Rapid Motion Perception MRI Navigator Method

Available for licensing and commercial development is a non-breathhold flow sensitive navigator technique for reducing respiratory motion artifacts in magnetic resonance (MR) images. The method, called Rapid Motion Perception (RaMP), tracks bulk translational motion of the heart in real-time. The position of the blood volume is a direct representation of the heart position. RaMP tracks fast-moving blood volume during systole as a marker for the heart position, while suppressing stationary or slow moving spins. This approach allows cardiac navigation in two orthogonal directions simultaneously, eliminates the need to obtain empirical correlations between the diaphragm and the heart, and increases tracking reliability among individual patients. The method uses a spoiled-Fast Low Angle Shot (FLASH) navigator and incorporates an alternating pair of bipolar velocity-encoding gradients. Data at 1.5T indicate that RaMP is capable of correcting bulk motion of the heart over multiple cardiac cycles to within +/-1.43 mm in the superior-inferior direction and +/- 0.84 mm in the anterior-posterior direction.