Noninvasive detection and staging of oral cancer in vivo with confocal opto-acoustic tomography

Confocal opto-acoustic transducer (COAT) was developed and applied for detection of early stages of squamous cell carcinoma in hamster model of oral cancer. COAT is a novel imaging modality with optical and acoustic lens utilized for detecting in-depth opto-acoustic profiles from a narrow cone of laser-irradiated tissue. The most important modification of COAT compared with early opto-acoustic front surface transducer (OAFST) is an improved lateral resolution of 60-μm. The bandwidth of the confocal opto-acoustic transducer is more than 100 MHz. Therefore, in-depth axial resolution defined by the laser pulse duration and detection system equals 15-μm. Imaging was performed at the wavelength of the Nd:YAG laser second harmonic (532 am), which provided sufficient depth of monitoring (approximately 1.5 mm) and significant tissue contrast. Correlation of the opto-acoustic images with H&E histology sections in control animals and in animals treated with carcinogenic agent, DMBA, confirmed previous findings that early cancer lesions invisible by the naked eye may be detected with the opto-acoustic tomography. Compact design of COAT allows, in principle, application of the opto-acoustic imaging in any organ of the human digestive system.