Dynamic susceptibility contrast F-MRI of inhaled perfluoropropane: a novel approach to combined pulmonary ventilation and perfusion imaging.

Purpose: To assess alveolar perfusion by applying dynamic susceptibility contrast MRI to F-MRI of inhaled perfluoropropane (PFP). We hypothesized that passage of gadolinium-based contrast agent (GBCA) through the pulmonary microvasculature would reduce magnetic susceptibility differences between water and gas components of the lung, elevating the of PFP.

Methods: Lung-representative phantoms were constructed of aqueous PFP-filled foams to characterize the impact of aqueous/gas phase magnetic susceptibility differences on PFP . Aqueous phase magnetic susceptibility was modulated by addition of different concentrations of GBCA. In vivo studies were performed to measure the impact of intravenously administered GBCA on the of inhaled PFP in mice (7.0 Tesla) and in healthy volunteers (3.0 Tesla).

Results: Perfluoropropane was sensitive to modulation of magnetic susceptibility difference between gas and water components of the lung, both in phantom models and in vivo. Negation of aqueous/gas phase magnetic susceptibility difference was achieved in lung-representative phantoms and in mice, resulting in a ~2 to 3× elevation in PFP (3.7 to 8.5 ms and 0.7 to 2.6 ms, respectively). Human studies demonstrated a transient elevation of inhaled PFP (1.50 to 1.64 ms) during passage of GBCA bolus through the lung circulation, demonstrating sensitivity to lung perfusion.

Conclusion: We demonstrate indirect detection of a GBCA in the pulmonary microvasculature via changes to the of gas phase PFP within directly adjacent alveoli. This approach holds potential for assessing alveolar perfusion by dynamic susceptibility contrast F-MRI of inhaled PFP, with concurrent assessment of lung ventilation properties, relevant to lung physiology and disease.