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1.
J Histochem Cytochem ; 67(12): 901-918, 2019 12.
Article de Anglais | MEDLINE | ID: mdl-31609157

RÉSUMÉ

There is an important need in immuno-oncology to develop reliable immunohistochemistry (IHC) to assess the expression of CTLA-4+ tumor-infiltrating lymphocytes in human cancers and quantify them with image analysis (IA). We used commercial polyclonal and monoclonal antibodies and characterized three chromogenic cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) assays with suitable specificity and sensitivity for use in formalin-fixed, paraffin-embedded (FFPE) tissues. We found variable numbers of CTLA-4+ lymphocytes in multiple types of cancer and secondary lymphoid organs (SLOs) and other normal human tissues. Combining CTLA-4 with CD3, CD4, or CD8 by immunofluorescence showed that CTLA-4+ lymphocytes in SLOs and tumors were typically CD3+ and CD4+, but not CD8+. Individual lymphocytes expressed CTLA-4 either as primarily granular cytoplasmic staining or as excentric globular deposits. The CTLA-4/FoxP3 (forkhead box P3 protein) duplex IHC demonstrated that CTLA-4+/FoxP3- lymphocytes predominated in the germinal centers of SLOs and tumor tertiary lymphoid structures (TLSs), whereas CTLA-4+/FoxP3+ lymphocytes populated the T-cell zone of SLOs and TLSs, plus tumor stroma. IA scoring was highly comparable with pathologist scoring for CTLA-4 and CTLA-4/FoxP3 assays and a FoxP3 single IHC. Our findings show that CTLA-4 IHC can be used to reliably label lymphocytes in FFPE human tissues, making it possible to investigate the role of CTLA-4 in the tumor microenvironment.


Sujet(s)
Antigène CTLA-4/analyse , Tumeurs/anatomopathologie , Lignée cellulaire tumorale , Facteurs de transcription Forkhead/analyse , Humains , Immunohistochimie/méthodes , Lymphocytes TIL/anatomopathologie , Imagerie optique/méthodes , Microenvironnement tumoral
2.
J Immunother Cancer ; 6(1): 20, 2018 03 06.
Article de Anglais | MEDLINE | ID: mdl-29510739

RÉSUMÉ

BACKGROUND: Immuno-oncology and cancer immunotherapies are areas of intense research. The numbers and locations of CD8+ tumor-infiltrating lymphocytes (TILs) are important measures of the immune response to cancer with prognostic, pharmacodynamic, and predictive potential. We describe the development, validation, and application of advanced image analysis methods to characterize multiple immunohistochemistry-derived CD8 parameters in clinical and nonclinical tumor tissues. METHODS: Commercial resection tumors from nine cancer types, and paired screening/on-drug biopsies of non-small-cell lung carcinoma (NSCLC) patients enrolled in a phase 1/2 clinical trial investigating the PD-L1 antibody therapy durvalumab (NCT01693562), were immunostained for CD8. Additional NCT01693562 samples were immunostained with a CD8/PD-L1 dual immunohistochemistry assay. Whole-slide scanning was performed, tumor regions were annotated by a pathologist, and images were analyzed with customized algorithms using Definiens Developer XD software. Validation of image analysis data used cell-by-cell comparison to pathologist scoring across a range of CD8+ TIL densities of all nine cancers, relying primarily on 95% confidence in having at least moderate agreement regarding Lin concordance correlation coefficient (CCC = 0.88-0.99, CCC_lower = 0.65-0.96). RESULTS: We found substantial variability in CD8+ TILs between individual patients and across the nine types of human cancer. Diffuse large B-cell lymphoma had several-fold more CD8+ TILs than some other cancers. TIL densities were significantly higher in the invasive margin versus tumor center for carcinomas of head and neck, kidney and pancreas, and NSCLC; the reverse was true only for prostate cancer. In paired patient biopsies, there were significantly increased CD8+ TILs 6 weeks after onset of durvalumab therapy (mean of 365 cells/mm2 over baseline; P = 0.009), consistent with immune activation. Image analysis accurately enumerated CD8+ TILs in PD-L1+ regions of lung tumors using the dual assay and also measured elongate CD8+ lymphocytes which constituted a fraction of overall TILs. CONCLUSIONS: Validated image analysis accurately enumerates CD8+ TILs, permitting comparisons of CD8 parameters among tumor regions, individual patients, and cancer types. It also enables the more complex digital solutions needed to better understand cancer immunity, like analysis of multiplex immunohistochemistry and spatial evaluation of the various components comprising the tumor microenvironment. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01693562 . Study code: CD-ON-MEDI4736-1108. Interventional study (ongoing but not currently recruiting). Actual study start date: August 29, 2012. Primary completion date: June 23, 2017 (final data collection date for primary outcome measure).


