Feasibility Study of Limited-Angle Reconstruction for in Vivo Optical Projection Tomography Based on Novel Sample Fixation

Optical projection tomography (OPT) is a novel three-dimensional imaging technique, which provides an approach to recreating the three-dimensional images of biological specimens ranging from millimeters to centimeters. In the current OPT setup, the specimen was immersed in the index-matching fluid. In this case, the specimen could not survive or the survival time was too short for longitudinal imaging. In this paper, we first designed a new type of sample fixation method for in vivo OPT imaging. The specimen was embedded into a transparent gel in a petri dish, and the dish was affixed to the rotational stage of our homemade OPT system. As the specimen does not need to be immersed in the index-matching fluid, this method can reduce the damage to the specimen and it is more conducive to longitudinal observation for in vivo OPT. However, this fixation method induces a problem of insufficient measurements. The angles parallel to or nearly parallel to the surface of the dish cannot be acquired. To address this problem, we, then, used a limited-angle reconstruction framework for the novel sample fixation-based OPT, which combines the algebraic reconstruction technique (ART) algorithm with prior information to solve the inverse reconstruction problem. The feasibility and effectiveness of the proposed sample fixation method and the limited-angle reconstruction framework were verified by the simulations and experiments.