L’IRM prend une place de plus en plus grande dans les études de recherche clinique, que ce soit au niveau des critères d’inclusion ou des critères d’évaluation. Des marqueurs basés sur l’exploitation des acquisitions IRM sont désormais considérés régulièrement comme critères principaux d’évaluation. Dans le cadre d’études multicentriques en particulier, la gestion des acquisitions IRM doit considérer l’hétérogénéité des systèmes IRM en termes de constructeurs, de champs magnétiques, d’antennes de réception et de versions logicielles. Cela s’explique par le nombre de paramètres importants qu’il est possible de spécifier pour obtenir une acquisition IRM, la variabilité entre les solutions proposées par les constructeurs et les innovations techniques régulières. L’objectif du présent article est de détailler les spécificités à prendre en compte et les personnes à impliquer pour réaliser une étude en IRM quel que soit l’organe concerné par l’imagerie. En s’appuyant sur l’expérience et l’expertise des membres du Réseau d’entraide multicentrique en IRM (REMI), nous proposons à la communauté francophone des recommandations détaillées, afin de mieux prendre en compte les spécificités de l’IRM à toutes les étapes de l’étude et de participer à l’amélioration de la qualité de la recherche en IRM. Ces recommandations prennent également en compte les spécificités des plateformes de recherche en IRM et des services d’imagerie clinique, ainsi que les contraintes réglementaires. MRI is becoming increasingly important in clinical research studies, both in terms of inclusion criteria and endpoints. Markers based on MRI acquisitions are now regularly considered as primary endpoints. Especially in multicentre studies, the management of MRI acquisitions has to take into account the heterogeneity of MRI systems in terms of manufacturers, magnetic fields, coils and software versions. This is due to the number of important parameters that can be specified and optimised to obtain MR images, the variability between the solutions proposed by the manufacturers and the regular technical innovations. The aim of this article is to detail the steps and the people to involve in order to carry out an MRI study. Based on the experience and expertise of the members of the Réseau d’entraide multicentrique en IRM (REMI), we propose detailed recommendations to the French-speaking community, in order to better take into account the specificities of MRI at all stages of the study and to participate in improving the quality of MRI research. These recommendations also take into account the specificities of MRI research platforms and clinical imaging services, as well as regulatory constraints.

BACKGROUND AND PURPOSE: Few data are available regarding the influence of the timing of ischemic stroke management, such as daytime and nighttime hours, on the delay of mechanical thrombectomy, the effectiveness of revascularization, and clinical outcomes. We aimed to investigate whether admission during nighttime hours could impact the clinical outcome (mRS at 90?days) of patients with acute ischemic stroke treated by mechanical thrombectomy. MATERIALS AND METHODS: We retrospectively analyzed 169 patients (112 treated during daytime hours and 57 treated during nighttime hours) with acute ischemic stroke in the anterior cerebral circulation. The main outcome was the rate of patients achieving functional independence at 90?days (mRS ?2), depending on admission time. RESULTS: In patients admitted during nighttime hours, the rate of mRS ? 2 at 90?days was significantly higher (51% versus 35%, P?=?.05) compared with those admitted in daytime hours. Patients in daytime and nighttime hours were comparable regarding admission and treatment characteristics. However, patients in nighttime hours tended to have a higher median NIHSS score at admission (P?=?.08) and to be younger (P?=?.08), especially among the mothership group (P?=?.09). The multivariate logistic regression analysis confirmed that patients in nighttime hours had better functional outcomes at 90?days than those in daytime hours (P = .018; 95% CI, 0.064?0.770; OR?= 0.221). CONCLUSIONS: In a highly organized stroke care network, mechanical thrombectomy is quite effective in the nighttime hours among acute ischemic stroke presentations. Unexpectedly, we found that those patients achieved favorable clinical outcomes more frequently than those treated during daytime hours. Larger series are needed to confirm these results.