Sujet(s)
Anticorps monoclonaux/usage thérapeutique , Antinéoplasiques immunologiques/usage thérapeutique , Lymphocytes T CD8+/immunologie , Carcinome pulmonaire non à petites cellules/immunologie , Traitement d'image par ordinateur , Tumeurs du poumon/immunologie , Lymphocytes TIL/immunologie , Adulte , Sujet âgé , Sujet âgé de 80 ans ou plus , Antigène CD274/antagonistes et inhibiteurs , Antigène CD274/immunologie , Carcinome pulmonaire non à petites cellules/traitement médicamenteux , Femelle , Humains , Tumeurs du poumon/traitement médicamenteux , Mâle , Adulte d'âge moyen , Jeune adulte
3.
PLoS One ; 12(4): e0174324, 2017.
Article de Anglais | MEDLINE | ID: mdl-28376110

RÉSUMÉ

Structural analysis of biological membranes is important for understanding cell and sub-cellular organelle function as well as their interaction with the surrounding environment. Imaging of whole cells in three dimension at high spatial resolution remains a significant challenge, particularly for thick cells. Cryo-transmission soft X-ray microscopy (cryo-TXM) has recently gained popularity to image, in 3D, intact thick cells (∼10µm) with details of sub-cellular architecture and organization in near-native state. This paper reports a new tool to segment and quantify structural changes of biological membranes in 3D from cryo-TXM images by tracking an initial 2D contour along the third axis of the microscope, through a multi-scale ridge detection followed by an active contours-based model, with a subsequent refinement along the other two axes. A quantitative metric that assesses the grayscale profiles perpendicular to the membrane surfaces is introduced and shown to be linearly related to the membrane thickness. Our methodology has been validated on synthetic phantoms using realistic microscope properties and structure dimensions, as well as on real cryo-TXM data. Results demonstrate the validity of our algorithms for cryo-TXM data analysis.


Sujet(s)
Membrane cellulaire/ultrastructure , Imagerie tridimensionnelle/méthodes , Microscopie/méthodes , Algorithmes , Lignée cellulaire , Cryoconservation , Humains , Imagerie tridimensionnelle/statistiques et données numériques , Microscopie/statistiques et données numériques , Fantômes en imagerie , Projets pilotes , Logiciel , Rayons X
4.
Eur Heart J Cardiovasc Imaging ; 18(7): 732-741, 2017 Jul 01.
Article de Anglais | MEDLINE | ID: mdl-28329054

RÉSUMÉ

BACKGROUND: While individual cardiac myocytes only have a limited ability to shorten, the heart efficiently pumps a large volume-fraction thanks to a cell organization in a complex 3D fibre structure. Subclinical subtle cardiac structural remodelling is often present before symptoms arise. Understanding and early detection of these subtle changes is crucial for diagnosis and prevention. Additionally, personalized computational modelling requires knowledge on the multi-scale structure of the whole heart and vessels. METHODS AND RESULTS: We developed a rapid acquisition together with visualization and quantification methods of the integrated microstructure of whole in-vitro rodents hearts using synchrotron based X-ray phase-contrast tomography. These images are formed not only by X-ray absorption by the tissue but also by wave propagation phenomena, enhancing structural information, thus allowing to raise tissue contrast to an unprecedented level. We used a (ex-vivo) normal rat heart and fetal rabbit hearts suffering intrauterine growth restriction as a model of subclinical cardiac remodelling to illustrate the strengths and potential of the technique. For comparison, histology and diffusion tensor magnetic resonance imaging was performed. CONCLUSIONS: We have developed a novel, high resolution, image acquisition, and quantification approach to study a whole in-vitro heart at myofibre resolution, providing integrated 3D structural information at microscopic level without any need of tissue slicing and processing. This superior imaging approach opens up new possibilities for a systems approach towards analysing cardiac structure and function, providing rapid acquisition of quantitative microstructure of the heart in a near native state.


