine-MRI examinations (steady-state free precession [SSFP] sequences, 1.5T or 3T) obtained from 60 healthy participants (mean age 49 ± 16 years) with 10 men and 10 women for each of the following age groups: [20,39], [40,59], and [60,79]. Interobserver and interexamination segmentation reproducibility was assessed by using Bland-Altman analysis and by computing the correlation coefficient. RESULTS: In normal participants, noncompacted and compacted masses were 6.29 ± 2.03 g/m(2) and 62.17 ± 11.32 g/m(2) , respectively. The NC:C mass ratio was 10.26 ± 3.27%. Correlation between the two observers was from 0.85 for NC:C ratio to 0.99 for end-diastolic volume (P < 10(-5) ). The bias between the two observers was -1.06 ± 1.02 g/m(2) for trabeculated mass, -1.41 ± 2.78 g/m(2) for compacted mass, and -1.51 ± 1.77% for NC:C ratio. CONCLUSION: We propose a semiautomatic method based on region growing, active contours, and thresholding to calculate the NC:C mass ratio. This method is highly reproducible and might help in the diagnosis of LV noncompaction cardiomyopathy. J. Magn. Reson. Imaging 2016;43:1398-1406.
    Mots-clés : cardiovascular magnetic resonance imaging, crmbm, cvs, left ventricle, noncompaction, papillary muscles, trabeculae.

  • DE LEENER B., TASO M., COHEN-ADAD J., CALLOT V. “Segmentation of the human spinal cord.”. Magma (New York, N.Y.) [En ligne]. April 2016. Vol. 29, n°2, p. 125-153. Disponible sur : < http://dx.doi.org/10.1007/s10334-015-0507-2 > (consulté le no date)
    Résumé : Segmenting the spinal cord contour is a necessary step for quantifying spinal cord atrophy in various diseases. Delineating gray matter (GM) and white matter (WM) is also useful for quantifying GM atrophy or for extracting multiparametric MRI metrics into specific WM tracts. Spinal cord segmentation in clinical research is not as developed as brain segmentation, however with the substantial improvement of MR sequences adapted to spinal cord MR investigations, the field of spinal cord MR segmentation has advanced greatly within the last decade. Segmentation techniques with variable accuracy and degree of complexity have been developed and reported in the literature. In this paper, we review some of the existing methods for cord and WM/GM segmentation, including intensity-based, surface-based, and image-based methods. We also provide recommendations for validating spinal cord segmentation techniques, as it is important to understand the intrinsic characteristics of the methods and to evaluate their performance and limitations. Lastly, we illustrate some applications in the healthy and pathological spinal cord. One conclusion of this review is that robust and automatic segmentation is clinically relevant, as it would allow for longitudinal and group studies free from user bias as well as reproducible multicentric studies in large populations, thereby helping to further our understanding of the spinal cord pathophysiology and to develop new criteria for early detection of subclinical evolution for prognosis prediction and for patient management. Another conclusion is that at the present time, no single method adequately segments the cord and its substructure in all the cases encountered (abnormal intensities, loss of contrast, deformation of the cord, etc.). A combination of different approaches is thus advised for future developments, along with the introduction of probabilistic shape models. Maturation of standardized frameworks, multiplatform availability, inclusion in large suite and data sharing would also ultimately benefit to the community.
    Mots-clés : crmbm, Gray matter, MRI, Segmentation, snc, Spinal Cord, white matter.

  • DOCHE E., LECOCQ A., MAAROUF A., DUHAMEL G., SOULIER E., CONFORT-GOUNY S., RICO A., GUYE M., AUDOIN B., PELLETIER J., RANJEVA J. - P., ZAARAOUI W. “Hypoperfusion of the thalamus is associated with disability in relapsing remitting multiple sclerosis.”. Journal of Neuroradiology. Journal De Neuroradiologie [En ligne]. 16 November 2016. Disponible sur : < http://dx.doi.org/10.1016/j.neurad.2016.10.001 > (consulté le no date)
    Résumé : BACKGROUND: While gray matter (GM) perfusion abnormalities have been evidenced in multiple sclerosis (MS) patients, the relationships with disability still remain unclear. Considering that atrophy is known to impact on perfusion, we aimed to assess perfusion abnormalities in GM of MS patients, outside atrophic regions and investigate relationships with disability. METHODS: Brain perfusion of 23 relapsing remitting MS patients and 16 matched healthy subjects were assessed at 3T using the pseudo-continuous arterial spin labeling magnetic resonance imaging technique. In order to locate potential GM perfusion abnormalities in regions spared by atrophy, we combined voxelwise comparisons of GM cerebral blood flow (CBF) maps (cortex and deep GM) (P<0.005, FWE-corrected) and voxel-based-morphometry analysis (P<0.005, FDR-corrected) to exclude atrophic regions. Disability was assessed using the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Functional Composite score (MSFC). RESULTS: In patients, significant GM hypoperfusion outside atrophic regions was depicted only in bilateral thalami. No other cluster was found to be hypoperfused compared to controls. Perfusion of thalami was correlated to MSFC (P=0.011, rho=0.523). A trend of correlation was found between perfusion of thalami and EDSS (P=0.061, rho=-0.396). CONCLUSION: In relapsing remitting MS, perfusion abnormalities in thalamic regions contribute to disability. These findings suggest that functional impairments of thalami, representing a major brain hub, may disturb various cerebral functions even before structural damage.
    Mots-clés : Atrophy, crmbm, Disability, Multiple Sclerosis, perfusion, Pseudo-continuous arterial spin labeling, snc, Thalamus.

