Biomedical subjects

K R Nightingale

Publications and source records attributed to K R Nightingale.

5 recordsLinked to original sources

PubMed2001

On the feasibility of remote palpation using acoustic radiation force.

A method of acoustic remote palpation, capable of imaging local variations in the mechanical properties of tissue, is under investigation. In this method, focused ultrasound is used to apply localized (on the order of 2 mm3) radiation force within tissue. and the resulting tissue displacements are mapped using ultrasonic correlation based methods. The tissue displacements are inversely proportional to the stiffness of the tissue, and thus a stiffer region of tissue exhibits smaller displacements than a more compliant region. In this paper, the feasibility of remote palpation is demonstrated experimentally using breast tissue phantoms with spherical lesion inclusions, and in vitro liver samples. A single diagnostic transducer and modified ultrasonic imaging system are used to perform remote palpation. The displacement images are directly correlated to local variations in tissue stiffness with higher contrast than the corresponding B-mode images. Relationships between acoustic beam parameters, lesion characteristics and radiation force induced tissue displacement patterns are investigated and discussed. The results show promise for the clinical implementation of remote palpation.

Breast↗

PubMed2000

A finite element model of remote palpation of breast lesions using radiation force: factors affecting tissue displacement.

The early detection of breast cancer reduces patient mortality. The most common method of breast cancer detection is palpation. However, lesions that lie deep within the breast are difficult to palpate when they are small. Thus, a method of remote palpation, which may allow the detection of small lesions lying deep within the breast, is currently under investigation. In this method, acoustic radiation force is used to apply localized forces within tissue (to tissue volumes on the order of 2 mm3) and the resulting tissue displacements are mapped using ultrasonic correlation based methods. A volume of tissue that is stiffer than the surrounding medium (i.e., a lesion) distributes the force throughout the tissue beneath it, resulting in larger regions of displacement, and smaller maximum displacements. The resulting displacement maps may be used to image tissue stiffness. A finite-element-model (FEM) of acoustic remote palpation is presented in this paper. Using this model, a parametric analysis of the affect of varying tissue and acoustic beam characteristics on radiation force induced tissue displacements is performed. The results are used to evaluate the potential of acoustic remote palpation to provide useful diagnostic information in a clinical setting. The potential for using a single diagnostic transducer to both generate radiation force and track the resulting displacements is investigated.

Acoustics↗

PubMed1999

The use of acoustic streaming in breast lesion diagnosis: a clinical study.

Results from a clinical study are presented, in which ultrasonically-induced acoustic streaming was successfully used to differentiate fluid-filled lesions (cysts) from solid lesions in the breast. In this study, high-intensity ultrasound pulses from a modified commercial scanner were used to induce acoustic streaming in cyst fluid, and this motion was detected using Doppler methods. Acoustic streaming was generated and detected in 14 of 15 simple cysts, and 4 of 14 sonographically indeterminate breast lesions. This lesion differentiation method appears to be particularly suited for diagnosis of small, possibly newer, cysts that appear indeterminate on conventional sonography due to their size. The results indicate that this method would be a useful adjunct to conventional sonography for the purpose of breast lesion classification.

Adult↗

PubMed1995

A novel ultrasonic technique for differentiating cysts from solid lesions: preliminary results in the breast.

The feasibility of a new ultrasonic technique to distinguish cysts from solid lesions is explored. High intensity pulses are used to induce acoustic streaming in cyst fluid, and this motion is detected using Doppler techniques. Acoustic streaming cannot be generated in solid lesions, therefore, its detection would indicate a cyst. In six of seven breast cysts motion was clearly generated and detected in vivo. Ultrasonic pulses with intensities up to 4.4 W cm-2 (I(spta) in water) were focused on the cysts for 10 s. Lesion diameters ranged from 0.6 to 2.5 cm; induced flow velocities were less than 4.0 cm s-1.

Breast Neoplasms↗

PubMedDate not supplied

Three-dimensional flow images by reconstruction from two-dimensional vector velocity maps.

A method for constructing three-dimensional images of flow is described. The technique involves the acquisition of numerous closely spaced planes, each comprised of a map of the two-dimensional velocities measured in that plane. Each such vector velocity map is formed by tracking the motion of small regions of ultrasonic speckle between two ultrasonic acquisitions separated by a short time interval. In contrast to current Doppler velocity methods, this technique measures both the axial and lateral components of flow and is not subject to aliasing. The resulting series of two-dimensional vector velocity maps is then combined into a three-dimensional data set, which can be manipulated with appropriate software to yield quantitative three-dimensional displays of the flow within the interrogated volume. In this article we present such images obtained from measurements of in vitro laminar flow in a vessel, as well as a free jet phantom. The results allow comprehensive visualization of the three-dimensional flow characteristics, indicating promise for more complete and quantitative clinical assessment of blood flow.

Blood Flow Velocity↗