3-DIMENSIONAL IMAGING OF VASCULATURE AND PARENCHYMA IN INTACT RODENT ORGANS WITH X-RAY MICRO-CT

A microcomputed tomography (micro-CT) scanner, which generates three-d imensional (3-D) images consisting of up to a billion cubic voxels, ea ch 5-25 mu m on a side, and which has isotropic spatial resolution, is described. Its main components are a spectroscopic X-ray source that produces selectable primary emission peaks at similar to 9, 18, or 25 keV and a fluorescing thin crystal plate that is imaged (at selectable magnification) with a lens onto a 2.5 x 2.5-cm, 1,024 x 1,024-pixel, charge-coupled device (CCD) detector array. The specimen is positioned close to the crystal and is rotated in 721 equiangular steps around 3 60 degrees between each X-ray exposure and its CCD recording. Tomograp hic reconstruction algorithms, applied to these recorded images, are u sed to generate 3-D images of the specimen. The system is used to scan isolated, intact, fixed rodent organs (e.g., heart or kidney) with th e image contrast of vessel lumens enhanced with contrast medium. 3-D i mage display and analysis are used to address physiological questions about the internal structure-to-function relationships of the organs.