OBJECTIVE:Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is characterized by heterogeneous clinical presentations and the absence of validated imaging biomarkers. Although several quantitative MRI (qMRI) parameters have been investigated individually, their respective diagnostic and clinical relevance remains unclear. METHODS:Twenty-eight CIDP patients (21 typical, 7 multifocal) were prospectively enrolled and compared with 13 age- and sex-matched healthy controls and 17 patients with symptomatic hereditary transthyretin amyloid neuropathy (vATTR). All participants underwent 1.5 T qMRI of the sciatic and tibial nerves and of the thigh and leg muscles. Nerve and muscle volume, magnetization transfer ratio (MTR), fat fraction (FF), and T2 relaxation time were extracted. Clinical assessment included ONLS, RODS, and MRC sum score, while electrophysiological evaluation included fibular compound motor action potentials and tibialis anterior MUNIX. Imaging parameters were compared between groups and correlated with clinical and neurophysiological measures. RESULTS:CIDP patients showed significant differences compared with controls in both nerve and muscle metrics. Nerve volume was increased and MTR decreased at both sciatic and tibial levels (p < 0.005). At the muscle level, leg muscles showed increased fat fraction and decreased MTR, while T2 values and muscle volume did not differ significantly. MTR showed the strongest correlations with disability scores and MUNIX. Compared with vATTR patients, CIDP patients had lower sciatic nerve MTR, whereas vATTR patients exhibited larger nerve volumes and more pronounced muscle abnormalities. CONCLUSIONS:Nerve volume appears to be a sensitive diagnostic marker, while MTR may reflect disease burden. A multiparametric qMRI approach may improve diagnosis and monitoring in CIDP.

Background Knee osteoarthritis (OA) is one of the most common degenerative diseases causing disability in elderly people. Although X-ray radiography is widely used as a diagnostic tool, several limitations have been identified [1]. MRI is a non-invasive imaging method widely used in order to assess articular and periarticular structures of the knee joint [2]. However, the image resolution provided by conventional MRI is not high enough to assess subchondral bone so that ultra-high field MRI (7 Tesla) has been proposed as an alternative of interest to compute bone microarchitectural parameters [3]. Objectives We used ultra-high field MRI (UHF 7 Tesla MRI) to assess cartilage and subchondral bone microarchitecture in patients with mild and severe OA. For each patient, compartments classified as osteoarthritic were compared with non-osteoarthritic compartments. Methods Twenty-four patients were divided into 3 groups according to the Kellgren Lawrence staging and 12 volunteers were recruited as controls. UHF MRI was used to calculate cartilage thickness (Tc), volume (Vc), and T2*. MRI sequences used were T1 3D gradient recalled echo sequence (T1 3D GRE) and sagittal T2* mapping. Bone microarchitecture was assessed on the basis of trabecular thickness (TbTh), trabecular number (TbN), trabecular space (TbSp), and bone volume fraction (BVF). Results For the medial tibial plateau, while Tc was unchanged between the two OA groups, Vc was decreased in patients with severe OA (Δ= -49%, p < 0.05). For the patella, Vc was decreased in patients with mild OA (Δ = -36%, p<0.05), while Tc was unchanged. Similar results were found for the lateral femoral condyle. The study of T2* cartilage relaxation (T2* mapping) revealed no statistically significant changes in all knee joint compartments. Computed TbSp in the lateral tibial plateau and patella was significantly higher in the mild OA group (Δlateral tibial plateau = +25%; Δpatella = +31.5, p<0.05), whereas most subchondral bone parameters were unchanged. Medial femoral condyle cartilage volume was significantly correlated with patellar cartilage thickness r=0.46 (p = 0.01). Medial tibial plateau cartilage thickness and patellar cartilage thickness were linearly related r = 0.587 (p < 0.05). Medial tibial plateau cartilage volume was significantly correlated with patella TbTh, r = 0.41 (p = 0.02) Conclusion Cartilage volume seems to be more sensitive than thickness for the assessment of cartilage changes in OA. TbSp would be a sensitive marker of subchondral bone degradation. Cartilage degradation in a given OA compartment would be accompanied by changes in subchondral bone and cartilage in the opposite healthy compartments. UHF MRI can provide interesting information for the analysis of cartilage and subchondral bone and could be considered as a tool of interest for the subtle evaluation of changes associated to therapeutic strategies.#8232;#8232; References [1]Lee LS, Chan PK, Fung WC, Chan VWK, Yan CH, Chiu KY. Imaging of knee osteoarthritis: A review of current evidence and clinical guidelines. Musculoskeletal Care. 2021;19(3):363-374. doi:10.1002/msc.1536 [2]Andreani L, Giuntoli M, Addevico F, Aringhieri G, Cosottini M, Marchetti S. The effect of viscosupplementation on early-stage knee osteoarthritis: Clinical evaluation and assessment of cartilage in vivo with 7 T MRI. J Clin Orthop Trauma. 2021;19:53-61. Published 2021 May 8. doi:10.1016/j.jcot.2021.04.024 [3]Krug R, Carballido-Gamio J, Banerjee S, Burghardt AJ, Link TM, Majumdar S. In vivo ultra-high-field magnetic resonance imaging of trabecular bone microarchitecture at 7 T. J Magn Reson Imaging. 2008;27(4):854-859. doi:10.1002/jmri.21325 Acknowledgements: NIL. Disclosure of Interests None Declared.

