Forward-looking Multimodal Endoscopic System based on Optical Multispectral and High-frequency Ultrasound Imaging techniques for Tumor Detection.

We developed a forward-looking (FL) multimodal endoscopic system that offers color, spectral classified, high-frequency ultrasound (HFUS) B-mode, and integrated backscattering coefficient (IBC) images for tumor detection in situ. Examination of tumor distributions from the surface of the skin to deeper inside is essential for determining a treatment plan of cancer. For example, the submucosal invasion depth of tumors is used as an indicator of whether the endoscopic dissection would be operated. Furthermore, the development of the FL endoscopic probe based on optical and ultrasound imaging modalities may be required for various in vivo applications. Thus, we devised the FL multimodal endoscopic system to offer information on the tumor distribution from the surface to deep tissue with high accuracy. This system was evaluated with bilayer gelatin phantoms which have different properties at each layer of the phantom in a lateral direction. After evaluating the system with phantoms, it was employed to characterize forty human colon tissues excised from cancer patients. The proposed system could obtain highly resolved chemical, anatomical, and macro-molecule information on excised colon tissues including tumors, thus facilitating the detection of tumor distributions from the surface to deep tissue. These results suggest that the FL multimodal endoscopic system could be an innovative screening instrument for quantitative tumor characterization.