Imaging of Vascular Aphasia

Brain imaging is essential for the diagnosis of acute stroke and vascular aphasia. Magnetic resonance imaging (MRI) is the modality of choice for the etiological diagnosis of aphasia, the assessment of its severity, and the prediction of recovery. Diffusion weighted imaging is used to detect, localize, and quantify the extension of the irreversibly injured brain tissue called ischemic core. Perfusion weighted imaging (from MRI or CT) is useful to assess the extension of hypoperfused but salvageable tissue called penumbra. Functional imaging (positron emission tomography (PET), functional MRI (fMRI)) may help predicting recovery and is useful for the understanding of language networks and individual variability. This chapter is meant to review the state of the art of morphological and functional imaging of vascular aphasia and to illustrate the MRI profiles of different aphasic syndromes

How can we combat multicenter variability in MR radiomics? Validation of a correction procedure

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Quality Indicators for Colonoscopy Procedures: A Prospective Multicentre Method for Endoscopy Units

BACKGROUND AND AIMS: Healthcare professionals are required to conduct quality control of endoscopy procedures, and yet there is no standardised method for assessing quality. The topic of the present study was to validate the applicability of the procedure in daily practice, giving physicians the ability to define areas for continuous quality improvement. METHODS: In ten endoscopy units in France, 200 patients per centre undergoing colonoscopy were enrolled in the study. An evaluation was carried out based on a prospectively developed checklist of 10 quality-control indicators including five dependent upon and five independent of the colonoscopy procedure. RESULTS: Of the 2000 procedures, 30% were done at general hospitals, 20% at university hospitals, and 50% in private practices. The colonoscopies were carried out for a valid indication for 95.9% (range 92.5-100). Colon preparation was insufficient in 3.7% (range 1-10.5). Colonoscopies were successful in 95.3% (range 81-99). Adenoma detection rate was 0.31 (range 0.17-0.45) in successful colonoscopies. CONCLUSION: This tool for evaluating the quality of colonoscopy procedures in healthcare units is based on standard endoscopy and patient criteria. It is an easy and feasible procedure giving the ability to detect suboptimal practice and differences between endoscopy-units. It will enable individual units to assess the quality of their colonoscopy techniques

