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International audience; No abstract available

Purpose The purpose of this study was to characterize the technical capabilities and feasibility of a large field-of-view clinical spectral photon-counting computed tomography (SPCCT) prototype for high-resolution (HR) lung imaging. Materials and methods Measurement of modulation transfer function (MTF) and acquisition of a line pairs phantom were performed. An anthropomorphic lung nodule phantom was scanned with standard (120 kVp, 62 mAs), low (120 kVp, 11 mAs), and ultra-low (80 kVp, 3 mAs) radiation doses. A human volunteer underwent standard (120 kVp, 63 mAs) and low (120 kVp, 11 mAs) dose scans after approval by the ethics committee. HR images were reconstructed with 1024 matrix, 300 mm field of view and 0.25 mm slice thickness using a filtered-back projection (FBP) and two levels of iterative reconstruction (iDose 5 and 9). The conspicuity and sharpness of various lung structures (distal airways, vessels, fissures and proximal bronchial wall), image noise, and overall image quality were independently analyzed by three radiologists and compared to a previous HR lung CT examination of the same volunteer performed with a conventional CT equipped with energy integrating detectors (120 kVp, 10 mAs, FBP). Results Ten percent MTF was measured at 22.3 lp/cm with a cut-off at 31 lp/cm. Up to 28 lp/cm were depicted. While mixed and solid nodules were easily depicted on standard and low-dose phantom images, higher iDose levels and slice thicknesses (1 mm) were needed to visualize ground-glass components on ultra-low-dose images. Standard dose SPCCT images of in vivo lung structures were of greater conspicuity and sharpness, with greater overall image quality, and similar image noise (despite a flux reduction of 23%) to conventional CT images. Low-dose SPCCT images were of greater or similar conspicuity and sharpness, similar overall image quality, and lower but acceptable image noise (despite a flux reduction of 89%). Conclusions A large field-of-view SPCCT prototype demonstrates HR technical capabilities and high image quality for high resolution lung CT in human.

International audience; BACKGROUND: Lung ultrasound can accurately detect pandemic coronavirus disease (COVID-19) pulmonary lesions. A lung ultrasound score (LUS) was developed to improve reproducibility of the technique. OBJECTIVES: To evaluate the clinical value of LUS monitoring to guide COVID-19-associated acute respiratory distress syndrome (ARDS) management. METHODS: We conducted a single center, prospective observational study, including all patients admitted with COVID-19-associated ARDS between March and April 2020. A systematic daily LUS evaluation was performed. RESULTS: Thirty-three consecutive patients were included. LUS was significantly and negatively correlated to P(aO2)/F(IO2). LUS increased significantly over time in non-survivors compared to survivors. LUS increased in 83% of ventilatory associated pneumonia (VAP) episodes, when compared to the previous LUS evaluation. LUS was not significantly higher in patients presenting post-extubation respiratory failure. CONCLUSIONS: In conclusion, our study demonstrates that LUS variations are correlated to disease severity and progression, and LUS monitoring could contribute to the early diagnosis of VAPs.

A 35-year-old woman was referred to our nuclear medicine center for a ventilation and perfusion (VQ) pulmonary scintigraphy to detect pulmonary embolism. She was treated with low-molecular-weight heparin following a proximal venous thrombosis of the right upper limb and had a previous history of an infiltrating ductal carcinoma of the right breast. Surprisingly, the VQ scintigraphy showed uptake of 99mTc-MAA in several superior vertebrae. A contrast-enhanced CT scan revealed a dilated collateral paravertebral venous system due to the deep vein thrombosis extended from superior vena cava to brachiocephalic trunk. 99mTc-MAA was trapped through the dilated vertebral venous system.

Introduction Les modalites d’imagerie qui aident a mieux comprendre le processus arthrosique sont la radiographie, l’IRM, la tomographie X, les ultrasons, la DXA et le TEP. A ce jour, seuls l’IRM et la tomographie sont des modalites tri-dimensionnelles (3D). L’analyse du cartilage sous forme de cartographie 3D ont ete largement developpe en IRM avec des applications in vivo reservees a la recherche clinique. L’arthroscanner permet de visualiser la surface du cartilage et la presence de calcifications mais est tres peu utilise en pratique clinique. La tomographie spectrale a comptage de photons est une nouvelle technologie qui est l’extension en multi-energie de la tomographie a double energie qui a montre son utilite pour la detection des cristaux d’urate de sodium. L’acces a des images mono-energetiques permet d’ameliorer le contraste des tissus mous habituellement non visibles en scanner classique en particulier le cartilage et le menisque. Nous proposons dans ce travail le developpement de biomarqueurs a type d’analyse morphologique quantitative du cartilage. Materiels et methodes Nous avons utilise un prototype (Philips Healthcare, Haifa) situe au CERMEP, Lyon, il s’agit appareil clinique dote d’un tube a rayons X classique et d’un detecteur a conversion directe de photons resolutif en energie qui permet l’obtention de voxels isotropes de 250 × 250 × 250 microns. L’acquisition dure quelques minutes. Cet appareil permet de recuperer une serie d’images mono-energetiques de 30 keV a 120 keV, nous avons selectionne les images a 60 keV qui offraient le meilleur contraste pour la visualisation du cartilage. Pour ce faire, nous avons etudie 24 specimens de genoux (15 normaux et 9 arthrosiques avec presence d’osteophytes), 5 hommes (âge moyen : 75,6 ± 14,3 ans), 17 femmes (87,7 ± 9,7 ans). Nous avons analyse le tibia et le femur separement des compartiments femoro-tibial medial et lateral. Nous avons utilise le logiciel itk-SNAP 3,8.0 selon un processus semi-automatique avec segmentation manuelle et interpolation. Le parametre mesure est l’epaisseur moyenne du cartilage en mm par la methode 3D des spheres. Resultats Les epaisseurs moyennes (ep_moys) du tibia lateral etaient de 2,82 ± 0,44 pour les normaux (Nx) versus 1,96 ± 0,94 mm pour les arthrosiques (OA), au tibia medial, les ep_moys etaient de 2,14 ± 0,36 Nx versus 1,95 ± 0,5 mm OA. Au femur lateral, les ep_moys etaient de 1,74 ± 0,34 Nx versus 1,32 ± 0,5 mm OA et au femur medial les ep_moys etaient de 1,35 ± 0,3 Nx versus 1,28 ± 0,7 mm OA. La difference a ete evalue a l’aide du test t et les differences etaient significatives au compartiment lateral pour le tibia (p = 0,002), femoral (p = 0,01), la difference n’etait pas significative au tibia medial et limite au niveau du femur medial (p = 0,04). Conclusion Le scanner spectral a comptage de photons est un nouvel outil qui permettra d’analyser sur la meme image des parametres quantitatifs 3D du cartilage et de l’os sous chondral pour ameliorer la comprehension du phenomene arthrosique et mieux suivre l’evolution naturelle ou sous l’effet des traitements.

Aims: ILDs are a heterogeneous group of disorders with distinct clinical, radiological and prognostic characteristics, which encompass a wide range of conditions. In some patients with fibrosing ILDs, a progressive phenotype similar to that observed in IPF may develop during the course of the disease. The collective estimated prevalence of PF-ILDs is 0.22, 0.59, and 2.0 per 10.000 persons in Belgium, Greece, and France respectively. The PROGRESS study aimed at assessing the epidemiology of non-IPF PF-ILD patients and associated health consumptions and outcomes in a real life nationwide setting in France. Methods: A longitudinal retrospective cohort study was conducted using the French administrative healthcare database (SNDS) between January 2010 and December 2017. Non-IPF PF-ILD patients were identified using an US algorithm based on ICD-10 codes and adapted to French specificities. Results: 17,560 non-IPF PF-ILD patients were identified. In 2017, the prevalence and incidence of non-IPF PF-ILD were respectively 17.9 per 100.000 and 3.0 per 100.000 per year. Sex ratio was close to 1 (51.2% of men) and mean age was 68.5 years (±15.2). Major underlying ILD diagnoses were non-autoimmune-related (50.0%), autoimmune-related (40.0%) and sarcoidosis (10.0%). The median overall survival of non-IPF PF-ILD patients was estimated at 4.1 years. The survival rate was 76.0%, 57.7%, 44.5%, and 33.7% at 1, 3, 5, and 8 years respectively. Conclusion: Based on an algorithm, non-IPF PF-ILD is rare and is associated with a poor prognosis comparable to that of IPF.