  • DONADIEU M., LE FUR Y., CONFORT-GOUNY S., LE TROTER A., GUYE M., RANJEVA J. - P. “Evidencing different neurochemical profiles between thalamic nuclei using high resolution 2D-PRESS semi-LASER (1)H-MRSI at 7 T.”. Magma (New York, N.Y.) [En ligne]. 8 April 2016. Disponible sur : < http://dx.doi.org/10.1007/s10334-016-0556-1 > (consulté le no date)
    Résumé : OBJECTIVE: To demonstrate that high resolution (1)H semi-LASER MRSI acquired at 7 T permits discrimination of metabolic patterns of different thalamic nuclei. MATERIALS AND METHODS: Thirteen right-handed healthy volunteers were explored at 7 T using a high-resolution 2D-semi-LASER (1)H-MRSI sequence to determine the relative levels of N-Acetyl Aspartate (NAA), choline (Cho) and creatine-phosphocreatine (Cr) in eight VOIs (volume <0.3 ml) centered on four different thalamic nuclei located on the Oxford thalamic connectivity atlas. Post-processing was done using the CSIAPO software. Chemical shift displacement of metabolites was evaluated on a phantom and correction factors were applied to in vivo data. RESULTS: The global assessment (ANOVA p < 0.05) of the neurochemical profiles (NAA, Cho and Cr levels) with thalamic nuclei and hemispheres as factors showed a significant global effect (F = 11.98, p < 0.0001), with significant effect of nucleus type (p < 0.0001) and hemisphere (p < 0.0001). Post hoc analyses showed differences in neurochemical profiles between the left and the right hemisphere (p < 0.05), and differences in neurochemical profiles between nuclei within each hemisphere (p < 0.05). CONCLUSION: For the first time, using high resolution 2D-PRESS semi-LASER (1)H-MRSI acquired at 7 T, we demonstrated that the neurochemical profiles were different between thalamic nuclei, and that these profiles were dependent on the brain hemisphere.
    Mots-clés : 1H-MRSI, Connectivity atlas, crmbm, Neurochemical profiles, snc, Thalamic nuclei, Ultra high field.

  • DONADIEU M., LE FUR Y., LECOCQ A., MAUDSLEY A. A., GHERIB S., SOULIER E., CONFORT-GOUNY S., PARIOLLAUD F., RANJEVA M. - P., PELLETIER J., GUYE M., ZAARAOUI W., AUDOIN B., RANJEVA J. - P. “Metabolic voxel-based analysis of the complete human brain using fast 3D-MRSI: Proof of concept in multiple sclerosis.”. Journal of magnetic resonance imaging: JMRI [En ligne]. August 2016. Vol. 44, n°2, p. 411-419. Disponible sur : < http://dx.doi.org/10.1002/jmri.25139 > (consulté le no date)
    Résumé : PURPOSE: To detect local metabolic abnormalities over the complete human brain in multiple sclerosis (MS) patients, we used optimized fast volumic echo planar spectroscopic imaging (3D-EPSI). MATERIALS AND METHODS: Weighted mean combination of two 3D-EPSI covering the whole brain acquired at 3T in AC-PC and AC-PC+15° axial planes was performed to obtain high-quality metabolite maps for five metabolites: N-acetyl aspartate (NAA), glutamate+glutamine (Glx), choline (Cho), myo-inositol (m-Ins), and creatine+phosphocreatine (tCr). After spatial normalization, maps from 19 patients suffering from relapsing-remitting MS were compared to 19 matched controls using statistical mapping analyses to determine the topography of metabolic abnormalities. Probabilistic white matter (WM) T2 lesion maps and gray matter (GM) atrophy maps were also generated. RESULTS: Two-group analysis of variance (ANOVA) (SPM8, P < 0.005, false discovery rate [FDR]-corrected P < 0.05 at the cluster level with age and sex as confounding covariates) comparing patients and controls matched for age and sex showed clusters of abnormal metabolite levels with 1) decreased NAA (around -15%) and Glx (around 20%) predominantly in GM within prefrontal cortices, motor cortices, bilateral thalami, and mesial temporal cortices in line with neuronal/neuro-astrocytic dysfunction; 2) increased m-Ins (around + 20%) inside WM T2 lesions and in the normal-appearing WM of temporal-occipital lobes, suggesting glial activation. CONCLUSION: We demonstrate the ability to noninvasively map over the complete brain-from vertex to cerebellum-with a validated sequence, the metabolic abnormalities associated with MS, for characterizing the topography of pathological processes affecting widespread areas of WM and GM and its functional impact. J. Magn. Reson. Imaging 2016;44:411-419.
    Mots-clés : crmbm, Inflammation, Multiple Sclerosis, neurodegeneration, proton magnetic resonance spectroscopic imaging, snc, statistical mapping analysis, whole brain.

