Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
J Magn Reson Imaging. 2018 Feb;47(2):362-371. doi: 10.1002/jmri.25755. Epub 2017 May 10.
The Iso3DGRE sequence with an isotropic 0.6 mm spatial resolution was developed on a clinical 3T MR scanner. Numerical simulations were performed to optimize the pulse sequence parameters. A phantom study was performed to validate the T estimation accuracy. The repeatability of the sequence was assessed in healthy volunteers (n = 7). T values were compared with those from a clinical standard 2D multislice multiecho (MSME) T mapping sequence in knees of healthy volunteers (n = 13) and in patients with knee osteoarthritis (OA, n = 5).
The numerical simulations resulted in 100 excitations per segment and an optimal radiofrequency (RF) excitation angle of 15°. The phantom study demonstrated a good correlation of the technique with the reference standard (slope 0.9 ± 0.05, intercept 0.2 ± 1.7 msec, R ≥ 0.99). Repeated measurements of cartilage T values in healthy volunteers showed a coefficient of variation of 5.6%. Both Iso3DGRE and MSME techniques found significantly higher cartilage T values (P < 0.03) in OA patients. Iso3DGRE precision was equal to that of the MSME T mapping in healthy volunteers, and significantly higher in OA (P = 0.01).
This study successfully demonstrated that high-resolution isotropic 3D T mapping for knee cartilage characterization is feasible, accurate, repeatable, and precise. The technique allows for multiplanar reformatting and thus T quantification in any plane of interest.
1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:362-371.
1）实现一种使用连续 T 准备分段梯度回波（Iso3DGRE）图像进行膝关节软骨评估的更高分辨率各向同性 3D T 映射技术，2）在健康志愿者和膝骨关节炎患者中进行体内和体外验证。
在临床 3T MR 扫描仪上开发了具有各向同性 0.6mm 空间分辨率的 Iso3DGRE 序列。进行数值模拟以优化脉冲序列参数。进行了一项体模研究以验证 T 估计准确性。在健康志愿者（n=7）中评估了该序列的重复性。在健康志愿者（n=13）和膝骨关节炎患者（OA，n=5）的膝关节中，将 T 值与临床标准 2D 多层多回波（MSME）T 映射序列进行了比较。
数值模拟得出每个段 100 次激发和最佳射频（RF）激发角 15°。体模研究表明，该技术与参考标准具有良好的相关性（斜率 0.9±0.05，截距 0.2±1.7msec，R≥0.99）。健康志愿者软骨 T 值的重复测量显示变异系数为 5.6%。Iso3DGRE 和 MSME 技术均发现 OA 患者的软骨 T 值明显更高（P<0.03）。Iso3DGRE 的精度与健康志愿者的 MSME T 映射相同，而在 OA 中则更高（P=0.01）。
本研究成功证明了用于膝关节软骨特征描述的高分辨率各向同性 3D T 映射是可行，准确，可重复且精确的。该技术允许在任何感兴趣的平面上进行多平面重建，从而进行 T 定量分析。
1 技术功效：第 2 阶段 J. Magn. Reson. Imaging 2018;47:362-371.
