High-Speed Volumetric Dual-Mode Ultrasound and Photoacoustic Tomography With a Single-Element Detector

Acoustic wave detection techniques like ultrasound (US) and photoacoustic (PA) tomography are widely used in biomedical imaging but often require expensive transducer arrays and complex setups for 3D imaging. To overcome these challenges, recent research has explored using an ergodic relay (ER) with a single-element transducer. This approach improves imaging speed at low cost and reduces complexity. This study presents a dual-mode system that utilizes an ER for single-shot, 3D PA and US imaging with a single-element detector. Each ultrasonic or optical excitation pulse generates a 1D signal, which is then used to reconstruct a 3D image in US or PA mode. While the PA mode provides optical absorption-based contrast, the US mode offers complementary acoustic scattering-based contrast. We demonstrate the system's capabilities through in vivo imaging of blood vessels and skin structure in human hands. The system is non-invasive, label-free, and ultrafast, enabling 4D imaging with simplified hardware requirements.