Aim: This retrospective, monocentric cohort study aimed at assessing clinical characteristics, lung function course and overall survival of patients with non-IPF PF-ILD in a real-world setting. Methods: All successive patients hospitalized in a French Rare Lung Disease Reference Centre between 2010 and 2017, aged ≥18 years, with at least 10% fibrosis extent at baseline high resolution computed tomography of chest (HRCT) were included. PF-ILD over a period of 2 years was defined as: relative decline in forced vital capacity (FVC) ≥ 10% with or without clinical deterioration (a); or a moderate relative decline between 5% and 10% associated with worsening respiratory symptoms or increased extent of fibrosis in HRCT (b); or increased extent of fibrosis on HRCT with worsening respiratory symptoms with or without FVC decline (c). Results: 165 patients (57% of women) were included with a mean age of 60 (±14 years). Most of patients (65%) were included with criterion (a), 24% with criterion (b) and 9% with criterion (c). Estimates of overall survival were 99%, 82%, and 66% at 1, 3 and 6 years, respectively. Mortality was significantly associated with FVC Conclusion: The natural history of non-IPF ILD in patients with PF phenotype follows a course characterized by worsening of respiratory symptoms, progressive lung function decline and early mortality despite appropriate management.

Aims: Interstitial lung disease (ILD) is frequent in patients with systemic sclerosis (SSc). It is characterized by progressive decline in lung function and is the leading cause of death in patients with SSc. In Europe, the prevalence and annual incidence of SSc-ILD have been estimated at 1.7-4.2 per 100,000 and 0.1-0.4 per 100,000 per year, respectively. This study aimed at assessing the epidemiology and mortality of patients with SSc-ILD in a real life nationwide setting in France. Methods: A longitudinal retrospective cohort study was conducted in the French administrative health care database. SSc-ILD patients were identified using an algorithm based on ICD-10 codes of SSc and of lung fibrosis between January 2010 and December 2017. Results: Among 9817 SSc patients identified, 3460 had associated ILD (35.0%). In 2017, the prevalence and incidence of SSc-ILD were respectively 4.5 per 100,000 (4.3-4.7) and 0.4 per 100,000 per year (0.3-0.5). Patients were predominantly females (75.6%) with a mean age of 60.7 years (±14.5). 73.6% and 20.8% of patients respectively had at least one claim of systemic corticosteroids and mycophenolate mofetil treatments during the study period. The overall survival rate was estimated to be 92.9%, 81.8%, 70.5%, and 65.1% 1, 3, 5, and 8 years, respectively. Median survival was better in women. Conclusion: This study demonstrated that SSc-ILD is a rare disease with significant mortality.

Computed tomography (CT) is an x-ray based medical imaging technique commonly used for non-invasive gastrointestinal tract (GIT) imaging. Iodine and barium based CT contrast agents are used in the clinic for GIT imaging, however, inflammatory bowel disease (IBD) imaging is challenging since iodinated and barium based CT agents are not specific for sites of inflammation. Cerium oxide nanoparticles (CeNP) can produce strong x-ray attenuation due to cerium’s k-edge at 40.4 keV, but have not yet been explored for CT imaging. In addition, we hypothesized that the use of dextran as a coating material on cerium oxide nanoparticles would encourage accumulation in IBD inflammation sites in a similar fashion to other inflammatory diseases. In this study, therefore, we sought to develop a CT contrast agent, i.e. dextran coated cerium oxide nanoparticles (Dex-CeNP) for GIT imaging with IBD. We synthesized Dex-CeNP, characterized them using various analytical tools and examined their in vitro biocompatibility, CT contrast generation and protective effect against oxidative stress. In vivo CT imaging was done with both healthy mice and a dextran sodium sulfate induced colitis (DSS-colitis) mouse model. Dex-CeNP’s CT contrast generation and accumulation in inflammation sites were compared with iopamidol, an FDA approved CT contrast agent. Dex-CeNP was found to be protective against oxidative damage. Dex-CeNP produced strong CT contrast and accumulated in the colitis area of large intestines. In addition, >97 % of oral doses were cleared from the body within 24 hrs. Therefore, Dex-CeNP can be used as a potential CT contrast agent for imaging GIT with IBD, while protecting against oxidative damage.

Previous studies have suggested the role of microcalcifications in plaque vulnerability. This exploratory study sought to assess the potential of hybrid positron-emission tomography (PET)/magnetic resonance imaging (MRI) usingWe included 12 patients with either recently symptomatic or asymptomatic carotid stenosis. All patients underwent

International audience

Introduction La sclerodermie systemique (ScS) est une maladie auto-immune rare, heterogene et chronique. Les pneumopathies interstitielles diffuses (PID) caracterisees par un declin progressif de la fonction respiratoire constituent une complication frequente de la ScS et sa principale cause de deces. En Europe, la prevalence de la PID-ScS a ete estimee a 1,7–4,2/100 000 individus et l’incidence annuelle a 0,1–0,4/100 000 individus. En France, l’epidemiologie de cette maladie est encore meconnue. Ainsi, les objectifs de cette etude etaient d’estimer la prevalence et l’incidence de la PID-ScS en France et de decrire les caracteristiques et la survie des patients. Methodes Une cohorte retrospective longitudinale a ete constituee a partir des donnees du Systeme national des donnees de sante entre 2010 et 2017. Les patients ont ete identifies comme etant atteints d’une PID-ScS grâce a un algorithme base sur l’utilisation de codes CIM-10. Ainsi, tous les patients de plus de 20 ans, affilies au regime general d’Assurance Maladie depuis plus de deux ans, et avec: – au moins une hospitalisation ou une affection de longue duree relative a une ScS; – au moins une hospitalisation avec un code de fibrose pulmonaire ont ete inclus. Resultats Parmi les patients identifies avec une ScS, 34 % presentaient une PID, soit 3333 patients. Les trois quarts etaient des femmes (75,6 %). La moyenne (ecart-type) d’âge etait de 60,6 (± 14,4) ans. Les principales comorbidites etaient l’hypertension (66,8 %) et le reflux gastro-œsophagien (65,8%). L’incidence globale estimee etait de 0,98–0,76/100 000 individus et la prevalence de 3,42–5,52/100 000 individus sur l’ensemble de la periode. Les taux de prevalence et d’incidence etaient trois fois plus eleves chez les femmes que chez les hommes et augmentaient avec l’âge. Les estimations de la survie globale etaient de 93 % a 1 an, 82% a 3 ans, 71 % a 5 ans et 55% a 8 ans. Les facteurs associes a la mortalite etaient le sexe masculin, la presence d’une hypertension pulmonaire, la presence d’un cancer du poumon et les classes d’âges les plus elevees. Conclusion Cette etude presente pour la premiere fois au niveau national l’epidemiologie de la PID-ScS. Notamment, elle a permis de montrer que la PID-ScS presente un taux de mortalite eleve, en particulier chez les patients a risque.

Introduction Les pneumopathies interstitielles diffuses (PID) regroupent un ensemble heterogene de maladies caracterisees par un processus inflammatoire diffus. Chez certains patients atteints de PID, un phenotype fibrosant progressif (FP) se developpe, comparable a celui observe dans la fibrose pulmonaire idiopathique (FPI). L’objectif de l’etude etait de fournir les caracteristiques des patients et les estimations d’incidence, de prevalence et de mortalite de la PID-FP (hors fibrose pulmonaire idiopathique) a l’echelle nationale en vie reelle. Methodes Une cohorte retrospective longitudinale de patients atteints de PID-FP a ete constituee a partir des donnees du Systeme National des Donnees de Sante (SNDS). Les patients PID-FP ont ete selectionnes selon un algorithme d’identification base sur l’utilisation de codes CIM-10 en trois etapes successives: identification des PID, exclusion des FPI, et selection des FP. Resultats 30 771 patients atteints de PID hors FPI ont ete identifies. Parmi eux, 14 413 patients (47 %) susceptibles de presenter une forme progressive ont ete inclus. Un peu plus de la moitie des patients etaient des hommes (52 %). L’âge moyen (ecart-type) etait de 68,4 ans (± 15,0). Les comorbidites les plus frequentes etaient l’hypertension (64 %) et le reflux gastro-œsophagien (55 %). La prevalence des patients avec un phenotype progressif variait de 6,6 a 19,4/100 000 individus selon l’annee et l’incidence annuelle de 3,1 a 4,7/100 000 individus. Les taux de prevalence et d’incidence etaient legerement plus faibles chez les femmes que chez les hommes, et augmentaient considerablement avec l’âge. La mediane de la survie globale a ete estimee a 3,7 ans [3,6–3,8]. Le taux de survie etait de 74 % a 1 an, 55 % a 3 ans, 42 % a 5 ans et 32 % a 8 ans. Les facteurs associes a la mortalite etaient le sexe masculin, l’âge et l’etiologie de la PID-FP. Conclusion Dans cette etude, 47 % des patients atteints de PID etaient susceptibles de presenter une forme progressive comparativement a environ 30 % dans la litterature. Cette difference pourrait s’expliquer par l’utilisation pour la selection des patients avec FP, d’un algorithme base sur l’utilisation de consommations de soin, sans possibilite de validation diagnostique des formes progressives. En conclusion, cette etude qui est la premiere a estimer l’epidemiologie des PID-FP en France grâce a l’utilisation du SNDS, suggere que les PID-FP representent au total un assez grand nombre de patients, et sont associees a un mauvais pronostic.

