Fast in vivo ²³Na imaging and mapping using accelerated 2D‐FID UTE magnetic resonance spectroscopic imaging at 3 T: Proof of concept and reliability study

Abstract

To implement an accelerated MR-acquisition method allowing to map T * 2 relaxation and absolute concentration of sodium within skeletal muscles at 3T. Methods: 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 mm 2 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 voxelby-voxel using a biexponential model for the 2D-MRSI data. Finally, intra-subject coefficients of variation (CV) were estimated. Results: 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%. The mean T * 2Fast in muscles was 0.7 ± 0.1 ms (contribution fraction = 37%), whereas T * 2Slow was 13.2 ± 0.2 ms (63%). The mean absolute muscle 23 Na concentration calculated from the T * 2-corrected data was 28.6 ± 3.3 mM. 1784 | ALHULAIL et AL. Conclusion: The proposed MRSI technique is a reliable technique to map sodium's absolute concentration and T * 2 within a clinically acceptable scan time at 3T.

In Vivo Renal Lipid Quantification by Accelerated Magnetic Resonance Spectroscopic Imaging at 3T: Feasibility and Reliability Study

“…Gridding and fast Fourier transform were performed using the nonuniform fast Fourier transform method [ 42 ] and without post hoc density compensation, as DW-CRT is already weighted by design [ 28 ]. B 0 inhomogeneity was corrected by calculating the ΔB 0 maps described in our previous work [ 43 ]. Here, the ΔB 0 maps were calculated based on the first 2 MRSI phase-unwrapped images (TE1 = 4 ms and TE2 = 4.8 ms).…”

Assessing muscle‐specific potassium concentrations in human lower leg using potassium magnetic resonance imaging

“…Differences in TSC between muscle groups of healthy lower leg have been reported before, and were assumed to be related to different muscular structure and fuction. 25,26 Our data suggest that these differences might be-similar as for 39 K-caused be a varying fiber angle and, consequently, differences in residual quadrupolar interaction. Based on 23 Na T 2 * decay curves, it was not possible to determine a muscle-specific residual quadrupolar interaction as it was done for 39 K (data not shown).…”

Comprehensive Account of Sodium Imaging and Spectroscopy for Brain Research

“…The MRSI technique based on fast-2D densityweighted concentric-ring-trajectory (DW-CRT) was also proposed for the absolute concentration of sodium within skeletal muscles at 3 T with a scan time of 15 min and 2.5 × 2.5 mm 2 in-plane resolution. 120 ■ COMPUTATIONAL TOOLS FOR SODIUM MRI AND SPECTROSCOPY Plenty of software tools are available for 23 Na imaging and spectroscopy, but no specific software has been dedicated for processing 23 Na MRI and MRS data. Available tools are commonly used for 1 H MRI and MRS data processing.…”

“…23 Na FID and TQF signals were significantly increased in filling and vascular-draining conditions, respectively, when compared to controlled healthy conditions. The MRSI technique based on fast-2D density-weighted concentric-ring-trajectory (DW-CRT) was also proposed for the absolute concentration of sodium within skeletal muscles at 3 T with a scan time of 15 min and 2.5 × 2.5 mm 2 in-plane resolution …”