Quantitative functional imaging and radiomic of orbital masses

Les masses orbitaires constituent un groupe hétérogène de lésions, avec des localisations et des étiologies très variées, et constituent un challenge diagnostique en clinique et en imagerie. Leur présentation clinique est évocatrice, mais non spécifique. L'imagerie orbitaire a donc un rôle majeur dans la démarche diagnostique. Elle permet de préciser le siège de la lésion, ses caractéristiques, son retentissement sur les composants orbitaires. Elle fait le bilan de son extension et permet un diagnostic de probabilité mais pas de certitude. Le développement de techniques d'imagerie ainsi que d'analyses bioinformatiques poussées permettant une approche plus fine de la caractérisation tumorale est donc particulièrement prometteur et pourrait permettre d'adapter la prise en charge et notamment d'éviter le recours à des prélèvements invasifs devant des lésions bénignes ou à faible évolutivité. Dans ce travail de thèse, nous nous sommes intéressés aux étapes de validation de différentes techniques d'imagerie utilisées à visée de caractérisation tumorale, telles que l'analyse des vaisseaux tumoraux en échographie-doppler, la diffusion optimisée IVIM , la perfusion quantitative T1 puis à la technique de radiomique utilisée. Nous avons obtenu les images destinées à la recherche à partir d'une cohorte de 200 patients atteints de masses orbitaires avec une preuve histologique obtenue à la Fondation Ophtalmologique Adolphe de Rothschild qui est un centre expert en chirurgie orbito-palpébrale. Ces patients ont été inclus dans trois cohortes prospectives, une échographique et deux IRM. La démarche de validation des biomarqueurs préconisée par l'Alliance QIBA (Quantitative Imaging Biomarkers Alliance), destinée à unir les chercheurs, les professionnels de santé et l'industrie pour améliorer les techniques d'imagerie quantitative et l'utilisation de biomarqueurs en pratique clinique et dans les projets de recherche, est une première étape particulièrement importante avant l'utilisation des techniques et des biomarqueurs en pratique clinique courante et en recherche. Dans le cadre de ce travail de thèse, mes travaux d'imagerie m'ont permis de réaliser une partie des étapes de validation requises, en échographie-Doppler avec l'utilisation de paramètres vasculaires reflétant l'angiogenèse tumorale, en IVIM avec la validation de l'ADC et du D issu de l'IVIM comme biomarqueurs robustes et reproductibles, et en perfusion T1 où j'ai montré l'importance de l'utilisation d'un modèle pharmacocinétique adapté à l'étude de l'orbite et des masses orbitaires. Le développement de nouvelles techniques diagnostiques est un processus long et complexe ; nécessitant la validation technique dans les conditions cliniques permettant d'étudier les artéfacts, les limites et la variabilité lors de l'utilisation chez des patients. Les limites de ces techniques avancées doivent être prises en compte pour toute analyse quantitative de l'image, dont la valeur du paramètre mesuré ne sera plus alors le reflet des seules caractéristiques biologiques et histologiques des tissus mais aussi de contingences techniques. Cela est particulièrement important lors de l'obtention de données quantitatives qui pourront être utilisées comme biomarqueurs en pratique clinique, pour le diagnostic, pronostic ou suivi des patients, ou lors de projets de recherche. Quoi qu'il en soit, ces techniques d'imagerie fonctionnelle semblent prometteuses pour la caractérisation des masses orbitaires et permettront d'élaborer des algorithmes décisionnels afin d'améliorer leur diagnostic, de diminuer le recours à des prélèvements invasifs, d'avoir un suivi précis et régulier et d'adapter les traitements. De même, l'aide de techniques biostatistiques avancées telles que la radiomique promettent également une révolution en terme d'aide au diagnostic et de pronostic en identifiant des biomarqueurs inaccessibles à l'oeil humain et en améliorant et en complétant nos capacités cliniques.Orbital masses make up a heterogeneous group of lesions, with very varied localizations and etiologies, and constitute a diagnostic clinical challenge. Their clinical presentation is evocative, but not specific. Orbital imaging therefore plays a major role in the diagnostic process. It makes it possible to specify the location of the lesion, its characteristics, its impact on orbital components. It assesses its extension and allows a diagnosis of probability but no certainty. The development of imaging techniques and advanced bioinformatics analysis, allowing a more detailed approach to tumour characterization, is therefore particularly promising and could make it possible to adapt the management and in particular to avoid recourse to invasive sampling in the event of benign or low progressive lesions. In this thesis work, we looked at the validation steps of different imaging techniques used for tumour characterization, such as analysis of the tumour vessels in ultrasound-doppler, optimized IVIM diffusion, Dynamic-Contrast-Enhanced MRI followed by the radiomics technique used. The research images were obtained from a cohort of 200 orbital mass patients with histological evidence obtained at the Adolphe de Rothschild Ophthalmological Foundation which is an expert center for orbito palpebral surgery. These patients were included in three prospective cohorts, one using ultrasound and two using MRI. The QIBA (Qantitative Imaging Biomarkers Alliance) approach to biomarker validation, which aims to unite researchers, health professionals and industry to improve quantitative imaging techniques and the use of biomarkers in clinical practice and research projects, is a particularly important first step before the use of techniques and biomarkers in routine clinical practice and research projects. As part of this thesis work, my imaging work allowed me to carry out part of the required validation steps, in ultrasonography-Doppler with the use of vascular parameters reflecting tumor angiogenesis, in IVIM with the validation of ADC and D derived from IVIM as robust and reproducible biomarkers, and in DCE imaging where we showed the importance of using a pharmacokinetic model adapted to orbit and orbital mass studies. The development of new diagnostic techniques is a long and complex process, requiring technical validation under clinical conditions to study artifacts, limitations and variability in patient use. The limits of these advanced techniques must be taken into account for any quantitative analysis of the image, whose value of the measured parameter will then no longer reflect only biological and histological characteristics of the tissues but also technical contingencies. This is particularly important when obtaining quantitative data that can be used as biomarkers in clinical practice, for the diagnosis, prognosis or follow-up of patients, or in research projects. In any case, these functional imaging techniques seem promising for the characterization of orbital masses and will allow the development of decisional algorithms to improve their diagnosis, reduce the use of invasive specimens, have a precise and regular follow-up and adapt treatments. Similarly, the use of advanced biostatistical techniques such as radiomics also promises a revolution in diagnostic and prognostic support by identifying biomarkers inaccessible to the human eye and improving and complementing our clinical capabilities

Congenital Achiasma

In evaluating a 3-month-old boy with horizontal nystagmus, brain MRI revealed absence of the optic chiasm. The remainder of the brain was normal in appearance. Achiasma was confirmed with diffusion tensor imaging and best visualized with optimized probabilistic-based tractography

