A Handheld Probe for Focused Shear Wave Transient Elastography

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Ultrasound Technology

Background:

• Noninvasive liver stiffness assessment is crucial for diagnosing liver diseases.
• Conventional shear wave elastography faces limitations due to shear wave attenuation in deep tissues.
• Deep tissue elastography is challenging for patients with obesity or deep liver lobes.

Purpose of the Study:

• To introduce and validate a handheld focused shear wave transient elastography (fTE) device.
• To enhance shear wave generation and propagation for improved deep tissue elastography.
• To address limitations of conventional transient elastography in deep or obese patients.

Main Methods:

• A handheld fTE device was developed using a 3D-printed concave piston and phased ultrasound array.
• Benchtop validation compared fTE measurements with conventional methods and ground-truth imaging.
• Handheld setup assessed repeatability using different piston geometries in tissue-mimicking phantoms.
• Supersonic shear wave imaging (SSI) was used for independent validation of shear wave speed (SWS) calculations.

Main Results:

• fTE-measured SWS showed agreement within 10% of conventional transient elastography.
• Focused pistons generated significantly higher shear wave amplitudes (2x-7x) at 45 mm depth compared to unfocused pistons.
• SWS measurement variance was significantly lower with focused shear waves (p < 0.0001).
• Handheld fTE demonstrated unbiased SWS measurements across piston geometries and against SSI.

Conclusions:

• Surface-generated focused shear waves are feasible for robust liver stiffness assessment.
• The handheld fTE device enhances shear wave amplitude and measurement consistency at depth.
• This technology offers a promising solution for noninvasive elastography in patients with deep livers or high BMI.