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Biomedical subjects

J C Bamber

Publications and source records attributed to J C Bamber.

47 records · Page 3Linked to original sources
PubMed1986

Ultrasonic study of in vivo kinetic characteristics of human tissues.

A method is described for quantifying tissue movement in vivo from the computation of correlation coefficient between pairs of A-scans with appropriate time separation. The method yields quantifiable and repeatable secondary patterns of soft tissue movement in response to primary cardiac movement in a given subject, shows consistently different results as between normal livers and a variety of abdominal tumours, and is sensitive to either progress or therapeutically-induced regression of malignant disease. While the results reported here have been obtained using somewhat simple and crude equipment, the method is well suited to implementation on a commercial real-time scanner.

Abdominal Neoplasms↗
PubMed1986

Tumour growth delay as a clinical endpoint for the measurement of radiation response.

Tumour growth delay has been investigated as an endpoint of radiation effect in selected patients with superficial metastases measured by calipers and ultrasound. Of 42 patients referred for study with two or more nodules, 17 were suitable for entry into protocols evaluating single or multifraction treatment. The reproducibility of tumour growth delay to the same dose schedule was evaluable in four patients and the sensitivity to 10-20% differences in total dose was evaluable in three patients. No significant size dependency was detected in the response of nodules to radiotherapy and the findings suggest that the growth delay endpoint is sensitive to 20% differences in radiation dose. Evaluable patients with multiple measurable nodules are uncommon but constitute a valuable resource for the testing of biological response modifiers, including radiosensitizers.

Breast↗
PubMed1982

A preliminary assessment of an ultrasonic Doppler method for the study of blood flow in human breast cancer.

A 10 MHz, continuous wave ultrasonic Doppler system was used to study the blood flow associated with normal and malignant mammary tissue in patients with breast cancer. Some patients were receiving endocrine therapy and were examined repeatedly over a period of months. each of 6 characteristics extracted from the time varying maximum Doppler-shift frequency were averaged over signals obtained from a number of sites in the vicinity of the tumour, and from corresponding sites in the normal breast. A method was devised to allow location of previously examined vessels for subsequent examinations. The preliminary results of analysing approx. 400 recordings of Doppler signals obtained from 16 patients (6 of whom received endocrine therapy) are presented. The most informative of the 6 characteristics were the maximum systolic frequency (A) and the "mean" frequency (M) (= A + B/2 where B is the maximum frequency during end diastole). The average values of A and M obtained from the tumourous breast were always greater than those obtained from the normal breast in the same patient. A and M were roughly proportional to tumour volume, with extrapolated values at zero volume only slightly greater than the corresponding mean values for normal breast tissue. On average, changes in the values of A and M obtained from tumour sites during endocrine therapy appeared to occur in association with, and possibly slightly in advance of, changes in the tumour volume.

Aminoglutethimide↗
PubMed1980

Ultrasonic B-scanning: a computer simulation.

A method has been developed which can predict the appearance and properties of B-scan images. The theoretical basis for the tissue models used, and the assumptions made in the simulation concerning the nature of pulse-echo imaging, are discussed. A key feature of the simulation is the Fourier domain synthesis of the tissue model, which permits convenient specification of some statistical properties of a randomly inhomogeneous scattering medium. Other characteristics that may be specified include the ultrasonic pulse and beam shapes, and subsequent signal processing. Both the initial tissue model and the simulated B-scan image are displayed as grey-scale pictures, allowing visual comparison in the same way that clinical B-scans are currently observed. Preliminary results of applying the simulation are shown to have a number of features in common with clinical images and with scans of a test object. A better understanding of the nature of pulse-echo images is gained and conclusions drawn regarding the range of system and tissue parameters over which these images convey information about the tissue structure. The method may also be of use to determine optimum design of equipment for imaging and tissue characterisation, and to investigate the extent to which the acoustic structure of tissues can be described in terms of simple mathematical models.

Computers↗
PubMedDate not supplied

Effect of gaseous inclusions on the frequency dependence of ultrasonic attenuation in liver.

The greatest variation in published data of the attenuation of ultrasound in mammalian liver in vitro occurs at the lower end of the 0.5 to 7 MHz frequency range and gives rise to some departure from a linear or simple power law dependence of attenuation on frequency. These effects do not appear to be highly dependent on the method of measurement. It is suggested that they are due to a varying presence of small gas bubbles distributed throughout the tissue--a suggestion based on calculated estimates of the attenuation due to microscopic bubbles and on the measured frequency dependence of attenuation in water loaded sponges containing varying amounts and distribution of gas. We now believe that preferred methods of tissue specimen preparation, for in vitro measurement of ultrasonic attenuation or scattering, should involve either pressurization as described elsewhere (Frizzell et al., 1979) or storage under refrigeration.

Animals↗