Abstract
The human brain is supplied with blood by four major arteries. Usually, these supply well-known regions of the brain. However, if one or more of these arteries fail to deliver a sufficient amount of blood, a highly efficient security mechanism closes the gap: Through a connection of the four arteries, the so-called Circle of Willis, any artery can contribute to the blood supply of any specific region. As a consequence, the regions supplied can change in shape and size. Although the vascular status and the cerebral blood supply of patients are both of highest neuroradiological interest, only little information on individual perfusion territories is available with established techniques. The day-to-day clinical practice still relies on the well-known standard perfusion territories obtained in post-mortem-studies which fail to reflect the individual patient situation. The present work develops methods to visualize the regions actually supplied by individual arteries. The most promising, basic method for such measurements is Arterial Spin Labeling (ASL). Based on a magnetic label applied to the flowing blood, images of the tissue perfusion can be obtained. The major work packages performed in this thesis are a parameter optimization of the underlying continuous ASL technique used, two different approaches towards a localized labeling of individual arteries and imaging of the corresponding perfusion territories, both evaluated in volunteer studies, and a case study of a patient with embolic stroke highlighting the immediate clinical relevance of the new diagnostic approach.
