Dresden 2017 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 13: Bioimaging and Spectroscopy II
BP 13.2: Vortrag
Dienstag, 21. März 2017, 10:00–10:15, HÜL 386
(Nanoscale) 3D virtual histology of neuronal tissues — •Mareike Töpperwien1, Martin Krenkel1, Kristin Müller1, Benjamin Cooper2, Jürgen Goldschmidt3, and Tim Salditt1 — 1Institute for X-Ray Physics, Göttingen, Germany — 2Max Planck Institute for Experimental Medicine, Göttingen, Germany — 3Leibniz Institute for Neurobiology, Magdeburg, Germany
Studies of the brain cytoarchitecture in mammals are routinely performed by classical histology, i.e. by examining the tissue under a light microscope after serial sectioning and subsequent staining of the sections. The procedure is labor-intensive and the threedimensional (3d) anatomy can only be determined after aligning the individual sections. Hard x-ray computed tomography (CT) is a promising alternative due to the potential resolution and high penetration depth, allowing for non-destructive imaging of the sample. However, in classical CT contrast formation is based on absorption of the x-rays, leading to a weak contrast for soft tissue like the brain and therefore diminishing the resolution. In order to visualize also weakly absorbing samples, the phase shift induced by the sample in the (partially) coherent beam can be used instead. As the optical constants leading to this shifted phase are up to 1000 times larger for soft tissues, contrast is increased. We use free-space propagation behind the object to convert this phase shift to a measurable intensity image. As contrast formation is based on interference of the disturbed wave fronts, the original phase distribution has to be reconstructed from the intensity images using suitable phase retrieval algorithms. In this work, we present x-ray phase-contrast tomography of neuronal tissues at our recently upgraded waveguide-based holo-tomography instrument GINIX at DESY. This setup allows for high resolution recordings with adjustable field of view and resolution, down to voxel sizes in the range of a few ten nanometers. We optimize for contrast and resolution by comparing different preparation techniques and recording strategies, reaching sub-cellular resolution in mm-sized tissue. Further, we show that even compact laboratory CT at an optimized liquid-metal jet microfocus source combined with suitable phase retrieval algorithms and preparation protocols enables single cell sensitivity in large reconstruction volumes of mouse brain which are consistent with classical histology results.