English: Animation: Comparison between particle tracing and Volume Tracking. Visualization of LV filling in volunteer 7, also shown in Figure 2. Left: particle tracing. Right: Volume Tracking. The left and right panels differ only in the visualization method used. Anatomical four-chamber Cine images are displayed in the background for orientation. See Figure 2 for a description of the anatomy. The four-chamber plane image is semi-transparent to show flow behind the plane. The color scale indicates velocities between 0 and 1.0 meters per second. Time is counted from the start of ventricular systole. The video starts just before the opening of the mitral valve. In the left panel, particles are released every 20 milliseconds. In the right panel, a plane is placed near the mitral valve. The plane is infinitely flexible and stretchable and deforms effortlessly with the flow, showing the boundary between inflow blood and blood already in the ventricle. Between t = 0.337 s and t = 0.5 s, particle tracing shows an ordered inflow, and Volume Tracking shows the inflow blood progressing quickly into the ventricle. After t = 0.5 s, particle tracing shows a complex arrangement of vortices decelerating almost to standstill around t = 0.8 s. In contrast, Volume Tracking clearly shows a clockwise rotation and further deformation in the apical region after t = 0.8s. Additionally, Volume Tracking shows that inflow blood is located closer to the lateral wall of the LV in this subject. A region near the basal parts of the septum contains no filling blood (see Figure 2, white arrow), something which is not clearly visible using particle trace visualization.