Institut Curie, Orsay, France.
Magn Reson Med. 2010 Jul;64(1):313-8. doi: 10.1002/mrm.22396.
Dynamic contrast-enhanced MRI is extensively studied to define and evaluate biomarkers for early assessment of vasculature-targeting therapies. In this study, two-dimensional and three-dimensional radial multi-gradient-echo techniques for dynamic R*(2)-corrected R(1) mapping based on the spoiled gradient recalled signal equation were implemented and validated at 4.7 T. The techniques were evaluated on phantoms and on a respiratory motion animated tumor model. R(1) measurements were validated with respect to a standard inversion-recovery spin-echo sequence in a four-compartment phantom covering a range of relaxation rates typically found in tumor tissue. In the range of [0.4, 3] sec(-1), R(1) differences were less than 10% for both two-dimensional and three-dimensional experiments. A dynamic contrast-enhanced MRI pilot study was performed on a colorectal tumor model subcutaneously implanted in mice at the abdominal level. Low motion sensitivity of radial acquisition allowed image recording without respiratory triggering. Three-dimensional K(trans) maps and significantly different mean K(trans) values were obtained for two contrast agents with different molecular weights. The radial multi-gradient-echo approach should be most useful for preclinical experimental conditions where the tissue of interest experiences physiologic motion, like spontaneous extracerebral tumors developed by transgenic mice, and where dynamic contrast-enhanced MRI is performed with high-relaxivity contrast agents.
动态对比增强 MRI 广泛用于定义和评估血管靶向治疗的早期评估生物标志物。在这项研究中，在 4.7T 上实现并验证了基于扰动脉冲回波信号方程的二维和三维径向多梯度回波技术，用于动态 R*(2)-校正 R(1)映射。这些技术在体模和呼吸运动模拟肿瘤模型上进行了评估。在覆盖肿瘤组织中常见的弛豫率范围的四腔室体模中，针对标准反转恢复自旋回波序列对 R(1)测量值进行了验证。在 [0.4,3] sec(-1) 的范围内，二维和三维实验的 R(1)差异均小于 10%。在腹部皮下植入结直肠肿瘤模型的小鼠中进行了动态对比增强 MRI 初步研究。径向采集的低运动灵敏度允许在不进行呼吸触发的情况下进行图像记录。两种具有不同分子量的对比剂获得了三维 K(trans)图和明显不同的平均 K(trans)值。径向多梯度回波方法最适用于感兴趣的组织经历生理运动的临床前实验条件，例如由转基因小鼠自发形成的脑外肿瘤，并且在这些条件下使用高弛豫性对比剂进行动态对比增强 MRI。
