title: Quantitative imaging of young's modulus of soft tissues from ultrasound water jet indentation: a finite element study.
abstract: Indentation testing is a widely used approach to evaluate mechanical characteristics of soft tissues quantitatively. Young's modulus of soft tissue can be calculated from the force-deformation data with known tissue thickness and Poisson's ratio using Hayes' equation. Our group previously developed a noncontact indentation system using a water jet as a soft indenter as well as the coupling medium for the propagation of high-frequency ultrasound. The novel system has shown its ability to detect the early degeneration of articular cartilage. However, there is still lack of a quantitative method to extract the intrinsic mechanical properties of soft tissue from water jet indentation. The purpose of this study is to investigate the relationship between the loading-unloading curves and the mechanical properties of soft tissues to provide an imaging technique of tissue mechanical properties. A 3D finite element model of water jet indentation was developed with consideration of finite deformation effect. An improved Hayes' equation has been derived by introducing a new scaling factor which is dependent on Poisson's ratios v, aspect ratio a/h (the radius of the indenter/the thickness of the test tissue), and deformation ratio d/h. With this model, the Young's modulus of soft tissue can be quantitatively evaluated and imaged with the error no more than 2%.
authors.affiliation: National-Regional Engineering Laboratory for Key Technology of Medical Ultrasound, Shenzhen University, Shenzhen 518060, China. minhua lu@hotmail.com
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Lu
authors.forename: Rui
authors.initials: R
authors.lastname: Mao
authors.forename: Yin
authors.initials: Y
authors.lastname: Lu
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Tian-Fu
authors.initials: TF
authors.lastname: Wang
authors.forename: Si-Ping
authors.initials: SP
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D000818:Animals; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D019245:Compressive Strength; D003198:Computer Simulation; D003238:Connective Tissue / Q000000981:diagnostic imaging*; D055119:Elastic Modulus; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D015233:Models, Statistical; D016012:Poisson Distribution; D013314:Stress, Mechanical; D014465:Ultrasonics; D014463:Ultrasonography; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water