Sujet(s)
Système cardiovasculaire/anatomie et histologie , Imagerie par résonance magnétique de diffusion/méthodes , Myocytes cardiaques/ultrastructure , Synchrotrons , Microtomographie aux rayons X/méthodes , Animaux , Simulation numérique , Imagerie tridimensionnelle , Modèles animaux , Lapins , Rats , Rat Sprague-Dawley , Sensibilité et spécificité
5.
Med Image Anal ; 24(1): 52-62, 2015 Aug.
Article de Anglais | MEDLINE | ID: mdl-26073786

RÉSUMÉ

The electrical activation of the heart is a complex physiological process that is essential for the understanding of several cardiac dysfunctions, such as ventricular tachycardia (VT). Nowadays, patient-specific activation times on ventricular chambers can be estimated from electro-anatomical maps, providing crucial information to clinicians for guiding cardiac radio-frequency ablation treatment. However, some relevant electrical pathways such as those of the Purkinje system are very difficult to interpret from these maps due to sparsity of data and the limited spatial resolution of the system. We present here a novel method to estimate these fast electrical pathways from the local activations maps (LATs) obtained from electro-anatomical maps. The location of Purkinje-myocardial junctions (PMJs) is estimated considering them as critical points of a distance map defined by the activation maps, and then minimal cost geodesic paths are computed on the ventricular surface between the detected junctions. Experiments to validate the proposed method have been carried out in simplified and realistic simulated data, showing good performance on recovering the main characteristics of simulated Purkinje networks (e.g. PMJs). A feasibility study with real cases of fascicular VT was also performed, showing promising results.


Sujet(s)
Potentiels d'action/physiologie , Cartographie du potentiel de surface corporelle/méthodes , Ventricules cardiaques/anatomie et histologie , Fibres de Purkinje/anatomie et histologie , Fibres de Purkinje/physiologie , Fonction ventriculaire gauche/physiologie , Algorithmes , Études de faisabilité , Humains , Amélioration d'image/méthodes , Interprétation d'images assistée par ordinateur/méthodes , Reproductibilité des résultats , Sensibilité et spécificité
6.
J R Soc Interface ; 10(84): 20130193, 2013 Jul 06.
Article de Anglais | MEDLINE | ID: mdl-23676893

RÉSUMÉ

One of the relevant phenomenon associated with in-stent restenosis in coronary arteries is an altered haemodynamics in the stented region. Computational fluid dynamics (CFD) offers the possibility to investigate the haemodynamics at a level of detail not always accessible within experimental techniques. CFD can quantify and correlate the local haemodynamics structures which might lead to in-stent restenosis. The aim of this work is to study the fluid dynamics of realistic stented coronary artery models which replicate the complete clinical procedure of stent implantation. Two cases of pathologic left anterior descending coronary arteries with their bifurcations are reconstructed from computed tomography angiography and conventional coronary angiography images. Results of wall shear stress and relative residence time show that the wall regions more prone to the risk of restenosis are located next to stent struts, to the bifurcations and to the stent overlapping zone for both investigated cases. Considering a bulk flow analysis, helical flow structures are generated by the curvature of the zone upstream from the stent and by the bifurcation regions. Helical recirculating microstructures are also visible downstream from the stent struts. This study demonstrates the feasibility to virtually investigate the haemodynamics of patient-specific coronary bifurcation geometries.


Sujet(s)
Biologie informatique/méthodes , Resténose coronaire/physiopathologie , Vaisseaux coronaires/anatomopathologie , Hémodynamique , Modèles cardiovasculaires , Phénomènes biomécaniques , Simulation numérique , Coronarographie , Humains , Modèles anatomiques
7.
IEEE Trans Med Imaging ; 32(9): 1587-99, 2013 Sep.
Article de Anglais | MEDLINE | ID: mdl-23674438

