title: Design and Testing of a Single-Element Ultrasound Viscoelastography System for Point-of-Care Edema Quantification.
abstract: Management of fluid overload in patients with end-stage renal disease represents a unique challenge to clinical practice because of the lack of accurate and objective measurement methods. Currently, peripheral edema is subjectively assessed by palpation of the patient's extremities, ostensibly a qualitative indication of tissue viscoelastic properties. New robust quantitative estimates of tissue fluid content would allow clinicians to better guide treatment, minimizing reactive treatment decision making. Ultrasound viscoelastography (UVE) can be used to estimate strain in viscoelastic tissue, deriving material properties that can help guide treatment. We are developing and testing a simple, low-cost UVE system using a single-element imaging transducer that is simpler and less computationally demanding than array-based systems. This benchtop validation study tested the feasibility of using the UVE system by measuring the mechanical properties of a tissue-mimicking material under large strains. We generated depth-dependent creep curves and viscoelastic parameter maps of time constants and elastic moduli for the Kelvin model of viscoelasticity. During testing, the UVE system performed well, with mean UVE-measured strain matching standard mechanical testing with maximum absolute errors ≤4%. Motion tracking revealed high correlation and signal-to-noise ratios, indicating that the system is reliable.
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Pitre
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA; Department of Veterans Affairs Medical Center, Ann Arbor, Michigan, USA.
authors.forename: Leo B
authors.initials: LB
authors.lastname: Koziol
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA; Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, USA; Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Grant H
authors.initials: GH
authors.lastname: Kruger
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA; Department of Veterans Affairs Medical Center, Ann Arbor, Michigan, USA.
authors.forename: Alan
authors.initials: A
authors.lastname: Vollmer
authors.affiliation: Ultrasonics Laboratory, Department of Diagnostic and Interventional Imaging, University of Texas Medical School, Houston, Texas, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Ophir
authors.affiliation: Department of Physics, Universidad de Santiago, Santiago, Chile; G.E.A. Universitas SpA, Santiago, Chile.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Ammann
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA; Department of Veterans Affairs Medical Center, Ann Arbor, Michigan, USA.
authors.forename: William F
authors.initials: WF
authors.lastname: Weitzel
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA. Electronic address: joebull@umich.edu.
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Bull
mesh_terms: D004487:Edema / Q000000981:diagnostic imaging*; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019047:Phantoms, Imaging; D019095:Point-of-Care Systems; D015203:Reproducibility of Results; D014783:Viscosity
keywords: Creep experiment; Edema; End-stage renal disease; Point-of-care; Poroelasticity; Speckle tracking; Srain imaging; Ultrasound; Viscoelastography