  • DUPONT S. M., DE LEENER B., TASO M., LE TROTER A., STIKOV N., CALLOT V., COHEN-ADAD J. “Fully-integrated framework for the segmentation and registration of the spinal cord white and gray matter.”. NeuroImage [En ligne]. 20 September 2016. Disponible sur : < http://dx.doi.org/10.1016/j.neuroimage.2016.09.026 > (consulté le no date)
    Résumé : The spinal cord white and gray matter can be affected by various pathologies such as multiple sclerosis, amyotrophic lateral sclerosis or trauma. Being able to precisely segment the white and gray matter could help with MR image analysis and hence be useful in further understanding these pathologies, and helping with diagnosis/prognosis and drug development. Up to date, white/gray matter segmentation has mostly been done manually, which is time consuming, induces a bias related to the rater and prevents large-scale multi-center studies. Recently, few methods have been proposed to automatically segment the spinal cord white and gray matter. However, no single method exists that combines the following criteria: (i) fully automatic, (ii) works on various MRI contrasts, (iii) robust towards pathology and (iv) freely available and open source. In this study we propose a multi-atlas based method for the segmentation of the spinal cord white and gray matter that addresses the previous limitations. Moreover, to study the spinal cord morphology, atlas-based approaches are increasingly used. These approaches rely on the registration of a spinal cord template to an MR image, however the registration usually doesn't take into account the spinal cord internal structure and thus lacks accuracy. In this study, we propose a new template registration framework that integrates the white and gray matter segmentation to account for the specific gray matter shape of each individual subject. Validation of segmentation was performed in 24 healthy subjects using T2⁎-weighted images, in 8 healthy subjects using diffusion weighted images (exhibiting inverted white-to-gray matter contrast compared to T2⁎-weighted), and in 5 patients with spinal cord injury. The template registration was validated in 24 subjects using T2⁎-weighted data. RESULTS: of automatic segmentation on T2⁎-weighted images was in close correspondence with the manual segmentation (Dice coefficient in the white/gray matter of 0.91/0.71 respectively). Similarly, good results were obtained in data with inverted contrast (diffusion-weighted image) and in patients. When compared to the classical template registration framework, the proposed framework that accounts for gray matter shape significantly improved the quality of the registration (comparing Dice coefficient in gray matter: p=9.5×10(-6)). While further validation is needed to show the benefits of the new registration framework in large cohorts and in a variety of patients, this study provides a fully-integrated tool for quantitative assessment of white/gray matter morphometry and template-based analysis. All the proposed methods are implemented in the Spinal Cord Toolbox (SCT), an open-source software for processing spinal cord multi-parametric MRI data.
    Mots-clés : Atlas-based analysis, crmbm, Gray matter, multi-parametric MRI, Registration, Segmentation, snc, Spinal Cord.

  • DUTOUR A., ABDESSELAM I., ANCEL P., KOBER F., MRAD G., DARMON P., RONSIN O., PRADEL V., LESAVRE N., MARTIN J. C., JACQUIER A., LEFUR Y., BERNARD M., GABORIT B. “Exenatide decreases liver fat content and epicardial adipose tissue in patients with obesity and type 2 diabetes: a prospective randomized clinical trial using magnetic resonance imaging and spectroscopy.”. Diabetes, Obesity & Metabolism [En ligne]. September 2016. Vol. 18, n°9, p. 882-891. Disponible sur : < http://dx.doi.org/10.1111/dom.12680 > (consulté le no date)
    Résumé : AIM: To conduct a prospective randomized trial to investigate the effect of glucagon-like peptide-1 (GLP-1) analogues on ectopic fat stores. METHODS: A total of 44 obese subjects with type 2 diabetes uncontrolled on oral antidiabetic drugs were randomly assigned to receive exenatide or reference treatment according to French guidelines. Epicardial adipose tissue (EAT), myocardial triglyceride content (MTGC), hepatic triglyceride content (HTGC) and pancreatic triglyceride content (PTGC) were assessed 45 min after a standardized meal with 3T magnetic resonance imaging and proton magnetic resonance spectroscopy before and after 26 weeks of treatment. RESULTS: The study population had a mean glycated haemoglobin (HbA1c) level of 7.5 ± 0.2% and a mean body mass index of 36.1 ± 1.1 kg/m(2) . Ninety five percent had hepatic steatosis at baseline (HTGC ≥ 5.6%). Exenatide and reference treatment led to a similar improvement in HbA1c (-0.7 ± 0.3% vs. -0.7 ± 0.4%; p = 0.29), whereas significant weight loss was observed only in the exenatide group (-5.5 ± 1.2 kg vs. -0.2 ± 0.8 kg; p = 0.001 for the difference between groups). Exenatide induced a significant reduction in EAT (-8.8 ± 2.1%) and HTGC (-23.8 ± 9.5%), compared with the reference treatment (EAT: -1.2 ± 1.6%, p = 0.003; HTGC: +12.5 ± 9.6%, p = 0.007). No significant difference was observed in other ectopic fat stores, PTGC or MTGC. In the group treated with exenatide, reductions in liver fat and EAT were not associated with homeostatic model assessment of insulin resistance index, adiponectin, HbA1c or fructosamin change, but were significantly related to weight loss (r = 0.47, p = 0.03, and r = 0.50, p = 0.018, respectively). CONCLUSION: Our data indicate that exenatide is an effective treatment to reduce liver fat content and epicardial fat in obese patients with type 2 diabetes, and these effects are mainly weight loss dependent.
    Mots-clés : crmbm, cvs, epicardial adipose tissue, glucagon-like peptide 1 receptor agonist, hepatic triglyceride content, Magnetic Resonance Imaging, magnetic-resonance imaging, myocardial triglyceride content, Obesity, pancreatic triglyceride content, Proton Magnetic Resonance Spectroscopy, proton magnetic-resonance spectroscopy, type 2 diabetes.

