TY  - GEN
A1  - Gregori, Johannes
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/10462/
N2  - Arterial Spin Labeling (ASL) is an MR imaging technique which can measure the brain perfusion locally without contrast agent. The inflowing blood is labeled by inverting the magnetization of the water molecules. During the blood flow through the vascular tree and the capillary bed, the signal can be acquired at different inflow times. Thereby, the signal decays with T1. An aspect which has not yet been investigated is the dynamics of further MR parameters during the inflow. In the present work, the dynamics of the parameters T2 and T2? of the perfusion signal are investigated. The employed MRI sequences have been developed and are presented in this thesis: a 3D-GRASE readout with variable echo time for T2 quantification, and a spin/gradient double echo double spiral 3D-GRASE readout for T2? estimation. Further, a model has been developed which describes the behavior of the perfusion signal which includes permeability, depending on the echo time. With the acquired data it has been possible to directly derive an estimate for the local water permeability of the capillary wall. The T2? data allows an estimation of dynamical changes of oxygenation and local apparent venous volume in the direct vicinity of the inflowing blood water spins. The double echo spiral sequence in conjunction with ASL can in principle acquire perfusion and oxygenation simultaneously and is therefore predestined for functional imaging applications. Both techniques allow deep insights in basic local perfusion mechanisms.
TI  - Dynamic Arterial Spin Labeling Measurements of Physiological Parameters - Permeability and Oxygenation
AV  - public
ID  - heidok10462
KW  - Arterial Spin Labeling 
KW  -  3T 
KW  -  Doppel Spiral 
KW  -  Multi Echo 
KW  -  ASLArterial Spin Labeling 
KW  -  3T 
KW  -  Double Spiral 
KW  -  Multi Echo 
KW  -  ASL
Y1  - 2009///
ER  -