Impaired lung deformation during expiration in chronic obstructive pulmonary disease using four-dimensional...

Area of Science:

• Pulmonary medicine
• Medical imaging
• Computational fluid dynamics

Background:

• Chronic obstructive pulmonary disease (COPD) involves progressive airflow limitation and lung destruction.
• Spirometry assesses global lung function but not regional mechanics.
• Four-dimensional dynamic-ventilation computed tomography (4D-CT) strain analysis offers regional lung deformation insights.

Purpose of the Study:

• To quantitatively evaluate lung deformation patterns across COPD severities using 4D-CT strain analysis.
• To investigate the utility of strain parameters in characterizing severe airflow limitation.
• To compare strain behavior during different phases of expiration.

Main Methods:

• Sixty-one COPD patients underwent spirometry and 4D-CT.
• Lung strain was quantified using an adapted computational fluid dynamics (CFD) algorithm (MicroVec V3.6.2).
• Strain parameters from whole and initial 2-second expiration phases were compared across Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I, II, and III-IV.

Main Results:

• Lung strain parameters significantly declined with increasing GOLD stage (P<0.05).
• Parameters from the whole expiration phase showed stronger correlations with disease severity than those from the initial 2-second phase.
• Maximum principal strain during the whole expiratory phase (P_Smax-all) strongly inversely correlated with GOLD classification (ρ=-0.732, P<0.001), decreasing over 70% in severe COPD.

Conclusions:

• Reduced lung deformation during expiration correlates with diminished lung function in COPD.
• Strain-related parameters, especially from the whole expiration phase, show promise for reflecting COPD severity.
• 4D-CT strain analysis provides valuable regional insights into COPD progression.