  • FAIVRE A., ROBINET E., GUYE M., ROUSSEAU C., MAAROUF A., LE TROTER A., ZAARAOUI W., RICO A., CRESPY L., SOULIER E., CONFORT-GOUNY S., PELLETIER J., ACHARD S., RANJEVA J. - P., AUDOIN B. “Depletion of brain functional connectivity enhancement leads to disability progression in multiple sclerosis: A longitudinal resting-state fMRI study.”. Multiple Sclerosis (Houndmills, Basingstoke, England) [En ligne]. November 2016. Vol. 22, n°13, p. 1695-1708. Disponible sur : < http://dx.doi.org/10.1177/1352458516628657 > (consulté le no date)
    Résumé : BACKGROUND: The compensatory effect of brain functional connectivity enhancement in relapsing-remitting multiple sclerosis (RRMS) remains controversial. OBJECTIVE: To characterize the relationships between brain functional connectivity changes and disability progression in RRMS. METHODS: Long-range connectivity, short-range connectivity, and density of connections were assessed using graph theoretical analysis of resting-state functional magnetic resonance imaging (fMRI) data acquired in 38 RRMS patients (disease duration: 120 ± 32 months) and 24 controls. All subjects were explored at baseline and all patients and six controls 2 years later. RESULTS: At baseline, levels of long-range and short-range brain functional connectivity were higher in patients compared to controls. During the follow-up, decrease in connections' density was inversely correlated with disability progression. Post-hoc analysis evidenced differential evolution of brain functional connectivity metrics in patients according to their level of disability at baseline: while patients with lowest disability at baseline experienced an increase in all connectivity metrics during the follow-up, patients with higher disability at baseline showed a decrease in the connectivity metrics. In these patients, decrease in the connectivity metrics was associated with disability progression. CONCLUSION: The study provides two main findings: (1) brain functional connectivity enhancement decreases during the disease course after reaching a maximal level, and (2) decrease in brain functional connectivity enhancement participates in disability progression.
    Mots-clés : crmbm, cvs, Disability, Functional connectivity, Functional MRI, graph theory, Multiple Sclerosis.

  • FATEHI F., SALORT-CAMPANA E., LE TROTER A., BENDAHAN D., ATTARIAN S. “Muscle MRI of facioscapulohumeral dystrophy (FSHD): A growing demand and a promising approach.”. Revue Neurologique [En ligne]. October 2016. Vol. 172, n°10, p. 566-571. Disponible sur : < http://dx.doi.org/10.1016/j.neurol.2016.08.002 > (consulté le no date)
    Résumé : Facioscapulohumeral muscular dystrophy (FSHD), an inherited and progressive muscle disorder, is among the most common hereditary muscle disorders. From a clinical vantage point, FSHD is characterized by weakness of the facial, shoulder (often with scapular winging), arm (including biceps and triceps) and abdominal muscles. Forearm muscles are usually spared and weakness is usually asymmetrical. Over the past few decades, muscle magnetic resonance imaging (MRI) has become established as a reliable and accurate noninvasive tool for the diagnosis and assessment of progression in neuromuscular diseases, showing specific patterns of muscle involvement for a number of myopathies. More recently, MRI has been used to noninvasively identify quantitative biomarkers, allowing evaluation of the natural progression of disease and assessment of therapeutic interventions. In the present review, the intention was to present the most significant MRI developments related to diagnosis and pattern recognition in FSHD and to discuss its capacity to provide outcome measures.
    Mots-clés : crmbm, Facioscapulohumeral dystrophy, FSHD, Measurement, MRI, msk, Pattern recognition.

