Non-destructive three-dimensional structural assessment of transbronchial cryobiopsy specimens using phase-contrast X-ray CT: a proof-of-concept study.

BACKGROUND: Histopathological evaluation of lung biopsy specimens is inherently destructive and reduces the three-dimensional tissue architecture to limited two-dimensional sections. For small bronchoscopic specimens, this may compromise the optimal tissue utilization for diagnosis and molecular testing. We investigated whether synchrotron-based phase-contrast X-ray computed tomography (CT) could be used to non-destructively visualize the three-dimensional architecture of clinically obtained transbronchial cryobiopsy specimens. METHODS: In this exploratory imaging study, we prospectively enrolled patients with peripheral pulmonary lesions who underwent bronchoscopy. An additional single cryobiopsy specimen was obtained and imaged using synchrotron-based phase-contrast CT. The structural features were evaluated by three blinded observers using predefined ordinal scores. Interobserver agreement was assessed using the weighted kappa and intraclass correlation coefficients. Representative cases underwent serial histological sectioning, and exploratory slow-freezing micro-CT imaging was performed on a subset. RESULTS: Fifteen patients were included. Phase-contrast CT revealed major structural features including alveolar-like airspaces, tissue density, glandular lumina, solid nest-like structures, thickened bronchial wall structures, and calcified foci. The imaging findings generally corresponded to the histological findings. Interobserver agreement was moderate to substantial for airspace preservation and tissue density, whereas agreement was poor for glandular and solid nest-like structures. Exploratory micro-CT showed partial visualization of finer structures but was limited by image blurring and distortion. CONCLUSIONS: Synchrotron-based phase-contrast CT enabled non-destructive three-dimensional structural visualization of clinically obtained transbronchial cryobiopsy specimens. Although the current resolution remains insufficient for detailed histological classification, this study represents a proof-of-concept for the feasibility of this imaging technique rather than a clinical workflow utility.