High resolution T2 weighted Lung Imaging with a radial Turbo Spin-Echo Sequence

Introduction: MRI of the lung is still a challenging task due to its inherently low proton density, continuous movement caused by respiration and heartbeat, as well as a very short T2* relaxation time of roughly 1-2 ms at 1.5 T [1]. The latter of which can be overcome by using Spin-Echo type sequences which correct for additional spin dephasing owing to inhomogeneities at the numerous air-tissue interfaces within the lung, therefore being affected by the pure T2 decay only. Since standard Spin-Echo type sequences are generally slow due to their need for relatively long TRs, ultrafast single-shot sequences such as HASTE are preferred to freeze motion. However, resolution is intrinsically limited by the T2 decay. To increase resolution without suffering from motion artifacts, gating mechanisms accompanying multishot techniques like Turbo Spin-Echo (TSE) Sequences are therefore required. In this work, the feasibility of a radial TSE sequence [2] for high resolution lung imaging was examined under free breathing conditions without any triggering techniques towards its robustness to motion artifacts [2, 3]. It is demonstrated that quantitative T2 maps can be obtained from a single radial TSE acquisition.