Lavini Cristina, Kramer Gem, Pieters-den Bos Indra, Hoekstra Otto, Marcus J T
Department of Radiology and Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands.
Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
Magn Reson Imaging. 2017 Dec;44:96-103. doi: 10.1016/j.mri.2017.08.010. Epub 2017 Sep 1.
In this study we systematically investigated different Dynamic Contrast Enhancement (DCE)-MRI protocols in the spine, with the goal of finding an optimal protocol that provides data suitable for quantitative pharmacokinetic modelling (PKM).
In 13 patients referred for MRI of the spine, DCE-MRI of the spine was performed with 2D and 3D MRI protocols on a 3T Philips Ingenuity MR system. A standard bolus of contrast agent (Dotarem - 0.2ml/kg body weight) was injected intravenously at a speed of 3ml/s. Different techniques for acceleration and motion compensation were tested: parallel imaging, partial-Fourier imaging and flow compensation. The quality of the DCE MRI images was scored on the basis of SNR, motion artefacts due to flow and respiration, signal enhancement, quality of the T map and of the arterial input function, and quality of pharmacokinetic model fitting to the extended Tofts model.
Sagittal 3D sequences are to be preferred for PKM of the spine. Acceleration techniques were unsuccessful due to increased flow or motion artefacts. Motion compensating gradients failed to improve the DCE scans due to the longer echo time and the T* decay which becomes more dominant and leads to signal loss, especially in the aorta. The quality scoring revealed that the best method was a conventional 3D gradient-echo acquisition without any acceleration or motion compensation technique. The priority in the choice of sequence parameters should be given to reducing echo time and keeping the dynamic temporal resolution below 5s. Increasing the number of acquisition, when possible, helps towards reducing flow artefacts. In our setting we achieved this with a sagittal 3D slab with 5 slices with a thickness of 4.5mm and two acquisitions.
The proposed DCE protocol, encompassing the spine and the descending aorta, produces a realistic arterial input function and dynamic data suitable for PKM.
在本研究中，我们系统地研究了脊柱的不同动态对比增强（DCE）-MRI方案，目的是找到一种能提供适用于定量药代动力学建模（PKM）数据的最佳方案。
对13例因脊柱MRI检查而转诊的患者，在3T飞利浦Ingenuity MR系统上采用二维和三维MRI方案进行脊柱DCE-MRI检查。以3ml/s的速度静脉注射标准剂量的造影剂（钆双胺-0.2ml/kg体重）。测试了不同的加速和运动补偿技术：并行成像、部分傅里叶成像和流动补偿。基于信噪比、流动和呼吸引起的运动伪影、信号增强、T图和动脉输入函数的质量以及药代动力学模型对扩展Tofts模型的拟合质量，对DCE MRI图像的质量进行评分。
矢状面三维序列更适合脊柱的PKM。由于流动或运动伪影增加，加速技术未成功。由于回波时间延长和T*衰减变得更加显著并导致信号丢失，尤其是在主动脉中，运动补偿梯度未能改善DCE扫描。质量评分显示，最佳方法是采用传统的三维梯度回波采集，不使用任何加速或运动补偿技术。在选择序列参数时，应优先考虑减少回波时间并将动态时间分辨率保持在5秒以下。尽可能增加采集次数有助于减少流动伪影。在我们的研究中，我们通过一个矢状面三维厚层，包含5层，层厚4.5mm，并进行两次采集来实现这一点。
所提出的DCE方案，涵盖脊柱和降主动脉，可产生适用于PKM的逼真动脉输入函数和动态数据。
