[OPTICAL REVIEW Vol. 10, No. 5 (2003) 447-451]
© 2003 The Optical Society of Japan

In Vivo Laser Tomographic Imaging of Mouse Leg by Coherent Detection Imaging Method

Shinji TANOSAKI, Yoshiaki SASAKI, Michiaki TAKAGI1, Akira ISHIKAWA1, Hiroki INAGE, Ryota EMORI, Jyota SUZUKI, Tetsuya YUASA, Hiroshi TANIGUCHI2, Balasigamani DEVARAJ3 and Takao AKATSUKA

Faculty of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan
1School of Medicine, Yamagata University, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
2Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551, Japan
3New Focus Inc., 5215 Hellyer Avenue, San Jose, CA 95138-1001, U.S.A.

(Received January 20, 2003; Accepted May 21, 2003)

The coherent detection imaging (CDI) technique based on the optical heterodyne detection method enables selective filtering of the directional coherent retaining emergent photons from biological tissues with a highly scattering nature. Therefore, the CDI can acquire on-axis information in the transillumination mode and use the same data-acquisition protocol and reconstruction algorithm as those in X-ray computed tomography (CT). Although the CDI-based laser CT cannot image thick subjects such as the head and chest, it can delineate subjects with a thickness up to several cm at a spatial resolution of sub-millimeters. We are planning to apply the technique to early diagnosis of rheumatoid arthritis (RA). Here, we performed an experiment using mice to confirm the feasibility. We compared in vivo CT images at the level of ankle joints of two mice, one normal and the other with collagen induced arthritis (CIA) as an RA model, and demonstrated that there occur significant discrepancies between the two distributions of image intensities, i.e., reconstructed scattering coefficients in each region of interest (ROI) prepared. We suggest that combining the morphological information with the quantitative information can be effective for early diagnosis of bone diseases and disorders such as rheumatoid arthritis.

Key words: laser computed tomography, coherent detection imaging, optical heterodyne detection, rheumatoid arthritis