Figure 1.

Bronchial thermoplasty (BT) guided by ¹²⁹Xe magnetic resonance imaging (MRI) study timeline. All subjects underwent routine testing prior to BT including baseline CT and PFT. Two baseline MRI sessions separated by 3 weeks were performed to assess for stability of ventilation defects. Subjects underwent the first BT and were allowed 12 weeks of recovery prior to a third MRI. Then, the second and third BTs were completed. The fourth MRI was performed after 12 weeks of recovery. Subjects were followed for 1 year. CT = computed tomography; PFT = pulmonary function testing.