Fig 4. Effect of physiological breathing motion simulator on displacement estimation.

(A) Schematic diagram of the MR-compatible respiratory motion simulator. A 1d linear motor is used to periodically depress a water bottle, which generates sinusoidal motion at a membrane connected to the bottle via plastic tubing. The phantom resting on the membrane is thus raised and lowered by the water pressure. The system generates 0.3 Hz sinusoid motion with an amplitude of 4 mm. (B) Comparison of the displacement with and without artificial sinusoidal motion. (C) Comparison of image quality of bovine gelatin phantom with and without motion, sonication and trigger. Magnitude and phase images are shown on the top and bottom row. Column (i) as a control, indicates the image quality without artificial motion. After motion was induced, images were acquired without (column (ii, iv)) and with the trigger (iii, v).