In vitro evaluation of normal and abnormal lungs with ultra-high-resolution CT.

Synchrotron radiation microtomography is a new technique with high directionality of a synchrotron radiation beam and a high-resolution detector array. In this study, we estimated the visualization of the peripheral human lung structure with an ultra-high-resolution computed tomography (CT) system, the synchrotron radiation CT. The synchrotron radiation CT system uses the bending magnet beamline emitted from the 8.0 GeV electron storage ring. Six lung specimens were obtained at autopsy: 3 normal, 1 cellular alveolitis, 1 diffuse alveolar damage, and 1 pulmonary hemorrhage. Each specimen was cut down to a cylindrical sample with 6-mm diameter and 15- to 25-mm height. The synchrotron radiation CT images of these lung samples were obtained using the ultra-high-resolution image detector system with a charge coupled device (CCD) array detector (1024 × 1024 pixels with 12 × 12 μm2 pixel size). After that, the sample specimens were sliced to 200 μm (micrometer) thickness, and were observed with a stereomicroscope and by contact radiography. Finally, approximately 10-μm thick microscopic images were obtained and compared with the synchrotron radiation CT images. The synchrotron radiation CT could depict the peripheral lung including peripheral airways, airspaces, and alveolar walls individually. Each finding in the 3 disease processes seen on the synchrotron radiation CT images correlated well with the microscopic findings. The synchrotron radiation CT allows microtomographic imaging of human lung specimens with ultra high-spatial resolution (12 μm) on a level approaching that of conventional histopathology, without sectioning.