Comparison of single breath hyperpolarized Xe MRI with dynamic F MRI in cystic fibrosis lung disease.

PURPOSE

To quantitatively compare dynamic F and single breath hyperpolarized Xe MRI for the detection of ventilation abnormalities in subjects with mild cystic fibrosis (CF) lung disease.

METHODS

Ten participants with stable CF and a baseline FEV1 > 70% completed a single imaging session where dynamic F and single breath Xe lung ventilation images were acquired on a 3T MRI scanner. Ventilation defect percentages (VDP) values between F early-breath, F maximum-ventilation, Xe low-resolution, and Xe high-resolution images were compared. Dynamic F images were used to determine gas wash-in/out rates in regions of ventilation congruency and mismatch between Xe and F.

RESULTS

VDP values from high-resolution Xe images were greater than from low-resolution images (P = .001), although these values were significantly correlated (r = 0.68, P = .03). Early-breath F VDP and max-vent F VDP also showed significant correlation (r = 0.75, P = .012), with early-breath F VDP values being significantly greater (P < .001). No correlation in VDP values were detected between either F method or high-res Xe images. In addition, the location and volume of ventilation defects were often different when comparing Xe and F images from the same subject. Areas of ventilation congruence displayed the expected ventilation kinetics, while areas of ventilation mismatch displayed abnormally slow gas wash-in and wash-out.

CONCLUSION

In CF subjects, ventilation abnormalities are identified by both F and HP Xe imaging. However, these ventilation abnormalities are not entirely congruent. F and HP Xe imaging provide complementary information that enable differentiation of normally ventilated, slowly ventilated, and non-ventilated regions in the lungs.