Three-dimensional visualization of intact mouse lung by synchrotron radiation CT

Airway is a complex branching structure of many compliant tubes, and then airway geometry and compliance have many biomechanical and clinical implications. In this study, we visualized an intact mouse lung without dehydration and fixation using synchrotron radiation CT at Spring-8 in Japan. The CT system consists of X-ray light source, a double crystal monochromator, a rotation stage and a high-resolution image detector. The angular projections were sequentially obtained during the sample rotation with the total scan shorter time than 15 min. The effective spatial resolution was 30 mum. Using this system, three-dimensional images of small airways and alveoli were obtained under physiological condition. Moreover, we visualized the same airways at FRC (functional residual capacity) and TLC (total lung capacity). The airway geometry deformed dramatically and the diameter expanded 1.2 - 1.7 times at TLC in comparison with at FRC. This deformation was larger for smaller airways. This system opens the way to new research of the pulmonary dynamics and physiological implications.