Dual phase 18 FDG-PET has been proven helpful to assess FDG-avid cerebral tumors as tracer will build up in metastases or tumor recurrences while its retention remains stable within normal tissue or inflammatory process. This is useful when MRI can’t discriminate brain tumor recurrence (TR) from radionecrosis (RN) after stereotaxic radiosurgery (SRS) for brain metastases (BM). Many studies sought to improve diagnostic performance by associating FDG-PET and MRI with interesting results but many bias, mostly within image post-processing. Coregistered MRI and dual phase FDG-PET images could alleviate these biases and be used to extract prognostic biomarkers. We retrospectively evaluated patients treated with SRS for BM which developed a contrast-enhanced MRI lesion with non-conclusive diagnosis for TR or RN. All patients underwent MRI and FDG-PET at least 3 months after their last SRS session. Dual FDG-PET comprised a one hour “based image” (H1) followed by a 4 hours “delayed image” (H4). MRI included contrast enhanced T1 (T1), FLAIR, ASL (BAT,CBF), T1 Perfusion (ktrans, SER) and T2* Permeability (k2, rBF, rBV). PET and MRI data were all coregistered on the T1 images. Semi-automated Regions of Interest (ROI) of the tumor were drawn on the T1 MRI, H1 and H4 FDG-PET images; a reference contralateral white-matter ROI (WM) was drawn for standardization. Imaging metrics were then evaluated for their association with TR or RN based on histological, radiological and clinical criteria after at least 6 months follow-up. Eleven patients matched the inclusion criteria; 7 with TR and 4 with RN; no additional treatment was introduced. On visual analysis, FDG-PET and MRI respectively obtained 100% and 83% Sensitivity and 100% and 80% Specificity. The two MRI-false negative diagnoses were subsequently identified on follow-up (1 patient, RN) and histology (1 patient, TR). When standardized on WM, PET SUVmax values were significantly different across groups at H1 (P < 0,044) and H4 (p < 0,00285). Among MRI metrics, relCBF (P < 0.02055), T1-perfusion AUC (P < 0.00425), SER (Signal Enhancement Ratio, P < 0.0195) and Washout (P < 0.0212) could significantly discriminate between TR or RN. Coregistered PET-MRI images accurately discriminates between TR and RN. With FDG being the most commonly used PET radiotracer, this protocol remains easily transposable and should be encouraged to obtain non-invasive prognostic and clinically relevant biomarkers.

Background-Neuroimaging studies suggest that social distress and suicidal vulnerability share common cerebral bases. Moreover, increased peripheral inflammatory activity is involved in both social distress and suicidal behavior. Objective: To evaluate, in suicidal and non-suicidal individuals, the association between the activation of specific cerebral regions (anterior cingulate, insula and orbitofrontal cortex) during experimental social exclusion and the baseline blood levels of the pro-inflammatory cytokines interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) and of the anti-inflammatory cytokine interleukin-2 (IL-2). Methods: In total, 101 euthymic women were recruited: 42 suicide attempters (SA), 40 affective controls (AC), and 19 healthy controls (HC). During functional MRI (fMRI), they performed the Cyberball game, a validated social exclusion task. Blood levels of IL-1 beta, IL-6, TNF-alpha and IL-2 were measured prior to fMRI. The activation of insula, orbitofrontal cortex (OFC) and anterior cingulate cortex (ACC) during the explicit social exclusion (ESE) vs social inclusion (INC) conditions of the Cyberball game was analyzed in function of the baseline cytokine levels. Results: IL-1 beta was negatively associated with right OFC activation (p = 0.01) in ESE vs. INC, whereas IL-2 was positively associated with activation of the right ACC (p = 0.02), insula (p = 0.002) and OFC (p = 0.004) in ESE vs. INC. These associations remained significant after controlling for group, indicating that they were independent of the suicidal status. Conclusion: Baseline IL-1 beta and IL-2 blood levels are differentially associated with cerebral activation involved in the perception of social exclusion, independently of suicidal behavior. Our results may help to better understand the role of basal inflammation in social distress and its link with mood disorder pathophysiology.

