Phase-contrast MRI with hybrid one and two-sided flow-encoding and velocity spectrum separation

Purpose: To develop and evaluate a phase-contrast MRI (PC-MRI) technique with hybrid one and two-sided flow-encoding and velocity spectrum separation (HOTSPA) for accelerated blood flow and velocity measurement. Methods: In the HOTSPA technique, the two-sided flow encoding (FE) is used for two FE directions and one-sided is used for the remaining FE direction. Such a temporal modulation of the FE strategy allows for separations of the Fourier velocity spectrum into components for the flow-compensated and the three-directional velocity waveforms, accelerating PC-MRI by encoding three-directional velocities using only two repetition times (TRs) instead of four TRs as in standard PC-MRI. The HOTSPA was evaluated and compared with standard PC-MRI in the common carotid arteries of six healthy volunteers. Results: Total volumetric flow and peak velocity measurements based on HOTSPA and the conventional PC-MRI were in good agreement with a bias of −0.005 mL (−0.1% relative bias error) for total volumetric flow and 1.21 cm/s (1.1% relative bias error) for peak velocity, although the total acquisition time was 50% of the conventional PC-MRI. Conclusion: The proposed HOTSPA technique achieved nearly two-fold acceleration of PC-MRI while maintaining accuracy for total volumetric flow and peak velocity quantification by separating the paired acquisitions in the Fourier velocity spectrum domain. Magn Reson Med 78:182–192, 2017.