Spectral photon-counting CT (SPCCT) is an emerging X-ray imaging technology that extends the scope of available diagnostic imaging tools. The main advantage of photon-counting CT technology is better sampling of the spectral information from the transmitted spectrum in order to benefit from additional physical information being produced during matter interaction, including photo-electric and Compton effects, and the K-edge effect. The K-edge, which is specific for a given element, is the increase in X-ray absorption of the element above the binding energy between its inner electronic shell and the nucleus. Hence, the spectral information contributes to better characterization of tissues and materials of interest, explaining the excitement surrounding this area of X-ray imaging. Other improvements of SPCCT compared with conventional CT, such as higher spatial resolution, lower radiation exposure and lower noise are also expected to provide benefits for diagnostic imaging. In this review, we describe multi-energy CT imaging, from dual energy to photon counting technology, and our initial experience results using a clinical-scale spectral photon counting CT (SPCCT) prototype system in vitro and in vivo. In addition, possible clinical applications are introduced.

Previous research has demonstrated that women have a higher risk of anterior cruciate ligament (ACL) injury than men. Tibiofemoral articular geometry may play a role in the occurrence of ACL tears. The purpose of this study was to analyze the gender-specific geometric characteristics differences in tibiofemoral morphology in ACL-deficient patients. Medial tibial slope (MTS), lateral tibial slope (LTS), medial tibial plateau concavity, medial and lateral femoral condyle convexity, and lateral plateau convexity were analyzed in 276 patients with complete ACL injuries (138 females and 138 males). Two blinded observers measured the anatomical parameters of tibiofemoral geometry with use of multiplanar CT scans. Intra- and inter-rater reliabilities were assessed and comparisons between anatomic measures were made between male and female patients. The average ICC for all measurements was 0.90 (range 0.83–0.97) indicating good reliability. Male ACL injured patients demonstrated significantly greater LTS (10.5° ± 2.8) than female patients (9.6° ± 3.5°; p

International audience; Suspensions of iodinated polymer nanoparticles are evaluated as contrast agent for Computed Tomography (CT) and Spectral Photon Counting Computed Tomography (SPCCT). Iodine containing moieties are grafted to poly(vinyl alcohol) by means of a covalent ester bond up to high degree of substitution of 0.77 providing high iodine content of 71 wt%. Polymer nanoparticles of 150 nm diameter stabilized by the block copolymer poly(caprolactone)-b-poly(ethylene glycol) are highly stable in water and human serum. High coverage of nanoparticles by PEG chains in a dense brush conformation (0.30 molecules•nm-2) provides resistance against fast elimination by mononuclear phagocytes system. Iodine concentration is increased up to 100 mg(I)•mL-1 by a centrifugation/redispersion step, which sets radiopacity of the contrast agent in the right range for imaging cardiovascular system and biodistribution. SPCCT 'Material Decomposition' and 'K-edge reconstruction' methods allow accurate quantification of iodine, as well as specific discrimination of iodine and gadolinium in mixed phantom samples. Intravenous injection of iodinated polymer nanoparticles to rats provides a clear visualization of the cardiovascular system over several hours followed by progressive accumulation in liver and spleen. This material is a 'blood pool' contrast agent with very long residence time in the blood stream.

International audience; BACKGROUND: Recent publications suggest that left atrial (LA) myopathy is a potential source of thromboembolism, independent of atrial fibrillation. AIMS: We sought to investigate whether the presence of atrial premature activity after an ischaemic stroke is associated with LA remodelling and dysfunction, and might be a surrogate marker of LA myopathy. METHODS: After an ischaemic stroke or a transient ischaemic attack, patients without known atrial fibrillation or overt heart disease were included prospectively in the study. All patients had a standard workup, including ambulatory Holter electrocardiogram monitoring and transthoracic echocardiography. In some patients, transoesophageal echocardiography was also performed. Anatomical and functional LA remodelling were assessed using minimal and maximal volumes and LA emptying fraction in two-dimensional and three-dimensional echocardiography. Patients were separated into two groups according to the burden of atrial premature complexes (APCs), measured by Holter electrocardiography. RESULTS: Among 148 eligible patients recruited from October 2015 to May 2016, 93 were included in the group with non-frequent APCs (nf-APC:\textless100 APCs/24hours) and 43 in the group with frequent APCs (f-APC:\textgreater100 APCs/24hours). Twelve patients had paroxysmal atrial fibrillation, and were not included in the statistical analysis. Maximal and minimal indexed LA volumes were significantly higher in the f-APC group than in the nf-APC group (P\textless0.01). LA emptying fraction was worse in the f-APC group than in the nf-APC group. In addition, LA appendage emptying velocity was impaired in the f-APC group, and was correlated with LA remodelling variables, especially LA emptying fraction (r=0.621). CONCLUSIONS: After an ischaemic stroke or a transient ischaemic attack, excessive APCs are associated with LA remodelling. Thus, LA dilatation and dysfunction reflect early LA myopathy, which might itself be responsible for cardioembolic stroke.

Previous studies have suggested the role of microcalcifications in plaque vulnerability. This exploratory study sought to assess the potential of hybrid positron-emission tomography (PET)/magnetic resonance imaging (MRI) using 18F-sodium fluoride (18F-NaF) to check simultaneously 18F-NaF uptake, a marker of microcalcifications, and morphological criteria of vulnerability. We included 12 patients with either recently symptomatic or asymptomatic carotid stenosis. All patients underwent 18F-NaF PET/MRI. 18F-NaF target-to-background ratio (TBR) was measured in culprit and nonculprit (including contralateral plaques of symptomatic patients) plaques as well as in other arterial walls. Morphological criteria of vulnerability were assessed on MRI. Mineral metabolism markers were also collected. 18F-NaF uptake was higher in culprit compared to nonculprit plaques (median TBR 2.6 [2.2-2.8] vs 1.7 [1.3-2.2]; P = 0.03) but was not associated with morphological criteria of vulnerability on MRI. We found a positive correlation between 18F-NaF uptake and calcium plaque volume and ratio but not with circulating tissue-nonspecific alkaline phosphatase (TNAP) activity and inorganic pyrophosphate (PPi) levels. 18F-NaF uptake in the other arterial walls did not differ between symptomatic and asymptomatic patients. 18F-NaF PET/MRI may be a promising tool for providing additional insights into the plaque vulnerability.

Purpose To determine the lowest suitable dose level for the detection of pulmonary arteriovenous malformation (PAVM) using a task-based image quality assessment. Material and methods A phantom was scanned using the standard chest protocol (STD) and 4 other ultra-low dose protocols (ULD) using various kVp. Raw data were reconstructed using level 5 of the hybrid iterative reconstruction algorithm (iDose4) for the STD protocol, and level 6 of iDose4 and levels 1 to 3 of model-based iterative reconstruction (IMR) for the ULD protocols. Both quantitative criteria and qualitative analysis were used to compare protocols. Noise-power-spectrum and Task-based transfer function were computed using imQuest software. The detectability-index (d’) was computed for the detection of PAVM. A subjective analysis was performed by 2 chest radiologists to validate the image-quality obtained on the anthropomorphic phantom for all protocols. Results Similar d’ values were found for ULD-140 using iDose4 6 compared to STD protocol. Greater d’ values were found for all ULD protocols using IMR compared to STD. Subjective image quality was rated as acceptable to excellent for ULD-140 and ULD-120 for all reconstruction types, for ULD-100 and ULD-80 using IMR2, and for ULD-100 using IMR1. Image smoothing was poor for IMR3 for ULD-100 and ULD-80. Finally, the ULD-80 protocol reconstructed with IMR2 was chosen for the detection of PAVM. With this protocol, the dose (CTDIvol of 0.3 mGy) was reduced by 91% compared with the STD protocol. Conclusion A dose level as low as 0.3 mGy reconstructed with IMR2 provides an image quality suitable for the detection of PAVM.

In-stent restenosis (ISR) is one of the main long-term complications after coronary stent placement, and the ability to evaluate ISR noninvasively using coronary computed tomography (CT) angiography remains challenging. For this application, spectral photon-counting CT (SPCCT) has the potential to increase image quality and reduce artifacts due to its advanced detector technology.Our study aimed to verify the technical and clinical potential of a novel SPCCT prototype using an ISR phantom setup.Soft plaque-like restenosis (45 HU; approximately 50% of the stent lumen) were inserted into 10 different coronary stents (3 mm diameter), which were placed in a vessel phantom and filled with a contrast agent (400 HU). A research prototype SPCCT and a clinical dual-layer CT (DLCT; IQon; Philips) with comparable acquisition and reconstruction parameters were used to scan the phantoms. Conventional polyenergetic (PolyE) and monoenergetic (MonoE) images with 4 different energy levels (40, 60, 90, 120 keV) were reconstructed. Qualitative (delineation of the stenosis and adjacent residual lumen using a 5-point Likert scale) and quantitative (image noise, visible lumen diameter, lumen diameter adjacent to the stenosis, contrast-to-noise ratio of the restenosis) parameters were evaluated for both systems.The qualitative results averaged over all reconstructions were significantly superior for SPCCT compared with DLCT (eg, subjective rating of the best reconstruction of each scanner: DLCT PolyE: 2.80 ± 0.42 vs SPCCT MonoE 40 keV: 4.25 ± 1.03). Stenosis could be clearly detected in 9 and suspected in 10 of the 10 stents with both SPCCT and DLCT. The residual lumen next to the stenosis was clearly delineable in 7 of 10 stents (0.64 ± 0.11 mm or 34.97% of the measured stent lumen) with SPCCT, while it was not possible to delineate the residual lumen for all stents using DLCT. The measured diameter of the lumen within the stent was significantly higher for SPCCT compared with DLCT in all reconstructions with the best results for the MonoE 40 keV images (SPCCT: 1.80 ± 0.17 mm; DLCT: 1.50 ± 0.31 mm). The image noise and the contrast-to-noise ratio were better for DLCT than for SPCCT (contrast-to-noise ratio: DLCT MonoE 40: 31.58 ± 12.54; SPCCT MonoE 40: 4.64 ± 1.30).Spectral photon-counting CT allowed for the noninvasive evaluation of ISR with reliable results regarding the residual lumen for most tested stents and the clear identification or suspicion of stenosis for all stents. In contrast, the residual lumen could not be detected for a single stent using DLCT.

