Quantitative Lung T1 and T2* Mapping with Upright 0.5T MR: investigating the effect of gravity on lung regions under low-field strength

Motivation: Quantitative lung parametric mapping can characterise morphometric and functional changes in pulmonary disorders. Higher field lung-MRIs suffer from field inhomogeneity, and supine MRI does not replicate physiology during daily tasks and is not suitable for some lung patients. Goal(s): Use low-field, upright-MR, quantify T1 and T2* of different lung regions and investigate how gravity impacts these parameters while seated. Approach: A 0.5T ASG MROpen scanner was used to acquire breath-hold images using multi-TE GE (T2*) and variable flip angle method (T1); linear regression extracted the relaxation times. Results: Although supine position showed similar T1 and T2*, gravity incurred a cranial-caudal gradient while seated. Impact: Our low-field, upright-MR parametric mapping mitigates the limitations of higher-field lung-MRI and explores how relaxations change with gravity. Using the proposed methods, clinicians can characterise pathologies like COPD as well as get crucial functional information of lungs during diurnal postures.