An HTML Tool for Production of Interactive Stereoscopic Compositions.

The benefits of stereoscopic vision in medical applications were appreciated and have been thoroughly studied for more than a century. The usage of the stereoscopic displays has a proven positive impact on performance in various medical tasks. At the same time the market of 3D-enabled technologies is blooming. New high resolution stereo cameras, TVs, projectors, monitors, and head mounted displays become available. This equipment, completed with a corresponding application program interface (API), could be relatively easy implemented in a system. Such complexes could open new possibilities for medical applications exploiting the stereoscopic depth. This work proposes a tool for production of interactive stereoscopic graphical user interfaces, which could represent a software layer for web-based medical systems facilitating the stereoscopic effect. Further the tool's operation mode and the results of the conducted subjective and objective performance tests will be exposed.

Estudio tractográfico de la anatomía helicoidal del miocardio ventricular mediante resonancia magnética por tensor de difusión / Helical structure of the cardiac ventricular anatomy assessed by diffusion tensor magnetic resonance imaging with multiresolution tractography

Introducción y objetivos. La integración de la anatomía y la función del miocardio ventricular es fundamental para una completa comprensión de la fisiología cardiaca, lo que podría revelar conocimientos clave para futuros estudios experimentales y procedimientos clínicos. Se han propuesto varios modelos conceptuales de la organización de las fibras miocárdicas, pero la dificultad para automatizar y analizar objetivamente una estructura anatómica tan compleja ha impedido que se llegue a un acuerdo. El objetivo de nuestro estudio es analizar objetivamente la arquitectura de las fibras miocárdicas mediante métodos avanzados de procesamiento gráfico por computadora aplicados a imágenes de resonancia magnética por tensor de difusión. Métodos. Se han realizado reconstrucciones tractográficas automatizadas de datos de imágenes de resonancia magnética por tensor de difusión sin segmentar de corazones provenientes de la base de datos pública de la Johns Hopkins University. Las reconstrucciones a máxima resolución se han construido con 200 semillas y se componen de perfiles calculados sobre el volumen de vectores propios primarios obtenidos del tensor de difusión. También aportamos una nueva técnica de visualización multiescalar para obtener tractografías simplificadas. Esta metodología permite mantener las principales propiedades geométricas de las fibras y descifrar las principales propiedades de la organización arquitectónica del miocardio. Resultados. En el análisis de las tractografías de todo el espectro multiescalar, encontramos una correlación exacta en los detalles de bajo nivel, así como de la conceptualización abstracta de la disposición helicoidal continua de las fibras miocárdicas que conforman la arquitectura ventricular. Conclusiones. El análisis objetivo de la arquitectura miocárdica mediante un método automatizado que incluye el miocardio completo y utiliza diferentes niveles de complejidad tridimensional revela una organización de las fibras en forma de estructura helicoidal continua que conforma ambos ventrículos. Estos datos concuerdan con el modelo de banda ventricular miocárdica descrita por F. Torrent-Guasp (AU)

Introduction and objectives. Deeper understanding of the myocardial structure linking the morphology and function of the heart would unravel crucial knowledge for medical and surgical clinical procedures and studies. Several conceptual models of myocardial fiber organization have been proposed but the lack of an automatic and objective methodology prevented an agreement. We sought to deepen this knowledge through advanced computer graphical representations of the myocardial fiber architecture by diffusion tensor magnetic resonance imaging. Methods. We performed automatic tractography reconstruction of unsegmented diffusion tensor magnetic resonance imaging datasets of canine heart from the public database of the Johns Hopkins University. Full-scale tractographies have been built with 200 seeds and are composed by streamlines computed on the vector field of primary eigenvectors at the diffusion tensor volumes. We also introduced a novel multiscale visualization technique in order to obtain a simplified tractography. This methodology retains the main geometric features of the fiber tracts, making it easier to decipher the main properties of the architectural organization of the heart. Results. Output analysis of our tractographic representations showed exact correlation with low-level details of myocardial architecture, but also with the more abstract conceptualization of a continuous helical ventricular myocardial fiber array. Conclusions. Objective analysis of myocardial architecture by an automated method, including the entire myocardium and using several 3-dimensional levels of complexity, reveals a continuous helical myocardial fiber arrangement of both right and left ventricles, supporting the anatomical model of the helical ventricular myocardial band described by F. Torrent-Guasp (AU)

Helical structure of the cardiac ventricular anatomy assessed by diffusion tensor magnetic resonance imaging with multiresolution tractography.

INTRODUCTION AND OBJECTIVES: Deeper understanding of the myocardial structure linking the morphology and function of the heart would unravel crucial knowledge for medical and surgical clinical procedures and studies. Several conceptual models of myocardial fiber organization have been proposed but the lack of an automatic and objective methodology prevented an agreement. We sought to deepen this knowledge through advanced computer graphical representations of the myocardial fiber architecture by diffusion tensor magnetic resonance imaging. METHODS: We performed automatic tractography reconstruction of unsegmented diffusion tensor magnetic resonance imaging datasets of canine heart from the public database of the Johns Hopkins University. Full-scale tractographies have been built with 200 seeds and are composed by streamlines computed on the vector field of primary eigenvectors at the diffusion tensor volumes. We also introduced a novel multiscale visualization technique in order to obtain a simplified tractography. This methodology retains the main geometric features of the fiber tracts, making it easier to decipher the main properties of the architectural organization of the heart. RESULTS: Output analysis of our tractographic representations showed exact correlation with low-level details of myocardial architecture, but also with the more abstract conceptualization of a continuous helical ventricular myocardial fiber array. CONCLUSIONS: Objective analysis of myocardial architecture by an automated method, including the entire myocardium and using several 3-dimensional levels of complexity, reveals a continuous helical myocardial fiber arrangement of both right and left ventricles, supporting the anatomical model of the helical ventricular myocardial band described by F. Torrent-Guasp.

Image-based cardiac phase retrieval in intravascular ultrasound sequences.

Longitudinal motion during in vivo pullbacks acquisition of intravascular ultrasound (IVUS) sequences is a major artifact for 3-D exploring of coronary arteries. Most current techniques are based on the electrocardiogram (ECG) signal to obtain a gated pullback without longitudinal motion by using specific hardware or the ECG signal itself. We present an image-based approach for cardiac phase retrieval from coronary IVUS sequences without an ECG signal. A signal reflecting cardiac motion is computed by exploring the image intensity local mean evolution. The signal is filtered by a band-pass filter centered at the main cardiac frequency. Phase is retrieved by computing signal extrema. The average frame processing time using our setup is 36 ms. Comparison to manually sampled sequences encourages a deeper study comparing them to ECG signals.

Approaching artery rigid dynamics in IVUS.

Tissue biomechanical properties (like strain and stress) are playing an increasing role in diagnosis and long-term treatment of intravascular coronary diseases. Their assessment strongly relies on estimation of vessel wall deformation. Since intravascular ultrasound (IVUS) sequences allow visualizing vessel morphology and reflect its dynamics, this technique represents a useful tool for evaluation of tissue mechanical properties. Image misalignment introduced by vessel-catheter motion is a major artifact for a proper tracking of tissue deformation. In this work, we focus on compensating and assessing IVUS rigid in-plane motion due to heart beating. Motion parameters are computed by considering both the vessel geometry and its appearance in the image. Continuum mechanics laws serve to introduce a novel score measuring motion reduction in in vivo sequences. Synthetic experiments validate the proposed score as measure of motion parameters accuracy; whereas results in in vivo pullbacks show the reliability of the presented methodologies in clinical cases.