Denoising algorithms via sparse representation are among the state-of-the art for 2D image restoration. In this work, we propose a novel sparse and prior-based algorithm for 3D image denoising (SPADE). SPADE is a modification of total variation (TV) problem with an additional functional that promotes sparsity with respect to a prior image. The prior is obtained from the noisy image by combining information from neighbor slices. The functional is minimized using the split Bregman method, which leads to an efficient method for large scale 3D denoising, with computational cost given by three FFT per iteration. SPADE is compared to TV and dictionary learning on the Shepp-Logan phantom and on human knee data acquired on a spectral computerized tomography scanner. SPADE converges in approximately ten iterations and provides comparable or better results than the other methods. In addition, the exploitation of the prior image avoids the patchy, cartoon-like images provided by TV and provides a more natural texture.

International audience; Osteoarthritis is the most common degenerative joint disease. Spectral computed tomography generates energy-resolved data which enable identification of materials within the sample and offer improved soft tissue contrast compared to conventional X-ray CT. In this work, we propose a realistic numerical phantom of a knee to assess the feasibility of spectral CT for osteoarthritis. The phantom is created from experimental synchrotron CT mono-energetic images. After simulating spectral CT data, we perform material decomposition using Gauss-Newton method, for different noise levels. Then, we reconstruct virtual mono-energetic images. We compare decompositions and mono-energetic images with the phantom using mean-squared error. When performing material decomposition and tomographic reconstruction, we obtain less than 1 % error for both, using noisy data. Moreover , it is possible to see cartilage with naked eye on virtual mono-energetic images. This phantom has great potential to assess the feasibility and current limitations of spectral CT to characterize knee osteoarthritis.

To evaluate the technical and diagnostic performance of three dimensional (3D) mDIXON versus 3D inversion recovery (3D VIAB) and 3D spectral presaturation with inversion recovery (3D SPIR) late gadolinium enhancement (LGE) sequences.A total of 78 patients (50 males and 28 females, age 49 ± 18 years) with 1.5 T CMR examination including three different 3D LGE sequences (3D mDIXON, 3D VIAB, and 3D SPIR) were evaluated for technical and diagnostic performance by two readers. Qualitative scores and quantitative signal and contrast-to-noise ratios were compared among sequences. Qualitative comparisons were made using Friedman and Wilcoxon signed rank tests. Quantitative comparisons were made using one way ANOVA. Reader agreements were tested using Cohen's Kappa. Any p-value0.05 was significant.19 out of 78 patients (24 %) were excluded due to poor (grade 4) image quality and 29 patients were excluded due to absence of LGE. For the remaining 30 patients, free breathing 3D mDIXON showed higher confidence in diagnosis of subepicardial LGE (p-value0.05). 3D mDIXON outperformed 3D SPIR in both visualization of LGE (p = 0.02) and quality of fat suppression (p = 0.001). Nevertheless, 3D mDIXON showed lower image quality compared to the other two sequences.Free breathing 3D mDIXON is a diagnostic problem-solving tool, especially when making a diagnosis of subepicardial enhancement and/or fat suppression is needed, owing to its high spatial resolution and robust fat suppression. Choice of 3D LGE sequence should be based on patient's breath-hold ability, diagnostic needs, and institutional availability considering the strengths and limitations of each sequence.

Introduction La sclerodermie systemique (ScS) est une maladie auto-immune rare, heterogene, et chronique. Les pneumopathies interstitielles diffuses (PID) caracterisees par un declin progressif de la fonction respiratoire constituent une complication frequente de la ScS et sa principale cause de deces. En Europe, la prevalence de la PID-ScS a ete estimee a 1,7–4,2/100 000 individus et l’incidence annuelle a 0,1–0,4/100 000 individus. En France, l’epidemiologie de cette maladie est encore meconnue. Ainsi, les objectifs de cette etude etaient d’estimer la prevalence, l’incidence de la PID-ScS en France et de decrire les caracteristiques et la survie des patients. Patients et methodes Une cohorte retrospective longitudinale a ete constituee a partir des donnees du Systeme National des Donnees de Sante entre 2010 et 2017. Les patients ont ete identifies comme etant atteints d’une PID-ScS grâce a un algorithme base sur l’utilisation de codes CIM-10. Ainsi, tous les patients de plus de 20 ans, affilies au regime general d’Assurance Maladie depuis plus de deux ans, et avec : – au moins une hospitalisation ou une affection de longue duree relative a une ScS ; – au moins une hospitalisation avec un code de fibrose pulmonaire ont ete inclus. Resultats Parmi les patients identifies avec une ScS, 34 % presentaient une PID, soit 3 333 patients. Les trois quarts etaient des femmes. La moyenne (ecart-type) d’âge etait de 60,6 (± 14,4) ans. L’incidence globale estimee etait de 0,98–0,76/100 000 individus et la prevalence de 3,42–5,52/100 000 individus sur l’ensemble de la periode. Les taux de prevalence et d’incidence etaient environ trois fois plus eleves chez les femmes que chez les hommes et augmentaient considerablement avec l’âge. Les estimations de la survie globale etaient de 93 % a 1 an, 82 % a 3 ans, 71 % a 5 ans et 55 % a 8 ans. Les facteurs associes a la mortalite etaient le sexe masculin, la presence d’une hypertension pulmonaire, la presence d’un cancer du poumon et les classes d’âges les plus elevees. Discussion La principale limite de l’etude pouvant impacter l’incidence et la prevalence repose sur les modalites de selection des patients et le risque de non-inclusion des patients n’ayant pas ete hospitalises. Neanmoins, les resultats sont coherents avec les donnees de la litterature. Conclusion Cette etude presente pour la premiere fois au niveau national l’epidemiologie de la PID-ScS. Notamment, elle a permis de montrer que la PID-ScS presente un taux de mortalite eleve, en particulier chez les patients a risque.

Introduction Les modalites d’imagerie qui aident a mieux comprendre le processus arthrosique sont la radiographie, l’IRM, la tomographie X, les ultrasons, la DXA et le TEP. A ce jour, seules l’IRM et la tomographie X sont des modalites tri-dimensionnelles (3D). Au niveau osseux, l’IRM permet surtout de visualiser l’existence d’un œdeme sous chondral. L’arthroscanner est tres peu utilise en pratique clinique. La tomographie spectrale a comptage de photons est une nouvelle technologie qui est l’extension en multi-energie de la tomographie a double energie qui a montre son utilite pour la detection des cristaux d’urate de sodium. L’acces a des images mono-energetiques permet d’ameliorer le contraste par rapport au scanner classique. La nouvelle generation de detecteurs ameliore la resolution et le rapport signal sur bruit permettant une meilleure visualisation de la structure osseuse. Nous proposons le developpement de biomarqueurs d’analyse morphologique quantitative des geodes de l’os sous chondral. Materiels et methodes Nous avons utilise pour ce projet un prototype (Philips Healthcare, Haifa) situe au CERMEP, Lyon. Il s’agit d’un appareil clinique dote d’un tube a rayons X classique et d’un detecteur a conversion directe de photons resolutif en energie et qui permet l’obtention de voxels isotropes de 250 × 250 × 250 microns. L’acquisition dure quelques minutes. Cet appareil permet d’obtenir une serie d’images mono-energetiques de 30 keV a 120 keV. Nous avons selectionne les images a 60 keV qui offraient le meilleur contraste pour la visualisation du cartilage tout en gardant une qualite suffisante pour l’examen de l’os. Pour ce faire, nous avons etudie 2 specimens de genoux arthrosiques avec presence d’osteophytes et de geodes sous chondrales. Pour la segmentation des geodes sous chondrales, nous avons utilise le logiciel AVIZO 9,0 avec une methode semi-automatique, l’initialisation est realisee par l’operateur, ensuite une croissance de regions permet de detecter le volume a l’interieur de la cavite. Les parametres mesures sont le nombre de geodes et leurs volumes (mm3). Nous avons analyse le compartiment femoro-patellaire en separant la partie mediale et laterale pour chacune des pieces osseuses (les volumes Resultats Pour le compartiment femoro-medial, les volumes medians (VM) etaient de 48 et 11,8 mm3 pour le genou 1 (G1) et genou 2 (G2), pour le compartiment femoro-lateral, les VM etaient de 101,5 et 4,1 mm3, respectivement. Pour le compartiment patello-medial, les VM etaient de 2,7 et 9,4 mm3, respectivement, pour le compartiment patello-lateral, les VM etaient de 2,1 et 1,8 mm3, respectivement. Nous avons examine la repartition en taille des geodes sous chondrales pour chacun des compartiments et a titre d’exemple, nous presentons la repartition des compartiments femoro-lateraux. Pour les tailles de 1,5-3 mm3, il y avait 1 geode G1 et 8 geodes G2, pour une taille de 3-20 mm3 14 geodes G2, pour une taille de 20-40 mm3 2 geodes G1 et G2, pour une taille > 50 mm3 2 geodes G1 et 1 geode G2. Conclusion Le scanner spectral a comptage de photons est un nouvel outil qui permettra d’analyser sur la meme image des parametres quantitatifs 3D du cartilage et de l’os sous chondral pour ameliorer la comprehension du phenomene arthrosique et mieux suivre l’evolution naturelle ou sous l’effet des traitements.

