Three-dimensional Phase-contrast MRA of Foot Vessels at 5T: Visualization Improved by Warm Water Immersion

Motivation: Unenhanced MRA on feet has always been challenging due to slow blood flow. The ultra-high field strength MR systems have been proved to offer improved visualization of distal small vessels. Goal(s): We aim to assess the visualization of foot vessels using three-dimensional phase contrast MRA (3D-PC-MRA) at 5T field-strength. Approach: Participants were prospectively recruited and underwent 5T 3D-PC-MRA on feet with and without warm water immersion. Results: Immersion of feet in warm water significantly improves visualization of distal small branches, and increases the average velocity of blood flow by 40%, resulting in the visualized enhancement in blood signal. Impact: 5T 3D phase-contrast MRA is effective in visualizing lower-extremity vasculatures and small branches, and its visualization can be significantly improved by immersing feet in warm water.