Fully automatic mapping of cerebral perfusion territories using Magnetic Resonance Imaging

该项目旨在完全开发一种加速的脑灌注区域图方法，而不需要手动计划个别采集。使用动脉自旋标记可以在不应用任何外部造影剂的情况下进行灌注成像，从而使该方法对于反复获取以及在健康志愿者中的应用具有吸引力。该方法的改进允许成像全脑灌注(非选择性)、主要动脉(颈动脉和椎动脉)的供血区域以及较小的颅内动脉。然而，选择性收购的一个主要缺点是在收购之前需要一个耗时的规划程序。当然，加快这一过程的方法是可取的。这些方法是存在的，但由于磁共振成像的物理原理而受到限制，它只允许获得相对灰度值，而不是定量灰度值。因此，需要新的算法，这些算法足够严格，只检测感兴趣的结构，但又足够灵活，以适应个别患者的解剖结构。该项目不仅旨在优化算法，而且使用组合方法来优化MR序列以最大化感兴趣组织的对比度，同时检测方法在其可靠性方面得到了改进。在这个项目中要解决的另一个主要限制是选择性动脉自旋标记方法的扫描持续时间较长。使用区域方法时，图像采集时间一般随着获取区域的数量而线性增加。这不必要地增加了总体扫描持续时间，并且可能导致在扫描期间出现更明显的运动伪影。这在选择性地标测较小的颅内动脉时尤其关键。因此，在本项目中进一步考虑了一种在不增加扫描时间的情况下在一次扫描中获取单个领土的方法。总之，一种自动计划选择性灌注采集的方法以及减少总体扫描时间的方法将是该项目的成果。

This projects aims towards the complete development of an accelerated brain perfusion territory mapping method without the need for manually planning the individual acquisitions. Using Arterial Spin Labeling it is possible to perform perfusion imaging without the application of any external contrast material, thereby making this method attractive for recurrent acquisitions as well as for the application in healthy volunteers. Modifications of the method allow for imaging of whole brain perfusion (non-selective), territories supplied by the major arteries (carotid and vertebral arteries) as well as smaller, intracranial arteries. A major disadvantage of selective acquisitions is however the need for a time-consuming planning procedure prior to the acquisition. Naturally, methods to speed up this process are desired. These approaches exist, yet are limited due to the physical principles of MRI, which allow only for obtaining relative rather than quantitative gray values. Therefore, novel algorithms are needed, which are stringent enough to only detect the structures of interest, yet are flexible enough to adapt to individual patients anatomies. This projects aims not only for algorithm optimization, but uses a combined approach to optimize MR sequences to maximize the contrast of the tissues of interest, while the detection methods are improved regarding their reliability. Another major limitation to be dealt with during this project is the longer scan duration of selective Arterial Spin Labeling approaches. Using territorial methods, generally the image acquisition time increases linearly with the number of acquired territories. This increases the overall scan duration unnecessarily and potentially leads to more pronounced motion artifacts during scanning. This is especially critical in mapping the smaller intracranial arteries selectively. Therefore, a method to acquire the individual territories within a single scan without increasing the scan time is furthermore considered in this project. In conclusion, a method to automatically plan the selective perfusion acquisitions in combination with a reduced overall scan time will be the outcome of this project.