In Vivo Measurement of Solid Organ Tissue Mechanical Properties

Surgical simulation is a field that shows much promise in terms of permitting surgeons to learn new skills, as well as enabling the development of new procedures and instruments while minimizing the use of animal subjects. Essential to simulation with realistic force feedback are material property data for the wide variety of soft tissues, both in healthy and diseased conditions. Properties are known to change significantly after death, so measurements should ideally be made in vivo. This paper reviews a number of methods in use to perform in vivo testing. It focuses on ongoing work using a minimally invasive instrument that uses normal indentation to acquire the forcedisplacement response of solid organ tissues such as liver, spleen and kidney. The design and characterization of the instrument as well as some of the in vivo and other test results will be presented.