Application-specific approaches to MicroCT for evaluation of mouse models of pulmonary disease

Abstract

The advent of micro-computed tomography (microCT) has provided significant advancement in our ability to generate clinically relevant assessments of lung health and disease in small animal models. As microCT use to generate outcomes analysis in pulmonary preclinical models has increased there have been substantial improvements in image quality and resolution, and data analysis software. However, there are limited published methods for standardized imaging and automated analysis available for investigators. Manual quantitative analysis of microCT images is complicated by the presence of inflammation and parenchymal disease. To improve the efficiency and limit user-associated bias, we have developed an automated pulmonary air and tissue segmentation (PATS) task list to segment lung air volume and lung tissue volume for quantitative analysis. We demonstrate the effective use of the PATS task list using four distinct methods for imaging, 1) in vivo respiration controlled scanning using a flexiVent, 2) longitudinal breath-gated in vivo scanning in resolving and non-resolving pulmonary disease initiated by lipopolysaccharide-, bleomycin-, and silica-exposure, 3) post-mortem imaging, and 4) ex vivo high-resolution scanning. The accuracy of the PATS task list was compared to manual segmentation. The use of these imaging techniques and automated quantification methodology across multiple models of lung injury and fibrosis demonstrates the broad applicability and adaptability of microCT to various lung diseases and small animal models and presents a significant advance in efficiency and standardization of preclinical microCT imaging and analysis for the field of pulmonary research.

Microcomputed tomography visualization and quantitation of the pulmonary arterial microvascular tree in mouse models of chronic lung disease

“…µCT analysis confirmed increased tissue volume indicative of fibrosis 35 as well as an increase in HU in bleomycin‐treated mice relative to vehicle (Figure 2a−c ). FlexiVent analysis further supported these findings demonstrating that the mice receiving bleomycin exhibited decreased inspiratory capacity (IC), compliance (Crs), increased resistance (Rrs), and elastance (Ers; Figure 2d−g ).…”

“…dose of bleomycin sulfate (0.05 U/18 g) or PBS vehicle mice were analyzed by µCT, FlexiVent to measure airway physiology as well as histology to confirm the phenotype of injury and fibrosis. µCT analysis confirmed increased tissue volume indicative of fibrosis 35 as well as an increase in HU in bleomycin-treated mice relative to vehicle (Figure 2a−c). FlexiVent analysis further supported these findings demonstrating that the mice receiving bleomycin exhibited decreased inspiratory capacity (IC), compliance (Crs), increased resistance (Rrs), and elastance (Ers; Figure 2d− We have developed a novel method to visualize the murine pulmonary arterial circulation with µCT imaging.…”

Semi-automated micro-computed tomography lung segmentation and analysis in mouse models

“…With lung toxicant exposures via aerosols or aspiration, there is a progression of inflammatory responses that can lead to specific pathological presentations. Biopsy histology and bronchoalveolar lavage fluid (BALF) samples are among the analytical procedures used in preclinical research settings; however, chest CT imaging is used in the clinic as a less invasive method to detect pathology, and is translationally relevant to preclinical animal studies [1] , [2] , [3] , [4] , [5] , [6] . For well-studied clinical pathologies, there are established clinical grading systems based on specific image features such as ground-glass opacities, as seen in Electronic Cigarette or vaping-use associated lung injury (EVALI), and the lungs of SARS-Co-V-2 patients [ 2 , 7 , 8 ].…”