Analysis of flow patterns using MRI

This paper describes new software programs for analysis and visualization of blood flow patterns derived from time-resolved 3D velocity data sets. Using the programs, data can be displayed in cross-sectional or 3D perspective view. Particle paths revealing the flow patterns are computed by forward and backward time integration of the velocity field. Vector arrowmaps are computed as short-duration paths starting from uniformly spaced points over the lumen volume. Background, divergence, and local boundary correction is done to improve the realism of the paths. The programs have been used to visualize flow patterns from nongated and cardiac-gated 3D velocity enclosed data in over 35 subjects: Arrowmaps are preferred for revealing local regions of different blood flow characteristics within the vessel, while particle paths are preferred for revealing global organization of the flow. They are complementary display strategies. Advanced data handling and display features are essential for analyzing and visualizing large velocity encoded data sets.