多时相ASL技术及非对比增强功能性MRA评估移植肾的灌注及血管功能的基础研究

The key to improve the success rate of kidney transplantation is that the potential post-operational renal vascular complications and renal parenchyma damages are early detected and timely treated, and the treatment strategy is largely depend on the accurate diagnosis and precise assessment. Presently, the angiography and perfusion imaging by CT or MRI using contrast agents are the main methods for assessing the abnormalities of vascular morphology and renal perfusion after renal transplantation. However the use of contrast agents may lead to contrast-induced nephropathy and gadolinium contrast agent may result in nephrogenic systemic fibrosis, which may hamper those methods to be performed on the patients with renal dysfunction. Developed from our previous researches on this respect, the project aimed to develop a new technique of magnetic resonance angiography without contrast agents by an integrated pulse sequence with SLEEK (spatial labeling with multiple inversion pulses) and 4D flow MRI technique. With this new technique, not only can the high-quality 3-Dimensional vascular images be obtained, but also the functional parameters such as the speed of blood flow, vascular shear stress are accurately measured, which may provide more reliable information for guiding the interventional management on renal artery stenosis. Meanwhile, in the project, multiple-phase arterial spin labeling (ASL) technique is developed from currently adopted single-phase ASL with an attempt to a better evaluation of renal perfusion, and diffusion-weighted imaging is combined with it to a more accurately evaluation of the parenchyma damages of transplanted kidney. Compared to the current methods, these new methods need no contrast agents which can thoroughly avoid the incidence of contrast induced nephropathy and nephrogenic systemic fibrosis, yet may have the better value in evaluating the post-operational renal vascular complications and renal parenchyma damages. Therefore, broad clinical use and good economic and social benefits are expected.

肾移植术后早期发现并及时处理可能发生的各种肾血管并发症及肾实质损伤是提高手术成功率的关键，这需要建立在准确的诊断与评估基础之上。使用对比剂的CT或MRI技术可评估血管的形态学改变及肾灌注状况，是目前肾移植术后评估的主要方法。但对比剂的使用可能会导致对比剂肾病或肾源性系统性纤维化（NSF），故已有肾功能损害的患者需慎重使用对比剂。本项目在前期研究基础上，采用SLEEK序列结合4D-flow技术，探索一种无需对比剂获得高质量三维血管图像的同时获得流速、血管切应力等功能参数的新型磁共振功能性血管成像技术，为指导肾动脉狭窄介入治疗提供更可靠依据；同时，在现有单时相ASL的基础上开发多时相ASL技术，以更准确评估肾灌注状况，联合DWI实现更准确肾实质损伤的评估。这些技术可能获得较现有技术更好的评估效果，且无需对比剂，避免了对比剂肾病及NSF的发生，因此其临床实用性强，将产生良好的经济效益与社会效益。

对于肾功能不良或者损害的患者，采用非对比剂MRI技术评估肾脏灌注、血管动力是目前研究的热点。在前期研究基础上，本课题利用ASL、4D-flow技术对肾脏灌注、肾动脉的显示、自体动静脉内瘘血流动力学做了初步研究。在ASL中，发现采用个性化的翻转时间（TI）有利于准确评估肾动脉及其病变的显示，其与呼吸频率(BR)及心率(HR)呈负相关（r = -0.536, P < 0.001）。利用4D-flow对肾功能不良建立自体动静脉内瘘（RCF）的血管进行评估，与彩超对照，发现4D-flow能准确显示RCF的血流动力学的变化及对血流速度进行定量，较彩超可以整体显示血流的走形和速度，为透析患者动静脉内瘘的评估能提供详细血流动力学信息。另外我们利用高分辨T2WI联合高分辨MRCP对透析导管血栓性并发症做有意义的探讨，认为它们能准确显示CDC尖端的位置及其相关并发症（纤维蛋白鞘、管腔内血凝块、附壁血栓及静脉血栓）,是一种很有前景的无创检查方法。综合上述结果，本研究为ASL、4D-flow、高分辨MRI的临床应用奠定了坚实的工作基础,无需对比剂，且避免了对比剂肾病及肾源性纤维化的发生，其临床实用性强，取得了较好的经济效益与社会效益。项目资助发表SCI论文2篇，核心论文2篇，另外2篇SCI在投。培养硕士生2名并顺利毕业，2名研究生在读。项目投入经费55万元，支出28.2099万元，各项支出基本与预算相符。剩余经费26.7901万元，剩余经费计划用于本项目研究后续支出。

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