Opto-acoustic window enabled plug-and-play photoacoustic-ultrasound dual-modal imaging

Photoacoustic imaging (PAI) and ultrasound imaging (USI) are important biomedical imaging techniques due to their unique and complementary advantages in tissue structure and function visualization. In this Letter, we propose a plug-and-play photoacoustic-ultrasound dual-modal imaging system (PnP-PAUS) with a disposable opto-acoustic window (OAW). This OAW allows part of the light to go through it, and another part of the light to be converted to a US transmission signal by the PA effect. By single laser pulse illumination, both PA signals and reflected US signals can be generated. Then, a linear array probe receives both PA and US signals, enabling simultaneous dual-modal PA and US imaging. Phantom experiments were conducted involving pencil lead, hair, and a plastic tube with a black spot, as well as an in vivo experiment on a human finger. The US signals generated by the OAW reached a cross-correlation coefficient of 0.988 with the signals from a commercial single-point probe. The stable cross-correlation coefficient between the laser-induced ultrasound signals over 1460 s is above 0.968. The system’s resolutions for PA and US imaging are 215 μm and 91 μm, with signal-to-noise ratios for PA and US signals reaching up to 37.48 dB and 29.75 dB, respectively, proving the feasibility of the PnP-PAUS dual-modal imaging. The proposed PnP-PAUS system with disposable OAW provides an immediate and cost-effective approach to enable US imaging capability based on an existing PA imaging system.