A Novel Solid Hydrogel Sleeve Couplant for Ultrasound Imaging.

Objectives: To address the challenges of ultrasound scanning on curvilinear skin surfaces at joints, this study introduces a novel Shapable and Elastic Couplants sleeve of Hydrogel (SECH) based on a "Curve-to-Smooth" strategy. The aim is to improve acoustic wave transmission, enhance image quality, and enable efficient 3D imaging of high-curvature body parts such as the hand, foot, shoulder, and neck.

Methods: The SECH was fabricated using acrylamide (AAm) as the primary monomer, N,N-methylenebisacrylamide (MBAA) as the crosslinking agent, ammonium persulfate (APS) as the initiator, and N,N,N',N'-tetramethylethylenediamine (TEMED) as the accelerator. A dual-mold strategy was employed to shape the hydrogel to specific body parts. Mechanical characterization was performed using tensile tests and manual stretching/compression cycles. Ultrasound imaging was conducted on a healthy adult male volunteer using the Vevo F2 system with an L38 linear probe transducer. Cyclic scans were performed on the hand, foot, shoulder, and neck, and 3D image reconstruction was achieved using Matlab and ImageJ.

Results: The SECH demonstrated effective mechanical properties, balancing softness and hardness to minimize air gaps and ensure stable acoustic wave transmission. Ultrasound imaging with SECH enabled high-quality 3D reconstructions of high-curvature body parts, including the hand, foot, shoulder, and neck. Multi-planar analysis of the images provided detailed diagnostic information for conditions such as hand fractures, Achilles tendon injuries, shoulder dislocations, and carotid artery stenosis.

Conclusion: The SECH represents a novel ultrasound scanning strategy that overcomes the limitations of conventional rigid probes on curvilinear surfaces. It facilitates large-area 3D imaging of high-curvature body parts, improving diagnostic accuracy and efficiency in clinical ultrasonography. This customizable hydrogel sleeve has the potential to enable convenient and automated ultrasound scanning for irregular anatomical areas.