Purpose <p>To provide a thorough comparison of the SNR between sodium MRI k-space sampling schemes in the brain within clinically feasible time constraints (∼10&#xa0;min) at 3&#xa0;T.</p> Materials and methods <p>Density-adapted radial (DA-3DPR), constant-amplitude radial, Cartesian, FLORET, rotated spiral, and 3D cones trajectories were designed with parameters optimized for brain tissue SNR. The sequences were acquired in both a phantom and 13 healthy participants (age = 28.7 ± 3.4, M:F = 7:6). SNR was measured and corrected for point-spread function (PSF) volume and scan duration for a less-biased assessment. CSF-to-brain-tissue contrast and CNR were also measured. The data were linearly modeled, and ANOVA was used to determine if the sampling scheme contributed to the variance with the obtained metrics.</p> Results <p>The sampling schemes contributed significantly to the variance (<i>p</i> &lt; 0.001) for all metrics. The DA-3DPR sampling scheme provided the highest SNR in both the phantom and the participants. The Cartesian sampling scheme had the highest absolute contrast, but the largest CNR was shared between the DA-3DPR, 3D cones, and FLORET sampling schemes.</p> Conclusions <p>When considering the PSF and the requirement for a clinically feasible scan time, a 15&#xa0;ms read-out DA-3DPR trajectory provides the highest SNR at 3&#xa0;T, without losing any desired contrast.</p>

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Signal-to-noise ratio comparison of k-space sampling schemes for sodium MRI of the brain at 3 T

  • Cameron Nowikow,
  • Rolf F. Schulte,
  • Michael Vaeggemose,
  • Christoffer Laustsen,
  • Michael D. Noseworthy

摘要

Purpose

To provide a thorough comparison of the SNR between sodium MRI k-space sampling schemes in the brain within clinically feasible time constraints (∼10 min) at 3 T.

Materials and methods

Density-adapted radial (DA-3DPR), constant-amplitude radial, Cartesian, FLORET, rotated spiral, and 3D cones trajectories were designed with parameters optimized for brain tissue SNR. The sequences were acquired in both a phantom and 13 healthy participants (age = 28.7 ± 3.4, M:F = 7:6). SNR was measured and corrected for point-spread function (PSF) volume and scan duration for a less-biased assessment. CSF-to-brain-tissue contrast and CNR were also measured. The data were linearly modeled, and ANOVA was used to determine if the sampling scheme contributed to the variance with the obtained metrics.

Results

The sampling schemes contributed significantly to the variance (p < 0.001) for all metrics. The DA-3DPR sampling scheme provided the highest SNR in both the phantom and the participants. The Cartesian sampling scheme had the highest absolute contrast, but the largest CNR was shared between the DA-3DPR, 3D cones, and FLORET sampling schemes.

Conclusions

When considering the PSF and the requirement for a clinically feasible scan time, a 15 ms read-out DA-3DPR trajectory provides the highest SNR at 3 T, without losing any desired contrast.