47 research outputs found

    Automated Measurement of Vascular Calcification in Femoral Endarterectomy Patients Using Deep Learning

    Full text link
    Atherosclerosis, a chronic inflammatory disease affecting the large arteries, presents a global health risk. Accurate analysis of diagnostic images, like computed tomographic angiograms (CTAs), is essential for staging and monitoring the progression of atherosclerosis-related conditions, including peripheral arterial disease (PAD). However, manual analysis of CTA images is time-consuming and tedious. To address this limitation, we employed a deep learning model to segment the vascular system in CTA images of PAD patients undergoing femoral endarterectomy surgery and to measure vascular calcification from the left renal artery to the patella. Utilizing proprietary CTA images of 27 patients undergoing femoral endarterectomy surgery provided by Prisma Health Midlands, we developed a Deep Neural Network (DNN) model to first segment the arterial system, starting from the descending aorta to the patella, and second, to provide a metric of arterial calcification. Our designed DNN achieved 83.4% average Dice accuracy in segmenting arteries from aorta to patella, advancing the state-of-the-art by 0.8%. Furthermore, our work is the first to present a robust statistical analysis of automated calcification measurement in the lower extremities using deep learning, attaining a Mean Absolute Percentage Error (MAPE) of 9.5% and a correlation coefficient of 0.978 between automated and manual calcification scores. These findings underscore the potential of deep learning techniques as a rapid and accurate tool for medical professionals to assess calcification in the abdominal aorta and its branches above the patella. The developed DNN model and related documentation in this project are available at GitHub page at https://github.com/pip-alireza/DeepCalcScoring.Comment: Published in MDPI Diagnostic journal, the code can be accessed via the GitHub link in the pape

    A fully automatic method for vascular tortuosity feature extraction in the supra-aortic region: unraveling possibilities in stroke treatment planning

    Get PDF
    Vascular tortuosity of supra-aortic vessels is widely considered one of the main reasons for failure and delays in endovascular treatment of large vessel occlusion in patients with acute ischemic stroke. Characterization of tortuosity is a challenging task due to the lack of objective, robust and effective analysis tools. We present a fully automatic method for arterial segmentation, vessel labelling and tortuosity feature extraction applied to the supra-aortic region. A sample of 566 computed tomography angiography scans from acute ischemic stroke patients (aged 74.8 ± 12.9, 51.0% females) were used for training, validation and testing of a segmentation module based on a U-Net architecture (162 cases) and a vessel labelling module powered by a graph U-Net (566 cases). Successively, 30 cases were processed for testing of a tortuosity feature extraction module. Measurements obtained through automatic processing were compared to manual annotations from two observers for a thorough validation of the method. The proposed feature extraction method presented similar performance to the inter-rater variability observed in the measurement of 33 geometrical and morphological features of the arterial anatomy in the supra-aortic region. This system will contribute to the development of more complex models to advance the treatment of stroke by adding immediate automation, objectivity, repeatability and robustness to the vascular tortuosity characterization of patients

    Improved Image Guidance in TACE Procedures

    Get PDF
    Purpose of the work in this thesis is to improve the image guidance in TACE procedures. More specifically, we intend to develop and evaluate technology that permits dynamic roadmapping based on a 3D model of the liver vasculature

    Multi-stage learning for segmentation of aortic dissections using a prior aortic anatomy simplification

    Get PDF
    Aortic dissection (AD) is a life-threatening cardiovascular disease with a high mortality rate. The accurate and generalized 3-D reconstruction of AD from CT-angiography can effectively assist clinical procedures and surgery plans, however, is clinically unavaliable due to the lacking of efficient tools. In this study, we presented a novel multi-stage segmentation framework for type B AD to extract true lumen (TL), false lumen (FL) and all branches (BR) as different classes. Two cascaded neural networks were used to segment the aortic trunk and branches and to separate the dual lumen, respectively. An aortic straightening method was designed based on the prior vascular anatomy of AD, simplifying the curved aortic shape before the second network. The straightening-based method achieved the mean Dice scores of 0.96, 0.95 and 0.89 for TL, FL, and BR on a multi-center dataset involving 120 patients, outperforming the end-to-end multi-class methods and the multi-stage methods without straightening on the dual-lumen segmentation, even using different network architectures. Both the global volumetric features of the aorta and the local characteristics of the primary tear could be better identified and quantified based on the straightening. Comparing to previous deep learning methods dealing with AD segmentations, the proposed framework presented advantages in segmentation accuracy

