From the Department of Radiology, Children's Hospital of Philadelphia.
J Comput Assist Tomogr. 2024;48(3):343-353. doi: 10.1097/RCT.0000000000001574. Epub 2024 Apr 9.
Accurate quantification of liver iron concentration (LIC) can be achieved via magnetic resonance imaging (MRI). Maps of liver T2*/R2* are provided by commercially available, vendor-provided, 3-dimensional (3D) multiecho Dixon sequences and allow automated, inline postprocessing, which removes the need for manual curve fitting associated with conventional 2-dimensional (2D) gradient echo (GRE)-based postprocessing. The main goal of our study was to investigate the relationship among LIC estimates generated by 3D multiecho Dixon sequence to values generated by 2D GRE-based R2* relaxometry as the reference standard.
A retrospective review of patients who had undergone MRI scans for estimation of LIC with conventional T2* relaxometry and 3D multiecho Dixon sequences was performed. A 1.5 T scanner was used to acquire the magnetic resonance studies. Acquisition of standard multislice multiecho T2*-based sequences was performed, and R2* values with corresponding LIC were estimated. The comparison between R2* and corresponding LIC estimates obtained by the 2 methods was analyzed via the correlation coefficients and Bland-Altman difference plots.
This study included 104 patients (51 male and 53 female patients) with 158 MRI scans. The mean age of the patients at the time of scan was 15.2 (SD, 8.8) years. There was a very strong correlation between the 2 LIC estimation methods for LIC values up to 3.2 mg/g (LIC quantitative multiecho Dixon [qDixon; from region of interest R2*] vs LIC GRE [in-house]: r = 0.83, P < 0.01; LIC qDixon [from segmentation volume R2*] vs LIC GRE [in-house]: r = 0.92, P < 0.01); and very weak correlation between the 2 methods at liver iron levels >7 mg/g.
Three-dimensional-based multiecho Dixon technique can accurately measure LIC up to 7 mg/g and has the potential to replace 2D GRE-based relaxometry methods.
磁共振成像（MRI）可实现肝铁浓度（LIC）的精确定量。商业提供的、供应商提供的三维（3D）多回波 Dixon 序列提供了肝脏 T2* / R2图，并允许自动进行在线后处理，从而无需进行与传统二维（2D）梯度回波（GRE）后处理相关的手动曲线拟合。我们研究的主要目标是研究 3D 多回波 Dixon 序列生成的 LIC 估计值与作为参考标准的 2D GRE 基于 R2弛豫率生成的 LIC 估计值之间的关系。
对接受 MRI 扫描以估计常规 T2弛豫率和 3D 多回波 Dixon 序列的 LIC 的患者进行了回顾性审查。使用 1.5 T 扫描仪采集磁共振研究。采集标准的多层多回波 T2-基于序列，并估计 R2值和相应的 LIC。通过相关系数和 Bland-Altman 差值图分析 2 种方法获得的 R2与相应 LIC 估计值之间的关系。
本研究包括 104 名患者（51 名男性和 53 名女性患者），共 158 次 MRI 扫描。患者扫描时的平均年龄为 15.2（SD，8.8）岁。在 LIC 值高达 3.2mg/g 时，两种 LIC 估计方法之间存在很强的相关性（LIC 定量多回波 Dixon [qDixon；来自 ROI R2*]与 LIC GRE [内部]：r=0.83，P<0.01；LIC qDixon [来自分段容积 R2*]与 LIC GRE [内部]：r=0.92，P<0.01）；而在肝脏铁水平>7mg/g 时，两种方法之间的相关性非常弱。
3D 多回波 Dixon 技术可精确测量高达 7mg/g 的 LIC，并且有可能取代 2D GRE 基于弛豫率的方法。