The dynamic connectome perspective states that brain functions arise from the functional integration of distributed and/or partly overlapping networks. Diffuse low-grade gliomas (DLGG) have a slow infiltrating character. Here we addressed whether and how anatomical disconnection following DLGG growth and resection might interfere with functional resting-state connectivity, specifically in relation to picture naming. Thirty-nine native French persons with a left DLGG were included. All underwent awake surgical resection of the tumor using direct brain electrostimulation to preserve critical eloquent regions. The anatomical disconnectivity risk following the DLGG volume and the resection, and the functional connectivity of resting-state fMRI images in relation to picture naming were evaluated prior to and three months after surgery. Resting-state connectivity patterns were compared with nineteen healthy controls. It was demonstrated that picture naming was strongly dependent on the semantic network that emerged from the integration and interaction of regions within multiple resting-state brain networks, in which their specific role could be explained in the light of the broader resting-state network they take part in. It emphasized the importance of a whole brain approach with specific clinical data input, during resting-state analysis in case of lesion. Adaptive plasticity was found in secondary regions, functionally connected to regions close to the tumor and/or cavity, marked by an increased connectivity of the right and left inferior parietal lobule with the left inferior temporal gyrus. In addition, an important role was identified for the superior parietal lobe, connected with the frontal operculum, suggesting functional compensation by means of attentional resources in order to name a picture via recruitment of the frontoparietal attention network.

Alors que l’anxiété et les symptômes dépressifs peuvent prendre une grande place dans le syndrome de Gougerot–Sjögren (SGS), les plaintes mnésiques et attentionnelles sont fréquentes mais mal objectivées. Notre travail décrit les anomalies d’imageries cérébrales chez des patients suivis pour un SGS, et recherche des associations avec les plaintes fonctionnelles et avec les résultats de tests neurocognitifs validés. Au CHRU de Montpellier, entre janvier 2017 à janvier 2019, des patients suivis en médecine interne pour un SGS et rapportant des symptômes cognitifs, ont pu bénéficier d’une IRM cérébrale (acquisition 3D pondérée T1 et 3D Flair) dans le cadre du soin, avec évaluation volumétriques des structures cérébrales par segmentation volumique à partir de la séquence 3DT1 MPRAGE qui a été réalisée en utilisant l’algorithme Morphobox [1]. En parallèle, une évaluation cognitive a pu être réalisée par le Centre Mémoire de Ressources et de Recherche (CMRR) (MMSE [Mini Mental State], Grober [test de rappel immédiat et de rappel différé de 16 mots], et Epreuve du Code [WAIS] notamment). Une auto-évaluation cognitive (Questionnaire de Plainte Cognitive [QPC] et de la plainte mnésique [AEPM]) ont pu aussi être recueillies. Les éléments cliniques et biologiques de la maladie, ainsi que son activité (ESSPRI et ESSDAI) ont été relevés. Comité local d’éthique (2018_IRB-MTP_06-08). Au total, 23 patients (22 femmes et 1 homme) ont pu bénéficier d’une IRM cérébrale. L’âge médian était de 53 ans [38–81] avec une durée médiane d’évolution de la maladie de 7 ans [2–38]. Le score moyen de l’ESSDAI était de 3,30 [0–13], et celui de l’ESSPRI de 6,54 [2,97–9]. Les IRM cérébrales ont montré des hypersignaux aspécifiques de la substance blanche (classification Fazekas) pour 64,3 % des patients analysés (9/14). En comparaison aux données volumétriques de référence d’une population saine appariée sur l’âge et le sexe, 52,1 % (12/23) des patients avec SGS présentaient une baisse de volume de certaines structures cérébrales : LCR (18,2 %, n = 22) ; corps calleux (13,6 %, n = 22) ; substance blanche profonde (9,1 %, n = 22) ; substance grise des lobes frontaux (9,1 %, n = 22). Pour 95,7 % (22/23) de ces patients, le volume de l’hippocampe était considéré comme normal. Des analyses complémentaires des données d’imagerie sont encore en cours. Chez ces patients, une altération objective des fonctions cognitives [vitesse de traitement de l’information (WAIS), perception visuo-spatiale (VOSP, Figure de Rey), du langage (DO 80) et de la mémoire (Grober)] a été mise en évidence, en comparaison aux résultats obtenus pour des sujets sains appariés sur l’âge, le sexe et le niveau socioculturel (Cohorte Constances [2]). Dans ce travail, sous réserve des analyses complémentaires en cours, plus de la moitié des patients présentant un SGS présenteraient des anomalies volumétriques à l’IRM cérébrales. L’hippocampe semble ici conserver un volume normal tandis que le corps calleux, responsable de la communication inter-hémisphérique, pourrait être atrophié. Nous retrouvons par ailleurs la fréquence élevée (déjà décrite dans la littérature) des hypersignaux de la substance blanche (malgré l’absence de facteurs de risque cardio-vasculaires patents). Ces résultats préliminaires suggèrent l’existence de variations volumétriques des structures cérébrales chez les patients atteints de SGS et rapportant des symptômes cognitifs, ceux-là même présentant des altérations subjectives et objectives cognitives. Ces données préliminaires nous incitent à compléter nos travaux par l’analyse des données d’imagerie fonctionnelle, permettant d’intégrer le fonctionnement et la connectivité cérébrale. Ceci pourrait permettre de mieux appréhender les mécanismes menant aux symptômes neurocognitifs au cours du SGS.