RÉSUMÉ

Anatomical labeling of the cerebral arteries forming the Circle of Willis (CoW) enables inter-subject comparison, which is required for geometric characterization and discovering risk factors associated with cerebrovascular pathologies. We present a method for automated anatomical labeling of the CoW by detecting its main bifurcations. The CoW is modeled as rooted attributed relational graph, with bifurcations as its vertices, whose attributes are characterized as points on a Riemannian manifold. The method is first trained on a set of pre-labeled examples, where it learns the variability of local bifurcation features as well as the variability in the topology. Then, the labeling of the target vasculature is obtained as maximum a posteriori probability (MAP) estimate where the likelihood of labeling individual bifurcations is regularized by the prior structural knowledge of the graph they span. The method was evaluated by cross-validation on 50 subjects, imaged with magnetic resonance angiography, and showed a mean detection accuracy of 95%. In addition, besides providing the MAP, the method can rank the labelings. The proposed method naturally handles anatomical structural variability and is demonstrated to be suitable for labeling arterial segments of the CoW.


Sujet(s)
Cercle artériel du cerveau/anatomie et histologie , Traitement d'image par ordinateur/méthodes , Adulte , Sujet âgé , Algorithmes , Femelle , Humains , Angiographie par résonance magnétique/méthodes , Mâle , Adulte d'âge moyen , Modèles statistiques , Reproductibilité des résultats
8.
Med Eng Phys ; 35(9): 1272-81, 2013 Sep.
Article de Anglais | MEDLINE | ID: mdl-23428836

RÉSUMÉ

Computational simulations of stenting procedures in idealized geometries can only provide general guidelines and their use in the patient-specific planning of percutaneous treatments is inadequate. Conversely, image-based patient-specific tools that are able to realistically simulate different interventional options might facilitate clinical decision-making and provide useful insights on the treatment for each individual patient. The aim of this work is the implementation of a patient-specific model that uses image-based reconstructions of coronary bifurcations and is able to replicate real stenting procedures following clinical indications. Two clinical cases are investigated focusing the attention on the open problems of coronary bifurcations and their main treatment, the provisional side branch approach. Image-based reconstructions are created combining the information from conventional coronary angiography and computed tomography angiography while structural finite element models are implemented to replicate the real procedure performed in the patients. First, numerical results show the biomechanical influence of stents deployment in the coronary bifurcations during and after the procedures. In particular, the straightening of the arterial wall and the influence of two overlapping stents on stress fields are investigated here. Results show that a sensible decrease of the vessel tortuosity occurs after stent implantation and that overlapping devices result in an increased stress state of both the artery and the stents. Lastly, the comparison between numerical and image-based post-stenting configurations proved the reliability of such models while replicating stent deployment in coronary arteries.


Sujet(s)
Vaisseaux coronaires , Analyse des éléments finis , Endoprothèses , Coronarographie , Vaisseaux coronaires/imagerie diagnostique , Humains , Traitement d'image par ordinateur , Plaque d'athérosclérose/imagerie diagnostique , Médecine de précision
9.
Med Phys ; 40(1): 013701, 2013 Jan.
Article de Anglais | MEDLINE | ID: mdl-23298123

RÉSUMÉ

PURPOSE: To generate accurate and realistic models of coronary artery bifurcations before and after percutaneous coronary intervention (PCI), using information from two image modalities. Because bifurcations are regions where atherosclerotic plaque appears frequently and intervention is more challenging, generation of such realistic models could be of high value to predict the risk of restenosis or thrombosis after stent implantation, and to study geometrical and hemodynamical changes. METHODS: Two image modalities have been employed to generate the bifurcation models: computer tomography angiography (CTA) to obtain the 3D trajectory of vessels, and 2D conventional coronary angiography (CCA) to obtain radius information of the vessel lumen, due to its better contrast and image resolution. In addition, CCA can be acquired right before and after the intervention in the operation room; therefore, the combination of CTA and CCA allows the generation of realistic preprocedure and postprocedure models of coronary bifurcations. The method proposed is semiautomatic, based on landmarks manually placed on both image modalities. RESULTS: A comparative study of the models obtained with the proposed method with models manually obtained using only CTA, shows more reliable results when both modalities are used together. The authors show that using preprocedure CTA and postprocedure CCA, realistic postprocedure models can be obtained. Analysis carried out of the Murray's law in all patient bifurcations shows the geometric improvement of PCI in our models, better than using manual models from CTA alone. An experiment using a cardiac phantom also shows the feasibility of the proposed method. CONCLUSIONS: The authors have shown that fusion of CTA and CCA is feasible for realistic generation of coronary bifurcation models before and after PCI. The method proposed is efficient, and relies on minimal user interaction, and therefore is of high value to study geometric and hemodynamic changes of treated patients.