In patients with chronic fibrosing interstitial lung disease (ILD), a progressive fibrosing phenotype (PF-ILD) may develop, but information on the frequency and characteristics of this population outside clinical trials is lacking. We assessed the characteristics and outcomes of patients with PF-ILD other than idiopathic pulmonary fibrosis (IPF) in a real-world, single-centre clinical cohort. The files of all consecutive adult patients with fibrosing ILD (2010–2017) were examined retrospectively for pre-defined criteria of ≥10% fibrosis on high-resolution computed tomography and progressive disease during overlapping windows of 2 years. Baseline was defined as the date disease progression was identified. Patients receiving nintedanib or pirfenidone were censored from survival and progression analyses. In total, 1395 patients were screened; 617 had ILD other than IPF or combined pulmonary fibrosis and emphysema, and 168 had progressive fibrosing phenotypes. In 165 evaluable patients, median age was 61 years; 57% were female. Baseline mean forced vital capacity (FVC) was 74±22% predicted. Median duration of follow-up was 46.2 months. Annualised FVC decline during the first year was estimated at 136±328 mL using a linear mixed model. Overall survival was 83% at 3 years and 72% at 5 years. Using multivariate Cox regression analysis, mortality was significantly associated with relative FVC decline ≥10% in the previous 24 months (p, In a real-world clinical cohort (PROGRESS), progressive fibrosing interstitial lung disease was characterised by continued lung function decline. Lung function decline, age and underlying diagnosis subgroup predicted mortality. https://bit.ly/2EB3OpF

Vascular involvement in coronavirus disease 2019 (COVID-19) has been suggested by several observations, such as the high rate of pulmonary embolism [1], the prothrombotic state and the proinflammatory biological profile [2, 3], as well as the pathological findings of severe endothelial injury and diffuse thrombosis [4]. Dual-energy computed tomography (DECT) allows specific imaging of the iodinated contrast agent distribution within the lung, which has been demonstrated as a surrogate marker of lung perfusion [5, 6]. Therefore, our goal was to assess in vivo pulmonary microvascular involvement in patients with COVID-19 pneumonia by using DECT and to determine whether vascular changes vary during the course of the disease., In COVID-19 pneumonia, dual-energy computed tomography has shown two patterns of lung perfusion along the course of the disease: an increase in perfusion blood volume (PBV) with ground-glass opacities and a decrease in PBV with consolidation https://bit.ly/2Zh0XcI

Purpose This work presents our contribution to one of the data challenges organized by the French Radiology Society during the Journees Francophones de Radiologie. This challenge consisted in segmenting the kidney cortex from coronal computed tomography (CT) images, cropped around the cortex. Materials and methods We chose to train an ensemble of fully-convolutional networks and to aggregate their prediction at test time to perform the segmentation. An image database was made available in 3 batches. A first training batch of 250 images with segmentation masks was provided by the challenge organizers one month before the conference. An additional training batch of 247 pairs was shared when the conference began. Participants were ranked using a Dice score. Results The segmentation results of our algorithm match the renal cortex with a good precision. Our strategy yielded a Dice score of 0.867, ranking us first in the data challenge. Conclusion The proposed solution provides robust and accurate automatic segmentations of the renal cortex in CT images although the precision of the provided reference segmentations seemed to set a low upper bound on the numerical performance. However, this process should be applied in 3D to quantify the renal cortex volume, which would require a marked labelling effort to train the networks.

International audience; correct visualization of the vascular lumen is impaired in standard computed tomography (ct) because of blooming artifacts, increase of apparent size, induced by metallic stents and vascular calcifications. Recently, due to the introduction of photon-counting detectors in the X-ray imaging field, a new prototype spectral photon-counting CT (SPCCT) based on a modified clinical CT system has been tested in a feasibility study for improving vascular lumen delineation and visualization of coronary stent architecture. Coronary stents of different metal composition were deployed inside plastic tubes containing hydroxyapatite spheres to simulate vascular calcifications and in the abdominal aorta of one New Zealand White (NZW) rabbit. Imaging was performed with an SPCCT prototype, a dual-energy CT system, and a conventional 64-channel CT system (B64). We found the apparent widths of the stents significantly smaller on SPCCT than on the other two systems in vitro (p < 0.01), thus closer to the true size. Consequently, the intra-stent lumen was significantly larger on SPCCT (p < 0.01). In conclusion, owing to the increased spatial resolution of SPCCT, improved lumen visualization and delineation of stent metallic mesh is possible compared to dual-energy and conventional CT. Coronary artery stenting has become the most important nonsurgical coronary revascularization procedure 1. Coronary angiography using computed tomography (CT) is limited in regards to a correct assessment of in-stent restenosis and its impact on coronary circulation, one of the major complications following the stenting procedure. Indeed, blooming artifacts impair a correct visualization of the vascular lumen. Blooming artifacts result in an apparent increase in the size of strongly attenuating objects, such as the stent's metallic struts and vascular cal-cifications, leading to an apparent reduction in size of the vascular lumen. Metal strut induced blooming artifacts are more significant in stents of diameter 3 mm or less, reducing intra-stent lumen interpretability to nearly 51% compared to 81% for larger stents 2. Furthermore, severe calcifications also induce blooming artifacts and their presence at a stent location may impair the detection of the stent itself. The recent development of a clinically based small field-of-view (FOV) spectral photon counting CT (SPCCT) prototype achieves higher spatial resolutions than standard CT at similar energies, owing to an important reduction in detector size 3. The higher spatial resolution is possible owing to the direct conversion pho-ton counting detectors, which convert single x-rays to electrical pulses. Ultra-high resolution mode resulting in a 0.25 × 0.25 mm pixel size at iso-center was demonstrated recently for a photon-counting CT system 4. This increase in spatial resolution is expected to strongly reduce blooming artifacts, potentially improving restenosis detection and interpretation 5. Reduction in blooming artifacts should allow morphological assessment of the mesh of the stent which is expected to improve detection of stent deployment problems and stent integrity degradation 6. Furthermore, owing to the spectral separation capabilities of photon counting, specific K-edge images

Computed tomography (CT) is one of the most commonly used clinical imaging modalities. There have recently been many reports of novel contrast agents for CT imaging. In particular, the development of gold nanoparticles (AuNP) as CT contrast agents is a topic of intense interest. AuNP have favorable characteristics for this application such as high payloads of contrast generating material, strong X-ray attenuation, excellent biocompatibility, tailorable surface chemistry, and tunable sizes and shapes. However, there have been conflicting reports on the role of AuNP size on their contrast generation for CT. We therefore sought to extensively investigate the AuNP size-CT contrast relationship. In order to do this, we synthesized AuNP with sizes ranging from 4 to 152 nm and capped them with 5 kDa m-PEG. The contrast generation of AuNP of different sizes was investigated with three clinical CT, a spectral photon counting CT (SPCCT) and two micro CT systems. X-ray attenuation was quantified as attenuation rate in Hounsfield units per unit concentration (HU/mM). No statistically significant difference in CT contrast generation was found among different AuNP sizes via phantom imaging with any of the systems tested. Furthermore, in vivo imaging was performed in mice to provide insight into the effect of AuNP size on animal biodistribution at CT dose levels, which has not previously been explored. Both in vivo imaging and ex vivo analysis with inductively coupled plasma optical emission spectroscopy (ICP-OES) indicated that AuNP that are 15 nm or smaller have long blood circulation times, while larger AuNP accumulated in the liver and spleen more rapidly. Therefore, while we observed no AuNP size effect on CT contrast generation, there is a significant effect of size on AuNP diagnostic utility.