Abstract Focal epilepsy is characterized by repeated spontaneous seizures that originate from cortical epileptogenic zone networks (EZN). Analysis of intracerebral recordings showed that subcortical structures, and in particular the thalamus, play an important role in seizure dynamics as well, supporting their structural alterations reported in the neuroimaging literature. Nonetheless, between‐patient differences in EZN localization (e.g., temporal vs. non‐temporal lobe epilepsy) as well as extension (i.e., number of epileptogenic regions) might impact the magnitude as well as spatial distribution of subcortical structural changes. Here we used 7 Tesla MRI T1 data to provide an unprecedented description of subcortical morphological (volume, tissue deformation, and shape) and longitudinal relaxation (T1) changes in focal epilepsy patients and evaluate the impact of the EZN and other patient‐specific clinical features. Our results showed variable levels of atrophy across thalamic nuclei that appeared most prominent in the temporal lobe epilepsy group and the side ipsilateral to the EZN, while shortening of T1 was especially observed for the lateral thalamus. Multivariate analyses across thalamic nuclei and basal ganglia showed that volume acted as the dominant discriminator between patients and controls, while (posterolateral) thalamic T1 measures looked promising to further differentiate patients based on EZN localization. In particular, the observed differences in T1 changes between thalamic nuclei indicated differential involvement based on EZN localization. Finally, EZN extension was found to best explain the observed variability between patients. To conclude, this work revealed multi‐scale subcortical alterations in focal epilepsy as well as their dependence on several clinical characteristics.

BACKGROUND AND PURPOSE:The detection of spinal cord lesions in patients with MS is challenging. Recently, the 3D MP2RAGE sequence demonstrated its usefulness at 3T. Benefiting from the high spatial resolution provided by ultra-high-field MR imaging systems, we aimed to evaluate the contribution of the 3D MP2RAGE sequence acquired at 7T for the detection of MS lesions in the cervical spine. MATERIALS AND METHODS:Seventeen patients with MS participated in this study. They were examined at both 3T and 7T. The MR imaging examination included a Magnetic Imaging in MS (MAGNIMS) protocol with an axial T2*-WI gradient recalled-echo sequence ("optimized MAGNIMS protocol") and a 0.9-mm isotropic 3D MP2RAGE sequence at 3T, as well as a 0.7-mm isotropic and 0.3-mm in-plane-resolution anisotropic 3D MP2RAGE sequences at 7T. Each data set was read by a consensus of radiologists, neurologists, and neuroscientists. The number of lesions and their topography, as well as the visibility of the lesions from one set to another, were carefully analyzed. RESULTS:A total of 55 lesions were detected. The absolute number of visible lesions differed among the 4 sequences (linear mixed effect ANOVA, P = .020). The highest detection was observed for the two 7T sequences with 51 lesions each (92.7% of the total). The optimized 3T MAGNIMS protocol and the 3T MP2RAGE isotropic sequence detected 41 (74.5%) and 35 lesions (63.6%), respectively. CONCLUSIONS:The 7T MP2RAGE sequences detected more lesions than the 3T sets. Isotropic and anisotropic acquisitions performed comparably. Ultra-high-resolution sequences obtained at 7T improve the identification and delineation of lesions of the cervical spinal cord in MS.

