Recent advances in coherent detection imaging (CDI) in biomedicine: laser tomography of human tissues in vivo and in vitro

We review the advantages of the optical heterodyne detection-based coherent detection imaging system, for transillumination laser computed tomography (CT) in biomedicine using CW and single-frequency lasers as light sources. The unique properties of the coherent detection imaging system such as excellent directionality, selectivity, and high sensitivity are exploited to differentiate and detect the minimally deviated on-axis/near-axis photons emerging from a tissue enabling the reconstruction high-resolution laser CT images. Our recent progress on the applications of the coherent detection imaging system to laser CT of human fingers in vivo and calcified tissues in vitro at different wavelengths in the visible and near-infrared regions are described. The laser CT images are obtained with low incident power of a few milliwatts and are comparable to conventional imaging techniques. The internal layers of the imaged tissues could be clearly differentiated and identified with submillimeter resolution. We propose that further refinements in the coherent detection imaging system could lead to a novel and potential diagnostic tool in dentistry, osteology, and bone and joint related diseases and disorders