Optical computed-tomographic microscope for three-dimensional quantitative histology.

A novel optical computed-tomographic microscope has been developed allowing quantitative three-dimensional (3D) imaging and analysis of fixed pathological material. Rather than a conventional two-dimensional (2D) image, the instrument produces a 3D representation of fixed absorption-stained material, from which quantitative histopathological features can be measured more accurately. The accurate quantification of these features is critically important in disease diagnosis and the clinical classification of cancer. The system consists of two high NA objective lenses, a light source, a digital spatial light modulator (DMD, by Texas Instrument), an x-y stage, and a CCD detector. The DMD, positioned at the back pupil-plane of the illumination objective, is employed to illuminate the specimen with parallel rays at any desired angle. The system uses a modification of the convolution backprojection algorithm for reconstruction. In contrast to fluorescent images acquired by a confocal microscope, this instrument produces 3D images of absorption stained material. Microscopic 3D volume reconstructions of absorption-stained cells have been demonstrated. Reconstructed 3D images of individual cells and tissue can be cut virtually with the distance between the axial slices less than 0.5 microm.