Sujet(s)
Coronarographie/méthodes , Vaisseaux coronaires/imagerie diagnostique , Modèles anatomiques , Vaisseaux coronaires/chirurgie , Humains , Intervention coronarienne percutanée , Fantômes en imagerie
10.
Med Biol Eng Comput ; 51(3): 343-52, 2013 Mar.
Article de Anglais | MEDLINE | ID: mdl-23224794

RÉSUMÉ

Geometrical aneurysm quantification is considered an important topic for the study of aneurysm formation, growth, risk of rupture and also in treatment planning. Usually, quantification involves aneurysm isolation, consisting in the operation of detecting the boundary between the aneurysm dome and its feeding arteries. This operation is sometimes performed manually, but it is a tedious task, subject to user variability. To obtain reproducible measurements, automatic techniques have been proposed. In this paper, we compare different aneurysm isolation techniques, two automatic and one manual-based on a cutting plane. All of them are compared against the results obtained by manual delineations of 26 real cases. We show from the results that automatic methods have good performance, providing results similar to manual methods in average. We also show that automatic methods improve reproducibility compared to direct measurements performed on volume rendering views. Each automatic method presents strengths and weaknesses in particular cases such as small aneurysms, aneurysms with multiple parent vessels or terminal aneurysms, but their reproducibility makes them suitable for robust population studies. Finally, based on this study, we have proposed a criterion that allows to use a combination of the two methods studied and that outperforms each of them individually.


Sujet(s)
Traitement d'image par ordinateur/méthodes , Anévrysme intracrânien/anatomopathologie , Angiographie cérébrale/méthodes , Simulation numérique , Bases de données factuelles , Humains , Anévrysme intracrânien/imagerie diagnostique , Modèles théoriques , Fantômes en imagerie , Reproductibilité des résultats
11.
Comput Methods Programs Biomed ; 108(2): 806-19, 2012 Nov.
Article de Anglais | MEDLINE | ID: mdl-22749086

RÉSUMÉ

Determining whether and how an intracranial aneurysm should be treated is a tough decision that clinicians face everyday. Emerging computational tools could help clinicians analyze clinical data and make these decisions. AngioLab is a single graphical user interface, developed on top of the open source framework GIMIAS, that integrates some of the latest image analysis and computational modeling tools for intracranial aneurysms. Two workflows are available: Advanced Morphological Analysis (AMA) and Endovascular Treatment Planning (ETP). AngioLab has been evaluated by a total of 62 clinicians, who considered the information provided by AngioLab relevant and meaningful. They acknowledged the emerging need of these type of tools and the potential impact they might have on the clinical decision-making process.


Sujet(s)
Anévrysme intracrânien/anatomopathologie , Anévrysme intracrânien/thérapie , Logiciel , Infographie , Humains , Modèles anatomiques , Interface utilisateur
12.
Med Image Anal ; 16(4): 889-903, 2012 May.
Article de Anglais | MEDLINE | ID: mdl-22377655

RÉSUMÉ

The geometry of the carotid siphon has a large variability between subjects, which has prompted its study as a potential geometric risk factor for the onset of vascular pathologies on and off the internal carotid artery (ICA). In this work, we present a methodology for an objective and extensive geometric characterization of carotid siphon parameterized by a set of anatomical landmarks. We introduce a complete and automated characterization pipeline. Starting from the segmentation of vasculature from angiographic image and its centerline extraction, we first identify ICA by characterizing vessel tree bifurcations and training a support vector machine classifier to detect ICA terminal bifurcation. On ICA centerline curve, we detect anatomical landmarks of carotid siphon by modeling it as a sequence of four bends and selecting their centers and interfaces between them. Bends are detected from the trajectory of the curvature vector expressed in the parallel transport frame of the curve. Finally, using the detected landmarks, we characterize the geometry in two complementary ways. First, with a set of local and global geometric features, known to affect hemodynamics. Second, using large deformation diffeomorphic metric curve mapping (LDDMCM) to quantify pairwise shape similarity. We processed 96 images acquired with 3D rotational angiography. ICA identification had a cross-validation success rate of 99%. Automated landmarking was validated by computing limits of agreement with the reference taken to be the locations of the manually placed landmarks averaged across multiple observers. For all but one landmark, either the bias was not statistically significant or the variability was within 50% of the inter-observer one. The subsequently computed values of geometric features and LDDMCM were commensurate to the ones obtained with manual landmarking. The characterization based on pair-wise LDDMCM proved better in classifying the carotid siphon shape classes than the one based on geometric features. The proposed characterization provides a rich description of geometry and is ready to be applied in the search for geometric risk factors of the carotid siphon.


