Holographic Imaging and Tomography of Biological Cells and Tissues

Abstract

This chapter reviews recent progress in propagation-based phase-contrast imaging and tomography of biological matter. We include both inhouse µ-CT results recorded in the direct-contrast regime of propagation imaging (large Fresnel numbers F), as well as nanoscale phase contrast in the holographic regime with synchrotron radiation. The current imaging capabilities starting from the cellular level all the way to small animal imaging are illustrated by recent examples of our group, with an emphasis on 3D histology.

Imaging intact human organs with local resolution of cellular structures using hierarchical phase-contrast tomography

“…Several other key procedures and modifications of the BM05 experimental hutch, summarized and prioritized in Table 1 and outlined in the Methods, describe essential developments for HiP-CT. Central to HiP-CT is the increased spatial coherence provided by the EBS. This spatial coherence allows propagation distances approaching the near-field limit for scans of the highest resolution and thus resolves faint density contrasts in soft tissue 1 .…”

“…We estimated the resolution of HiP-CT by Fourier shell correlation (FSC) analysis 1,16 . Resolution was estimated at the half-bit criterion to be 10.4 µm ± 0.17 µm for images at 2.5 µm per voxel, 18.3 µm ± 0.6 µm for images at 6.5 µm per voxel and 72 µm ± 3.4 µm for images at 25 µm per voxel (Extended Data Fig.…”

“…We estimated the resolution of HiP-CT via Fourier shell correlation analysis (FSC) 1 , 16 . Resolution was estimated at the 1/2 bit criterion to be 10.4±0.17 μm for 2.5 μm/voxel images, 18.3±0.6 μm for 6.5 μm/voxel and 72±3.4 μm for 25 μm/voxel images (see Extended Data 3 ).…”

“…Spatial mapping at the single-cell level for entire human organs is presently unfeasible in terms of existing techniques, data-storage requirements and analysis or interpretability 1 . A more practical approach is to provide overall spatial context at a lower resolution and then use this data to select smaller regions for higher-resolution imaging; this type of imaging can be considered hierarchical imaging.…”

“…Local tomography or zoom tomography is an established synchrotron technique that enables this hierarchical approach. While it has been developed for use in small (500-μm) biological tissue samples, contrast agents such as barium or osmium are often used 1,15,16 . For large objects for which staining is far more challenging, local tomography has been confined to objects with high density differences, such as those found in bones or fossilized remains [17][18][19] .…”