Sensitivity of laser opto-acoustic imaging in detection of small deeply embedded tumors

Current imaging modalities fail to detect small tumors in the breast. Opto- acoustic tomography is a novel technique for early cancer detection with pr omising diagnostic capability. The experimental limit of sensitivity and ma ximal depth of the laser opto-acoustic detection for small model tumors loc ated within bulk phantom tissue were studied, Two phantoms with optical pro perties similar to that of breast tissue in the near infrared spectral rang e were used in these studies: turbid gelatin slabs with the thickness of 10 0 mm and chicken breast muscle slabs with the thickness of up to 80 mm, Gel atin spheres with enhanced absorption coefficient relative to the backgroun d absorption and liver tissue were used to simulate small tumors. The exper iments demonstrated the capability of laser optoacoustic imaging to detect and localize phantom tumors with the diameter of 2 mm at a depth of up to 6 0 mm within the gelatin phantoms and 3 x 2 x 0.6-mm piece of liver tissue w ithin 80-mm chicken breast tissue, Theoretical studies on sensitivity of op to-acoustic detection at various diameters, depths of location, and absorpt ion coefficients of small tumors mere performed using the experimental data . Our results suggest that the opto-acoustic imaging may occupy a significa nt niche in early detection of cancer in the breast and other organs.