Yamashiro T, et al. – The study aimed to determine the relationship between interlobar synchrony in lung density and spirometric values in chronic obstructive pulmonary disease (COPD) patients and smokers, by measuring the continuous changes in lung density during respiration on the dynamic–ventilation CT. Results of this study suggested that the synchrony of respiratory movements between the pulmonary lobes is limited or lost in patients with more severe airflow limitation.

Methods

• For this study, 32 smokers, including 10 with COPD, underwent dynamic-ventilation CT during free breathing.
• After that, CT data were persistently reconstructed every 0.5 sec.
• Mean lung density (MLD) of the 5 lobes (right upper [RU], right middle [RM], right lower [RL], left upper [LU], and left lower [LL]) was continuously measured by commercially available software utilizing a fixed volume of volume of interest which was placed and tracked on a single designated point in each lobe.
• Concordance between the MLD time curves of 6 pairs of lung lobes (RU-RL, RU-RM, RM-RL, LU-LL, RU-LU, and RL-LL lobes) was expressed by cross-correlation coefficients.
• Finally, the connection between these cross-correlation coefficients and the forced expiratory volume in one second/forced vital capacity (FEV_1.0/FVC) values was evaluated by Spearman rank correlation analysis.

Results

• The cross-correlation coefficients of the two MLD curves were significantly positively correlated with FEV_1.0/FVC (ρ =0.60–0.73, P<0.001) in all six pairs of the pulmonary lobes.
• The results of this study showed that the mean value of the six coefficients strongly correlated with FEV_1.0/FVC (ρ =0.80, P<0.0001).