Ultrasound Viscoelastic Imaging of Breast Lesions : A Practical Hybrid Freehand Technique for Data Acquisition

ABSTRACT Ultrasound imaging of the breast is a standard method in breast cancer screening, along with mammography. The viscoelastic properties of soft tissue can provide supplementary information for radiologist to consider in their assessment of pathology and tissue characterization. Measuring these properties generally entails acquiring a time sequence of ultrasound images and calculating parametric data from it. As images are necessarily accumulated over time, acquisition is limited by the frame rate and memory capacity of the ultrasound machine, and practical considerations such as movement from the clinicians hands and patient breathing. This paper describes a technique for hybrid-freehand imaging of viscoelasticity (HYFIVE). It involves acquiring a time sequence of images making use of a simple purpose built canister enclosure for the ultrasound probe which allows for a stable and accurate manipulation of applied forces, without the need of motors, sensors or other sophisticated and costly parts. A sequence of ultrasound strain images was computed and a first order Kelvin-Voigt tissue model fit to the resulting strain vs. time curves to obtain parametric data related to tissue stiffness and viscosity. Experiments were conducted on both gelatin phantoms and clinical patient data