Preclinical photoacoustic imaging endoscope based on acousto-optic coaxial system using ring transducer array.

We developed and fabricated a preclinical photoacoustic imaging endoscope (PAIE) with an acousto-optic coaxial structure for cavity imaging that integrates a Plexiglas tube, an optical fiber, a ring transducer array, a taper reflector, and an ultrasonic coupling medium. A photoacoustic image for a section of pig colorectal tissue embedded in a transparent gelatin phantom was reconstructed. Furthermore, human colorectal cancer and normal colorectal tissue were imaged ex vivo with a contrast ratio of approximately 2.3. Experimental results demonstrate that the PAIE has potential for detecting colorectal cancer in clinical use.