School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.
Siemens Healthcare Limited, Frimley, United Kingdom.
Magn Reson Med. 2019 Mar;81(3):1795-1805. doi: 10.1002/mrm.27540. Epub 2018 Oct 28.
To develop a fast and accurate method for 3D T mapping of prostate cancer using undersampled acquisition and dictionary-based fitting.
3D high-resolution T -weighted images (0.9 × 0.9 × 3 mm ) were obtained with a multishot T -prepared balanced steady-state free precession (T -prep-bSSFP) acquisition sequence using a 3D variable density undersampled Cartesian trajectory. Each T -weighted image was reconstructed using total variation regularized sensitivity encoding. A flexible simulation framework based on extended phase graphs generated a dictionary of magnetization signals, which was customized to the proposed sequence. The dictionary was matched to the acquired T -weighted images to retrieve quantitative T values, which were then compared to gold-standard spin echo acquisition values using monoexponential fitting. The proposed approach was validated in simulations and a T /T phantom, and feasibility was tested in 8 healthy subjects.
The simulation analysis showed that the proposed T mapping approach is robust to noise and typically observed T variations. T values obtained in the phantom with T prep-bSSFP and the acquisition-specific, dictionary-based matching were highly correlated with the gold-standard spin echo method (r = 0.99). Furthermore, no differences were observed with the accelerated acquisition compared to the fully sampled acquisition (r = 0.99). T values obtained in prostate peripheral zone, central gland, and muscle in healthy subjects (age, 26 ± 6 years) were 97 ± 14, 76 ± 7, and 36 ± 3 ms, respectively.
3D quantitative T mapping of the whole prostate can be achieved in 3 minutes.
开发一种使用欠采样采集和基于字典拟合的快速准确的前列腺癌 3D T 映射方法。
使用多shot T 准备平衡稳态自由进动（T-prep-bSSFP）采集序列，使用 3D 变密度欠采样笛卡尔轨迹获得 3D 高分辨率 T 加权图像（0.9×0.9×3mm）。使用全变分正则化灵敏度编码重建每个 T 加权图像。基于扩展相位图的灵活仿真框架生成了磁化信号字典，该字典针对所提出的序列进行了定制。字典与采集的 T 加权图像匹配以检索定量 T 值，然后使用单指数拟合将其与金标准自旋回波采集值进行比较。该方法在模拟和 T/T 体模中进行了验证，并在 8 名健康受试者中进行了可行性测试。
模拟分析表明，所提出的 T 映射方法对噪声和典型的观察到的 T 变化具有鲁棒性。使用 T-prep-bSSFP 和特定于采集的基于字典匹配获得的体模中的 T 值与金标准自旋回波方法高度相关（r=0.99）。此外，与完全采样采集相比，加速采集没有观察到差异（r=0.99）。健康受试者（年龄，26±6 岁）前列腺外周区、中央腺和肌肉中的 T 值分别为 97±14、76±7 和 36±3ms。
可以在 3 分钟内实现整个前列腺的 3D 定量 T 映射。
