Visualisation and Analysis of Speech Production with Electropalatography.

The process of speech production, i.e., the compression of air in the lungs, the vibration activity of the larynx, and the movement of the articulators, is of great interest in phonetics, phonology, and psychology.

Feasibility of skin surface elastography by tracking skin surface topography.

Recent advances have led to a multitude of image modalities being used for visualization of tissue stiffness. High-resolution images of tissue stiffness are desirable, as they have the potential to provide useful diagnostic information. A noncontact optical imaging method has the attractions of low cost, simplicity, and utility when skin contact is undesirable.

The effect of object speed and direction on the performance of 3D speckle tracking using a 3D swept-volume ultrasound probe.

Three-dimensional (3D) soft tissue tracking using 3D ultrasound is of interest for monitoring organ motion during therapy. Previously we demonstrated feature tracking of respiration-induced liver motion in vivo using a 3D swept-volume ultrasound probe. The aim of this study was to investigate how object speed affects the accuracy of tracking ultrasonic speckle in the absence of any structural information, which mimics the situation in homogenous tissue for motion in the azimuthal and elevational directions.

Speckle tracking in a phantom and feature-based tracking in liver in the presence of respiratory motion using 4D ultrasound.

We have evaluated a 4D ultrasound-based motion tracking system developed for tracking of abdominal organs during therapy. Tracking accuracy and precision were determined using a tissue-mimicking phantom, by comparing tracked motion with known 3D sinusoidal motion. The feasibility of tracking 3D liver motion in vivo was evaluated by acquiring 4D ultrasound data from four healthy volunteers.

The spatio-temporal strain response of oedematous and nonoedematous tissue to sustained compression in vivo.

Poroelastic theory predicts that compression-induced fluid flow through a medium reveals itself via the spatio-temporal behaviour of the strain field. Such strain behaviour has already been observed in simple poroelastic phantoms using generalised elastographic techniques (Berry et al. 2006a, 2006b).

Performance of ultrasound based measurement of 3D displacement using a curvilinear probe for organ motion tracking.

Three-dimensional (3D) soft tissue tracking is of interest for monitoring organ motion during therapy. Our goal is to assess the tracking performance of a curvilinear 3D ultrasound probe in terms of the accuracy and precision of measured displacements. The first aim was to examine the depth dependence of the tracking performance.

Towards an acoustic model-based poroelastic imaging method: II. experimental investigation.

Soft biological tissue contains mobile fluid. The volume fraction of this fluid and the ease with which it may be displaced through the tissue could be of diagnostic significance and may also have consequences for the validity with which strain images can be interpreted according to the traditional idealizations of elastography. In a previous paper, under the assumption of frictionless boundary conditions, the spatio-temporal behavior of the strain field inside a compressed cylindrical poroelastic sample was predicted (Berry et al.

Towards an acoustic model-based poroelastic imaging method: I. Theoretical foundation.

The ultrasonic measurement and imaging of tissue elasticity is currently under wide investigation and development as a clinical tool for the assessment of a broad range of diseases, but little account in this field has yet been taken of the fact that soft tissue is porous and contains mobile fluid. The ability to squeeze fluid out of tissue may have implications for conventional elasticity imaging, and may present opportunities for new investigative tools. When a homogeneous, isotropic, fluid-saturated poroelastic material with a linearly elastic solid phase and incompressible solid and fluid constituents is subjected to stress, the behaviour of the induced internal strain field is influenced by three material constants: the Young's modulus (E(s)) and Poisson's ratio (nu(s)) of the solid matrix and the permeability (k) of the solid matrix to the pore fluid.

Ultrasonic temperature imaging for guiding focused ultrasound surgery: effect of angle between imaging beam and therapy beam.

Ultrasonic temperature imaging is a promising technique for guiding focused ultrasound surgery (FUS). The FUS system is run at an initial, nonablative intensity and a diagnostic transducer images the heat-induced echo strain, which is proportional to the temperature rise. The echo strain image portrays an elliptical "hot spot" corresponding to the focal region of the therapy transducer.

Characterization of cardiovascular liver motion for the eventual application of elasticity imaging to the liver in vivo.

Elastography, which uses ultrasound to image the tissue strain that results from an applied displacement, can display tumours and heat-ablated tissue with high contrast. However, its application to liver in vivo may be problematic due to the presence of respiratory and cardiovascular sources of displacement. The aim of this study was to measure the cardiovascular-induced component of natural liver motion for the purpose of planning future work that will either use the motion to produce elasticity images or will compensate for it when employing an external source of displacement.

Imaging of temperature-induced echo strain: preliminary in vitro study to assess feasibility for guiding focused ultrasound surgery.

Ultrasonic estimation of heat-induced echo strain has been suggested as a noninvasive technique for guiding focused ultrasound (US) surgery (FUS), that is, for predicting the location of the thermal lesion before it is formed. The proposed strategy is to run the FUS system at a nonablative intensity and to use a diagnostic transducer to image the heat-induced echo strain, which, over a sufficiently small temperature range, is proportional to the temperature rise. The principal aim of this in vitro study was to determine if temperature-induced strain imaging is likely to be able to visualise the small (< 0.

Fundamental limitations of noninvasive temperature imaging by means of ultrasound echo strain estimation.

Ultrasonic estimation of temperature-induced echo strain has been suggested as a means of predicting the location of thermal lesions formed by focused ultrasound (US) surgery before treatment. Preliminary investigations of this technique have produced optimistic results because they were carried out with rubber phantoms and used room temperature, rather than body temperature, as the baseline. The objective of the present study was to determine, through modelling, the likely feasibility of using ultrasonic temperature imaging to detect and localise the focal region of the heating beam for a medium with a realistic temperature-dependence of sound speed subjected to a realistic temperature rise.