Resume L’imagerie tomodensitometrique conventionnelle permet de differencier des structures anatomiques par la difference d’attenuation globale des tissus aux rayons X. Cette difference, directement liee aux effets photoelectriques et Compton, depend principalement du numero atomique Z et de la densite ρ des elements etudies. La TDM double energie etend les capacites de l’imagerie TDM conventionnelle en permettant de distinguer des elements de meme attenuation globale par leur differences d’attenuation photoelectrique et Compton. L’objectif de cette mise au point est d’aborder le principe de l’imagerie tomodensitometrique spectrale et d’en decrire la technologie actuelle, basee sur les differences d’attenuation des structures explorees a haute et basse energie. Nous decrirons ensuite les principales applications cliniques de cette technique. Nous evoquerons enfin les evolutions futures vers la tomodensitometrie spectrale a comptage photonique.

Introduction Les pneumopathies interstitielles diffuses (PID) regroupent un ensemble heterogene de maladies caracterisees par un processus diffus inflammatoire et/ou fibrosant. Certains patients atteints de PID fibrosante peuvent developper un phenotype a evolution progressive (PID-FP) similaire a celui observe dans la fibrose pulmonaire idiopathique (FPI). L’objectif de cette etude est de developper des algorithmes pour identifier les patients avec PID-FP au sein du Systeme national des donnees de sante (SNDS) afin de mieux connaitre l’epidemiologie et le fardeau de ces maladies en France. Methodes Un premier algorithme base sur des travaux americains existants et l’expertise de cliniciens a ete developpe. Il consiste a identifier, a travers le Programme de medicalisation des systemes d’informations (PMSI) et les affections de longue duree (ALD), les patients atteints d’une PID. Apres exclusion des FPI, les formes progressives sont selectionnees a partir des donnees de demandes de remboursement pour des traitements specifiques, de consultations chez le pneumologue, d’actes d’imagerie, d’examens de la fonction pulmonaire et/ou d’hospitalisations. Une seconde approche consistera a creer un algorithme via une approche par apprentissage automatique grâce au recoupement des donnees du SNDS et d’une cohorte clinique suivie par le Centre national de reference des maladies pulmonaires rares de Lyon. Resultats Le premier algorithme a ete developpe et est actuellement applique sur les donnees du SNDS afin de detecter les cas prevalents et incidents de PID-FP non-FPI entre 2010 et 2017. L’ensemble des resultats de l’etude est attendu pour la fin de l’annee 2019 et les resultats finaux seront presentes au congres. Discussion/Conclusion Le developpement de ces deux algorithmes par des approches differentes permettra de comparer les resultats obtenus et de choisir l’approche la plus valide pour approfondir les connaissances sur ces pathologies. Cette etude permettra d’estimer le nombre de patients atteints de PID-FP non-FPI, de decrire leur parcours de soins et les couts associes, ainsi que d’explorer les facteurs associes a leur morbi-mortalite.

Introduction Les pneumopathies interstitielles diffuses (PID) regroupent un ensemble heterogene de maladies caracterisees par un processus inflammatoire, diffus, et parfois fibrosant (PID) [1] . Certains patients atteints de PID fibrosante, peuvent developper un phenotype d’evolution progressive comparable a celui observe dans la fibrose pulmonaire idiopathique ; ces pathologies sont regroupees sous le terme de PID de phenotype ou de forme progressive (PID-FP) [2] . L’objectif est de decrire la frequence, les caracteristiques cliniques et l’evolution des patients PID-FP hors FPI. Methodes L’etude a porte sur tous les patients successifs hospitalises dans un centre de reference des maladies pulmonaires rares entre janvier 2010 et decembre 2017, âges de 18 ans et plus, et presentant une PID fibrosante diagnostiquee par scanner thoracique. Parmi eux, les patients presentant une PID-FP ont ete selectionnes sur les criteres de progression definis par une baisse de la CVF ≥ 10 % avec ou sans deterioration clinique, ou une baisse de la CVF entre 5 et 10 % associee a une aggravation des symptomes respiratoires, ou une baisse de la CVF entre 5 et 10 % associee a une etendue croissante de la fibrose au scanner en moins de 24 mois. Cette etude a ete approuvee par la CNIL le 09/2018 (918305). Resultats Actuellement 149 patients presentant une PID-FP ont ete inclus. La majorite des patients etaient des femmes (57 %) d’âge moyen 59 ± 14 ans. La CVF moyenne etait de 73,3 ± 21 % de la theorique et la DLco de 43,0 ± 17,5 %. Pour les 104 patients dont l’information est disponible, la duree entre le diagnostic de la PID et celui de la progression etait de 2,7 ± 3,8 ans. La repartition etiologique etait : 8 % de pneumopathie d’hypersensibilite, 6 % de pneumopathie interstitielle non specifique idiopathique, 24 % de PID inclassable, 48 % de PID auto-immune, et 14 % d’autres PID. Les criteres de progression etaient une baisse de la CVF ≥ 10 % (65 %), une baisse de la CVF de 5–10 % associee a une aggravation des symptomes (24 %), une baisse de la CVF de 5–10 % associee a une etendue croissante de la fibrose au scanner (2 %) ou une aggravation des symptomes et une etendue croissante de la fibrose au scanner (9 %) en moins de 24 mois. Conclusion Ces resultats preliminaires fournissent des elements sur l’epidemiologie des patients PID-FP pour lesquels un essai therapeutique avec le nintedanib est actuellement en cours.

International audience; OBJECTIVES: Endovascular renal denervation (RDN) using catheter-based radiofrequency (RF) ablation has emerged as a potential treatment option for drug-resistant hypertension. Its efficacy is currently under debate. We aimed to evaluate the capability of contrast-enhanced magnetic resonance imaging (MRI) to assess the effects of RDN on the renal arterial wall in patients presenting with drug-resistant hypertension.METHODS: Patients were included prospectively following institutional review board approval and written informed consent. Renal arteries were imaged using a two-dimensional T1-weighted TSE sequence pre- and post-administration of a gadolinium-based contrast agent, before (D0), 2 days (D2) and 6 months (M6) after RDN. Mean enhancement of the wall (mENH) and mean wall thickness (mWT) were compared across time using an ANOVA with repeated measures and post-hoc paired t-test.RESULTS: Follow-up was completed for 23 patients (median age, 57 years; 16 men). The mENH at D2 (96.3 \textpm 36.0 %) was significantly higher than at D0 (61.1 \textpm 26.3%, p < 0.001) and M6 (66.1\textpm22.7%, p < 0.001). Similarly, mWT was significantly higher at D2 (3.1 \textpm 0.4 m) than at D0 (2.7 \textpm 0.4mm, p < 0.001) and M6 (2.9 \textpm 0. 5 mm, p = 0.002).CONCLUSIONS: MRI demonstrated abnormalities of the arterial wall 2 days after RDN that had resolved at 6 months.KEY POINTS: \textbullet Contrast-enhanced MRI provides anatomic evidence of renal artery RF ablation \textbullet Temperature increase related to RF ablation induces transient arterial wall inflammation \textbullet Morphological effects observed 2 days post RF ablation are not visible after 6 months.

Supplemental digital content is available in the text., Objectives To validate in vitro the capability of a high-spatial-resolution prototype spectral photon-counting computed tomography (SPCCT) scanner to differentiate between 2 contrast agents and to assess in vivo the image quality and the feasibility to image the peritoneal cavity in rats using the 2 contrast agents simultaneously within the vascular and peritoneal compartments. Materials and Methods The authors performed SPCCT imaging (100 mAs, 120 kVp) with energy bin thresholds set to 30, 51, 64, 72, and 85 keV in vitro on a custom-made polyoxymethylene cylindrical phantom consisting of tubes with dilutions of both contrast agents and in vivo on 2 groups of adult rats using 2 injection protocols. Approval from the institutional animal ethics committee was obtained. One group received macrocylic gadolinium chelate intraperitoneal (IP) and iodine intravenous (IV) injections (protocol A, n = 3), whereas the second group received iodine IP and gadolinium IV (protocol B, n = 3). Helical scans were performed 35 minutes after IP injection and 20 seconds after IV injection. The SPCCT and contrast material images, that is, iodine and gadolinium maps, were reconstructed with a field of view of 160 mm, an isotropic voxel size of 250 μm, and a matrix size of 640 × 640 pixels using a soft reconstruction kernel. The SPCCT images were reconstructed with 2 different spatial resolutions to compare the image quality (sharpness, diagnostic quality, and organ visualization) of SPCCT (250 μm) with single-energy computed tomography (CT) (600 μm). Two radiologists evaluated the peritoneal opacification index in 13 regions (score = 0–3 per region) on each type of image. Concentrations of contrast agents were measured in the organs of interest. Results In vitro, the concentration measurements correlated well with the expected concentrations. The linear regressions both had R2 values of 0.99, slopes of 0.84 and 0.87, and offsets at −0.52 and −0.38 mg/mL for iodine and gadolinium, respectively. In vivo, the SPCCT images were of better diagnostic quality, with increased sharpness compared with the CT-like images (P < 0.0001). Intraperitoneal diffusion was excellent, with similar peritoneal opacification index on SPCCT images and overlay of contrast material maps (P = 1) without a significant difference between protocol A (37.0 ± 1.7) and protocol B (35.3 ± 1.5) (P = 0.34). Only the contrast material maps demonstrated clear visual separation of the contrast agents, allowing specific quantification of the physiological enhancement in the liver, spleen, and kidney and the urinary clearance in the renal pelvis and bladder. Renal excretion of the contrast agents injected IP was observed and was consistent with blood diffusion. Conclusions Spectral photon-counting CT can be used to perform a complete peritoneal dual-contrast protocol, enabling a good assessment of the peritoneal cavity and abdominal organs in rats.