Rehabilitation, aiming to stimulate underlying neural plasticity, takes an important place in patients' treatment post-stroke. Here we confront fine-grained movement kinematics with corresponding brain activations to reveal recovery markers usable to individualize therapeutic approaches favoring plasticity and maximizing recovery. Twenty-one participants early post-stroke with initial severe motor deficits were compared with 13 controls. Participants were evaluated twice, < 8 weeks post-stroke and after 6 weeks of rehabilitation. Kinematic data were collected during movement execution within the fMRI. The movement consisted of a continuous elbow flexion/extension. Calculated kinematics captured the movements' shaping (amplitude, frequency) and the structure (fluency, directness, and the variability's entropy). People post-stroke generally moved with decreased amplitude, smoothness, directness and entropy compared to controls. The frequency was lower for the paretic upper limb and during bilateral movements, but comparable to controls during ipsilesional upper limb movement. The variability's entropy was in both controls and patients related to increased activations in the middle frontal lobe, presumably indicating more feed forward based control. In patients, the amplitude and smoothness were correlated with strong implication of the occipital lobe, and additional recruitment of the rolandic opercularis (visualization) was observed during both paretic and ipsilesional movement, related to motor learning. Patients' kinematic characteristics were unrelated to clinical scores and lesion characteristics, supporting the idea that they reflect motor control strategies. The co-registration of fine-grained kinematics and fMRI measures revealed how different kinematic profiles are related to different motor control organizations. Analyzing kinematics in a standardized manner might contribute to the implementation of a personalized rehabilitation strategy, and more targeted brain stimulation protocols to stimulate plasticity and optimize recovery.

A methodology for non-invasive estimation of the pressure in internal carotid arteries is proposed. It uses data assimilation and Ensemble Kalman filters in order to identify unknown parameters in a mathematical description of the cerebral network. The approach uses patient specific blood flow rates extracted from Magnetic Resonance Angiography and Magnetic Resonance Imaging. This construction is necessary as the simulation of blood flows in complex arterial networks, such as the circle of Willis, is not straightforward because hemodynamic parameters are unknown as well as the boundary conditions necessary to close this complex system with many outlets. For instance, in clinical cases, the values of Windkessel model parameters or the Young's modulus and the thickness of the arteries are not available on per-patient cases. To make the approach computational efficient, a reduced order zero-dimensional compartment model is used for blood flow dynamics. Using this simplified model, the proof-of-concept study demonstrates how to use the EnKF as an optimization tool to find parameters and how to make the inverse hemodynamic problem tractable. The predicted blood flow rates in the internal carotid arteries and the predicted systolic and diastolic brachial blood pressures are found to be in good agreement with the clinical measurements.

In rhythmical movement performance, our brain has to sustain movement while correcting for biological noise-induced variability. Here, we explored the functional anatomy of brain networks during voluntary rhythmical elbow flexion/extension using kinematic movement regressors in fMRI analysis to verify the interest of method to address motor control in a neurological population. We found the expected systematic activation of the primary sensorimotor network that is suggested to generate the rhythmical movement. By adding the kinematic regressors to the model, we demonstrated the potential involvement of cerebellar-frontal circuits as a function of the irregularity of the variability of the movement and the primary sensory cortex in relation to the trajectory length during task execution. We suggested that different functional brain networks were related to two different aspects of rhythmical performance: rhythmicity and error control. Concerning the latter, the partitioning between more automatic control involving cerebellar-frontal circuits versus less automatic control involving the sensory cortex seemed thereby crucial for optimal performance. Our results highlight the potential of using co-registered fine-grained kinematics and fMRI measures to interpret functional MRI activations and to potentially unmask the organisation of neural correlates during motor control.

