Daniel Pflugfelder1, Kaveh Vahedipour1, Kamil Uludag2, Nadim Jon Shah1,3, Tony Stcker1
1Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum Jlich GmbH, Jlich, Germany; 2Max-Planck Institute for Biological Cybernetics, Tuebingen, Germany; 3Faculty of Medicine, Department of Neurology, RWTH Aachen University, Aachen, Germany
To increase the spatial specificity of the BOLD signal, a large ratio R of microvascular to macrovascular BOLD signal is desirable. This can be be achieved using spin echo sequences. To simplify the calculation the extravascular BOLD signal (EV) is often approximated by a mono-exponential decay (MEA). To investigate the effect of the MEA we calculated R for multiple B0 and TE without using this approximation. The parameter range for an optimal R was considerable different to the results obtained using the MEA. This is mainly due to an vessel radius dependent delay of the EV which is not reproduced by the MEA.