Sujet(s)
Algorithmes , Angiographie/méthodes , Artère carotide interne/imagerie diagnostique , Imagerie tridimensionnelle/méthodes , Reconnaissance automatique des formes/méthodes , Interprétation d'images radiographiques assistée par ordinateur/méthodes , Humains , Amélioration d'image radiographique/méthodes , Reproductibilité des résultats , Sensibilité et spécificité
13.
Article de Anglais | MEDLINE | ID: mdl-22003716

RÉSUMÉ

Automated anatomical labeling of the arteries forming the Circle of Willis is of great interest as facilitates inter-subject comparison required to discover geometric risk factors for the development of vascular pathologies. In this paper, we present a method for anatomical labeling of vessels forming anterior part of the Circle of Willis by detecting the five main vessel bifurcations. The method is first trained on a set of pre-labeled examples, where it learns local bifurcation features as well as global variation in the anatomy of the extracted vascular trees. Then the labeling of the target vascular tree is formulated as maximum a posteriori solution where the classifications of individual bifurcations are regularized by the prior learned knowledge of the tree they span. The method was evaluated by cross-validation on 30 subjects, which showed the vascular trees were correctly anatomically labeled in 90% of cases. The proposed method can naturally handle anatomical variations and is shown to be suitable for labeling arterial segments of Circle of Willis.


Sujet(s)
Cercle artériel du cerveau/anatomie et histologie , Traitement d'image par ordinateur/méthodes , Algorithmes , Artère carotide interne/anatomopathologie , Circulation cérébrovasculaire , Cercle artériel du cerveau/anatomopathologie , Humains , Imagerie tridimensionnelle , Fonctions de vraisemblance , Modèles anatomiques , Modèles statistiques , Probabilité , Reproductibilité des résultats
14.
Med Image Comput Comput Assist Interv ; 14(Pt 3): 395-402, 2011.
Article de Anglais | MEDLINE | ID: mdl-22003724

RÉSUMÉ

Coronary artery bifurcations are regions where the atherosclerotic plaque appears more frequently and where the percutaneous treatment is more challenging. To analyze these important vascular regions, in this paper is proposed a method for the extraction of realistic 3D models of coronary bifurcations combining information from pre operative computer tomography angiography (CTA) to obtain the 3D structure of the vessels and pre and post operative conventional coronary angiography (CCA) to extract a more accurate estimation of the lumen radius before and after stenting. The method proposed is semiautomatic, starting from a set of user defined landmarks, and has been successfully applied to data from five patients that underwent endovascular treatment in a coronary bifurcation. The results obtained are satisfactory by visual inspection and in comparison with manual measurements.


Sujet(s)
Coronarographie/méthodes , Vaisseaux coronaires/anatomopathologie , Traitement d'image par ordinateur/méthodes , Imagerie tridimensionnelle/méthodes , Tomodensitométrie/méthodes , Algorithmes , Imagerie diagnostique/méthodes , Humains , Modèles statistiques , Analyse multifactorielle , Reconnaissance automatique des formes , Fantômes en imagerie , Reproductibilité des résultats
15.
Med Phys ; 38(5): 2439-49, 2011 May.
Article de Anglais | MEDLINE | ID: mdl-21776779

