Cardio-Respiratory tolerability of perfluoropropaneEnhanced MRI of pulmonary ventilation

Rationale: Recent advances in perfluoropropane magnetic resonance imaging of the lung have provided the means to assess pulmonary ventilation and gas distribution throughout the pulmonary airways and acini in a non-invasive manner. Objectives: The increased density of the inhaled PFP/O2 gas mixture generates longer wash-in times compared to wash-out while breathing room air and leads to slight increases in airway resistance (Raw) and respiratory effort by the subject during imaging. As a consequence of these gas-related effects, we sought to evaluate the cardio-respiratory tolerability of the PFP/O2 gas mixtures in our sequential breath-hold imaging protocol in normal subjects and subjects with obstructive lung disease. Methods: Tolerability was determined by evaluation of changes in vital signs (Heart Rate, Systolic and Diastolic Blood Pressure, Respiratory Rate and Temperature (otic)) at 3 time points (screening, pre-imaging and post-imaging) Measurements and Main Results: Assessment of vital signs before and after the administration of perfluoropropane gas mixture by matched pair analysis demonstrated statistically different values for Heart rate (Mean Difference =-2.417 bpm), Systolic BP (Mean Difference=6.95 mmHg), Diastolic BP (Mean Difference=3.86 mmHg) and SpO2 (Mean Difference=0.56%) even though these do not represent physiologically significant differences compared to activities of daily living such as climbing a flight of stairs. Conclusions: Our data demonstrate no negative outcomes in using PFP gas to image pulmonary ventilation. The PFP gas mixture is safe, well tolerated, and provides a three dimensional ‘picture’ (representation) of inhaled gas distribution for subject cohorts of normal and obstructive lung disease.