Visualization of Swirling Flow in a 3-dimensional Helical Stent Model using Color-coded Circulation and 4-dimensional...

To clarify how intraluminal flow in 3-dimensional helical and straight stent models is displayed differently using color-coded circulation and 4-dimensional flow magnetic resonance imaging.

Three-dimensional-printed stent models were created to evaluate intraluminal flow by 4-dimensional flow magnetic resonance imaging without stent-related artifacts. Three different helical shapes with different curvatures were created by deploying a 3-dimensional helical stent into poly(vinyl alcohol) hydrogel tubes with different stiffness. Stented poly(vinyl alcohol) hydrogel tube geometries were acquired by micro-computed tomography and replicated using a 3-dimensional printer. Three helical models with different curvatures (high, moderate, and mild) and one straight model were tested under constant flow conditions (200 mL/min, 40% glycerin solution). Flow dynamics were visualized using color-coded circulation based on time-to-arrival digital subtraction angiography and by 4-dimensional flow magnetic resonance imaging.

A swirling flow was observed in the helical models, whereas laminar flow was seen in the straight model. The swirling flow decreased as the curvature decreased. Color-coded circulation imaging revealed eccentric color distribution in the helical models and central-to-peripheral laminar stratification in the straight model. Similarly, 4-dimensional flow magnetic resonance imaging showed eccentric high- and low-velocity regions in the helical models and a central high-velocity region in the straight model.

4-dimensional flow magnetic resonance imaging revealed swirling flow in the helical models and laminar flow in the straight model. Color-coded circulation demonstrated eccentric color distribution in the helical models and central-to-peripheral laminar distribution in the straight model, which might reflect the high-and-low-velocity regions according to the streamline image.