Castets Charles R, Ribot Emeline J, Lefrançois William, Trotier Aurélien J, Thiaudière Eric, Franconi Jean-Michel, Miraux Sylvain
Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France.
NMR Biomed. 2015 Jul;28(7):881-9. doi: 10.1002/nbm.3327. Epub 2015 May 19.
Mapping longitudinal relaxation times in 3D is a promising quantitative and non-invasive imaging tool to assess cardiac remodeling. Few methods are proposed in the literature allowing us to perform 3D T1 mapping. These methods often require long scan times and use a low number of 3D images to calculate T1 . In this project, a fast 3D T1 mapping method using a stack-of-spirals sampling scheme and regular RF pulse excitation at 7 T is presented. This sequence, combined with a newly developed fitting procedure, allowed us to quantify T1 of the whole mouse heart with a high spatial resolution of 208 × 208 × 315 µm(3) in 10-12 min acquisition time. The sensitivity of this method for measuring T1 variations was demonstrated on mouse hearts after several injections of manganese chloride (doses from 25 to 150 µmol kg(-1) ). T1 values were measured in vivo in both pre- and post-contrast experiments. This protocol was also validated on ischemic mice to demonstrate its efficiency to visualize tissue damage induced by a myocardial infarction. This study showed that combining spiral gradient shape and steady RF excitation enabled fast and robust 3D T1 mapping of the entire heart with a high spatial resolution.
三维纵向弛豫时间映射是一种很有前景的用于评估心脏重塑的定量无创成像工具。文献中提出的用于进行三维T1映射的方法很少。这些方法通常需要较长的扫描时间，并且使用少量的三维图像来计算T1。在本项目中，提出了一种在7T场强下使用螺旋堆叠采样方案和常规射频脉冲激发的快速三维T1映射方法。该序列与新开发的拟合程序相结合，使我们能够在10 - 12分钟的采集时间内，以208×208×315µm³的高空间分辨率对整个小鼠心脏的T1进行量化。在多次注射氯化锰（剂量为25至150µmol kg⁻¹）后的小鼠心脏上，证明了该方法测量T1变化的灵敏度。在造影前和造影后的实验中均在体内测量了T1值。该方案也在缺血小鼠身上得到验证，以证明其可视化心肌梗死所致组织损伤的有效性。本研究表明，将螺旋梯度形状与稳定的射频激发相结合，能够以高空间分辨率对整个心脏进行快速且稳健的三维T1映射。
