Quantification of sodium T1 in abdominal tissues at 3 T

Although relevant for assessment of sodium in multiple endocrine pathways, ²³Na-T1 quantification is challenging due to technical limitations (SAR, B1 inhomogeneity) or influence of tissue's local molecular dynamics. Hereby, we propose T1 quantification of ²³Na-MRI signal acquired over the abdomen using a centric-reordered saturation-recovery (SR) true fast imaging with steady state precession (TrueFISP) sequence.

Measurements were performed at 3T using a dual-tunable ²³Na/¹H coil in 7 healthy volunteers (TR/TE = 858-928/1.57 ms; flip angle = 90°; bandwidth = 450 Hz/px; voxel size = 5 × 5 × 10 mm³). Variable T1-weighting was achieved applying non-selective saturation pre-pulses delayed from the centre of the k-space acquisition by 25, 40, 60, 120 and 250 ms. T1-curve fitting was performed slice-wise, separately for average intensity values from the manually segmented areas of the renal parenchyma and spinal canal, over the increasing SR times- assuming monoexponential signal pattern.

Mean ± standard deviation of ²³Na-T1 was found as 29 ± 10 ms and 35 ± 8 ms for the renal parenchyma and the spinal canal, respectively.

²³Na-T1 quantification using a SR-TrueFISP is feasible in clinical settings, in the images constrained by clinically applicable acquisition time of reduced spatial resolution or averages.