%0 Journal Article %A Alhulail, Ahmad A %A Xia, Pingyu %A Shen, Xin %A Nichols, Miranda %A Volety, Srijyotsna %A Farley, Nicholas %A Thomas, Micheal Albert %A Nagel, Armin M %A Dydak, Ulrike %A Emir, Uzay E %T Fast in vivo 23 Na imaging and T 2 ∗ mapping using accelerated 2D-FID UTE magnetic resonance spectroscopic imaging at 3 T: Proof of concept and reliability study. %J Magnetic resonance in medicine %V 85 %N 4 %@ 1522-2594 %C New York, NY [u.a.] %I Wiley-Liss %M DKFZ-2020-02418 %P 1783-1794 %D 2021 %Z 2021 Apr;85(4):1783-1794 %X To implement an accelerated MR-acquisition method allowing to map T 2 ∗ relaxation and absolute concentration of sodium within skeletal muscles at 3T.A fast-UTE-2D density-weighted concentric-ring-trajectory 23 Na-MRSI technique was used to acquire 64 time points of FID with a spectral bandwidth of 312.5 Hz with an in-plane resolution of 2.5 × 2.5 mm2 in 15 min. The fast-relaxing 23 Na signal was localized with a single-shot, inversion-recovery-based, non-echo (SIRENE) outer volume suppression (OVS) method. The sequence was verified using simulation and phantom studies before implementing it in human calf muscles. To evaluate the 2D-SIRENE-MRSI (UTE = 0.55 ms) imaging performance, it was compared to a 3D-MRI (UTE = 0.3 ms) sequence. Both data sets were acquired within 2 same-day sessions to assess repeatability. The T 2 ∗ values were fitted voxel-by-voxel using a biexponential model for the 2D-MRSI data. Finally, intra-subject coefficients of variation (CV) were estimated.The MRSI-FID data allowed us to map the fast and slow components of T 2 ∗ in the calf muscles. The spatial distributions of 23 Na concentration for both MRSI and 3D-MRI acquisitions were significantly correlated (P < .001). The test-retest analysis rendered high repeatability for MRSI with a CV of 5 %F PUB:(DE-HGF)16 %9 Journal Article %$ pmid:33166096 %R 10.1002/mrm.28576 %U https://inrepo02.dkfz.de/record/165842