Fig. 2
Comparative imaging of fresh and formaldehyde (FA) vapour-fixed pig lung tissue. (a) Three-dimensional rendering of a passively inflated fresh pig lung positioned within the anthropomorphic chest phantom, acquired using near-field propagation-based phase-contrast imaging (NF-PBI). (b) The same lung imaged 11.5 h later following 6 h of FA vapour fixation, without negative pressure during acquisition. No significant loss of NF-PBI image quality was observed post-fixation. (c) Photograph of the same lung prepared for histological analysis approximately 4 weeks after imaging. The magnified region (black rectangle) reveals successful preservation of the porous pulmonary architecture and the absence of residual liquid in the bronchial tree. The heart was removed prior to fixation to ensure consistent tissue penetration. Nine fixed paraffin-embedded (FFPE) tissue blocks were generated from the imaged slice. (d) Montage of the hematoxylin and eosin (H&E)-stained superficial sections of the FFPE blocks spanning the full cross-section of the fixed lung. White arrowheads in a–d indicate the same bronchus used as an anatomical reference point across modalities. Three-dimensional renderings (a and b) were virtually re-sliced to match the histological cutting plane (c) as closely as possible. (e and f) Higher-magnification views of a representative region (indicated by magnifying glass icons in d and e), demonstrating structural integrity and preservation of alveolar microanatomy.