    Analytical approaches for the segmentation of the zebrafish brain vasculature

    Get PDF
    With advancements in imaging techniques, data visualization allows new insights into fundamental biological processes of development and disease. However, although biomedical science is heavily reliant on imaging data, interpretation of datasets is still often based on subjective visual assessment rather than rigorous quantitation. This overview presents steps to validate image processing and segmentation using the zebrafish brain vasculature data acquired with light sheet fluorescence microscopy as a use case. Blood vessels are of particular interest to both medical and biomedical science. Specific image enhancement filters have been developed that enhance blood vessels in imaging data prior to segmentation. Using the Sato enhancement filter as an example, we discuss how filter application can be evaluated and optimized. Approaches from the medical field such as simulated, experimental, and augmented datasets can be used to gain the most out of the data at hand. Using such datasets, we provide an overview of how biologists and data analysts can assess the accuracy, sensitivity, and robustness of their segmentation approaches that allow extraction of objects from images. Importantly, even after optimization and testing of a segmentation workflow (e.g., from a particular reporter line to another or between immunostaining processes), its generalizability is often limited, and this can be tested using double-transgenic reporter lines. Lastly, due to the increasing importance of deep learning networks, a comparative approach can be adopted to study their applicability to biological datasets. In summary, we present a broad methodological overview ranging from image enhancement to segmentation with a mixed approach of experimental, simulated, and augmented datasets to assess and validate vascular segmentation using the zebrafish brain vasculature as an example. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC

    Inferring Geodesic Cerebrovascular Graphs: Image Processing, Topological Alignment and Biomarkers Extraction

    Get PDF
    A vectorial representation of the vascular network that embodies quantitative features - location, direction, scale, and bifurcations - has many potential neuro-vascular applications. Patient-specific models support computer-assisted surgical procedures in neurovascular interventions, while analyses on multiple subjects are essential for group-level studies on which clinical prediction and therapeutic inference ultimately depend. This first motivated the development of a variety of methods to segment the cerebrovascular system. Nonetheless, a number of limitations, ranging from data-driven inhomogeneities, the anatomical intra- and inter-subject variability, the lack of exhaustive ground-truth, the need for operator-dependent processing pipelines, and the highly non-linear vascular domain, still make the automatic inference of the cerebrovascular topology an open problem. In this thesis, brain vessels’ topology is inferred by focusing on their connectedness. With a novel framework, the brain vasculature is recovered from 3D angiographies by solving a connectivity-optimised anisotropic level-set over a voxel-wise tensor field representing the orientation of the underlying vasculature. Assuming vessels joining by minimal paths, a connectivity paradigm is formulated to automatically determine the vascular topology as an over-connected geodesic graph. Ultimately, deep-brain vascular structures are extracted with geodesic minimum spanning trees. The inferred topologies are then aligned with similar ones for labelling and propagating information over a non-linear vectorial domain, where the branching pattern of a set of vessels transcends a subject-specific quantized grid. Using a multi-source embedding of a vascular graph, the pairwise registration of topologies is performed with the state-of-the-art graph matching techniques employed in computer vision. Functional biomarkers are determined over the neurovascular graphs with two complementary approaches. Efficient approximations of blood flow and pressure drop account for autoregulation and compensation mechanisms in the whole network in presence of perturbations, using lumped-parameters analog-equivalents from clinical angiographies. Also, a localised NURBS-based parametrisation of bifurcations is introduced to model fluid-solid interactions by means of hemodynamic simulations using an isogeometric analysis framework, where both geometry and solution profile at the interface share the same homogeneous domain. Experimental results on synthetic and clinical angiographies validated the proposed formulations. Perspectives and future works are discussed for the group-wise alignment of cerebrovascular topologies over a population, towards defining cerebrovascular atlases, and for further topological optimisation strategies and risk prediction models for therapeutic inference. Most of the algorithms presented in this work are available as part of the open-source package VTrails

    Anatomical Modeling of Cerebral Microvascular Structures: Application to Identify Biomarkers of Microstrokes

