A Comprehensive Study of Laboratory-Based Micro-CT for 3D Virtual Histology of Human FFPE Tissue Blocks

Abstract

Advances in laboratory-based X-ray computed tomography (CT) have enabled X-ray 3D virtual histology. This method shows a great potential as a complementary technique to conventional 2D histology where extensive volumetric sampling is necessary. While formalin-fixed paraffin-embedded (FFPE) tissue blocks are the backbone of clinical histology, there exists no generic optimization, and technical study of the X-ray 3D virtual histology of FFPE blocks. X-ray micro-CT of FFPE blocks is studied and optimized in their native state within the cassette to minimize the interference of X-ray 3D virtual histology with clinical workflows and standards, hence facilitating the technology transfer to the clinics. The optimization is carried on the sample positioning, tungsten tubes acceleration voltage, and artifact reduction. Then propagation-based imaging of FFPE blocks is extensively discussed. Hierarchical (local) tomography and laminography are presented as viable approaches for achieving higher spatial resolutions. In the end, future perspectives are given by considering state-of-the-art micro-CT scanners using liquid-metal-jet sources, large-area detectors, and photon counting detectors. The results achieved here are generic and can be applicable to any laboratory-based scanner with a tungsten target source and cone-beam geometry. This article provides a starting point for anyone new to X-ray 3D virtual histology on FFPE blocks, but also serves as a useful source for more experienced users.INDEX TERMS 3D virtual histology, computed tomography, formalin-fixed paraffin-embedded blocks, phase-contrast imaging, propagation-based imaging, transport of intensity equation, X-ray imaging.