  • FOURé A., NOSAKA K., GASTALDI M., MATTEI J. - P., BOUDINET H., GUYE M., VILMEN C., LE FUR Y., BENDAHAN D., GONDIN J. “Effects of branched-chain amino acids supplementation on both plasma amino acids concentration and muscle energetics changes resulting from muscle damage: A randomized placebo controlled trial.”. Clinical Nutrition (Edinburgh, Scotland) [En ligne]. February 2016. Vol. 35, n°1, p. 83-94. Disponible sur : < http://dx.doi.org/10.1016/j.clnu.2015.03.014 > (consulté le no date)
    Résumé : BACKGROUND & AIMS: Branched-chain amino acids promote muscle-protein synthesis, reduce protein oxidation and have positive effects on mitochondrial biogenesis and reactive oxygen species scavenging. The purpose of the study was to determine the potential benefits of branched-chain amino acids supplementation on changes in force capacities, plasma amino acids concentration and muscle metabolic alterations after exercise-induced muscle damage. METHODS: (31)P magnetic resonance spectroscopy and biochemical analyses were used to follow the changes after such damage. Twenty six young healthy men were randomly assigned to supplemented branched-chain amino acids or placebo group. Knee extensors maximal voluntary isometric force was assessed before and on four days following exercise-induced muscle damage. Concentrations in phosphocreatine [PCr], inorganic phosphate [Pi] and pH were measured during a standardized rest-exercise-recovery protocol before, two (D2) and four (D4) days after exercise-induced muscle damage. RESULTS: No significant difference between groups was found for changes in maximal voluntary isometric force (-24% at D2 and -21% at D4). Plasma alanine concentration significantly increased immediately after exercise-induced muscle damage (+25%) in both groups while concentrations in glycine, histidine, phenylalanine and tyrosine decreased. No difference between groups was found in the increased resting [Pi] (+42% at D2 and +34% at D4), decreased resting pH (-0.04 at D2 and -0.03 at D4) and the slower PCr recovery rate (-18% at D2 and -24% at D4). CONCLUSIONS: The damaged muscle was not able to get benefits out of the increased plasma branched-chain amino acids availability to attenuate changes in indirect markers of muscle damage and muscle metabolic alterations following exercise-induced muscle damage.
    Mots-clés : crmbm, Double blind randomized placebo controlled trial, Exercise induced-muscle damage, Magnetic Resonance Spectroscopy, msk.

  • JOUBERT S., GOUR N., GUEDJ E., DIDIC M., GUéRIOT C., KORIC L., RANJEVA J. - P., FELICIAN O., GUYE M., CECCALDI M. “Early-onset and late-onset Alzheimer's disease are associated with distinct patterns of memory impairment.”. Cortex; a Journal Devoted to the Study of the Nervous System and Behavior [En ligne]. January 2016. Vol. 74, p. 217-232. Disponible sur : < http://dx.doi.org/10.1016/j.cortex.2015.10.014 > (consulté le no date)
    Résumé : The goal of this study was to investigate the specific patterns of memory breakdown in patients suffering from early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD). Twenty EOAD patients, twenty LOAD patients, twenty matched younger controls, and twenty matched older controls participated in this study. All participants underwent a detailed neuropsychological assessment, an MRI scan, an FDG-PET scan, and AD patients had biomarkers as supporting evidence of both amyloïdopathy and neuronal injury. Results of the neuropsychological assessment showed that both EOAD and LOAD groups were impaired in the domains of memory, executive functions, language, praxis, and visuoconstructional abilities, when compared to their respective control groups. EOAD and LOAD groups, however, showed distinct patterns of memory impairment. Even though both groups were similarly affected on measures of episodic, short term and working memory, in contrast semantic memory was significantly more impaired in LOAD than in EOAD patients. The EOAD group was not more affected than the LOAD group in any memory domain. EOAD patients, however, showed significantly poorer performance in other cognitive domains including executive functions and visuoconstructional abilities. A more detailed analysis of the pattern of semantic memory performance among patient groups revealed that the LOAD was more profoundly impaired, in tasks of both spontaneous recall and semantic recognition. Voxel-Based Morphometry (VBM) analyses showed that impaired semantic performance in patients was associated with reduced gray matter volume in the anterior temporal lobe (ATL) region, while PET-FDG analyses revealed that poorer semantic performance was associated with greater hypometabolism in the left temporoparietal region, both areas reflecting key regions of the semantic network. Results of this study indicate that EOAD and LOAD patients present with distinct patterns of memory impairment, and that a genuine semantic impairment may represent one of the clinical hallmarks of LOAD.
    Mots-clés : Age Factors, Age of Onset, Aged, Aged, 80 and over, Alzheimer Disease, Brain, Cognition, crmbm, Early-onset Alzheimer's disease, Executive Function, Female, Humans, Language, Late-onset Alzheimer's disease, Magnetic Resonance Imaging, Male, Memory, Memory Disorders, Middle Aged, Neuropsychological Tests, Semantic memory, snc.

