Real-time photoacoustic and ultrasonic dual-modality imaging system for early gastric cancer: Phantom and ex vivo studies

Photoacoustic (PA) and ultrasonic (US) imaging are promising techniques for imaging biological tissue and diagnosing internal organs. This paper presents a real-time PA and US dual-modality imaging system for early gastric cancer (EGC) based on a clinical US transducer. It has the advantage that only the PA excitation is inside the body but the US imaging system is outside the body, which makes the system less invasive for EGC detection and will be a potential tool for clinical use. The first experiments produced real-time PA images of blood vessel phantoms. Cross-sectional 2D PA images and reconstructed 3D PA images of the blood vessel phantoms demonstrate the system can clearly identity tissue structure. The experiments show that the system has a high axial spatial resolution but a relatively low lateral spatial resolution. The second experiments combining US and PA imaging, an artificial slightly elevated tumor and three artificial superficial flat tumors embedded inside the pig stomach mucosa ex vivo, demonstrate that the system is able to detect EGC accurately.