Purpose:To evaluate an optimized method for oxygenenhanced MRI of the lung, using simultaneous electrocardiograph (ECG) and navigator triggering. To correlate oxygen-enhanced MRI with lung function tests assessing alveolar-capillary gas exchange.
Materials and Methods:A total of 12 healthy volunteers (aged 20 -32 years) and 10 patients (aged 37-87 years) with interstitial lung diseases (ILD) underwent oxygen-enhanced MRI and pulmonary functional tests (PFTs) assessing alveolar-capillary gas exchange. The paradigm roomair-oxygen-room-air was acquired with a nonselective inversion-recovery half-Fourier single-shot turbo spin-echo sequence (inversion time ϭ 1200 msec; acquisition time ϭ 134.5 msec; slice thickness ϭ 20 mm; matrix size ϭ 128 ϫ 128), using simultaneous double triggering (navigator plus ECG trigger). Cross-correlation was performed in regions of interest (ROIs) encompassing both lungs. The number of oxygen-activated pixels over the total number of pixels in the ROIs (OAP%) of volunteers and patients was compared. OAP%s were correlated with PFTs.
Results:The mean OAP% of patients was significantly lower than that of volunteers (36.7 vs. 81.7, P ϭ 0.001). OAP% correlated with the transfer lung factor for carbon monoxide (Tlco) (r ϭ 0.64; P ϭ 0.002), the transfer coefficient (Kco) (r ϭ 0.75; P ϭ 0.001), the arterial partial pressure (r ϭ 0.77; P Ͻ 0.001), and the saturation (r ϭ 0.70; P Ͻ 0.001) of oxygen.
Conclusion:Navigator-triggered oxygen-enhanced MRI of the lung may have a potential role in the quantitative assessment of lung function in ILD.