Our body is hierarchically organized down to individual cells. Cutting-edge clinical imaging facilities reach a spatial resolution of a fraction of a millimeter, living cells invisible. A decade ago, post-mortem X-ray imaging by means of synchrotron radiation enabled the identification of Os-stained ganglion and unstained Purkinje cells. Very recently, even sub-cellular structures, such as nucleolus and the dendritic tree of Purkinje cells, were extracted by means of phase-contrast single-distance synchrotron radiation-based hard X-ray tomography. At the same time, conventional absorption-contrast, laboratory-based micro computed tomography was successfully applied to visualize brain components including individual Purkinje cells within a cerebellum specimen. Thus, the goal of isotropic-cellular-resolution visualization of soft tissues within a laboratory environment without application of any dedicated contrast agent was achieved. In this communication, we are discussing (1) to which extend the quality gain of the laboratory-based absorption-contrast tomography can be driven with respect to optical microscopy of stained tissue sections and (2) what value such a technique would add. As a proof of principle, four histological sections were affine-registered to corresponding three-dimensional (3D) tomography dataset. We are discussing a semi-automatic landmark-based 2D-3D registration framework and compare registration results based on mean square difference (MSD) metrics.
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