Background Echo-planar imaging ( EPI) with fast imaging times minimize the effect of bulk motions from pulsation, involuntary motion, bowel peristalsis, respiration and cardiac movement. 背景平面回波成像(echo-planarimaging,EPI)技术成像时间很短,可明显减少脉搏、不自主运动、肠蠕动、呼吸和心脏跳动等运动伪影。