Four-dimensional phase contrast MRI with accelerated dual velocity encoding

Purpose: To validate a novel approach for accelerated four-dimensional phase contrast MR imaging (4D PC-MRI) with an extended range of velocity sensitivity. Materials and Methods: 4D PC-MRI data were acquired with a radially undersampled trajectory (PC-VIPR). A dual V_enc (dV_enc) processing algorithm was implemented to investigate the potential for scan time savings while providing an improved velocity-to-noise ratio. Flow and velocity measurements were compared with a flow pump, conventional 2D PC MR, and single V_enc 4D PC-MRI in the chest of 10 volunteers. Results: Phantom measurements showed excellent agreement between accelerated dV_enc 4D PC-MRI and the pump flow rate (R² ≥ 0.97) with a three-fold increase in measured velocity-to-noise ratio (VNR) and a 5% increase in scan time. In volunteers, reasonable agreement was found when combining 100% of data acquired with V_enc = 80 cm/s and 25% of the high V_enc data, providing the VNR of a 80 cm/s acquisition with a wider velocity range of 160 cm/s at the expense of a 25% longer scan. Conclusion: Accelerated dual V_enc 4D PC-MRI was demonstrated in vitro and in vivo. This acquisition scheme is well suited for vascular territories with wide ranges of flow velocities such as congenital heart disease, the hepatic vasculature, and others.