embalming involves cadaver perfusion and immersion for several months in a fluid made up mainly of water, glycol, and various salts, used by medical schools for educational purposes. Moreover, other human spinal cord samples were extracted from the bony intervertebral canal and formalin-fixed. All samples were imaged with monochromatic 60-keV X-rays and a propagation-based X-ray phase-contrast micro-CT with 463 μm3 and 83 μm3 voxel sizes. Phase-retrieved CT datasets were reconstructed and rendered in 3D after segmentation of hard versus soft tissues.
The volumetric nature of the collected CT data permitted 2D to 3D visualisations and explorations of micrometric spinal anatomy without the need for sample sectioning. Imaging of the Thiel-embalmed samples demonstrated macroscopic spinal column anatomy and inter-tissue boundaries, and resulted in soft- tissue contrast within the vertebral canal, and in the rendering of gross spinal cord anatomy, spinal meninges, spinal spaces, and contrast agent-enhanced spinal vasculature alongside surrounding vertebral bone structure (Figure 60). It also demonstrated the feasibility of concurrent high-contrast soft-tissue and bone-tissue morphologic visualisations with the same X-ray phase-contrast micro-CT data, with image gray levels optimisable alternatively for soft tissue or for bone structure visualisations. The extracted and formalin-fixed human cadaveric spinal cord samples lead to intra-cord grey versus white matter contrast and, notably, to the contrast agent-free visualisation of micrometre-scale intramedullary vascular and cellular structures. These data permitted detailed examination of the medullary blood supply network, including both its central and peripheral systems, and of neuron cell somas populating anterior grey column nuclei (Figure 61).
Fig. 60: a) Sagittal, (b) axial and (c) zoomed axial view of phase-contrast micro-CT slices depicting cervical-level human spinal column anatomy within a Thiel-embalmed specimen. Spinal cord: SC, epidural space: eDS, spinal meninges: SM, dorsal and ventral nerves: dN, vN,
dorsal root ganglia: dRG, vertebral body: VB. Red asterisks label vasculature perfused with ANGIOFIL (iodinated contrast agent).
Fig. 61: a) Two-dimensional maximum intensity projection and (b) zoomed view, of an extracted formalin-fixed human spinal cord specimen, obtained from 100 consecutive slices of the same phase-
contrast micro-CT 3D image stack. c) 3D rendering (and zoom, inset) of intramedullary vascular and cellular microanatomy. Grey matter:
gM, white matter: wM, vascular features (red arrows), cellular features (magenta arrows).