    Get PDF
    Les rĂ©seaux microvasculaires corticaux sont responsables du transport de l’oxygĂšne et des substrats Ă©nergĂ©tiques vers les neurones. Ces rĂ©seaux rĂ©agissent dynamiquement aux demandes Ă©nergĂ©tiques lors d’une activation neuronale par le biais du couplage neurovasculaire. Afin d’élucider le rĂŽle de la composante microvasculaire dans ce processus de couplage, l’utilisation de la modĂ©lisation in-formatique pourrait se rĂ©vĂ©ler un Ă©lĂ©ment clĂ©. Cependant, la manque de mĂ©thodologies de calcul appropriĂ©es et entiĂšrement automatisĂ©es pour modĂ©liser et caractĂ©riser les rĂ©seaux microvasculaires reste l’un des principaux obstacles. Le dĂ©veloppement d’une solution entiĂšrement automatisĂ©e est donc important pour des explorations plus avancĂ©es, notamment pour quantifier l’impact des mal-formations vasculaires associĂ©es Ă  de nombreuses maladies cĂ©rĂ©brovasculaires. Une observation courante dans l’ensemble des troubles neurovasculaires est la formation de micro-blocages vascu-laires cĂ©rĂ©braux (mAVC) dans les artĂ©rioles pĂ©nĂ©trantes de la surface piale. De rĂ©cents travaux ont dĂ©montrĂ© l’impact de ces Ă©vĂ©nements microscopiques sur la fonction cĂ©rĂ©brale. Par consĂ©quent, il est d’une importance vitale de dĂ©velopper une approche non invasive et comparative pour identifier leur prĂ©sence dans un cadre clinique. Dans cette thĂšse,un pipeline de traitement entiĂšrement automatisĂ© est proposĂ© pour aborder le prob-lĂšme de la modĂ©lisation anatomique microvasculaire. La mĂ©thode de modĂ©lisation consiste en un rĂ©seau de neurones entiĂšrement convolutif pour segmenter les capillaires sanguins, un gĂ©nĂ©rateur de modĂšle de surface 3D et un algorithme de contraction de la gĂ©omĂ©trie pour produire des mod-Ăšles graphiques vasculaires ne comportant pas de connections multiples. Une amĂ©lioration de ce pipeline est dĂ©veloppĂ©e plus tard pour allĂ©ger l’exigence de maillage lors de la phase de reprĂ©sen-tation graphique. Un nouveau schĂ©ma permettant de gĂ©nĂ©rer un modĂšle de graphe est dĂ©veloppĂ© avec des exigences d’entrĂ©e assouplies et permettant de retenir les informations sur les rayons des vaisseaux. Il est inspirĂ© de graphes gĂ©omĂ©triques dĂ©formants construits en respectant les morpholo-gies vasculaires au lieu de maillages de surface. Un mĂ©canisme pour supprimer la structure initiale du graphe Ă  chaque exĂ©cution est implĂ©mentĂ© avec un critĂšre de convergence pour arrĂȘter le pro-cessus. Une phase de raffinement est introduite pour obtenir des modĂšles vasculaires finaux. La modĂ©lisation informatique dĂ©veloppĂ©e est ensuite appliquĂ©e pour simuler les signatures IRM po-tentielles de mAVC, combinant le marquage de spin artĂ©riel (ASL) et l’imagerie multidirectionnelle pondĂ©rĂ©e en diffusion (DWI). L’hypothĂšse est basĂ©e sur des observations rĂ©centes dĂ©montrant une rĂ©orientation radiale de la microvascularisation dans la pĂ©riphĂ©rie du mAVC lors de la rĂ©cupĂ©ra-tion chez la souris. Des lits capillaires synthĂ©tiques, orientĂ©s alĂ©atoirement et radialement, et des angiogrammes de tomographie par cohĂ©rence optique (OCT), acquis dans le cortex de souris (n = 5) avant et aprĂšs l’induction d’une photothrombose ciblĂ©e, sont analysĂ©s. Les graphes vasculaires informatiques sont exploitĂ©s dans un simulateur 3D Monte-Carlo pour caractĂ©riser la rĂ©ponse par rĂ©sonance magnĂ©tique (MR), tout en considĂ©rant les effets des perturbations du champ magnĂ©tique causĂ©es par la dĂ©soxyhĂ©moglobine, et l’advection et la diffusion des spins nuclĂ©aires. Le pipeline graphique proposĂ© est validĂ© sur des angiographies synthĂ©tiques et rĂ©elles acquises avec diffĂ©rentes modalitĂ©s d’imagerie. ComparĂ© Ă  d’autres mĂ©thodes effectuĂ©es dans le milieu de la recherche, les expĂ©riences indiquent que le schĂ©ma proposĂ© produit des taux d’erreur gĂ©omĂ©triques et topologiques amoindris sur divers angiogrammes. L’évaluation confirme Ă©galement l’efficacitĂ© de la mĂ©thode proposĂ©e en fournissant des modĂšles reprĂ©sentatifs qui capturent tous les aspects anatomiques des structures vasculaires. Ensuite, afin de trouver des signatures de mAVC basĂ©es sur le signal IRM, la modĂ©lisation vasculaire proposĂ©e est exploitĂ©e pour quantifier le rapport de perte de signal intravoxel minimal lors de l’application de plusieurs directions de gradient, Ă  des paramĂštres de sĂ©quence variables avec et sans ASL. Avec l’ASL, les rĂ©sultats dĂ©montrent une dif-fĂ©rence significative (p <0,05) entre le signal calculĂ© avant et 3 semaines aprĂšs la photothrombose. La puissance statistique a encore augmentĂ© (p <0,005) en utilisant des angiogrammes capturĂ©s Ă  la semaine suivante. Sans ASL, aucun changement de signal significatif n’est trouvĂ©. Des rapports plus Ă©levĂ©s sont obtenus Ă  des intensitĂ©s de champ magnĂ©tique plus faibles (par exemple, B0 = 3) et une lecture TE plus courte (<16 ms). Cette Ă©tude suggĂšre que les mAVC pourraient ĂȘtre carac-tĂ©risĂ©s par des sĂ©quences ASL-DWI, et fournirait les informations nĂ©cessaires pour les validations expĂ©rimentales postĂ©rieures et les futurs essais comparatifs.