Mean Aneurysm Flow Amplitude Ratio Comparison between DSA and CFD.

The Mean Aneurysm Flow Amplitude ratio (MAFA-ratio) has been proposed to evaluate the efficacy of flow diverting stents during minimally invasive intracranial aneurysm treatment. A method has been described for calculating the MAFA-ratio on high frame-rate digital subtraction angiography (DSA) acquisitions using an optical flow algorithm. In this article we have generated computational fluid dynamics (CFD) simulations using six distinct aneurysms and computed the MAFA-ratios based on these data. Furthermore, the simulations have been used to create virtual angiograms, in order to calculate the MAFA-ratios using the DSA approach. An analysis of the MAFA-ratios generated by both methods shows that there is a monotone increasing relation between the DSA and CFD based ratios, albeit without a slope being identity. Overall, it can be concluded that the DSA-based ratio is a predictor for the magnitude of aneurysm flow reduction, i.e., for the efficacy of flow diverting stents.