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Author |
Aura Hernandez-Sabate |
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Title |
Exploring Arterial Dynamics and Structures in IntraVascular Ultrasound Sequences |
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2009 |
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PhD Thesis, Universitat Autonoma de Barcelona-CVC |
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Cardiovascular diseases are a leading cause of death in developed countries. Most of them are caused by arterial (specially coronary) diseases, mainly caused by plaque accumulation. Such pathology narrows blood flow (stenosis) and affects artery bio- mechanical elastic properties (atherosclerosis). In the last decades, IntraVascular UltraSound (IVUS) has become a usual imaging technique for the diagnosis and follow up of arterial diseases. IVUS is a catheter-based imaging technique which shows a sequence of cross sections of the artery under study. Inspection of a single image gives information about the percentage of stenosis. Meanwhile, inspection of longitudinal views provides information about artery bio-mechanical properties, which can prevent a fatal outcome of the cardiovascular disease. On one hand, dynamics of arteries (due to heart pumping among others) is a major artifact for exploring tissue bio-mechanical properties. On the other one, manual stenosis measurements require a manual tracing of vessel borders, which is a time-consuming task and might suffer from inter-observer variations. This PhD thesis proposes several image processing tools for exploring vessel dy- namics and structures. We present a physics-based model to extract, analyze and correct vessel in-plane rigid dynamics and to retrieve cardiac phase. Furthermore, we introduce a deterministic-statistical method for automatic vessel borders detection. In particular, we address adventitia layer segmentation. An accurate validation pro- tocol to ensure reliable clinical applicability of the methods is a crucial step in any proposal of an algorithm. In this thesis we take special care in designing a valida- tion protocol for each approach proposed and we contribute to the in vivo dynamics validation with a quantitative and objective score to measure the amount of motion suppressed. |
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Ph.D. thesis |
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Ediciones Graficas Rey |
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Debora Gil |
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978-84-937261-6-4 |
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IAM; |
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IAM @ iam @ Her2009 |
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1543 |
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Author |
Aura Hernandez-Sabate |
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Title |
Automatic adventitia segmentation in IntraVascular UltraSound images |
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Report |
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2005 |
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CVC Technical Report |
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85 |
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A usual tool in cardiac disease diagnosis is vessel plaque assessment by analysis of IVUS sequences. Manual detection of lumen-intima, intima-media and media-adventitia vessel borders is the main activity of physicians in the process of plaque quantification. Large variety in vessel border descriptors, as well as, shades, artifacts and blurred response due to ultrasound physical properties troubles automated media-adventitia segmentation. This experimental work presents a solution to such a complex problem. The process blends advanced anisotropic filtering operators and statistic classification techniques, achieving an efficient vessel border modelling strategy. First of all, we introduce the theoretic base of the method. After that, we show the steps of the algorithm, validating the method with statistics that show that the media-adventitia border detection achieves an accuracy in the range of inter-observer variability regardless of plaque nature, vessel geometry and incomplete vessel borders. Finally, we present a little Matlab application to the automatic media-adventitia border. |
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Master's thesis |
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08193 Bellaterra, Barcelona (Spain) |
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IAM; |
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IAM @ iam @ Her2005 |
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1544 |
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Author |
Aura Hernandez-Sabate; Debora Gil; Petia Radeva |
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Title |
A Deterministic-Statistical Strategy for Adventitia Segmentation in IVUS images |
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Report |
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2005 |
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CVC Technical Report |
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89 |
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A useful tool for some specific studies in cardiac disease diagnosis is vessel plaque assessment by analysis of IVUS sequences. Manual detection of luminal (inner) and media-adventitia (external) vessel borders is the main activity of physicians in the process of lumen narrowing (plaque) quantification. Difficult definition of vessel border descriptors, as well as, shades, artifacts and blurred signal response due to ultrasound physical properties troubles automated adventitia segmentation. In order to efficiently approach such a complex problem, we propose blending advanced anisotropic filtering operators and statistical classification techniques into a vessel border modelling strategy. Our systematic statistical analysis shows that the reported adventitia detection achieves an accuracy in the range of inter-observer variability regardless of plaque nature, vessel geometry and incomplete vessel borders. |
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IAM; MILAB |
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IAM @ iam @ HGR2005a |
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1548 |
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Author |
Aura Hernandez-Sabate; Debora Gil; Petia Radeva |
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Title |
On the usefulness of supervised learning for vessel border detection in IntraVascular Imaging |
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Conference Article |
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2005 |
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Proceeding of the 2005 conference on Artificial Intelligence Research and Development |
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67-74 |
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Keywords |
classification; vessel border modelling; IVUS |