BACKGROUND AND PURPOSE:While conventional MR imaging has limited value in amyotrophic lateral sclerosis, nonconventional MR imaging has shown alterations of microstructure using diffusion MR imaging and recently sodium homeostasis with sodium MR imaging. We aimed to investigate the topography of brain regions showing combined microstructural and sodium homeostasis alterations in amyotrophic lateral sclerosis subgroups according to their disease-progression rates.MATERIALS AND METHODS:Twenty-nine patients with amyotrophic lateral sclerosis and 24 age-matched healthy controls were recruited. Clinical assessments included disease duration and the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale. Patients were clinically differentiated into fast (n = 13) and slow (n = 16) progressors according to the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale progression rate. 3T MR imaging brain protocol included 1H T1-weighted and diffusion sequences and a 23Na density-adapted radial sequence. Quantitative maps of diffusion with fractional anisotropy, mean diffusivity, and total sodium concentration were measured. The topography of diffusion and sodium abnormalities was assessed by voxelwise analyses.RESULTS:Patients with amyotrophic lateral sclerosis showed significantly higher sodium concentrations and lower fractional anisotropy, along with higher sodium concentrations and higher mean diffusivity compared with healthy controls, primarily within the corticospinal tracts, corona radiata, and body and genu of the corpus callosum. Fast progressors showed wider-spread abnormalities mainly in the frontal areas. In slow progressors, only fractional anisotropy measures showed abnormalities compared with healthy controls, localized in focal regions of the corticospinal tracts, the body of corpus callosum, corona radiata, and thalamic radiation.CONCLUSIONS:The present study evidenced widespread combined microstructural and sodium homeostasis brain alterations in fast amyotrophic lateral sclerosis progressors.

Whole brain, large-scale functional connectivity networks or connectomes have been characterized on different temporal and spatial scales in humans using EEG and fMRI. Whole brain epileptic networks have been investigated with both EEG and fMRI, but due to the different acquisition approaches it is unclear to what extent those results can be related. In consequence clinical research in epilepsy would profit from a unified multimodal functional connectome description as a linking framework to better map underlying brain function and pathological functional networks. In this study we aim to characterize the spatial correlation between EEG and fMRI connectivity in temporal lobe epilepsy. From two independent centers, we acquired resting-state concurrent EEG-fMRI from a total of 35 healthy controls and 34 TLE patients (18 right TLE and 16 left TLE). Data was projected into the Desikan brain atlas (mean BOLD activity for fMRI and source reconstruction for EEG). Whole brain functional connectivity from fMRI (Pearson correlation) and EEG (corrected imaginary part of the coherency) were correlated for all subjects. In healthy controls, average EEG and fMRI whole-brain connectivity was moderately correlated (r~0.3). For both imaging centers, correlation between EEG and fMRI whole brain connectivity was increased in rTLE when compared to controls for lower frequency bands (EEG-delta, theta and alpha). Conversely correlation between EEG and fMRI connectivity of lTLE patients was decreased in respect to healthy subjects (EEG-beta vs. fMRI connectivity only). While the alteration of the EEG-fMRI correlation in rTLE patients could not be related to a local effect, in lTLE patients it was locally linked to the Default Mode Network. We demonstrated, using two independent datasets, that EEG and fMRI connectivity is correlated for both healthy subjects and patients. The increased correlation of EEG and fMRI connectivity in rTLE patients vs. controls and decreased correlation in lTLE patients vs. controls suggests a differential organization of mono-lateral focal epilepsy of the same type, which needs to be considered when comparing fMRI to EEG connectivity. It also demonstrates that each modality provides distinct information, highlighting the benefit of multimodal assessment in epilepsy. The observed property of distinct topological patterns depending on the lateralization of the epilepsy could be taken into account when clinically defining the epileptic focus of patients.

