We have developed a novel functional proton magnetic resonance imaging (MRI) technique to measure regional ventilation-perfusion (VA/Q ) ratio in the lung. We conducted a comparison study of this technique in healthy subjects (n=7, age=42±16, Forced expiratory volume in 1 second=94% predicted), by comparing data measured using MRI to that obtained from the multiple inert gas elimination technique (MIGET). Regional ventilation measured in a sagittal lung slice using Specific Ventilation Imaging was combined with proton density measured using a fast gradient-echo sequence to calculate regional alveolar ventilation, registered with perfusion images acquired using arterial spin labeling, and divided on a voxel-by-voxel basis to obtain regional VA/Q ratio. LogSDV and LogSDQ, measures of heterogeneity derived from the standard deviation (log scale) of the ventilation and perfusion vs. VA/Q ratio histograms respectively, were calculated. On a separate day, subjects underwent study with MIGET and LogSDV and LogSDQ were calculated from MIGET data using the 50-compartment model. MIGET LogSDV and LogSDQ were normal in all subjects. LogSDQ was highly correlated between MRI and MIGET (R=0.89, P=0.007); the intercept was not significantly different from zero (-0.062, P=0.65) and the slope did not significantly differ from identity (1.29, P=0.34). MIGET and MRI measures of LogSDV were well correlated (R=0.83, P=0.02); the intercept differed from zero (0.20, P=0.04) and the slope deviated from the line of identity (0.52,P=0.01). Conclusion: In normal subjects, there is a reasonable agreement between MIGET measures of heterogeneity and those from proton MRI measured in a single slice of lung.
- Magnetic resonance imaging
- arterial spin labeling
- ventilation perfusion ratio
- specific ventilation imaging
- multiple inert gas elimination technique
- Copyright © 2016, Journal of Applied Physiology