Department of Radiology, Charité Universitätsmedizin Berlin, Berlin, Germany.
Clinic for Nuclear Medicine, Charité Universitätsmedizin Berlin, Berlin, Germany.
J Magn Reson Imaging. 2018 Nov;48(5):1410-1420. doi: 10.1002/jmri.26045. Epub 2018 Apr 16.
Quantitative susceptibility mapping (QSM) is an MRI postprocessing technique that allows quantification of the spatial distribution of tissue magnetic susceptibility in vivo. Contributing sources include iron, blood products, calcium, myelin, and lipid content.
To evaluate the reproducibility and consistency of QSM across clinical field strengths of 1.5T and 3T and to optimize the contrast-to-noise ratio (CNR) at 1.5T through bandwidth tuning.
Prospective.
Sixteen healthy volunteers (10 men, 6 women; age range 24-37; mean age 27.8 ± 3.2 years).
FIELD STRENGTHS/SEQUENCES: 1.5T and 3T systems from the same vendor. Four spoiled gradient echo (SPGR) sequences were designed with different acquisition bandwidths.
QSM reconstruction was achieved through a nonlinear morphology-enabled dipole inversion (MEDI) algorithm employing L1 regularization. CNR was calculated in seven regions of interest (ROIs), while reproducibility and consistency of QSM measurements were evaluated through voxel-based and region-specific linear correlation analyses and Bland-Altman plots.
Interclass correlation, Wilcoxon rank sum test, linear regression analysis, Bland-Altman analysis, Welch's t-test.
CNR analysis showed a statistically significant (P < 0.05) increase in four out of seven ROIs for the lowest bandwidth employed with respect to the highest (25.18% increase in CNR of caudate nucleus). All sequences reported an excellent correlation across field strength and bandwidth variation (R ≥ 0.96, widest limits of agreement from -18.7 to 25.8 ppb) in the ROI-based analysis, while the correlation was found to be good for the voxel-based analysis of averaged maps (R ≥ 0.90, widest limits of agreement from -9.3 to 9.1 ppb).
CNR of QSM images reconstructed from 1.5T acquisitions can be enhanced through bandwidth tuning. MEDI-based QSM reconstruction demonstrated to be reproducible and consistent both across field strengths (1.5T and 3T) and bandwidth variation.
1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1410-1420.
定量磁敏感图（QSM）是一种 MRI 后处理技术，可在体内定量组织磁化率的空间分布。贡献源包括铁、血液制品、钙、髓鞘和脂质含量。
评估 QSM 在 1.5T 和 3T 临床场强下的可重复性和一致性，并通过带宽调谐优化 1.5T 的对比噪声比（CNR）。
前瞻性。
16 名健康志愿者（10 名男性，6 名女性；年龄范围 24-37 岁；平均年龄 27.8±3.2 岁）。
场强/序列：来自同一供应商的 1.5T 和 3T 系统。设计了四个带有不同采集带宽的扰动脉冲梯度回波（SPGR）序列。
通过采用 L1 正则化的非线性形态学使偶极子反转（MEDI）算法实现 QSM 重建。在七个感兴趣区域（ROI）中计算 CNR，通过体素和区域特定的线性相关分析和 Bland-Altman 图评估 QSM 测量的可重复性和一致性。
组内相关系数、Wilcoxon 秩和检验、线性回归分析、Bland-Altman 分析、Welch's t 检验。
CNR 分析显示，与最高带宽相比，四个 ROI 中的四个 ROI 的 CNR 有统计学意义（P<0.05）（尾状核的 CNR 增加 25.18%）。在 ROI 基于分析中，所有序列均显示出优异的相关性（R≥0.96，最宽的一致性界限为-18.7 至 25.8 ppb），而在基于体素的平均图分析中，相关性良好（R≥0.90，最宽的一致性界限为-9.3 至 9.1 ppb）。
通过带宽调谐可以增强从 1.5T 采集重建的 QSM 图像的 CNR。基于 MEDI 的 QSM 重建证明在磁场强度（1.5T 和 3T）和带宽变化方面具有可重复性和一致性。
1 技术功效：第 1 阶段 J. Magn. Reson. Imaging 2018;47:1410-1420.
