Conformable transducers for large-volume, operator-independent imaging

Abstract

While ultrasound's cost, safety and interesting contrast mechanisms are of great clinical value, its operatordependence, extensive sonographer training needs, uncompetitive scan times, poor ergonomics and low reproducibility in serial studies limit its proliferation. This paper examines opportunities to solve these problems and increase ultrasound's application space via arrays which conform to the patient's body contours. Progress towards a conformable array maintaining ultrasound's existing feature set has been promising, but a complete system is yet to be demonstrated. The article first outlines the motivation for such arrays, defines design requirements, and describes an ideal design. Next, work on partial hardware realizations of conformable arrays is reviewed, and types of signal processing specific to conformable systems are discussed. Finally, future research directions are envisioned.Operator-independent ultrasound requires large acquisition volumes with voxels isotropic enough to allow post-scan clinical assessment without regard for scanning geometry. Information rate is presented as a useful metric to compare the diagnostic utility of these systems. Two new hardware realizations are described to illustrate progress towards the conformable array goal. An automated breast-scanning design with a matrix receiver using silicon transducers (cMUTs) shows provocative performance in a micro-calcification detection simulation. A reconfigurable matrix array, also using cMUTs, provides volume imaging performance characteristic of a fully-sampled aperture with sufficiently modest interconnect demands to be feasible in a transesophageal echo (TEE) application.

Ubiquitous conformable systems for imperceptible computing

“…Given that various optical (Ko, 2008), mechanical (Dagdeviren, 2014a;Dagdeviren, 2015;Dagdeviren, 2014b;Daft, 2010), electrical (Fayyaz Shahandashti et al, 2019Oribe, 2019) and chemical (Dagdeviren, 2018) stimuli have been sensed or actuated in conformable or near-conformable form factors thus far, the use of conformable sensor readings interpretable via machine learning algorithms (Picard, 2000;Bernal et al, 2018) could enable the decoding of human psychological states. As current mechanisms for interpreting psychological states involve direct measurement of a few weakly correlated signals (electrodermal activity [EDA], heart rate, breathing rate, epidermal temperature), the wealth of multisensory probing of both human and environmental factors made possible by conformable sensors expands the available phase space from which more accurate hyperplanes for distinguishing distinct psychological phenomena may be deduced.…”

A CMUT-based finger-mounted 3D ultrasound probe

“…A 3D image can relieve the user from physically maintaining the viewing plane. A holistic hands-free 3D design has been proposed by Daft [1] where a conformable array was used. Another innovative design that offers hands-free scanning is the finger ultrasound probe designed by Sonivate Medical [2].…”

Simultaneous Bilateral Real-Time 3-D Transcranial Ultrasound Imaging at 1 MHz Through Poor Acoustic Windows

“…This group is currently attempting to train paramedics to perform such exams (Holscher 2012); the outcome of this training program will provide an important indicator as to the feasibility of performing transcranial ultrasound examinations by operators with limited training. Manufacturers of ultrasound scanners have also investigated reducing the operator dependence of ultrasound scans in various anatomical regions, including designing conformal arrays for abdominal imaging (Daft 2010), developing an automated breast scanner (Porter and Seck 2009) and providing on-screen feedback of probe placement in transcranial imaging (Vignon et al 2009). If emergency medical personnel could acquire diagnostically useful images in the field, those images might be transferred to the stroke team at the hospital via telemedicine, as has recently been demonstrated with a portable CT scanner and a telemedicine unit (Walter et al 2012).…”