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FIGURE 5. Comparison of difference of phases obtained when 8 frames per cycle (left panel) or 16 frames per cycle (right panel) data acquisition are used. Points in right panel are counts of a pixel arbitrarily chosen from the anterior region of polar maps given by a set of gated (16 frames per cycle) short-axis images. These points are regional maximum counts and their variations represent wall thickness changes at region over the cardiac cycle. Points in left panel are down-sampled from points in right panel. Curves are the first harmonics that approximate wall thickness changes during the cardiac cycle. With first harmonic approximation, phase difference between 8 frames per cycle and 16 frames per cycle is very small at –0.5° (360° corresponds to 1 cardiac cycle).