RÉSUMÉ

PURPOSE: Morphological descriptors are practical and essential biomarkers for diagnosis and treatment selection for intracranial aneurysm management according to the current guidelines in use. Nevertheless, relatively little work has been dedicated to improve the three-dimensional quantification of aneurysmal morphology, to automate the analysis, and hence to reduce the inherent intra and interobserver variability of manual analysis. In this paper we propose a methodology for the automated isolation and morphological quantification of saccular intracranial aneurysms based on a 3D representation of the vascular anatomy. METHOD: This methodology is based on the analysis of the vasculature skeleton's topology and the subsequent application of concepts from deformable cylinders. These are expanded inside the parent vessel to identify different regions and discriminate the aneurysm sac from the parent vessel wall. The method renders as output the surface representation of the isolated aneurysm sac, which can then be quantified automatically. The proposed method provides the means for identifying the aneurysm neck in a deterministic way. The results obtained by the method were assessed in two ways: they were compared to manual measurements obtained by three independent clinicians as normally done during diagnosis and to automated measurements from manually isolated aneurysms by three independent operators, nonclinicians, experts in vascular image analysis. All the measurements were obtained using in-house tools. The results were qualitatively and quantitatively compared for a set of the saccular intracranial aneurysms (n = 26). RESULTS: Measurements performed on a synthetic phantom showed that the automated measurements obtained from manually isolated aneurysms where the most accurate. The differences between the measurements obtained by the clinicians and the manually isolated sacs were statistically significant (neck width: p <0.001, sac height: p = 0.002). When comparing clinicians' measurements to automatically isolated sacs, only the differences for the neck width were significant (neck width: p <0.001, sac height: p = 0.95). However, the correlation and agreement between the measurements obtained from manually and automatically isolated aneurysms for the neck width: p = 0.43 and sac height: p = 0.95 where found. CONCLUSIONS: The proposed method allows the automated isolation of intracranial aneurysms, eliminating the interobserver variability. In average, the computational cost of the automated method (2 min 36 s) was similar to the time required by a manual operator (measurement by clinicians: 2 min 51 s, manual isolation: 2 min 21 s) but eliminating human interaction. The automated measurements are irrespective of the viewing angle, eliminating any bias or difference between the observer criteria. Finally, the qualitative assessment of the results showed acceptable agreement between manually and automatically isolated aneurysms.


Sujet(s)
Algorithmes , Angiographie cérébrale/méthodes , Imagerie tridimensionnelle/méthodes , Anévrysme intracrânien/imagerie diagnostique , Reconnaissance automatique des formes/méthodes , Interprétation d'images radiographiques assistée par ordinateur/méthodes , Intelligence artificielle , Humains , Amélioration d'image radiographique/méthodes , Reproductibilité des résultats , Sensibilité et spécificité
16.
IEEE Trans Med Imaging ; 30(10): 1863-76, 2011 Oct.
Article de Anglais | MEDLINE | ID: mdl-21622072

RÉSUMÉ

A new automatic approach for saccular intracranial aneurysm isolation is proposed in this work. Due to the inter- and intra-observer variability in manual delineation of the aneurysm neck, a definition based on a minimum cost path around the aneurysm sac is proposed that copes with this variability and is able to make consistent measurements along different data sets, as well as to automate and speedup the analysis of cerebral aneurysms. The method is based on the computation of a minimal path along a scalar field obtained on the vessel surface, to find the aneurysm neck in a robust and fast manner. The computation of the scalar field on the surface is obtained using a fast marching approach with a speed function based on the exponential of the distance from the centerline bifurcation between the aneurysm dome and the parent vessels. In order to assure a correct topology of the aneurysm sac, the neck computation is constrained to a region defined by a surface Voronoi diagram obtained from the branches of the vessel centerline. We validate this method comparing our results in 26 real cases with manual aneurysm isolation obtained using a cut-plane, and also with results obtained using manual delineations from three different observers by comparing typical morphological measures.


Sujet(s)
Angiographie cérébrale/méthodes , Traitement d'image par ordinateur/méthodes , Anévrysme intracrânien/anatomopathologie , Algorithmes , Bases de données factuelles , Humains , Reproductibilité des résultats
17.
Article de Anglais | MEDLINE | ID: mdl-21096256

RÉSUMÉ

Geometric characteristics and arrangement of the cerebral vessels are assumed to be related to the development of vascular diseases. Identifying anatomical segments and bifurcations of the cerebral vasculature allows the comparison of these characteristics across and within subjects. In this paper, we focus on the automatic identification of internal carotid artery (ICA) from 3D rotational angiographic images. The steps of the proposed method are the following: Arterial vascular tree is first segmented and centerlines are computed. From a set of centerlines, vascular tree topology is constructed and its bifurcations geometrically characterized. Finally, ICA terminal bifurcation is detected, which enables ICA identification. To detect ICA terminal bifurcation, a support vector machine classifier is trained. We processed 82 images to obtain 274 feature vectors of bifurcations around the ICA. 10×5-fold cross-validation showed an average accuracy of 99.6%, with 99.5% specificity and 100% sensitivity. The two most discriminating bifurcation features were: radius ratio between the smaller branch and its parent vessel, and the long-axis component of the smaller branch vector.


