Development of custom-made RF coil for magnetic resonance velocimeter with a high spatial resolution

Magnetic resonance velocimetry (MRV) is a versatile flow visualization technique that is used to measure three-component velocity vectors in a 3D space. However, the spatial resolution of MRV is relatively poor in comparison with optical flow visualization techniques, thereby limiting its applicability to small-scale flows and wall shear stress (WSS) estimation. Thus, we built a solenoid RF coil and evaluated its performance in terms of spatial resolution improvement by measuring the laminar flow in a circular tubing. The coil was developed for a 4.7 Tesla MRI system and for tightly wrapping a flow tubing with an inner diameter of 2 mm. The custom-made RF coil could precisely capture the velocity vectors in a voxel that was 11 times smaller than a commercial coil at the same SNR. Therefore, the WSS errors estimated using the custom-made and commercial coils were 8.5 % and 42.3 %, respectively.