背景:临床磁共振成像(MRI)研究通常使用约2毫秒回波时间(TE)的笛卡尔梯度回波(GRE)序列来监测表观总钠浓度(aTSC)。我们比较了笛卡尔GRE和超短回波时间三维(3D)径向读出序列,用于测量骨骼肌aTSC。
方法:我们回顾性评估了112名62.3±12.1岁志愿者的211个数据集(平均值±标准差),从小腿3T获得。对于23NaMRI采集,我们使用了二维笛卡尔GRE序列和具有长方体视场的密度适应的3D径向读出序列(DA-3D-RAD-C)。我们使用有或没有琼脂糖的参考管校准了23NaMR信号,随后进行了弛豫校正。此外,我们采用了六回波1HGRE序列和多回波自旋回波序列来计算质子密度脂肪分数(PDFF)和水T2。配对Wilcoxon符号秩检验,成对样本的Cohendz,使用Spearman相关性。
结果:松弛校正有效地减少了两种采集和校准方法之间的肌肉aTSC差异(使用NaCl/琼脂糖参考的DA-3D-RAD-C:20.05对19.14mM;dz=0.395;使用NaCl/琼脂糖参考的笛卡尔GRE:19.50对18.82mM;dz=0.427)。DA-3D-RAD-C的aTSC和笛卡尔GRE采集均显示出与PDFF以及水T2的小但显着的相关性。
结论:不同的23NaMRI采集和校准方法影响aTSC值。建议应用弛豫校正以最小化序列参数对定量的影响,对于脂肪含量增加的患者,建议进行额外的脂肪校正。
结论:这项研究强调了松弛校正在提高钠MRI准确性方面的作用,为更好的疾病评估和患者测得的钠信号的可比性铺平了道路。
结论:•MRI采集方法的差异妨碍了钠MRI测量的可比性。•测量的钠值取决于使用的MRI序列和校准方法。•后处理期间的松弛校正减轻了这些差异。•Thus,松弛校正提高了钠MRI的准确性,帮助其临床使用。
BACKGROUND: Clinical magnetic resonance imaging (MRI) studies often use Cartesian gradient-echo (GRE) sequences with ~2-ms echo times (TEs) to monitor apparent total sodium concentration (aTSC). We compared Cartesian GRE and ultra-short echo time three-dimensional (3D) radial-readout sequences for measuring skeletal muscle aTSC.
METHODS: We retrospectively evaluated 211 datasets from 112 volunteers aged 62.3 ± 12.1 years (mean ± standard deviation), acquired at 3 T from the lower leg. For 23Na MRI acquisitions, we used a two-dimensional Cartesian GRE sequence and a density-adapted 3D radial readout sequence with cuboid field-of-view (DA-3D-RAD-C). We calibrated the 23Na MR signal using reference tubes either with or without agarose and subsequently performed a relaxation correction. Additionally, we employed a six-echo 1H GRE sequence and a multi-echo spin-echo sequence to calculate proton density fat fraction (PDFF) and water T2. Paired Wilcoxon signed-rank test, Cohen dz for paired samples, and Spearman correlation were used.
RESULTS: Relaxation correction effectively reduced the differences in muscle aTSC between the two acquisition and calibration methods (DA-3D-RAD-C using NaCl/agarose references: 20.05 versus 19.14 mM; dz = 0.395; Cartesian GRE using NaCl/agarose references: 19.50 versus 18.82 mM; dz = 0.427). Both aTSC of the DA-3D-RAD-C and Cartesian GRE acquisitions showed a small but significant correlation with PDFF as well as with water T2.
CONCLUSIONS: Different 23Na MRI acquisition and calibration approaches affect aTSC values. Applying relaxation correction is advised to minimize the impact of sequence parameters on quantification, and considering additional fat correction is advisable for patients with increased fat fractions.
CONCLUSIONS: This study highlights relaxation correction\'s role in improving sodium MRI accuracy, paving the way for better disease assessment and comparability of measured sodium signal in patients.
CONCLUSIONS: • Differences in MRI acquisition methods hamper the comparability of sodium MRI measurements. • Measured sodium values depend on used MRI sequences and calibration method. • Relaxation correction during postprocessing mitigates these discrepancies. • Thus, relaxation correction enhances accuracy of sodium MRI, aiding its clinical use.