Quantification of extravascular lung water using a dual contrast extracellular volume approach

Motivation: Extravascular lung water is a feature in heart failure. Current lung water MRI methods cannot distinguish between intravascular and extravascular fluid, and therefore cannot fully isolate the pathology. Goal(s): To isolate and quantify extravascular lung water by developing a dual-contrast extracellular volume (ECV) method, leveraging different extracellular compartmentalization of gadolinium and ferumoxytol. Approach: We calculated ECVextravascular=ECVgadolinium-ECVferumoxytol from lung T1-maps with native, gadolinium and ferumoxytol contrast. Validation was performed in porcine models of increased extravascular and intravascular lung water. Results: As expected, ECVextravascular differed between baseline and the extravascular intervention (27±4.1% vs 32±1.6%, p=0.005), but not for the intravascular model (22±4.7% vs 22±4.4%, p=0.91). Impact: Dual contrast extracellular volume measurements, leveraging the different compartment uptakes of gadolinium and ferumoxytol contrasts, is a promising method for extravascular lung water quantification, and may enable mechanistic studies of lung water accumulation in patients with dyspnea.