  • JUBEAU M., GONDIN J. “Methodological considerations for investigating the influence of neuromuscular electrical stimulation on pH heterogeneity.”. Magnetic Resonance in Medicine [En ligne]. 7 December 2016. Disponible sur : < http://dx.doi.org/10.1002/mrm.26511 > (consulté le no date)

  • KOBER F., JAO T., TROALEN T., NAYAK K. S. “Myocardial arterial spin labeling.”. Journal of Cardiovascular Magnetic Resonance: Official Journal of the Society for Cardiovascular Magnetic Resonance [En ligne]. 2016. Vol. 18, n°1, p. 22. Disponible sur : < http://dx.doi.org/10.1186/s12968-016-0235-4 > (consulté le no date)
    Résumé : Arterial spin labeling (ASL) is a cardiovascular magnetic resonance (CMR) technique for mapping regional myocardial blood flow. It does not require any contrast agents, is compatible with stress testing, and can be performed repeatedly or even continuously. ASL-CMR has been performed with great success in small-animals, but sensitivity to date has been poor in large animals and humans and remains an active area of research. This review paper summarizes the development of ASL-CMR techniques, current state-of-the-art imaging methods, the latest findings from pre-clinical and clinical studies, and future directions. We also explain how successful developments in brain ASL and small-animal ASL-CMR have helped to inform developments in large animal and human ASL-CMR.
    Mots-clés : arterial spin labeling, Cardiovascular magnetic resonance, crmbm, cvs, Ischemic heart disease, myocardial perfusion.

  • KOOB M., GIRARD N., GHATTAS B., FELLAH S., CONFORT-GOUNY S., FIGARELLA-BRANGER D., SCAVARDA D. “The diagnostic accuracy of multiparametric MRI to determine pediatric brain tumor grades and types.”. Journal of Neuro-Oncology [En ligne]. April 2016. Vol. 127, n°2, p. 345-353. Disponible sur : < http://dx.doi.org/10.1007/s11060-015-2042-4 > (consulté le no date)
    Résumé : Childhood brain tumors show great histological variability. The goal of this retrospective study was to assess the diagnostic accuracy of multimodal MR imaging (diffusion, perfusion, MR spectroscopy) in the distinction of pediatric brain tumor grades and types. Seventy-six patients (range 1 month to 18 years) with brain tumors underwent multimodal MR imaging. Tumors were categorized by grade (I-IV) and by histological type (A-H). Multivariate statistical analysis was performed to evaluate the diagnostic accuracy of single and combined MR modalities, and of single imaging parameters to distinguish the different groups. The highest diagnostic accuracy for tumor grading was obtained with diffusion-perfusion (73.24 %) and for tumor typing with diffusion-perfusion-MR spectroscopy (55.76 %). The best diagnostic accuracy was obtained for tumor grading in I and IV and for tumor typing in embryonal tumor and pilocytic astrocytoma. Poor accuracy was seen in other grades and types. ADC and rADC were the best parameters for tumor grading and typing followed by choline level with an intermediate echo time, CBV for grading and Tmax for typing. Multiparametric MR imaging can be accurate in determining tumor grades (primarily grades I and IV) and types (mainly pilocytic astrocytomas and embryonal tumors) in children.
    Mots-clés : Brain Neoplasms, Child, crmbm, Diffusion Magnetic Resonance Imaging, Magnetic Resonance Angiography, Magnetic Resonance Spectroscopy, snc.

  • LAYEC G., BRINGARD A., LE FUR Y., MICALLEF J. - P., VILMEN C., PERREY S., COZZONE P. J., BENDAHAN D. “Mitochondrial Coupling and Contractile Efficiency in Humans with High and Low V˙O2peaks.”. Medicine and Science in Sports and Exercise [En ligne]. May 2016. Vol. 48, n°5, p. 811-821. Disponible sur : < http://dx.doi.org/10.1249/MSS.0000000000000858 > (consulté le no date)
    Résumé : INTRODUCTION: Endurance training elicits tremendous adaptations of the mitochondrial energetic capacity. Yet, the effects of training or physical fitness on mitochondrial efficiency during exercise are still unclear. Accordingly, the purpose of the present study was to examine in vivo the differences in mitochondrial efficiency and ATP cost of contraction during exercise in two groups of adults differing in their aerobic capacity. METHOD: We simultaneously assessed the ATP synthesis and O2 fluxes with P-magnetic resonance spectroscopy and pulmonary gas exchange measurements in seven endurance-trained (ET, V˙O2max: 67 ± 8 mL·min·kg) and seven recreationally active (RA, V˙O2max: 43 ± 7 mL·min·kg) subjects during 6 min of dynamic moderate-intensity knee extension. RESULTS: The ATP cost of dynamic contraction was not significantly different between ET and RA (P > 0.05). Similarly, end-exercise O2 consumption was not significantly different between groups (ET: 848 ± 155 mL·min and RA: 760 ± 131 mL·min, P > 0.05). During the recovery period, the PCr offset time constant was significantly faster in ET compared with RA (ET: 32 ± 8 s and RA: 43 ± 10 s, P < 0.05), thus indicating an increased mitochondrial capacity for ATP synthesis in the quadriceps of ET. In contrast, the estimated mitochondrial efficiency during exercise was not significantly different (P/O, ET: 2.0 ± 1.0 and RA: 1.8 ± 0.4, P > 0.05). Consequently, the higher mitochondrial capacity for ATP synthesis in ET likely originated from an elevated mitochondrial volume density, mitochondria-specific respiratory capacity, and/or slower postexercise inactivation of oxidative phosphorylation by the parallel activation mechanism. CONCLUSION: Together, these findings reveal that 1) mitochondrial and contractile efficiencies are unaltered by several years of endurance training in young adults, and 2) the training-induced improvement in mitochondrial energetic capacity appears to be independent from changes in mitochondrial coupling.
    Mots-clés : crmbm, msk.

