Hyperpolarised gas MRI shows a decrease in lung ventilation defects at increased inspiratory lung volumes in Cystic Fibrosis

The effect of lung inflation level on ventilation defects, using hyperpolarised (HP) gas ventilation MRI, has not been assessed. The most commonly adopted method of inhaling a volume of 1L from functional residual capacity (FRC) will result in a lung volume closer to total lung capacity (TLC) for smaller people, compared with taller people. We assessed HP-MRI in 21 people with cystic fibrosis at both end inspiratory tidal volume (EIVt) and at TLC. Ventilation defects decreased in all subjects at TLC when compared to EIVt and therefore the inspiratory volume should be carefully considered when interpreting ventilation-imaging results.