The retinal vascular fractal dimension (FD) is a marker of retinal complexity of vascular tree. It has been associated with neurodegenerative and cerebrovascular diseases. Arterial spin labelling is a non-invasive technique to evaluate the cerebral blood flow (CBF). The purpose of this study was to explore the relationship between retinal vascular FD and CBF. Cross sectional analysis comprising 29 individuals aged 65 years and over from the Cognitive REServe and Clinical ENDOphenotype (CRESCENDO) cohort of healthy older adults. Retinal vascular FD was measured from fundus photographs using semi-automated standardized imaging software “Singapore Eye Vessel Assessment (SIVA)” system. CBF was estimated in various gray matter regions from a 2D Pulsed arterial spin labelling sequence from MRI. A higher venular FD was associated with higher CBF in all cerebral regions of interest (p < 0.01). No significant associations were found between CBF and other parameters derived from SIVA or the central retinal arterial or venular equivalent. This association was stronger for opposite eye to handedness (p = 0.03). No relationship was observed between arterial FD and CBF (p > 0.07). Venular FD was the main parameter associated to cerebral perfusion whereas retinal vascular calibers were not. It may be evaluated in clinical studies for early and non-invasive detection of subclinical cerebro-vascular pathologies including dementia and stroke.

BACKGROUND AND PURPOSE: Mechanical thrombectomy for patients with acute ischemic stroke with tandem occlusions has been shown to present varying reperfusion successes and clinical outcomes. However, the heterogeneity of tandem occlusion etiology has been strongly neglected in previous studies. We retrospectively investigated patients with acute ischemic stroke atherothrombotic tandem occlusion. MATERIALS AND METHODS: All consecutive patients with acute ischemic stroke with atherothrombotic tandem occlusions treated with mechanical thrombectomy in our center between September 2009 and April 2015 were analyzed. They were compared with patients with acute ischemic stroke with dissection-related tandem occlusion and isolated intracranial occlusion treated during the same period. Comparative univariate and multivariate analyses were conducted, including demographic data, safety, and rates of successful recanalization and good clinical outcome. RESULTS: Despite comparable baseline severity of neurologic deficits and infarct core extension, patients with atherothrombotic tandem occlusions were older (P < .001), were more frequently smokers (P < .001), and had globally more cardiovascular risk factors (P < .001) than the other 2 groups of patients. The patients with atherothrombotic tandem occlusions had significantly longer procedural times (P < .001), lower recanalization rates (P = .004), and higher global burden of procedural complications (P < .001). In this group, procedural complications (OR = 0.15, P = .02) and the TICI 2b/3 reperfusion scores (OR = 17.76, P = .002) were independently predictive factors of favorable clinical outcome. CONCLUSIONS: Our study suggests that atherothrombotic tandem occlusions represent a peculiar and different nosologic entity compared with dissection-related tandem occlusions. This challenging cause of acute ischemic stroke should be differentiated from other etiologies in patient management in future prospective studies.