  • LE TROTER A., FOURÉ A., GUYE M., CONFORT-GOUNY S., MATTEI J. - P., GONDIN J., SALORT-CAMPANA E., BENDAHAN D. “Volume measurements of individual muscles in human quadriceps femoris using atlas-based segmentation approaches.”. Magma (New York, N.Y.) [En ligne]. April 2016. Vol. 29, n°2, p. 245-257. Disponible sur : < http://dx.doi.org/10.1007/s10334-016-0535-6 > (consulté le no date)
    Résumé : OBJECTIVES: Atlas-based segmentation is a powerful method for automatic structural segmentation of several sub-structures in many organs. However, such an approach has been very scarcely used in the context of muscle segmentation, and so far no study has assessed such a method for the automatic delineation of individual muscles of the quadriceps femoris (QF). In the present study, we have evaluated a fully automated multi-atlas method and a semi-automated single-atlas method for the segmentation and volume quantification of the four muscles of the QF and for the QF as a whole. SUBJECTS AND METHODS: The study was conducted in 32 young healthy males, using high-resolution magnetic resonance images (MRI) of the thigh. The multi-atlas-based segmentation method was conducted in 25 subjects. Different non-linear registration approaches based on free-form deformable (FFD) and symmetric diffeomorphic normalization algorithms (SyN) were assessed. Optimal parameters of two fusion methods, i.e., STAPLE and STEPS, were determined on the basis of the highest Dice similarity index (DSI) considering manual segmentation (MSeg) as the ground truth. Validation and reproducibility of this pipeline were determined using another MRI dataset recorded in seven healthy male subjects on the basis of additional metrics such as the muscle volume similarity values, intraclass coefficient, and coefficient of variation. Both non-linear registration methods (FFD and SyN) were also evaluated as part of a single-atlas strategy in order to assess longitudinal muscle volume measurements. The multi- and the single-atlas approaches were compared for the segmentation and the volume quantification of the four muscles of the QF and for the QF as a whole. RESULTS: Considering each muscle of the QF, the DSI of the multi-atlas-based approach was high 0.87 ± 0.11 and the best results were obtained with the combination of two deformation fields resulting from the SyN registration method and the STEPS fusion algorithm. The optimal variables for FFD and SyN registration methods were four templates and a kernel standard deviation ranging between 5 and 8. The segmentation process using a single-atlas-based method was more robust with DSI values higher than 0.9. From the vantage of muscle volume measurements, the multi-atlas-based strategy provided acceptable results regarding the QF muscle as a whole but highly variable results regarding individual muscle. On the contrary, the performance of the single-atlas-based pipeline for individual muscles was highly comparable to the MSeg, thereby indicating that this method would be adequate for longitudinal tracking of muscle volume changes in healthy subjects. CONCLUSION: In the present study, we demonstrated that both multi-atlas and single-atlas approaches were relevant for the segmentation of individual muscles of the QF in healthy subjects. Considering muscle volume measurements, the single-atlas method provided promising perspectives regarding longitudinal quantification of individual muscle volumes.
    Mots-clés : crmbm, Fusion, Individual muscle volume measurements, MRI, msk, Multi-atlas-based segmentation, Non-linear registration, Quadriceps femoris muscle.