----------ABSTRACT Cortical microvascular networks are responsible for carrying the necessary oxygen and energy substrates to our neurons. These networks react to the dynamic energy demands during neuronal activation through the process of neurovascular coupling. A key element in elucidating the role of the microvascular component in the brain is through computational modeling. However, the lack of fully-automated computational frameworks to model and characterize these microvascular net-works remains one of the main obstacles. Developing a fully-automated solution is thus substantial for further explorations, especially to quantify the impact of cerebrovascular malformations associ-ated with many cerebrovascular diseases. A common pathogenic outcome in a set of neurovascular disorders is the formation of microstrokes, i.e., micro occlusions in penetrating arterioles descend-ing from the pial surface. Recent experiments have demonstrated the impact of these microscopic events on brain function. Hence, it is of vital importance to develop a non-invasive and translatable approach to identify their presence in a clinical setting. In this thesis, a fully automatic processing pipeline to address the problem of microvascular anatom-ical modeling is proposed. The modeling scheme consists of a fully-convolutional neural network to segment microvessels, a 3D surface model generator and a geometry contraction algorithm to produce vascular graphical models with a single connected component. An improvement on this pipeline is developed later to alleviate the requirement of water-tight surface meshes as inputs to the graphing phase. The novel graphing scheme works with relaxed input requirements and intrin-sically captures vessel radii information, based on deforming geometric graphs constructed within vascular boundaries instead of surface meshes. A mechanism to decimate the initial graph struc-ture at each run is formulated with a convergence criterion to stop the process. A refinement phase is introduced to obtain final vascular models. The developed computational modeling is then ap-plied to simulate potential MRI signatures of microstrokes, combining arterial spin labeling (ASL) and multi-directional diffusion-weighted imaging (DWI). The hypothesis is driven based on recent observations demonstrating a radial reorientation of microvasculature around the micro-infarction locus during recovery in mice. Synthetic capillary beds, randomly- and radially oriented, and op-tical coherence tomography (OCT) angiograms, acquired in the barrel cortex of mice (n=5) before and after inducing targeted photothrombosis, are analyzed. The computational vascular graphs are exploited within a 3D Monte-Carlo simulator to characterize the magnetic resonance (MR) re-sponse, encompassing the effects of magnetic field perturbations caused by deoxyhemoglobin, and the advection and diffusion of the nuclear spins. The proposed graphing pipeline is validated on both synthetic and real angiograms acquired with different imaging modalities. Compared to other efficient and state-of-the-art graphing schemes, the experiments indicate that the proposed scheme produces the lowest geometric and topological error rates on various angiograms. The evaluation also confirms the efficiency of the proposed scheme in providing representative models that capture all anatomical aspects of vascular struc-tures. Next, searching for MRI-based signatures of microstokes, the proposed vascular modeling is exploited to quantify the minimal intravoxel signal loss ratio when applying multiple gradient di-rections, at varying sequence parameters with and without ASL. With ASL, the results demonstrate a significant difference (p<0.05) between the signal-ratios computed at baseline and 3 weeks after photothrombosis. The statistical power further increased (p<0.005) using angiograms captured at week 4. Without ASL, no reliable signal change is found. Higher ratios with improved significance are achieved at low magnetic field strengths (e.g., at 3 Tesla) and shorter readout TE (<16 ms). This study suggests that microstrokes might be characterized through ASL-DWI sequences, and provides necessary insights for posterior experimental validations, and ultimately, future transla-tional trials
    corecore