Bronchial Thermoplasty for Severe Asthmatics Guided by HXe MRI

HXe MRI consists in imaging the inhaled xenon gas inside the human lungs during a short breath-hold. High resolution 3D maps of the HXe distribution inside the lungs provide information regarding ventilation of the lungs, as the signal is proportional to the local concentration of HXe. A high MRI signal translates in unobstructed ventilation, while ventilation defects appear as dark regions on the map. HXe MRI will be performed pre and post bronchodilator in order to determine the airways which potentially are the most responsive to BT treatment. All HXe MRI images will be repeated within the same day for consistency check and after three weeks to study temporal variability. The reactivity of the airways will establish the treatment order, with the most problematic airways to be treated in the first BT session (not to exceed six).

Patients undergoing standard BT procedure will have HXe MRI performed at time intervals similar to HXe MRI guided BT patients. While HXe images will not be used for guiding the sequence for airways to receive the BT treatment, metrics extracted from HXe images will be compared with clinically accepted asthma severity metrics (spirometry and asthma questionnaires) to assess HXe MRI as a biomarker for asthma severity.