Quantitative assessment of lung mechanical properties in ARDS using X-ray computed tomography

Acute Respiratory Distress Syndrome (ARDS) is marked by spatial heterogeneity in lung structure and mechanical behavior, limiting the ability of global physiologic measurements to guide ventilatory management and prevent ventilator-induced lung injury (VILI). X-ray computed tomography (CT) has emerged as a central imaging modality for characterizing regional differences in lung aeration, deformation, and mechanical properties that underlie such heterogeneity. When combined with quantitative image processing, deformable image registration, and computational modeling, CT enables regional assessment of lung strain, recruitment, and computationally inferred estimates of regional mechanical stress in injured lungs. This review summarizes CT-based methods for the quantitative evaluation of lung mechanical properties in ARDS, including image acquisition, segmentation, aeration analysis, deformable registration, and biomechanical modeling. Experimental and translational evidence is discussed to illustrate how CT has advanced the mechanistic understanding of regional ventilation distribution and deformation patterns that contribute to VILI. Methodological limitations and translational challenges are also discussed. Emerging directions, such as portable, low-dose, and photon counting CT are considered in the context of critically ill patients and their potential use for bedside assessment of lung mechanics.