La bronchopneumopathie chronique obstructive (BPCO) est caractérisée par une obstruction bronchique responsable d’un handicap respiratoire. Chez les patients emphysémateux s’ajoute une destruction du parenchyme pulmonaire s’accompagnant de lésions vasculaires. Pourtant, le diagnostic de cette vasculopathie n’est bien souvent réalisé que tardivement, lorsqu’une hypertension pulmonaire (HTP) apparaît et retentit sur le cœur droit. Cette complication signe un tournant évolutif péjoratif dans la BPCO. L’imagerie par résonance magnétique (IRM) est une technique non invasive de référence dans l’évaluation fonctionnelle du cœur droit et permet l’évaluation de la vascularisation pulmonaire. Nous avons émis l’hypothèse qu’il existe une atteinte fonctionnelle précoce des vaisseaux pulmonaires évaluable par IRM chez les patients BPCO emphysémateux avant l’apparition d’une HTP. Dans ce travail toujours en cours (NCT04126616), nous avons inclus des patients BPCO emphysémateux et des volontaires sains non-fumeurs appariés en âge et en sexe (n = 7). Une IRM thoracique a été réalisée afin d’évaluer la fonction ventriculaire droite, le flux et la distensibilité du tronc de l’artère pulmonaire ainsi que le temps de transit pulmonaire [1]. Celui-ci était déterminé en suivant le rehaussement du signal par un produit de contraste au niveau de l’artère pulmonaire et du confluent des veines pulmonaires. Les 7 patients inclus avaient une obstruction modérée (VEMS moyen 54 % théoriques), une diminution du transfert alvéolaire (DLCO moyen 46 % théoriques) et un dépistage d’HTP négatif en échographie cardiaque (Tableau 1). Au repos, les paramètres de fonction biventriculaire et le débit cardiaque droit étaient similaires entre les deux groupes. La distensibilité de l’artère pulmonaire au cours du cycle cardiaque montrait une tendance à une valeur inférieure chez les patients (15,0 vs 24,4 %, p = 0,12). Le temps de transit pulmonaire de repos était significativement plus faible chez les patients (5,89 s vs 7,39 s, p = 0,03). Chez les patients BPCO emphysémateux ne présentant pas d’HTP, des anomalies fonctionnelles vasculaires pulmonaires seraient décelables par IRM. Elles pourraient précéder l’apparition d’une HTP et former ainsi une cible thérapeutique préventive et de suivi évolutif.

Despite the importance and frequent use of Bayesian frameworks in brain network modeling for parameter inference and model prediction, the advanced sampling algorithms implemented in probabilistic programming languages to overcome the inference difficulties have received relatively little attention in this context. In this technical note, we propose a probabilistic framework, namely the Bayesian Virtual Epileptic Patient (BVEP), which relies on the fusion of structural data of individuals to infer the spatial map of epileptogenicity in a personalized large-scale brain model of epilepsy spread. To invert the individualized whole-brain model employed in this study, we use the recently developed algorithms known as No-U-Turn Sampler (NUTS) as well as Automatic Differentiation Variational Inference (ADVI). Our results indicate that NUTS and ADVI accurately estimate the degree of epileptogenicity of brain regions, therefore, the hypothetical brain areas responsible for the seizure initiation and propagation, while the convergence diagnostics and posterior behavior analysis validate the reliability of the estimations. Moreover, we illustrate the efficiency of the transformed non-centered parameters in comparison to centered form of parameterization. The Bayesian framework used in this work proposes an appropriate patient-specific strategy for estimating the epileptogenicity of the brain regions to improve outcome after epilepsy surgery.

