准连续性动脉自旋标记技术在磁共振系统上的序列实现和参数优化

发布时间：2018-12-08 19:18

【摘要】：准连续性动脉自旋标记技术(p CASL)是一种新兴的动脉自旋标记脑灌注成像技术(ASL):一方面,它克服了连续性动脉自旋标记技术(CASL)需要独立发射线圈的硬件限制;另一方面,也避免了脉冲式动脉自旋标记技术(PASL)带来的标记效率低的影响.为了在1.5T磁共振系统上开发一款可稳定应用于临床扫描的p CASL序列;并使用该序列准确获得反应灌注功能的局部脑血流量值(Regional Cerebral Blood Flow,r CBF).该文利用水模测试p CASL序列,验证了标记部分的标记性能并通过人体实验,优化了协议中标记位置中心到成像层面中心的距离和标记部分结束点到成像脉冲开始前的等待时间这两项参数.基于优化了参数的p CASL协议,扫描12组正常志愿者,观测灌注信号分布情况,并对特定灰质区域定量计算,对比不同个体该区域的r CBF值.通过人体实验,经验性地确定了延迟时间为1 200 ms、标记距离为70 mm时灌注图像的信噪比达到最优.将两项优化后的参数存入协议中,并使用协议扫描,共获取12组结果,其中的10组都表明灌注信号稳定均匀,并且灰质区域的CBF值同经验结果一致.该工作在1.5 T的磁共振系统上成功实现了p CASL序列,经优化参数后的协议扫描,可以获得准确稳定的脑部灌注信号.
[Abstract]:Quasi continuous arterial spin labeling (p CASL) is a new arterial spin labeling technique for cerebral perfusion imaging (ASL):). On the one hand, it overcomes the hardware limitation of continuous arterial spin labeling (CASL), which requires independent emission coils. On the other hand, it can avoid the low labeling efficiency caused by pulsed arterial spin labeling (PASL). In order to develop a stable p CASL sequence for clinical scanning on 1.5T magnetic resonance system, and use the sequence to accurately obtain the regional cerebral blood flow (Regional Cerebral Blood Flow,r CBF).) value of reactive perfusion function. In this paper, the p CASL sequence was tested by water model, and the labeling performance of the labeled part was verified. The distance between the marking center and the imaging plane center and the waiting time from the end point of the marking part to the beginning of the imaging pulse are optimized. Based on the p CASL protocol with optimized parameters, 12 groups of normal volunteers were scanned to observe the distribution of perfusion signals, and to quantitatively calculate the specific gray matter area, and to compare the r CBF values of different individuals in this region. Through human experiments, it has been determined empirically that the SNR of perfusion image is optimal when the delay time is 1 200 ms, label distance is 70 mm. The two optimized parameters are stored in the protocol and scanned by the protocol. A total of 12 groups of results are obtained, of which 10 groups show that the perfusion signal is stable and uniform, and the CBF values in the gray matter region are consistent with the empirical results. In this work, the p CASL sequence was successfully realized on 1. 5 T magnetic resonance system. After the optimized parameters were scanned by protocol, accurate and stable cerebral perfusion signals could be obtained.
【作者单位】：高端医学影像技术研究中心(中国科学院上海高等研究院);中国科学院大学;上海联影医疗科技有限公司;复旦大学附属华山医院;
【基金】：中国科学院重点部署资助项目(Y325511211)
【分类号】：R445.2;O482.532

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