Magnetic resonance phase velocity mapping through NiTi stents in a flow phantom model

Abstract

Purpose: To assess constant and pulsatile flow velocity within the lumen of a peripheral NiTi stent using phase velocity mapping for comparison with independent assessments of flow velocity in a phantom model. Materials and Methods: A 9 × 20-mm stent installed in flexible tubing was placed in a phantom filled with stationary fluid. Constant and pulsatile flow (produced by a pump programmed to produce a simulation of the carotid artery flow) was assessed using phase velocity mapping at 4.1 T (for constant flow) and at 1.5 T (for pulsatile flow). In all cases 256 × 256 gradient echo phase velocity maps were acquired. For the pulsatile flow condition, cine images with acquisition gated to the pump cycle were acquired with 40 msec temporal resolution across the simulated cardiac cycle. Computed flow volume rates were compared with fluid volume collection for the constant flow model, and with ultrasonic Doppler flow meter measurements for the pulsatile model. Results: The data showed that volume flow rate assessments by phase velocity mapping agreed with independent measurements within 10% to 15%. Conclusion: Phase velocity mapping of the lumen of peripheral size NiTi stents is possible in an in vitro model.