title: Correspondence of ultrasound elasticity imaging to direct mechanical measurement in aging DVT in rats.
abstract: Previous ultrasound elasticity imaging experiments supported a generally accepted concept that the hardness of deep venous thrombi increases with thrombus aging. Results also showed that this noninvasive imaging technique can accurately predict thrombus age through strain estimates, in a well-controlled animal study. In the present study, as an alternative means to characterize elastic properties of thrombi, we used a direct mechanical measurement system to estimate Young's modulus of ex vivo thrombi. Unlike conventional indentation tests, the device uses a specific compression geometry for cylindrical tissue specimens. We also proposed an approximation scheme to retrieve Young's modulus from force-displacement measurements made using the device. Finite element simulations and calibrations on tissue-mimicking phantoms validated the system. Then, using two groups of rats with surgically-induced thrombi, we further investigated the correlation between Young's modulus measured ex vivo and elasticity images reconstructed in vivo. This comparison was accomplished by converting the intrathrombus strains measured in the in vivo studies into Young's modulus estimates using a model-based approach. Good agreement between time-dependent Young's modulus estimates observed in vivo and direct measurements of Young's modulus using the mechanical device helps to confirm the ability of elasticity imaging to age deep venous thrombi for efficient treatment.
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Xie
authors.forename: Kang
authors.initials: K
authors.lastname: Kim
authors.forename: Salavat R
authors.initials: SR
authors.lastname: Aglyamov
authors.forename: Stanislav Y
authors.initials: SY
authors.lastname: Emelianov
authors.forename: Matthew
authors.initials: M
authors.lastname: O'Donnell
authors.forename: William F
authors.initials: WF
authors.lastname: Weitzel
authors.forename: Shirley K
authors.initials: SK
authors.lastname: Wrobleski
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Myers
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Wakefield
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Rubin
mesh_terms: D000375:Aging; D000818:Animals; D003198:Computer Simulation; D004548:Elasticity; D020342:Finite Element Analysis; D023421:Models, Animal; D019047:Phantoms, Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000000981:diagnostic imaging* / Q000503:physiopathology