Segmentation in Echocardiographic Sequences Using Shape-based Snake Model

A method for segmentation of cardiac structures especially for mitral valve in echocardiographic sequences is presented. The method is motivated by the observation that the structures of neighboring frames have consistent locations and shapes that aid in segmentation. To cooperate with the constraining information provided by the neighboring frames, we combine the template matching with the conventional snake model. It means that the model not only is driven by conventional internal and external forces, but also combines an additional constraint, the matching degree to measure the similarity between the neighboring prior shape and the derived contour. Furthermore, in order to automatically or semi-automatically segment the sequent images without manually drawing the initial contours in each image, generalized Hough transformation (GHT) is used to roughly estimate the initial contour by transforming the neighboring prior shape. Based on the experiments on forty sequences, the method is particularly useful in case of the large frame-to-frame displacement of structure such as mitral valve. As a result, the active contour can easily detect the desirable boundaries in ultrasound images and has a high penetrability through the interference of various undesirables, such as the speckle, the tissue-related textures and the artifacts

Lv volume quantification via spatiotemporal analysis of real-time 3-d echocardiography

Abstract—This paper presents a method of four-dimensional (4-D) (3-D + Time) space–frequency analysis for directional denoising and enhancement of real-time three-dimensional (RT3D) ultrasound and quantitative measures in diagnostic cardiac ultrasound. Expansion of echocardiographic volumes is performed with complex exponential wavelet-like basis functions called brushlets. These functions offer good localization in time and frequency and decompose a signal into distinct patterns of oriented harmonics, which are invariant to intensity and contrast range. Deformable-model segmentation is carried out on denoised data after thresholding of transform coefficients. This process attenuates speckle noise while preserving cardiac structure location. The superiority of 4-D over 3-D analysis for decorrelating additive white noise and multiplicative speckle noise on a 4-D phantom volume expanding in time is demonstrated. Quantitative validation, computed for contours and volumes, is performed on in vitro balloon phantoms. Clinical applications of this spaciotemporal analysis tool are reported for six patient cases providing measures of left ventricular volumes and ejection fraction. Index Terms—Echocardiography, LV volume, spaciotemporal analysis, speckle denoising. I

Ultrasonido tridimensional en cardiología

El análisis de imágenes cardiovasculares constituyeuna herramienta útil para el diagnóstico,tratamiento y monitoreo de enfermedades cardiovasculares.Las técnicas de procesamiento de imágenespermiten la evaluación cuantitativa no-invasiva de la funcióncardiaca, proporcionando información morfológica, funcionaly dinámica. Los progresos tecnológicos recientes en ultrasonidohan permitido incrementar la calidad del tratamientoal paciente, gracias al uso de técnicas modernas de procesamientoy análisis de las imágenes. Sin embargo, la adquisiciónde estas imágenes tridimensionales (3D) dinámicas conduce ala producción de grandes volúmenes de datos para procesar,a partir de los cuales las estructuras cardiacas deben ser extraídasy analizadas durante el ciclo cardiaco. Herramientas deextracción, de visualización tridimensional, y de cuantificaciónson usadas actualmente dentro de la rutina clínica, pero desafortunadamentenecesitan de una interacción importante conel médico. Estos elementos justifican el desarrollo de nuevosalgoritmos eficaces y robustos para la extracción de estructurasy estimación del movimiento cardiaco a partir de imágenestridimensionales. Como resultado, poner a disposicióndel personal clínico nuevos medios para evaluar de maneraprecisa la anatomía y la función cardiaca a partir de imágenestridimensionales, representa un avance certero dentro de lainvestigación de una descripción completa del corazón a partirde un ´único examen. El objetivo de este artículo es mostrarcuáles han sido los avances en imagenología cardiaca 3D porultrasonido y adicionalmente observar qué áreas han sido estudiadasbajo esta modalidad imagenológica