TE-dependent observed lung T1 measured using inversion recovery radial turbo spin echo

Motivation: Observed lung T1 from Look-Locker inversion recovery depends on TE due to compartments in the lungs. These differ in T2* and T1, changig visible T1 dependent on TE. Goal(s): To examine further whether this dependence is due to differences in T2' or T2. Approach: Lung T1 was quantified in volunteers using inversion recovery radial TSE at 5 TIs. rTSE was acquired in free breathing using golden angle encoding. Results: Observed lung T1 was found to increase from T1(5.7ms)=985ms±69ms up to T1=1136±168ms at about TE=57ms and subsequently decreased but with greatly increased spread at longer TEs. Impact: Observed T1 in the lungs shows a dependence on TE in gradient echo sequences due to different T2* and T1 in tissue compartments. Here, we show TE-dependence due to T2 weighting and thus compartments also differ in T2.