Towards validating stent induced micro flow patterns in left main coronary artery bifurcations.

We investigated if blood flow changes induced through the presence of a stent could be detected using in vitro dynamically scaled 4D Phase-Contrast Magnetic Resonance Imaging (PC-MRI). Using idealized and patient-specific left main coronary artery bifurcations, we 3D-printed the dynamically large scaled geometries and incorporated them into a flow circuit for non-invasive acquisition with a higher effective spatial resolution. We tested the effects of using non-Newtonian and Newtonian fluids for the experiment. We also numerically simulated the same geometries in true scale for comparison using computational fluid dynamics (CFD). We found that the experimental setup increased the effective spatial resolution enough to reveal stent induced blood flow changes close to the vessel wall. Non-Newtonian fluid replicated all of the flow field well with a strong agreement with the computed flow field (R > 0.9). Fine flow structures were not as prominent for the Newtonian compared to non-Newtonian fluid consideration. In the patient-specific geometry, arterial non-planarity increased the difficulty to capture the near wall slow velocity changes. Findings demonstrate the potential to dynamically scale in vitro 4D MRI flow acquisition for micro blood flow considerations.