We present a multimodal imaging system that seamlessly integrates ultrasound imaging, photoacoustic imaging, and optical coherence tomography using a transparent ultrasonic transducer. We demonstrate the system’s use in imaging responses to mouse body in vivo.
Multi-modal imaging technique has significantly spotlighted since it can provide a variety of information by combining the complementary merits of several single-modal imaging. In particular, in order to compensate for each shortcoming and improve image quality, an integrated optical and ultrasonic imaging system is being actively researched. However, the non-transparency of the ultrasound transducer made it difficult to integrate the optical and ultrasound imaging system. In previous study, we introduced the transparent ultrasound transducer (TUT) and dual-modal photoacoustic imaging (PAI)/ultrasound imaging (USI) system using the TUT. In this study, we present the multi-modal imaging system integrated with PA, US and optical coherence tomography (OCT). OCT has the advantage of acquiring anatomical information at optical resolution under subsurface and transparent media. To explore the usefulness of the multi-modal imaging system, we have successfully performed in vivo animal experiments: 1) eye imaging experiments and 2) subcutaneous melanoma imaging. In PAI, blood vessels and melanoma are clearly visualized. In OCT, the morphological information in shallow depth are observed in detail. In USI, the melanoma boundary and surrounding tissues are clearly confirmed. These results show that TUT based multi-modal imaging system can serve as a comprehensive in various applications.
Ultrasound transducers, one of the most widely used sensors in the era of the fourth Industrial Revolution, have been recognized and used in a variety of industries including medical, automotive, and robotics. In particular, recent research has focused on the development of multi-mode imaging systems that combine ultrasound and optical imaging to improve the accuracy of information acquisition. Unfortunately, its efficient combination has been severely limited due to the inherent opacity of conventional ultrasound transducers. These limitations cause off-axes between the ultrasound (US) and optical signal paths, resulting in low signal-to-ratio and bulky system. This is especially a critical problem for a photoacoustic (PA) imaging system that requires the ultrasonic transducer to detect the photoacoustic signal. Here, we introduce a newly developed optically transparent ultrasound transducer (TUT) to overcome the limitation. We combined the developed TUT with an optical resolution photoacoustic microscopy (OR-PAM). Using a mouse, we successfully acquired in vivo PA and US images and confirmed the feasibility of the TUT and TUT integrated OR-PAM system.