Flow Field Abstraction and Vortex Detection for MR Velocity Mapping

The evolution of blood flow patterns (vortical flow features in particular) and their interactions with cardiovascular structure is important in the study of cardiovascular function. The winding index method is widely used for vortex detection and has shown to be very sensitive to noise. We propose a novel technique for the detection of vortical flow features that consists of three main components: flow restoration, abstraction and vortex detection. Firstly, an abstract flow field is obtained by clustering the flow field restored using our proposed restoration method. Afterwards, critical points are computed from the abstract flow field and then phase portrait theory is employed to identify vortices. The proposed technique is applied to 12 sets of MR velocity maps acquired from patients with sequential MR examination following myocardial infarction and the results show that vortical flow patterns are more readily detected compared to the winding index method.