Design of Electromechanical Attachments for Improved Ultrasound Imaging Repeatability

Abstract

Ultrasound imaging (or ultrasonography) is a common tool used for medical diagnostics. It has many advantages over other imaging modalities (such as MRI and CT) such as being more portable, less expensive, and lower power. Ultrasound imaging is emerging as a noninvasive diagnostic alternative in many applications that traditionally rely on biopsies.

Ultrasound imaging also has notable limitations, such as being highly operator dependent and having low resolution at large imaging depths. In recent years, several engineering solutions have been designed to overcome these limitations, such as force-coupled ultrasound, external mechanical vibration (EMV) for shear wave elastography (SWE), and volume ultrasound. Each of these technologies also has its limitations and some have not been optimized for clinical settings.

In this work, these technologies are developed further into attachments to allow for easier and simultaneous use in clinical ultrasound settings. A more compact force coupling attachment was designed using a linear DC servomotor and validated with external sensors. An external vibration system for SWE, designed in previous work, was developed to improve resistance to debris and its dynamic performance was experimentally validated. An optical tracking module was incorporated for estimating the probe’s 6 degrees of freedom and its performance was quantified. Electronic hardware and a Robot Operating System (ROS) network were developed to synchronize the three attachments for control through a single, custom MATLAB application.

The ultrasound probe attachments were used in experiments on calibrated phantoms and human subjects. Initial experimental results validated the effectiveness of force coupling on improving imaging variability. The combination of force coupling and optical tracking enabled force-coupled, elastogram volumes to be created in post-processing.