  • LUTZ N. W., BANERJEE P., WILSON B. J., MA J., COZZONE P. J., FRANK M. H. “Expression of Cell-Surface Marker ABCB5 Causes Characteristic Modifications of Glucose, Amino Acid and Phospholipid Metabolism in the G3361 Melanoma-Initiating Cell Line.”. PloS One [En ligne]. 2016. Vol. 11, n°8, p. e0161803. Disponible sur : < http://dx.doi.org/10.1371/journal.pone.0161803 > (consulté le no date)
    Résumé : We present a pilot study aimed at determining the effects of expression of ATP-binding cassette member B5 (ABCB5), a previously described marker for melanoma-initiating cells, on cellular metabolism. Metabolic profiles for two groups of human G3361 melanoma cells were compared, i.e. wildtype melanoma cells with intact ABCB5 expression (ABCB5-WT) and corresponding melanoma cell variants with inhibited ABCB5 expression, through shRNA-mediated gene knockdown (ABCB5-KD). A comprehensive metabolomic analysis was performed by using proton and phosphorus NMR spectroscopy of cell extracts to examine water-soluble metabolites and lipids. Parametric and non-parametric statistical analysis of absolute and relative metabolite levels yielded significant differences for compounds involved in glucose, amino acid and phospholipid (PL) metabolism. By contrast, energy metabolism was virtually unaffected by ABCB5 expression. The sum of water-soluble metabolites per total protein was 17% higher in ABCB5-WT vs. ABCB5-KD G3361 variants, but no difference was found for the sum of PLs. Enhanced abundance was particularly pronounced for lactate (+ 23%) and alanine (+ 26%), suggesting an increase in glycolysis and potentially glutaminolysis. Increases in PL degradation products, glycerophosphocholine and glycerophosphoethanolamine (+ 85 and 123%, respectively), and redistributions within the PL pool suggested enhanced membrane PL turnover as a consequence of ABCB5 expression. The possibility of glycolysis modulation by an ABCB5-dependent IL1β-mediated mechanism was supported by functional studies employing monoclonal antibody (mAb)-dependent ABCB5 protein inhibition in wildtype G3361 melanoma cells. Our metabolomic results suggest that the underlying biochemical pathways may offer targets for melanoma therapy, potentially in combination with other treatment forms.
    Mots-clés : crmbm.

  • MARCHITELLI R., MINATI L., MARIZZONI M., BOSCH B., BARTRÉS-FAZ D., MÜLLER B. W., WILTFANG J., FIEDLER U., ROCCATAGLIATA L., PICCO A., NOBILI F., BLIN O., BOMBOIS S., LOPES R., BORDET R., SEIN J., RANJEVA J. - P., DIDIC M., GROS-DAGNAC H., PAYOUX P., ZOCCATELLI G., ALESSANDRINI F., BELTRAMELLO A., BARGALLÓ N., FERRETTI A., CAULO M., AIELLO M., CAVALIERE C., SORICELLI A., PARNETTI L., TARDUCCI R., FLORIDI P., TSOLAKI M., CONSTANTINIDIS M., DREVELEGAS A., ROSSINI P. M., MARRA C., SCHÖNKNECHT P., HENSCH T., HOFFMANN K. - T., KUIJER J. P., VISSER P. J., BARKHOF F., FRISONI G. B., JOVICICH J. “Test-retest reliability of the default mode network in a multi-centric fMRI study of healthy elderly: Effects of data-driven physiological noise correction techniques.”. Human Brain Mapping [En ligne]. June 2016. Vol. 37, n°6, p. 2114-2132. Disponible sur : < http://dx.doi.org/10.1002/hbm.23157 > (consulté le no date)
    Résumé : Understanding how to reduce the influence of physiological noise in resting state fMRI data is important for the interpretation of functional brain connectivity. Limited data is currently available to assess the performance of physiological noise correction techniques, in particular when evaluating longitudinal changes in the default mode network (DMN) of healthy elderly participants. In this 3T harmonized multisite fMRI study, we investigated how different retrospective physiological noise correction (rPNC) methods influence the within-site test-retest reliability and the across-site reproducibility consistency of DMN-derived measurements across 13 MRI sites. Elderly participants were scanned twice at least a week apart (five participants per site). The rPNC methods were: none (NPC), Tissue-based regression, PESTICA and FSL-FIX. The DMN at the single subject level was robustly identified using ICA methods in all rPNC conditions. The methods significantly affected the mean z-scores and, albeit less markedly, the cluster-size in the DMN; in particular, FSL-FIX tended to increase the DMN z-scores compared to others. Within-site test-retest reliability was consistent across sites, with no differences across rPNC methods. The absolute percent errors were in the range of 5-11% for DMN z-scores and cluster-size reliability. DMN pattern overlap was in the range 60-65%. In particular, no rPNC method showed a significant reliability improvement relative to NPC. However, FSL-FIX and Tissue-based physiological correction methods showed both similar and significant improvements of reproducibility consistency across the consortium (ICC = 0.67) for the DMN z-scores relative to NPC. Overall these findings support the use of rPNC methods like tissue-based or FSL-FIX to characterize multisite longitudinal changes of intrinsic functional connectivity. Hum Brain Mapp 37:2114-2132, 2016. © 2016 Wiley Periodicals, Inc.
    Mots-clés : crmbm, default mode network, independent component analysis, multisite, physiological noise correction, resting-state networks, snc, task-free fMRI, test-retest reliability.

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