Development of an ultrasound system for measuring tissue strain of lymphedema.

This paper develops a portable measurement system for tissue strain distribution using ultrasonic pulse echo method. A single element ultrasonic transducer attached to a force sensor compresses biological tissue and observes the deformation process of the tissue. The center frequency of the ultrasound pulse is 3 MHz. The force applied to the tissue is kept at 10 N by an internal coil spring. Received echo signals are transferred to a personal computer via Universal Serial Bus. The developed measurement system was applied to measuring strain of subcutaneous fat for lymphedema patients and healthy subjects. The results quantified the fact that affected tissue becomes harder than unaffected tissue. Our experiment demonstrated that the system can be used for evaluating the condition of lymphedema with measurement of strain in subcutaneous tissue.