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We present an algorithm which combines non-rigid image-based registration and conventional position sensing to correct probe-pressure-induced registration errors in freehand three-dimensional (3D) ultrasound volumes. The local accuracy of image-based registration enables the accurate freehand acquisition of high resolution (>15 MHz) 3D ultrasound data,(More)
The clinical utility of pulse-echo ultrasound images is severely limited by inherent poor resolution that impacts negatively on their diagnostic potential. Research into the enhancement of image quality has mostly been concentrated in the areas of blind image restoration and speckle removal, with little regard for accurate modeling of the underlying tissue(More)
We solve the equation that governs acoustic wave propagation in an inhomogeneous medium to show that the radio-frequency (RF) ultrasound signal can be expressed as the result of filtering the scatterer field with a point-spread function. We extend the analysis to make the link between the RF ultrasound signal and the representation of ultrasound scatterers(More)
We present a new, intelligent interface for freehand strain imaging, which has been designed to support clinical trials investigating the potential of ultrasonic strain imaging for diagnostic purposes across a broad range of target pathologies. The aim with this interface is to make scanning easier and to help clinicians learn the necessary scanning(More)
Displacement estimation is a key step in the evaluation of tissue elasticity by quasistatic strain imaging. An efficient approach may incorporate a tracking strategy whereby each estimate is initially obtained from its neighbours' displacements and then refined through a localized search. This increases the accuracy and reduces the computational expense(More)
BACKGROUND Individuals with osteoporosis are predisposed to hip fracture during trips, stumbles or falls, but half of all hip fractures occur in those without generalised osteoporosis. By analysing ordinary clinical CT scans using a novel cortical thickness mapping technique, we discovered patches of markedly thinner bone at fracture-prone regions in the(More)
Pulse-echo ultrasound display relies on many assumptions that are known to be incorrect. Departure from these makes interpretation of conventional ultrasound images difficult, and three-dimensional (3-D) visualizations harder still. For instance, shadowing and enhancement are the result of an incorrect assumption that sound attenuation is a function only of(More)
Freehand 3D ultrasound can be acquired without a position sensor by finding the separations of pairs of frames using information in the images themselves. Previous work has not considered how to reconstruct entirely freehand data, which can exhibit irregularly spaced frames, intersecting frames, nonmonotonic out-of-plane probe motion and significant(More)
The distribution of cortical bone in the proximal femur is believed to be critical in determining fracture resistance. Current CT technology is limited in its ability to measure cortical thickness, especially in the sub-millimetre range which lies within the point spread function of today's clinical scanners. In this paper, we present a novel technique that(More)