Using Free-breathing Proton Ventilation MRI to Evaluate Treatment Response in Asthma

Purpose: Hyperpolarized noble gas magnetic resonance imaging (MRI) provides a way to map both functional and structural pulmonary information. Specifically in asthmatics, inhaled hyperpolarized gas MRI has been used to evaluate bronchoconstriction (methacholine-challenge [MCh]) and bronchodilation (salbutamol), showing ventilation defects that respond to MCh and salbutamol [1]. Fourier decomposition of pulmonary proton (H) MRI (FDMRI) acquired during free-tidal breathing patients over the course of a few minutes has emerged as a non-contrast enhanced method to generate ventilation images by exploiting non-rigid registration and fast MR image acquisition techniques [2]. Here our objective was to evaluate asthmatics using FDMRI and directly compare with hyperpolarized noble gas MRI following MCh and salbutamol. We hypothesized that the ventilation defects measured using FDMRI would increase after a MCh and would decrease after salbutamol administration and thought that ventilation defects observed using all MR ventilation imaging methods would be quantitatively and spatially related.