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Vendor variations and options for respiratory compensation exist. GE offers a "high sort" option that is similar to their "No Phase Wrap" technique. In GE's "high sort" the phase FOV and number of phase-encoding steps is doubled while the number of excitations (NEX) is cut in half. This has the effect of spreading the respiratory motion ghosts farther apart, many of which will now lie outside the displayed FOV. The downside of this technique is that vascular motion may increase.
Bailes DR, Gildendale DJ, Bydder GM et al. Respiratory ordered phase encoding (ROPE): a method for reducing respiratory motion artifacts in MR imaging. J Comput Assist Tomogr 1985; 9:835-838. (The original method. Most respiratory compensation techniques in use today employ a variant or ROPE known as COPE - central ordered phase encoding).
Ehman RL, McNamara MT, Pallack M, et al. Magnetic resonance imaging with respiratory gating: techniques and advantages. AJR Am J Roentgenol 1984; 143:1175-1182.
Lewis CE, Prato FS, Drost DJ, Nicholson RL. Comparison of respiratory triggering and gating techniques for the removal of respiratory artifacts in MR imaging. Radiology 1986; 160:803-810.
How are cardiac and respiratory gating performed?