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We present an automated, knowledge-based method for segmenting chest computed tomography (CT) datasets. Anatomical knowledge including expected volume, shape, relative position, and X-ray attenuation of organs provides feature constraints that guide the segmentation process. Knowledge is represented at a high level using an explicit anatomical model. The(More)
Spectral tissue strain (STS) is a new technique for measuring and imaging tissue strain from a set of images using intravascular ultrasound. The technique is based on the Fourier scaling property and uses the chirp z-transform (CZT) to estimate strain within the vessel walls. Some preliminary results, both in vitro and in vivo, are described. A novel(More)
The data on the relationship of sound speed to tissue condition, and the development of methods for measurement of sound speed in vivo, are outlined. The methods developed by the authors are discussed. These include methods which use the spatial shift in images of targets viewed from different directions, time-of-flight measurements along incrementally(More)
OBJECTIVES Healthcare is now routinely delivered by telecommunications-based services in all developed countries and an increasing number of developing countries. Telemedicine is used in many clinical specialities and across numerous healthcare settings, which range from mobile patient-centric applications to complex interactions amongst clinicians in(More)
We present a knowledge-based approach to segmentation and analysis of the lung boundaries in chest X-rays. Image edges are matched to an anatomical model of the lung boundary using parametric features. A modular system architecture was developed which incorporates the model, image processing routines, an inference engine and a blackboard. Edges associated(More)
Ultrasonic attenuation has been measured using frequency domain signal processing in clinical trials of patients with liver and spleen diseases. By comparing the variance encountered in local measurements and in measurements at a number of adjoining sites, the need for averaging over large volumes of tissue to avoid the effects of large fluctuations is(More)
The action of reflection and refraction in producing shadows and enhancement in ultrasonic echograms behind cystic structures is well known, but the physical explanations usually used are incomplete. In this paper the emergent beam patterns for a number of cases are plotted and this data used to explain the shadows and enhancement observed. Cases are also(More)
A frequency domain signal processing scheme is developed for measuring attenuation and attenuation slope in vivo, using equally spaced depth samples and linear regression techniques. The algorithm may be expressed in terms of linear, commuting operators acting on an array of log power spectra. By interchanging operators, a computationally efficient scheme(More)
The advent of real-time ultrasound in the 1970s, together with a growing interest in tissue characterization, led to a number of investigators using the nature of tissue motion to distinguish healthy from diseased tissue. Our group at the (then) Ultrasonics Institute demonstrated the use of phase methods for detecting very small tissue motions, using(More)