Development of a novel actuator for the dynamic palpation of soft tissue for use in the assessment of prostate tissue quality

Abstract This paper reports on a novel device suitable for the in vivo assessment of prostate tissue quality. One of the first steps in the assessment of a patient who may have prostate cancer is a digital rectal examination (DRE). Our aim is to instrument this procedure to allow us to quantify results and add a dimension of assessment in that a dynamic stiffness measurement is made. The device is finger mounted and comprises a pneumatically actuated membrane which applies modulated force to the tissue to which it is applied. A strain gauge embedded in the membrane measures the response ( i.e. the modulated displacement) and allows the dynamic stiffness of the tissue to be measured. Changes in dynamic stiffness with location allow a mechanical assessment of tissue quality. As a proof of concept, a prototype device has been fabricated and its performance assessed through a series of measurements on both cadavers and excised prostate glands for ex vivo assessment. Measurements have been compared to results obtained by non-instrumented palpation and traditional DRE. Although part of a wider study aimed at identifying correlations between tissue morphology and its mechanical characteristics, this paper demonstrates that the probe can sense qualitative differences between parts of a prostate with and without tumours. Ultimately, scanning the prostate with the device allows stiffness maps of the gland to be built which can then be used for diagnostic purposes to identify diseased prostatic tissue.