Figure 2

Minimum achievable TE (a) and TR (b) plotted as a function of the target VENC for conventional flow compensated and flow encoded velocity encoding (FCFE; solid black), Bipolar velocity encoding (black dashed), and convex gradient optimized PC-MRI (CVX; solid gray). As the VENC increases, a theoretical minimum TE/TR is reached for FCFE and Bipolar because of limitations associated with the plateau of the readout gradient overlapping with the velocity encoding gradients gradient. The CVX sequence constructs asymmetrically weighted velocity encoding gradients and a flow compensated readout gradient to be of equal duration, thus overcoming this limitation and offering shorter values for TE/TR compared FCFE and Bipolar. All other imaging parameters were held constant (1.8 mm × 1.8 mm × 5 mm resolution, 30° flip angle, 814 Hz/px receiver bandwidth, 600 μs RF pulse width, 4π gradient spoiling for CVX and a vendor hard-coded 9π gradient spoiling for FCFE and Bipolar).