cancelled

BACKGROUND AND PURPOSE: Patients with vascular parkinsonism have higher cognitive decline and more basal ganglia lesions. We aimed to evaluate the relationship of cognitive impairment with functional connectivity between the basal ganglia and cingulate cortex in vascular parkinsonism.MATERIALS AND METHODS: Thirty patients (8 with vascular parkinsonism and 22 with Parkinson disease) and 23 controls were enrolled. The Mattis Dementia Rating Scale and the Stroop Task were used to assess cognitive decline. MR imaging examinations included T1-MPRAGE, FLAIR, and resting-state fMRI sequences. MPRAGE was segmented to obtain basal ganglia and cingulate cortex volumes. FLAIR was segmented to obtain white matter hyperintensity lesion volume. Resting-state fMRI sequences were used to compare basal ganglia functional connectivity with the cingulate cortex between patients and controls.RESULTS: Patients with vascular parkinsonism exhibited impaired attention, resistance to interference, and inhibitory control and an increased number of errors on the Stroop Task. They also had higher caudate nucleus and white matter hyperintensity lesion volumes, which were positively correlated (rho = 0.75, P<.0001). Caudate nucleus functional connectivity with the perigenual anterior cingulate cortex was increased in patients with vascular parkinsonism compared with controls and patients with Parkinson disease, and it was positively correlated with the caudate nucleus volume (rho = 0.44, P=.016). Caudate nucleus functional connectivity with the posterior cingulate cortex was decreased in patients with vascular parkinsonism compared with controls and negatively correlated with the number of errors on the Stroop test (rho = -0.51, P=.0003).CONCLUSIONS: In patients with vascular parkinsonism, cognitive decline could be related to changes of caudate nucleus functional connectivity with the cingulate cortex at resting-state, which may be induced by ischemia-related remodelling.

To evaluate the additional value of adding movement kinematics into the design matrix in order to gain fine-grained insight in motor control strategies. Ten healthy volunteers (age 41.8 ± 14.5, 5 males) performed a continuous elbow flexion/extension within a 1.5 MRI system. Movement kinematics were registered with the Zebris, a MRI compatible 3D motion capture system. Without taking the movement kinematics into consideration we found the expected systematic activation of the primary sensorimotor network, thought to generate movement execution [1]. By adding the kinematics to the fMRI design matrix we unmasked the involvement of fronto-cerebellar circuits and of the sensory cortex, as a function of both the irregularity and the frequency of movement, highlighting underlying processes of error-control to ensure optimal execution [2]. Our results reveal the modular and hierarchical structure of rhythmic motor control within brain networks: rhythmical movement generation relies on the activation of the primary sensorimotor network and error control of that movement results from the trade-off between automatically driven intermittent control involving cerebellar-frontal loops and continuous feedback involving the sensory cortex. Motor planning and error-control are important process involved in recovery post-stroke, and the detailed kinematic analysis during fMRI measurements seems to have an additional value possibly contributing to further understanding motor learning post-stroke.

The vulnerability to suicidal behavior has been modeled in deficits in both valuation and cognitive control processes, mediated by ventral and dorsal prefrontal cortices. To uncover potential markers of suicidality based on this model, we measured several brain morphometric parameters using 1.5T magnetic resonance imaging in a large sample and in a specifically designed study. We then tested their classificatory properties. Three groups were compared: euthymic suicide attempters with a past history of mood disorders and suicidal behavior (N=67); patient controls with a past history of mood disorders but not suicidal behavior (N=82); healthy controls without any history of mental disorder (N=82). A hypothesis-driven region-of-interest approach was applied targeting the orbitofrontal cortex (OFC), ventrolateral (VLPFC), dorsal (DPFC) and medial (including anterior cingulate cortex; MPFC) prefrontal cortices. Both voxel-based (SPM8) and surface-based morphometry (Freesurfer) analyses were used to comprehensively evaluate cortical gray matter measure, volume, surface area and thickness. Reduced left VLPFC volume in attempters vs both patient groups was found (P=0.001, surviving multiple comparison correction, Cohen’s d=0.65 95% (0.33–0.99) between attempters and healthy controls). In addition, reduced measures in OFC and DPFC, but not MPFC, were found with moderate effect sizes in suicide attempters vs healthy controls (Cohen’s d between 0.34 and 0.52). Several of these measures were correlated with suicidal variables. When added to mood disorder history, left VLPFC volume increased within-sample specificity in identifying attempters in a significant but limited way. Our study, therefore, confirms structural prefrontal alterations in individuals with histories of suicide attempts. A future clinical application of these markers will, however, necessitate further research.

Hypometabolism has been observed in the contralesional cerebellum hemisphere after various cortical lesions, and is referred as crossed cerebellar diaschisis. It is unknown whether it can be measured after awake surgery for brain diffuse low-grade glioma. Using resting state fMRI we suggest that crossed cerebellar diaschisis can be assessed postoperatively.