Gene and protein expressions display circadian oscillations, which can be disrupted in diseases in most body organs. Whether these oscillations occur in the healthy hippocampus and whether they are altered in epilepsy are not known. We identified more than 1200 daily oscillating transcripts in the hippocampus of control mice and 1600 in experimental epilepsy, with only one-fourth oscillating in both conditions. Comparison of gene oscillations in control and epilepsy predicted time-dependent alterations in energy metabolism, which were verified experimentally. Although aerobic glycolysis remained constant from morning to afternoon in controls, it increased in epilepsy. In contrast, oxidative phosphorylation increased in control and decreased in epilepsy. Thus, the control hippocampus shows circadian molecular remapping, which is altered in epilepsy. We suggest that the hippocampus operates in a different functioning mode in epilepsy. These alterations need to be considered when studying epilepsy mechanisms, designing drug treatments, and timing their delivery.

Purpose: The purpose of this study was to investigate the potential additional value of cardiac magnetic resonance (CMR) in the assessment of left ventricular (LV) dilatation and dysfunction by comparison to standard echocardiography in patients with chronic left-sided valvular regurgitation. Materials and methods: We prospectively enrolled patients with chronic severe mitral regurgitation (MR) or aortic regurgitation (AR). They underwent standard echocardiography and CMR using aortic flow and LV-function sequences. LV dilatation or dysfunction was assessed with each technique, based on thresholds used for surgery indication. Reference regurgitation severity was defined following previously reported CMR-based regurgitant volume thresholds. Results: A total of 71 patients with chronic severe MR (n= 44) or severe AR (n= 27) were prospectively included. There were 60 men and 11 women with a mean age of 61 + 14 (SD) years (range: 18-83 years). CMR-based regurgitation severity was significantly greater in the LV dysfunction group when assessed with CMR (MR, P = 0.011; AR, P= 0.006) whereas it was not different when LV dysfunction was assessed using standard echocardiography. Among standard echocardiography and CMR volumetric indices, CMR-derived end-diastolic volume showed the best ability to predict regurgitation severity (area under the curve [AUC] = 0.78 for MR; AUC = 0.91 for AR). Diagnostic thresholds identified on receiver operating characteristics-curve analysis were lower than those of current European recommendations and closer to North-American guidelines. Conclusion: CMR assessment of LV end-diastolic volume in chronic severe left-sided regurgitations is more reliably associated with CMR-based regurgitant volume by comparison with standard echocardiography diameter. CMR may provide useful evaluation before surgery decision for severe asymptomatic regurgitations. (C) 2020 Societe francaise de radiologie. Published by Elsevier Masson SAS. All rights reserved.

