title: Ultrasonic characterization of the nonlinear properties of canine livers by measuring shear wave speed and axial strain with increasing portal venous pressure.
abstract: Elevated hepatic venous pressure is the primary source of complications in advancing liver disease. Ultrasound imaging is ideal for potential noninvasive hepatic pressure measurements as it is widely used for liver imaging. Specifically, ultrasound based stiffness measures may be useful for clinically monitoring pressure, but the mechanism by which liver stiffness increases with hepatic pressure has not been well characterized. This study is designed to elucidate the nonlinear properties of the liver during pressurization by measuring both hepatic shear wave speed (SWS) and strain with increasing pressure. Tissue deformation during hepatic pressurization was tracked in 8 canine livers using successively acquired 3-D B-mode volumes and compared with concurrently measured SWS. When portal venous pressure was increased from clinically normal (0-5mmHg) to pressures representing highly diseased states at 20mmHg, the liver was observed to expand with axial strain measures up to 10%. At the same time, SWS estimates were observed to increase from 1.5-2m/s at 0-5mmHg (baseline) to 3.25-3.5m/s at 20mmHg.
authors.affiliation: Department of Biomedical Engineering, Duke University, Room 136 Hudson Hall, Box 90281, Durham, NC 27708, USA. veronica.rotemberg@duke.edu
authors.forename: Veronica
authors.initials: V
authors.lastname: Rotemberg
authors.forename: Brett
authors.initials: B
authors.lastname: Byram
authors.forename: Mark
authors.initials: M
authors.lastname: Palmeri
authors.forename: Michael
authors.initials: M
authors.lastname: Wang
authors.forename: Kathryn
authors.initials: K
authors.lastname: Nightingale
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D004285:Dogs; D008099:Liver / Q000098:blood supply* / Q000000981:diagnostic imaging*; D008102:Liver Circulation / Q000502:physiology*; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D017082:Portal Pressure / Q000502:physiology*; D011169:Portal Vein / Q000502:physiology; D014463:Ultrasonography; D059289:Vascular Stiffness / Q000502:physiology
keywords: Acoustic radiation force impulse (ARFI); Hepatic pressure; Nonlinear mechanics; Shear wave speed