Sodium quantification in skeletal muscle: comparison between Cartesian gradient-echo and radial ultra-short echo time...

Area of Science:

• Biomedical Imaging
• Magnetic Resonance Imaging
• Skeletal Muscle Physiology

Background:

• Clinical magnetic resonance imaging (MRI) commonly uses Cartesian gradient-echo (GRE) sequences with short echo times (TEs) to measure apparent total sodium concentration (aTSC).
• Standardization of skeletal muscle aTSC measurements is crucial for clinical applications.

Purpose of the Study:

• To compare Cartesian GRE and ultra-short echo time 3D radial-readout sequences for skeletal muscle aTSC measurement.
• To evaluate the impact of relaxation correction on sodium MRI quantification.

Main Methods:

• Retrospective analysis of 211 datasets from 112 volunteers (mean age 62.3 ± 12.1 years) at 3 T.
• Acquisition using 2D Cartesian GRE and density-adapted 3D radial readout (DA-3D-RAD-C) sequences for ²³Na MRI.
• Calibration using reference tubes and application of relaxation correction; proton density fat fraction (PDFF) and water T2 were also calculated.

Main Results:

• Relaxation correction significantly reduced discrepancies in muscle aTSC between the two acquisition methods (DA-3D-RAD-C: 20.05 vs 19.14 mM; Cartesian GRE: 19.50 vs 18.82 mM).
• Both aTSC measurements showed a small but significant correlation with PDFF and water T2.

Conclusions:

• ²³Na MRI acquisition and calibration methods influence aTSC values.
• Relaxation correction is essential to minimize sequence parameter impact on quantification.
• Fat correction should be considered for patients with increased fat fractions to enhance sodium MRI accuracy.