Over the last decade, dual-energy CT scanners have gone from prototypes to clinically available machines, and spectral photon counting CT scanners are following. They require a specific reconstruction process, consisting of two steps: material decomposition and tomographic reconstruction. Image-based methods perform reconstruction, then decomposition, while projection-based methods perform decomposition first, and then reconstruction. As an alternative, 'one-step inversion' methods have been proposed, which perform decomposition and reconstruction simultaneously. Unfortunately, one-step methods are typically slower than their two-step counterparts, and in most CT applications, reconstruction time is critical. This paper therefore proposes to compare the convergence speeds of five one-step algorithms. We adapted all these algorithms to solve the same problem: spectral photon-counting CT reconstruction from five energy bins, using a three materials decomposition basis and spatial regularization. The paper compares a Bayesian method which uses non-linear conjugate gradient for minimization (Cai et al 2013 Med. Phys. 40 111916-31), three methods based on quadratic surrogates (Long and Fessler 2014 IEEE Trans. Med. Imaging 33 1614-26, Weidinger et al 2016 Int. J. Biomed. Imaging 2016 1-15, Mechlem et al 2018 IEEE Trans. Med. Imaging 37 68-80), and a primal-dual method based on MOCCA, a modified Chambolle-Pock algorithm (Barber et al 2016 Phys. Med. Biol. 61 3784). Some of these methods have been accelerated by using μ-preconditioning, i.e. by performing all internal computations not with the actual materials the object is made of, but with carefully chosen linear combinations of those. In this paper, we also evaluated the impact of three different μ-preconditioners on convergence speed. Our experiments on simulated data revealed vast differences in the number of iterations required to reach a common image quality objective: Mechlem et al (2018 IEEE Trans. Med. Imaging 37 68-80) needed ten iterations, Cai et al (2013 Med. Phys. 40 111916-31), Long and Fessler (2014 IEEE Trans. Med. Imaging 33 1614-26) and Weidinger et al (2016 Int. J. Biomed. Imaging 2016 1-15) several hundreds, and Barber et al (2016 Phys. Med. Biol. 61 3784) several thousands. We also sum up other practical aspects, like memory footprint and the need to tune extra parameters.

Introduction Les pneumopathies interstitielles diffuses (PID) regroupent un ensemble heterogene de maladies caracterisees par un processus diffus inflammatoire et/ou fibrosant [1] . Certains patients atteints de pneumopathie interstitielle diffuse fibrosante, peuvent developper un phenotype a evolution progressive similaire a celui observe dans la fibrose pulmonaire idiopathique (FPI), ces pathologies etant regroupees sous le terme de pneumopathie interstitielle diffuse a forme progressive (PID-FP) [2] . L’objectif de cette etude est de developper des algorithmes pour identifier les patients avec PID-FP non-FPI afin de decrire l’epidemiologie, et le fardeau global de ces maladies en France. Methodes Un algorithme bases sur la CIM-10, et reposant sur des algorithmes americains, a ete developpe en France afin de selectionner entre le 01/01/2010 et le 31/12/2017 les cas prevalents et incidents de PID-FP non-FPI au sein du Systeme national des donnees de sante (SNDS). Un algorithme sera aussi developpe a partir de la cohorte clinique de patients avec PID-FP non-FPI suivis par le Centre national de reference des maladies pulmonaires rares de Lyon. Description des algorithmes Un premier algorithme a ete developpe pour extraire les sejours des patients atteints de PID-FP, base sur la selection de l’ensemble des sejours avec un code de diagnostic de fibrose pulmonaire puis l’exclusion des patients FPI. Les formes progressives seront enfin extraites a partir des donnees de demandes de remboursement pour des traitements specifiques, de consultations chez le pneumologue, d’actes d’imagerie, d’examens de la fonction pulmonaire et/ou d’hospitalisations. La seconde approche consistera a creer un algorithme via une approche par apprentissage automatique grâce au recoupement des donnees du SNDS et de la cohorte clinique. Conclusion Le developpement de ces deux algorithmes par des approches differentes permettra de comparer les resultats obtenus et de choisir l’approche la plus valide pour approfondir les connaissances sur ces pathologies. Cette etude permettra d’estimer le nombre de patients atteints de PID-FP non-FPI, de decrire leur parcours de soins et les couts associes, ainsi que d’explorer la correlation entre la capacite vitale forcee de ces patients et leur morbi-mortalite.

[DOI:\hrefhttps://dx.doi.org/10.1007/s00330-015-4090-810.1007/s00330-015-4090-8] [PubMed:\hrefhttps://www.ncbi.nlm.nih.gov/pubmed/1496318114963181]; To evaluate the value of the diameter of the draining vein of pulmonary arteriovenous malformation (PAVM) on unenhanced chest MDCT in diagnosing reperfusion after percutaneous vaso-occlusion therapy.\ We retrospectively reviewed our long-term experience of patients with hereditary haemorrhagic telangiectasia and selected cases on the following criteria: an initial pulmonary angiogram with embolotherapy of at least one PAVM, a follow-up MDCT examination in the following year followed by a second pulmonary angiogram with embolotherapy if needed. Follow-up unenhanced chest MDCT examinations were analyzed blindly from results of pulmonary artery angiogram and clinical data, the diameter of the efferent vein close to the PAVM sac was measured, then compared to those of pulmonary artery angiogram as a gold standard.\ Eighty-eight of 100 patients met inclusion criteria, in whom 62 of 176 PAVMs were reperfused at angiogram. The mean diameter of the efferent vein on MDCT was 4.3 ± 2.1 mm in patent PAVMs and 1.8 ± 0.9 mm in non-patent PAVMs (p < 0.0001). The optimal cutoff diameter based on ROC analysis was 2.5 mm (sensitivity = 98.4 %; specificity = 87.7 %).\ A diameter of the draining vein of PAVM of 2.5 mm or greater on unenhanced MDCT is a strong predictor of reperfusion.\ • Diameter of draining vein of 2.5 mm or greater is associated with reperfusion. • Unenhanced chest MDCT predicts reperfusion of PAVMs with good sensitivity and specificity. • Unenhanced MDCT can guide a decision of repeat pulmonary angiogram and embolotherapy. • The mean vein diameter change of PAVMs occluded at follow-up is 3.8 mm. • Overall success rate after a median of 6 months embolotherapy was 64.7 %.

International audience; Objective:To evaluate the accuracy of diffusion-weighted MRI with background suppression (DWIBS) in differentiating between malignant and benign mediastinal lymph-nodes.Methods:Consecutive patients with enlarged mediastinal lymph-nodes underwent MRI DWIBS within 10 days prior to mediastinoscopy. Relative contrast ratios (RCRs) were computed on b800 and apparent diffusion coefficient (ADC) maps by dividing the node signal with the chest muscle signal, using manually drawn regions of interest (ROIs) by radiologists, blinded to pathology. Unpaired Student's t-tests were used to compare RCR-b800 and ADC between malignant and benign nodes. Receiver operating characteristic curves analyses were also performed.Results:Six patients were excluded for poor image quality. Analysis was performed for 54 patients. Mean ADC values were significantly higher for benign (1740 ± 401 × 10−6 mm2 s–1) compared with malignant nodes (1266 ± 403 × 10−6 mm2 s–1, p = 0.0001). Mean RCR-b800 values were significantly lower for benign (2.64 ± 1.07) compared with malignant nodes (6.44 ± 3.47, p < 0.0001).Receiver operating characteristic analysis for RCR-b800 (cut-off of 3.6), showed a sensitivity of 90.9%, a specificity 83% and an accuracy 85% for differentiating benign from malignant nodes. For ADC (cut-off of 1285), the sensitivity was 68.2%, the specificity 84.6% and the accuracy 80.4%.Conclusion:DWIBS can accurately differentiate malignant from benign states in enlarged mediastinal lymph-nodes and represents an alternative method in aetiological work-up of mediastinal lymphadenopathies.Advances in knowledge:DWIBS may represent a useful adjunctive imaging modality, particularly for diagnosis of benign mediastinal lymph node, and thus may reduce the frequency of futile mediastinoscopy, which remains an invasive procedure.

