A multiscale X-ray phase-contrast tomography dataset of a whole human left lung

Abstract

Technological advancements in X-ray imaging using bright and coherent synchrotron sources now allows the decoupling of sample size and resolution while maintaining high sensitivity to the microstructures of soft, partially dehydrated tissues. The continuous developments in multiscale X-ray imaging resulted in hierarchical phase-contrast tomography, a comprehensive approach to address the challenge of organ-scale (up to tens of centimeters) soft tissue imaging with resolution and sensitivity down to the cellular level. Using this technique, we imaged ex vivo an entire human left lung at an isotropic voxel size of 25.08 μm along with local zooms down to 6.05–6.5 μm and 2.45–2.5 μm in voxel size. The high tissue contrast offered by the fourth-generation synchrotron source at the European Synchrotron Radiation Facility reveals the complex multiscale anatomical constitution of the human lung from the macroscopic (centimeter) down to the microscopic (micrometer) scale. The dataset provides comprehensive organ-scale 3D information of the secondary pulmonary lobules and delineates the microstructure of lung nodules with unprecedented detail.

A closer look at high-energy X-ray-induced bubble formation during soft tissue imaging

“…The postmortem study was conducted according to QUACS (Quality Appraisal for Cadaveric Studies) scale recommendations [68]. The postmortem processing of organs (human brain, lung, and liver) follows the previously discussed procedure involving formalin fixation and ethanol dehydration [6], [25], [69]. The human liver sample was imaged twice with HiP-CT, an X-ray phase-contrast imaging technique compatible with large soft tissue samples [6].…”

“…The slices fit laterally into the cylindrical plastic containers such that the section plane is parallel with the lid to simulate the imaging geometry in tomography [6] and to facilitate gas escape as they are formed on the tissue interior and surfaces. The tissue slices were immersed in 70% ethanol solution in water and immobilized with crushed agar [6], [25], [69]. The non-tissue controls contain only the agar-ethanol mixture.…”

“…Although exogenous micrometer-sized bubbles (microbubbles) may be injected into the sample to enhance contrast[21], [22], their uncontrolled creation during X-ray irradiation[23] is detrimental to long scans often required for high-resolution imaging of large samples[6] or for in vivo dynamic monitoring in developmental biology[8] and physiology[24]. Due to bubble growth and their motion, the experiments need to be interrupted and the sample reprocessed to mitigate the strong imaging artifacts[25] (see Fig. 1a-c).…”

Preparation of large biological samples for high-resolution, hierarchical, synchrotron phase-contrast tomography with multimodal imaging compatibility

“…Some organs, such as the lung, may require inflation. This can be partially accomplished at the fixation stage by using the instillation of formalin in the lungs under controlled pressure 59 . The lung is perfused with 4% formalin through the trachea using a 30 cm water column, the trachea can then be ligated to maintain the inflated configuration over a period of 2 d. The lung is subsequently immersed in a 4% formalin solution after extraction.…”

A closer look at high-energy X-ray-induced bubble formation during soft tissue imaging

“…Although exogenous micrometre-sized bubbles (microbubbles) may be injected into the sample to enhance contrast (La ˚ng et al, 2019;Tang et al, 2021), their uncon-trolled creation during X-ray irradiation (Bras et al, 2021) is detrimental to long scans required for high-resolution imaging of large samples (Walsh et al, 2021) or for in vivo dynamic monitoring in developmental biology (Moosmann et al, 2013), physiology (Leong et al, 2014) and beyond. Due to bubble growth and their motion, the experiments need to be interrupted and the sample reprocessed to mitigate the strong imaging artifacts (Xian et al, 2022) [see Figs. 1(a)-1(c)].…”