Abnormal MRI findings of the orbital or visual pathways in patients with severe COVID-19: Observations from the French multicenter COVID-19 cohort

OBJECTIVES: COVID-19 is a multisystemic disease. Ophthalmological abnormalities are relatively rare among COVID-19-infected patients. The aim of our study was to report orbital and visual pathways MRI findings in a nationwide multicenter cohort of patients with severe COVID-19. METHODS: This IRB-approved retrospective multi-center study included participants presenting with severe COVID-19, who underwent brain MRI from March 4(th) to May 1(st) 2020. Two neuroradiologists (“blinded”), blinded to all data, individually analyzed morphological MRIs focusing on the orbits and the visual pathways. A second consensus reading session was performed in the case of disagreement between both readers. Clinical and ophthalmological data were compared to MRI findings. Descriptive statistical analysis and interobserver agreement for MRI reading using non-weighted Cohen kappa statistics were performed. RESULTS: 129 participants (43 [33%] women and 86 [67%] men, mean age 63 ± 14 years) were included in the study. 17/129 (13%) patients had abnormal MRI findings of the orbit or visual pathways. 11/17 (65%) patients had a FLAIR-WI hyperintense optic disc. 6/17 (35%) patients had abnormal signal of at least one of the visual pathway structures: 6/6 (100%) of the optic nerve, 1/6 (17%) of the optic chiasm, 2/6 (33%) of the optic tract and 1/6 (17%) of the optic radiations. CONCLUSIONS: Our study showed that a substantial number of patients with severe COVID-19 presented with abnormal MRI findings of the orbit or visual pathways, which might lead to potentially severe visual impairment

Artificial intelligence in diagnostic and interventional radiology: Where are we now?

International audienceThe emergence of massively parallel yet affordable computing devices has been a game changer for research in the field of artificial intelligence (AI). In addition, dramatic investment from the web giants has fostered the development of a high-quality software stack. Going forward, the combination of faster computers with dedicated software libraries and the widespread availability of data has opened the door to more flexibility in the design of AI models. Radiomics is a process used to discover new imaging biomarkers that has multiple applications in radiology and can be used in conjunction with AI. AI can be used throughout the various processes of diagnostic imaging, including data acquisition, reconstruction, analysis and reporting. Today, the concept of "AI-augmented" radiologists is preferred to the theory of the replacement of radiologists by AI in many indications. Current evidence bolsters the assumption that AI-assisted radiologists work better and faster. Interventional radiology becomes a data-rich specialty where the entire procedure is fully recorded in a standardized DICOM format and accessible via standard picture archiving and communication systems. No other interventional specialty can bolster such readiness. In this setting, interventional radiology could lead the development of AI-powered applications in the broader interventional community. This article provides an update on the current status of radiomics and AI research, analyzes upcoming challenges and also discusses the main applications in AI in interventional radiology to help radiologists better understand and criticize articles reporting AI in medical imaging

A Magnetic Resonance Imaging Radiomics Signature to Distinguish Benign From Malignant Orbital Lesions

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Relationship between watershed infarcts and recent intra plaque haemorrhage in carotid atherosclerotic plaque.

Watershed infarcts (WSI) are thought to result from hemodynamic mechanism, but studies have suggested that microemboli from unstable carotid plaques may distribute preferentially in watershed areas, i.e., between two cerebral arterial territories. Intraplaque haemorrhage (IPH) is an emerging marker of plaque instability and microembolic activity. We assessed the association between WSI and IPH in patients with recently symptomatic moderate carotid stenosis.We selected 65 patients with symptomatic moderate (median NASCET degree of stenosis = 31%) carotid stenosis and brain infarct on Diffusion-Weighted Imaging (DWI) on Magnetic Resonance Imaging (MRI) from a multicentre prospective study. Fourteen (22%) had WSI (cortical, n = 8; internal, n = 4; cortical and internal, n = 2). Patients with WSI were more likely to have IPH than those without WSI although the difference was not significant (50% vs. 31%, OR = 2.19; 95% CI, 0.66-7.29; P = 0.20). After adjustment for degree of stenosis, age and gender, the results remained unchanged.About one in fifth of brain infarcts occurring in patients with moderate carotid stenosis were distributed in watershed areas. Albeit not significant, an association between IPH--more generally plaque component--and WSI, still remains possible

Intravoxel incoherent motion (IVIM) 3 T MRI for orbital lesion characterization

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