Purpose: To compare the assessment of diffuse interstitial myocardial fibrosis in valvular diseases using cardiac magnetic resonance (CMR) extracellular volume fraction (ECV) quantification and serum biomarkers of collagen turnover using results of myocardial biopsy as standard of reference. Materials and methods: This prospective monocentric study included consecutive patients before aortic valvular replacement. All patients underwent: i), 1.5 T CMR with pre and post contrast T-1 mapping sequence and ECV computation; ii), serum quantification of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) and iii), myocardial biopsies were collected during surgery to assess collagen volume fraction (CVF). Patients with coronary artery disease were excluded. Correlation between native T1, ECV, CVF and serum biomarkers were assessed using Pearson correlation test. Agreement between basal anteroseptal ECV with global ECV was assessed using Bland-Altman test. Results: Twenty-one patients, 16 with aortic stenosis and 5 with aortic regurgitation were included. There were 12 men and 9 women with a mean age of 74.1 +/- 6.8 ( SD) years (range: 32-84 years). Mean global ECV value was 26.7 +/- 2.7 (SD) % (range: 23.4-32.5%) and mean CVF value was 12.4 +/- 9.7% (range: 3.2-25.7%). ECV assessed at the basal anteroseptal segment correlated moderately with CVF (r=0.6; P=0.0026). There was a strong correlation and agreement between basal anteroseptal ECV and global ECV, (r= 0.8; P< 0.0001; bias 5.4 +/- 6.1%) but no correlation between global ECV and CVF (r = 0.5; P=0.10). Global ECV poorly correlated with serum TIMP-1 (r =0.4; P=0.037) and MMP-2 (r = 0.4; P=0.047). No correlation was found between serum biomarkers and basal anteroseptal-ECV or native T1. Conclusion: In patients with severe aortic valvulopathy, diffuse myocardial fibrosis assessed by anterosepto-basal ECV correlates with histological myocardial fibrosis. Anteroseptobasal ECV strongly correlates with global ECV, which poorly correlates with TIMP-1 and MMP-2, serum biomarkers involved in the progression of heart failure. (C) 2020 Published by Elsevier Masson SAS on behalf of Societe francaise de radiologie.

PURPOSE:The purpose of this prospective study was to assess the value of biventricular extracellular volume (ECV) in pre-capillary pulmonary hypertension (PH) obtained using cardiac magnetic resonance imaging (CMR) and to correlate ECV with markers of prognosis such as strain echocardiography and blood biomarkers of fibrosis. MATERIALS AND METHODS:Twelve patients with PH (6 men, 6 women; mean age=50±16 [SD] years; age range: 22-73 years) underwent the same day: (i), transthoracic echocardiography including measurement of right ventricular (RV) fractional shortening (RVfs), tricuspid annular plane systolic excursion (TAPSE), maximal tricuspid annular velocity, RV global and segmental deformation; (ii), right heart catheterization measuring pulmonary arterial pressures (inmmHg) and cardiac output (inL/min); (iii), CMR at 1.5-T measuring RV volumes and ejection fraction; (iv), native and 15min post-contrast T1 mapping using modified look-locker inversion-recovery sequence; and (v), serum quantification of two biomarkers of collagen turnover and hematocrit. Non-parametric Mann-Whitney tests were used to search for differences between categorical variables. Spearman correlation test was used for search for correlation between quantitative values. RESULTS:Global RV ECV was 34%±4.2 (SD) for our entire population. A significant correlation was found between RV ECV and RVfs (r=0.6; P=0.026), S wave velocity (r=0.7; P=0.009), TAPSE (r=0.6; P=0.040) and RV systolic ejection fraction on CMR (r=0.6; P=0.04). There were no correlations between the ECV values in the lateral wall of the RV and in the septum (r=0.4; P=0.206). A significant correlation was found between septal ECV and 2D septal strain (r=0.7; P=0.013). CONCLUSION:ECV in PH as obtained using CMR appears to correlate with known echocardiographic prognostic markers and more specifically with the markers, which assess RV systolic function.

