Lung Water Density (LWD) Imaging with MRI: Normative Values and Dependence on Field Strength, Pulse Sequence and Breathing Maneuver

Motivation: Lung water density (LWD) is an emerging quantitative measure of lung health; normal values and sources of bias are not established. Goal(s): Determine normative values for LWD with consideration of age, sex, acquisition approach (pulse sequence, field strength) and breathing maneuver. Approach: LWD maps were compared for different ultra-short TE pulse sequences (yarnball, Double-half-echo-Cartesian, Spiral-VIBE), field strengths (1.5T/2.89T) and breathing maneuvers (end-expiration(EE), end-inspiration(EI) or free breathing(FB)) (N=118 participants). Results: Normative LWD values were ~26% for EE/FB studies and ~16% at EI, for all acquisition approach's (~2% higher including the vascular pool), with slightly higher values for Spiral-VIBE. No age, sex, field strength dependence. Impact: MRI-derived lung water density (LWD) is independent of age, sex and field-strength in healthy individuals but highly sensitive lung inflation (breathing maneuver) and with potential bias due to acquisition approach (k-space trajectory).