In our study, the imaging of alveoli has shown promising results without any contrast agent. The 3D reconstruction technique provided an excellent view of lung and revealed structural details that were invisible to conventional radiography. The surface rendering results gave a perfect description of complex spatial relationships among bronchi, bronchioles and alveoli. The 3D volume data allowed virtual endoscope of the lung airways which helped the doctor visualize the 3D model of lung and perform a diagnosis without having to operate on the patient. Moreover, the measurement of alveoli showed the ability of PCI to observe the morphology of lung. Therefore, this technique has the potential use in disease diagnosis, such as asthma, chronic bronchitis and emphysema, which are associated with the size or morphology of lung airways. There are also potential uses in pharmacology when determining the optimum diameter of aerosolized drugs in lungs.