Comparison of single breath hyperpolarized ¹²⁹ Xe MRI with dynamic ¹⁹ F MRI in cystic fibrosis lung disease

To quantitatively compare dynamic ¹⁹ F and single breath hyperpolarized ¹²⁹ Xe MRI for the detection of ventilation abnormalities in subjects with mild cystic fibrosis (CF) lung disease.

Ten participants with stable CF and a baseline FEV1 > 70% completed a single imaging session where dynamic ¹⁹ F and single breath ¹²⁹ Xe lung ventilation images were acquired on a 3T MRI scanner. Ventilation defect percentages (VDP) values between ¹⁹ F early-breath, ¹⁹ F maximum-ventilation, ¹²⁹ Xe low-resolution, and ¹²⁹ Xe high-resolution images were compared. Dynamic ¹⁹ F images were used to determine gas wash-in/out rates in regions of ventilation congruency and mismatch between ¹²⁹ Xe and ¹⁹ F.

VDP values from high-resolution ¹²⁹ Xe images were greater than from low-resolution images (P = .001), although these values were significantly correlated (r = 0.68, P = .03). Early-breath ¹⁹ F VDP and max-vent ¹⁹ F VDP also showed significant correlation (r = 0.75, P = .012), with early-breath ¹⁹ F VDP values being significantly greater (P < .001). No correlation in VDP values were detected between either ¹⁹ F method or high-res ¹²⁹ Xe images. In addition, the location and volume of ventilation defects were often different when comparing ¹²⁹ Xe and ¹⁹ 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.

In CF subjects, ventilation abnormalities are identified by both ¹⁹ F and HP ¹²⁹ Xe imaging. However, these ventilation abnormalities are not entirely congruent. ¹⁹ F and HP ¹²⁹ Xe imaging provide complementary information that enable differentiation of normally ventilated, slowly ventilated, and non-ventilated regions in the lungs.