Josepa Mauri Ferré

Ultrasound Despeckle Methods

Speckle, a form of multiplicative noise, affects imaging applications such as medical Ultrasound (US). The effectiveness of a segmentation and registration process can be improved when the noise is removed without affecting important image features. This chapter details the main speckle reducing filtering categories and provides an extended comparison of various state-of-the-art algorithms focusing on the anisotropic filters family. A series of in silico experiments has been designed with the aim to compare the performances of the state-of-the-art approaches on synthetic images corrupted by a controlled amount of speckle noise. Additional in vivo experiments have been designed for illustrating the interest of using an accurate filtering method as pre-processing stage, in order to improve the performance of the segmentation methods.

Función endotelial en segmentos arteriales previamente sometidos a angioplastia coronaria

Introduccion y objetivo . La angioplastia coronaria comporta una denudacion endotelial y una posterior reendotelizacion. El objetivo de nuestro estudio ha sido determinar el estado de la funcion endotelial en segmentos coronarios sometidos a angioplastia y sin reestenosis. Metodos . Se analizo la respuesta vasodilatadora dependiente del endotelio en 12 pacientes con enfermedad de un vaso a los 6 meses de practicada la angioplastia mediante la infusion intracoronaria selectiva a dosis crecientes de acetilcolina (10–6, 10–5, 10–4 M) en la arteria previamente tratada. Siete pacientes con arterias coronarias normales o con minimas irregularidades y sin factores de riesgo constituyeron el grupo control. La respuesta vasomotora a las diferentes dosis de acetilcolina se analizo mediante angiografia coronaria cuantitativa. Resultados . El estudio de la funcion endotelial demostro una respuesta global vasodilatadora en el segmento dilatado a la maxima dosis de acetilcolina (incremento del diametro del 3,6 ± 3,5%), similar a la respuesta observada en el grupo control (incremento del diametro del 3 ± 6%; p = NS). En particular, se observo una funcion endotelial normal en 8 pacientes (67%) y una respuesta vasoconstrictora en 4 enfermos (33%). Se ha detectado una correlacion positiva entre la respuesta a la maxima dosis de acetilcolina y la lesion residual a los 6 meses de evolucion (r = 0,67; p = 0,02). Conclusiones . En pacientes que han sido tratados mediante angioplastia y que no presentan reestenosis, los segmentos dilatados muestran frecuentemente una funcion endotelial normal. Un mayor grado de estenosis residual en las zonas dilatadas se asocia a una menor alteracion de la funcion endotelial.

Coronary Atherosclerotic Plaque Characterization By Intravascular Ultrasound

The accurate characterization of in vivo atherosclerotic plaques represents an important task during percutaneous intervention. Intravascular Ultrasound (IVUS) is a catheter-based imaging technique that provides a detailed cross-sectional representation of the internal morphology of the vessel, thus allowing to assess plaque amount and composition. In this chapter the state of the art methods for automatic plaque characterization in IVUS are analyzed. The main classification techniques as well as the most discriminative features are illustrated. Furthermore, a recently presented technique for the fusion of in vivo and in vitro IVUS data is illustrated.