Design and Testing of a Single-Element Ultrasound Viscoelastography System for Point-of-Care Edema Quantification

摘要

Management of fluid overload in patients with end stage renal disease represents a unique challenge where clinical practice still lacks 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 UVE system feasibility 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 less than or equal to 4%. Motion tracking showed high correlation and signal-to-noise ratios, indicating that the system is reliable.