From Macro- to Microvascular ASL: ASL Angiography & Flow Territory Mapping

Nowadays, a large number of methods exist for the visualization the vascular system and the arterial blood supply to various organs of the human body. Angiography techniques are used to image the bulk blood flow in the large vessels of the body like arteries and veins and allow the identification of vascular malformations and vascular alterations like stenosis or occlusions. Such diseases are quite often the cause for a compromised blood supply to organs downstream, which can be characterized by the measurement of blood volume delivered to the capillary bed of a certain amount of tissue in a given period of time (e.g. in units of ml/100g/min). This is also referred to as perfusion and directly reflects the blood flow at the capillary level where exchange of nutrients between blood and tissue occurs. Many commonly used angiography or perfusion imaging techniques rely on the administration of exogenous contrast agents and/or the use of ionizing radiation which can be harmful or even associated with a certain risk of complications. As a consequence, the demand for more patient-friendly and non-contrast enhanced imaging methods has increased.