title: Predicting bone strength with ultrasonic guided waves.
abstract: Recent bone quantitative ultrasound approaches exploit the multimode waveguide response of long bones for assessing properties such as cortical thickness and stiffness. Clinical applications remain, however, challenging, as the impact of soft tissue on guided waves characteristics is not fully understood yet. In particular, it must be clarified whether soft tissue must be incorporated in waveguide models needed to infer reliable cortical bone properties. We hypothesize that an inverse procedure using a free plate model can be applied to retrieve the thickness and stiffness of cortical bone from experimental data. This approach is first validated on a series of laboratory-controlled measurements performed on assemblies of bone- and soft tissue mimicking phantoms and then on in vivo measurements. The accuracy of the estimates is evaluated by comparison with reference values. To further support our hypothesis, these estimates are subsequently inserted into a bilayer model to test its accuracy. Our results show that the free plate model allows retrieving reliable waveguide properties, despite the presence of soft tissue. They also suggest that the more sophisticated bilayer model, although it is more precise to predict experimental data in the forward problem, could turn out to be hardly manageable for solving the inverse problem.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7371, INSERM UMR S1146, Laboratoire d'imagerie biomédicale, 15 rue de l'école de médecine, F-75006, Paris, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bochud
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7371, INSERM UMR S1146, Laboratoire d'imagerie biomédicale, 15 rue de l'école de médecine, F-75006, Paris, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Vallet
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7371, INSERM UMR S1146, Laboratoire d'imagerie biomédicale, 15 rue de l'école de médecine, F-75006, Paris, France.
authors.forename: Jean-Gabriel
authors.initials: JG
authors.lastname: Minonzio
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7371, INSERM UMR S1146, Laboratoire d'imagerie biomédicale, 15 rue de l'école de médecine, F-75006, Paris, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Laugier
mesh_terms: D000465:Algorithms; D032701:Biomimetics / Q000379:methods; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D000071538:Cortical Bone / Q000000981:diagnostic imaging; D006801:Humans; D055595:Mechanical Phenomena; D008954:Models, Biological; D019047:Phantoms, Imaging; D000069453:Ultrasonic Waves; D014463:Ultrasonography / Q000379:methods