[PubMed Central:\hrefhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC6028848PMC6028848] [DOI:\hrefhttps://dx.doi.org/10.1007/s00330-017-5252-710.1007/s00330-017-5252-7] [PubMed:\hrefhttps://www.ncbi.nlm.nih.gov/pubmed/2743602727436027]; International audience; After endovascular aortic repair (EVAR), discrimination of endoleaks and intra-aneurysmatic calcifications within the aneurysm often requires multiphase computed tomography (CT). Spectral photon-counting CT (SPCCT) in combination with a two-contrast agent injection protocol may provide reliable detection of endoleaks with a single CT acquisition.\ To evaluate the feasibility of SPCCT, the stent-lined compartment of an abdominal aortic aneurysm phantom was filled with a mixture of iodine and gadolinium mimicking enhanced blood. To represent endoleaks of different flow rates, the adjacent compartments contained either one of the contrast agents or calcium chloride to mimic intra-aneurysmatic calcifications. After data acquisition with a SPCCT prototype scanner with multi-energy bins, material decomposition was performed to generate iodine, gadolinium and calcium maps.\ In a conventional CT slice, Hounsfield units (HU) of the compartments were similar ranging from 147 to 168 HU. Material-specific maps differentiate the distributions within the compartments filled with iodine, gadolinium or calcium.\ SPCCT may replace multiphase CT to detect endoleaks without sacrificing diagnostic accuracy. It is a unique feature of our method to capture endoleak dynamics and allow reliable distinction from intra-aneurysmatic calcifications in a single scan, thereby enabling a significant reduction of radiation exposure.\ • SPCCT might enable advanced endoleak detection. • Material maps derived from SPCCT can differentiate iodine, gadolinium and calcium. • SPCCT may potentially reduce radiation burden for EVAR patients under post-interventional surveillance.

International audience; Background Several preliminary analyses suggested an association between neprilysin (NEP) levels and myocardial infarction. Hypothesis The objective was to assess whether NEP plasma levels following reperfusion might be a surrogate for infarct size (IS) or predict adverse outcomes in acute ST-segment elevation myocardial infarction (STEMI) patients. Methods We measured NEP levels in a prospective cohort of 203 patients with STEMI referred for primary percutaneous coronary intervention. Circulating soluble NEP was measured by enzyme-linked immunosorbent assay at admission (t0) and 4 hours later (t4) following reperfusion and on 7 times points (t0, t4, t12, t24, t48, day 7 and day 30) in a subset of 21 patients. IS and left ventricular ejection fraction (LVEF) were measured at 1 month by cardiac magnetic resonance. Adverse cardiovascular outcomes were collected at 12-month follow-up. Results Median t0 and t4 NEP levels in 203 patients were respectively 88.3 pg/mL (interquartile range [IQR] [14; 375.4]) and 101.5 pg/mL (IQR [18.5; 423.8]). These levels remained unchanged over 1 month (P = 0.70). NEP levels did not correlate significantly with IS (P = 0.51) or LVEF (P = 0.34). There was no correlation between NEP and troponin, creatine kinase and interleukin-6 levels at h0 and h4. NEP levels above the median were not associated with adverse outcomes at follow-up (hazard ratio = 1.28, 95% confidence interval [0.69; 2.37]; P = 0.42). Conclusions NEP serum levels were widely distributed and did not change significantly in the first hours and 1-month period following reperfusion in STEMI patients. There was no significant relationship with markers of infarct size and inflammation, and 1-year adverse outcomes

Introduction De precedentes etudes ont pu montrer un risque majore de rupture du ligament croise anterieur (LCA) chez les femmes. La geometrie articulaire femoro-tibiale pourrait jouer un role dans la survenue de ces lesions ligamentaires. Le but de cette etude etait d’analyser les specificites morphologiques articulaires du genou selon le sexe dans une population de patients ayant presente une rupture du LCA. Materiel et methodes La pente tibiale mediale (PTm), la pente tibiale laterale (PTl), la concavite du plateau tibial medial, la convexite du plateau tibial lateral, la convexite des condyles femoraux medial et lateral ont pu etre analyses chez 276 patients ayant presente une rupture complete du LCA (138 hommes et 138 femmes). Les mesures des parametres anatomiques ont ete realisees par deux observateurs independants a l’aide de reconstructions scanographiques multiplanaires. Les variabilites intra- et inter-observateur ont ete evaluees et les comparaisons anatomiques ont ete menees entre les populations masculine et feminine. Resultats Le coefficient de correlation intraclasse moyen pour toutes les mesures morphologiques etait de 0,90 (0,83–0,97) indiquant une reproductibilite tres satisfaisante. Les hommes presentaient une PTl (10,5°±2,8) significativement plus importante que les femmes (9,6°±3,5° ; p > 0,05). Aucune difference concernant la PTm n’etait retrouvee (p = 0,95). La concavite tibiale mediale, ainsi que les convexites condyliennes femorales mediales et laterales etaient plus elevees chez les hommes que chez les femmes (tous p > 0,05). La convexite du plateau tibial lateral etait significativement plus elevee chez les femmes (p > 0,001). Le compartiment femorotibial medial apparaissait plus congruent chez les hommes (p > 0,01) alors que le compartiment lateral etait retrouve davantage incongruent chez les femmes (p > 0,001). Conclusions Les individus de sexe masculin presentaient une congruence femoro-tibiale mediale plus elevee et un compartiment lateral moins incongruent que les femmes. Ces differences concernant les parametres de la geometrie articulaire femoro-tibiale pourraient en partie expliquer la predisposition feminine a la rupture du LCA et necessitent davantage d’investigations.

Purpose To evaluate the radiation dose reduction, image quality and diagnostic confidence with thoraco-abdominopelvic computed tomography (TACT) using a new organ based dose modulation system (liver dose right index [Liver DRI]), compared to TACT using a standard automatic exposure control adjusting mA according to attenuation. Methods A total of 37 patients who had two TACT examinations on 2 different CT scanners, one using standard automatic exposure control (combination of a DoseRight automatic current selection and Z modulation) and one using Liver DRI were included. There were 19 men and 18 women with a mean age of 67.6 ± 11.7 (SD) years (range: 36–85 years) For each patient, volume CT dose index (CTDIvol), size-specific dose estimates (SSDE) and signal-to-noise ratio (SNR) were evaluated at each anatomic level (lung, breast, liver and pelvis area) for each protocol. Two radiologists assessed independently image quality, artifacts and diagnostic confidence. Results The radiation dose decreased significantly using Liver DRI compared to standard automatic exposure control on the total scan length, lung, breast and pelvis area, with a significant CTDIvol reduction of 27% ( P = 0.0001), 23% ( P = 0.0002), 24% ( P = 0.0002) and 31% ( P = 0.0001), respectively; and a significant SSDE reduction of 23% ( P = 0.0001), 28% ( P = 0.0001), 23% ( P = 0.0002) and 29% ( P = 0.0001), respectively. No significant SNR reductions were observed in all measured tissues at the level of the aortic arch, celiac trunk and iliac bifurcation, except in the muscle ( P = 0.0013) and fat tissue ( P = 0.0052) at the level of the ureteral meatus. No significant differences were noted between both protocols in overall image quality, artifacts and diagnostic confidence with an excellent inter observer agreement between radiologists (Kappa values of 0.83, 0.85 and 0.88, respectively). Conclusion Liver DRI organ based dose modulation technique allows significant dose reduction compared to standard automatic exposure control while preserving diagnostic image quality in all thoraco-abdominopelvic areas.

International audience

Computed tomography (CT) is the modality of choice to characterise pulmonary arteriovenous malformations (PAVMs) in patients with hereditary haemorrhagic telangiectasia (HHT). Our objective was to determine if CT findings were associated with frequency of brain abscess and ischaemic stroke. This retrospective study included patients with HHT-related PAVMs. CT results, i.e. PAVM presentation (unique, multiple, disseminated or diffuse), the number of PAVMs and the largest feeding artery size, were correlated to prevalence of ischaemic stroke and brain abscess. All CTs were reviewed in consensus by two radiologists. Of 170 patients, 73 patients had unique (42.9 %), 49 multiple (28.8 %), 36 disseminated (21.2 %) and 12 diffuse (7.1 %) PAVMs. Fifteen patients presented with brain abscess; 26 patients presented with ischaemic stroke. The number of PAVMs was significantly correlated with brain abscess (11.5 vs. 6.2, respectively; p=0.025). The mean diameter of the largest feeding artery was significantly correlated with ischaemic stroke frequency (4.9 vs. 3.2 mm, respectively; p=0.0098). The number of PAVMs correlated significantly with risk of brain abscess, and a larger feeding artery significantly with more ischaemic strokes. These findings can lead to a better recognition and management of the PAVMs at risk of cerebral complications. • Chest CT helps clinicians to facilitate appropriate PAVM management strategies. • Pulmonary arteriovenous malformation CT findings are correlated with risk of cerebral complications. • Risk of brain abscess is significantly correlated with number of PAVMs. • Risk of ischaemic stroke is significantly correlated with large feeding artery PAVMs. • Prevalence of observed of brain abscess and ischaemic stroke is 26 %.

Prolidase deficiency is a new genetic cause of combined pulmonary fibrosis and emphysema syndrome in the adulthttp://bit.ly/2QRgqMH