L’exploration fine des enthèses, éléments clefs dans plusieurs pathologies rhumatologiques est un challenge. L’IRM de routine (1,5 T) peut détecter pour la plupart des tissus mous des modifications précoces. Pour l’enthèse leur faible valeur de T2 rend difficile leur exploration. Il y a de nombreuses études récentes utilisant l’IRM à très haut champ (> 3Teslas) plus fine, mais aucune d’elles n’a encore évalué les enthèses chez l’humain in vivo. Nous avons étudié in vivo l’enthèse du tendon quadricipital chez des sujets sains en IRM à 7 Teslas (7 T). Onze hommes sains volontaires, d’âge moyen de 22 ans [19–25] ont été sélectionnés. Les critères d’inclusion étaient : pas d’antécédent traumatique du genou, indice de Lequesne à 0, moins de 3 heures d’activités sportives par semaine, stade de Kellgren et Lawrence à 0. Les images IRM ont été acquises à 7 T en 3D, suivant des séquences GRE et de cartographie T2*. Les régions d’intérêt (RI) du genou soit l’os trabéculaire, l’os sous-chondral, l’enthèse et le corps tendineux ont été délimitées manuellement sur 5 coupes sagittales sur les scans GRE, et les RI ont été délimitées sur les autres coupes sagittales en utilisant une interpolation linéaire. Puis les masques correspondants ont été transférés sur les cartographies T2*. La normalité de distribution des valeurs de T2* a été évaluée par le test de Shapiro–Wilk. La comparaison des valeurs moyennes de T2* entre chaque zone constitutive a été réalisée grâce au test non paramétrique de Friedman, et les comparaisons par paires ont été réalisées selon le test de Nemenyi. L’enthèse quadricipitale, en hypersignal, était bien visible avec cette technique. Les données chiffrées de T2* ont pu être obtenues. La plus grande valeur de T2* (16,99 ms) a été retrouvée dans l’os sous-chondral alors que la plus faible valeur (6,94 ms) a été identifiée dans le corps tendineux. La valeur de T2* dans l’os sous-chondral était significativement plus haute que dans l’enthèse (p = 0,02). De même, le T2* de l’os sous-chondral était significativement plus haut que dans le corps tendineux entier (p = 0,001). Nous avons observé de façon nette des changements de T2* le long de l’axe de l’enthèse vers le corps tendineux chez ces hommes sains âgés de 19 à 25 ans. Les variations de T2* pourraient être liées à des changements dans la composition moléculaire ou cellulaire dans chaque région anatomique allant de la zone de l’os sous-chondral au corps de l’enthèse. Ces résultats offrent les premières valeurs normatives de l’ensemble du tendon. Ces données pourront être un élément de comparaison lors de l’exploration des tendons dans des maladies rhumatologiques inflammatoires et mécaniques. Cette étude devra être poursuivie notamment chez la femme et dans d’autres groupes d’âge. Dans notre étude, nous rapportons des résultats montrant qu’une évaluation fine de l’enthèse quadricipitale est possible en IRM 7 T avec l’acquisition de valeurs normatives. Dans de futures études, ces valeurs pourront être utilisées comme références quantitatives dans les pathologies impliquant l’enthèse.

Background: Fibrocartilaginous enthesis is composed of different histological zones which are commonly referred to the tendon distal extremity (a lamellar tissue with a low cell density, collagen and connective tissue), the fibrocartilaginous zone (with chondrocytes), a progressively mineralized zone and the bone. The MRI visualization of the water content of entheses is challenging given the very short relation time so that entheses has been very poorly assessed using MRI (1). Objectives: The main objective of the study was to assess the structural elements of the knee enthesis based on the quantitative T2* measurements using Ultra High Field (UHF) MRI. Methods: Twelve healthy subjects without any osteoarticular pathology were included in the study after they provided their informed consent. 3D gradient echo sequence with a 4.3 ms echo time and T2* mapping were performed. The lateral internal, external and crossed ligaments, patellar and quadricipital tendons were assessed. T2* measurements were performed specifically on the quadricipital tendon. Results: The quadricipital tendon and the bone trabeculation could be visualized on the UHF MR image. The T2* mapping analysis illustrated a large value (16.4 ± 4 ms) for the subchondral bone and much lower values for the trabecular bone (11 ± 4.5 ms) and the different zones of the keen entheses (7.7 ± 1.9 ms). Conclusion: Based on T2* measurements performed using UHF MRI, the different structural elements of the knee entheses were distinguished. This quantitative stratification could be used to assess changes in pathological conditions such as SpA and trauma. References: [1]Benjamin M, Bydder GM. Magnetic resonance imaging of entheses using ultrashort TE (UTE) pulse sequences. Journal of magnetic resonance imaging: JMRI. 2007;25(2):381-9. Disclosure of Interests: None declared