Charles L. Dumoulin1, Richard P. Mallozzi2,
Robert D. Darrow3, Ehud J. Schmidt4
1Imaging Research Center, Cincinnati
Children's Hospital Medical Center, Cincinnati, OH, United States; 2ONI
Medical Systems, Inc., Wilmington, MA, United States; 3General
Electric Global Research, Niskayuna, NY, United States; 4Radiology,
Brigham and Womens Hospital, Boston, MA, United States
An
orthogonal gradient pulse is added to an MR tracking pulse sequence to change
the phases of the detected MR signals.
Since the phase of the signals is unknown in the absence of the
orthogonal dephaser, the dephasing gradient can either increase or decrease
the strength of the acquired signal.
Consequently, the direction of the orthogonal gradient pulse is
rotated through a cycle and the data in each cycle is processed to extract
the most desired feature (e.g. maximum pixel detection). This approach increases the robustness of
MR tracking in low SNR conditions.