Shear acoustic properties of soft biological tissues in medical diagnostics

This report is a summary of the studies of shear acoustic properties of soft biological tissues performed by the author and his co-workers in the period from 1966 to the present. A number of techniques for measuring shear elastic moduli of soft tissue in a range of frequencies are described. Methods are considered based on the measurements of acoustic impedance, the shear and surface wave speeds, as well as of static moduli. Results of invitro studies of animal and human tissues and of such model systems as various gels and rubbers are presented. Invivo studies were made on superficial tissues such as the skin and the nearest underlying tissues. It has been shown that surface acoustic waves can be successfully used in the diagnosis of various dermatitis and skin cancer as well as for monitoring of the efficacy of treatment. In response to the needs of the newly developing technique of ultrasonic elasticity imaging of the breast, systematic studies involving 162 excised samples of glandular, fatty, cancerous, and fibroadenoma tissues were performed and the ranges of variation of shear moduli were evaluated. a)Permanent address: Inst. of Theoret. and Exp. Biophys., Russian Acad. Sci., Pushchino 142292, Russia.