Sujet(s)
Artère carotide interne/anatomie et histologie , Coronarographie/méthodes , Imagerie tridimensionnelle/méthodes , Rotation , Algorithmes , Automatisation , Humains , Reproductibilité des résultats
18.
Article de Anglais | MEDLINE | ID: mdl-21097326

RÉSUMÉ

Realistic models of the muscle fibers in the myocardium improve the understanding and simulation of the bio-mechanical behavior of the heart. Since Diffusion Tensor Imaging (DTI) allows to visualize the fiber structures in the tissues, this modality can be used to build fiber models. In this paper, we propose an automatic method for the analysis of the helix and transverse angles between the fibers and the myocardial wall. It computes automatically the theoretical value of these angles (according to a mathematical model described in the literature) at each voxel of the image as well as the real value based on the DTI acquisition. In addition, new parameters of the mathematical model can be estimated based on our approach to personalize the model for specific data-sets.


Sujet(s)
Imagerie par tenseur de diffusion/méthodes , Coeur/anatomie et histologie , Coeur/physiologie , Fibres musculaires squelettiques/physiologie , Animaux , Chiens , Ventricules cardiaques/anatomie et histologie , Myocarde
19.
Article de Anglais | MEDLINE | ID: mdl-21095707

RÉSUMÉ

Until today, geometrical descriptors of intracranial aneurysms are largely used for diagnosis and treatment selection. Nevertheless, relatively little work has been devoted to automatize these measurements. In this work we propose a methodology for the automated isolation and quantification from vascular segmentation. The proposed methodology is based on skeleton topology analysis, geometrical analysis and deformable models to isolate, automatically, the aneurysm dome as well as its geometrical characteristics. The accuracy of this methodology when compared to manually isolated aneurysms is evaluated in 10 patient-specific vascular geometries. Good correspondence is observed between manual and automated results.


Sujet(s)
Anévrysme intracrânien/diagnostic , Anévrysme intracrânien/physiopathologie , Algorithmes , Anévrysme , Automatisation , Simulation numérique , Imagerie diagnostique/méthodes , Humains , Traitement d'image par ordinateur , Modèles anatomiques , Modèles théoriques , Reproductibilité des résultats , Traitement du signal assisté par ordinateur , Logiciel
20.
Neuroimage ; 50(1): 27-39, 2010 Mar.
Article de Anglais | MEDLINE | ID: mdl-20006710

RÉSUMÉ

In this work, we propose to use fiber tracking in order to analyze and quantify the state of the pyramidal tracts in patients affected by tumors. We introduce a framework that includes an automatic method to obtain the fibers involved in the pyramidal tract of any subject, in order to compare robustly fiber bundles affected by tumors with healthy fiber tracts from control subjects and also to quantify the relative state of degeneration between the fiber tracts in the two hemispheres of the same patient. The comparative analyses proposed in our methodology are based on a new set of measures on the pyramidal tract, which take into account intrinsic properties of the fibers involved in the bundle as well as the similarity with the pyramidal tract of a standard healthy subject, modeled as the average of a set of controls. In order to perform better comparison studies and to take into account more information of the whole bundle, a mapping technique is used to represent the fiber tracts in 2D. Here, we show a set of experiments using 5 tumor patients and 10 control subjects, including pre- and post-operative studies in patients that have been treated with partial or total tumor resection. The results obtained indicate the usefulness of the method showing good overall performance. A reproducibility study using several acquisitions of the same patient is also presented to validate the techniques employed.


Sujet(s)
Cartographie cérébrale/méthodes , Tumeurs du cerveau/physiopathologie , Imagerie par tenseur de diffusion/méthodes , Tractus pyramidaux/physiopathologie , Traitement du signal assisté par ordinateur , Adulte , Sujet âgé , Algorithmes , Automatisation , Tumeurs du cerveau/chirurgie , Simulation numérique , Humains , Adulte d'âge moyen , Modèles neurologiques , Reproductibilité des résultats , Jeune adulte
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