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IntraVascular UltraSound (IVUS) imaging is a useful tool in diagnosis of cardiac diseases since sequences completely show the morphology of coronary vessels. Vessel borders detection, especially the external adventitia layer, plays a central role in morphological measures and, thus, their segmentation feeds development of medical imaging techniques. Deterministic approaches fail to yield optimal results due to the large amount of IVUS artifacts and vessel borders descriptors. We propose using classification techniques to learn the set of descriptors and parameters that best detect vessel borders. Statistical hypothesis test on the error between automated detections and manually traced borders by 4 experts show that our detections keep within inter-observer variability. |
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IOS Press |
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Amsterdam, The Netherlands |
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IAM;MILAB |
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IAM @ iam @ HGR2005c |
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1549 |
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Author |
Aura Hernandez-Sabate; Debora Gil; Josefina Mauri; Petia Radeva |
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Title |
Reducing cardiac motion in IVUS sequences |
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Conference Article |
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2006 |
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Proceeding of Computers in Cardiology |
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33 |
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685-688 |
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Cardiac vessel displacement is a main artifact in IVUS sequences. It hinders visualization of the main structures in an appropriate orientation and alignment and affects extracting vessel measurements. In this paper, we present a novel approach for image sequence alignment based on spectral analysis, which removes rigid dynamics, preserving at the same time the vessel geometry. First, we suppress the translation by taking, for each frame, the center of mass of the image as origin of coordinates. In polar coordinates with such point as origin, the rotation appears as a horizontal displacement. The translation induces a phase shift in the Fourier coefficients of two consecutive polar images. We estimate the phase by adjusting a regression plane to the phases of the principal frequencies. Experiments show that the presented strategy suppress cardiac motion regardless of the acquisition device. 1. |
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IAM; MILAB |
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IAM @ iam @ HGM2006a |
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1554 |
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Author |
Ole Larsen; Petia Radeva; Enric Marti |
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Title |
Calculating the Bounds on the Optimal Parameters of Elasticity for a Snake |
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1994 |
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Technical Report |
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Aalborg University |
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Aalborg University, Laboratory of image Analysis. |
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Denmark |
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Aalborg University, Laboratory of image Analysis. |
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MILAB;IAM |
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IAM @ iam @ LRM1994 |
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1560 |
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Author |
Josep Llados; Horst Bunke; Enric Marti |
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Using cyclic string matching to find rotational and reflectional symmetric shapes |
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1996 |
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Dagstuhl Seminar on Modelling and Planning for Sensor–based Intelligent Robot Systems |
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World Scientific |
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Saarbrucken (Germany). |
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R.C. Bolles, H.B.H.N. |
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DAG;IAM |
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IAM @ iam @ LBM1996 |
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1564 |
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Josep Llados; Horst Bunke; Enric Marti |
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Title |
Structural Recognition of hand drawn floor plans |
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1996 |
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VI National Symposium on Pattern Recognition and Image Analysis |
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Rotational Symmetry; Reflectional Symmetry; String Matching. |
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A system to recognize hand drawn architectural drawings in a CAD environment has been deve- loped. In this paper we focus on its high level interpretation module. To interpret a floor plan, the system must identify several building elements, whose description is stored in a library of pat- terns, as well as their spatial relationships. We propose a structural approach based on subgraph isomorphism techniques to obtain a high-level interpretation of the document. The vectorized input document and the patterns to be recognized are represented by attributed graphs. Discrete relaxation techniques (AC4 algorithm) have been applied to develop the matching algorithm. The process has been divided in three steps: node labeling, local consistency and global consistency verification. The hand drawn creation causes disturbed line drawings with several accuracy errors, which must be taken into account. Here we have identified them and the AC4 algorithm has been adapted to manage them. |
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Cordoba |
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IAM @ iam @ LIM1995 |
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1565 |
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Author |
Josep Llados; Jaime Lopez-Krahe; Gemma Sanchez; Enric Marti |
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Interprétation de cartes et plans par mise en correspondance de graphes de attributs |
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2000 |
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12 Congrès Francophone AFRIF–AFIA |
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3 |
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225-234 |
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RFIA |
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DAG;IAM |
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IAM @ iam @ LLS2000 |
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1567 |
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Josep Llados; Enric Marti |
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A graph-edit algorithm for hand-drawn graphical document recognition and their automatic introduction into CAD systems |
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1999 |
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Machine Graphics & Vision |
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8 |
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195-211 |
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DAG;IAM; |
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IAM @ iam @ LIM1999 |
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1568 |
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