Measurement of the regurgitant orifice by 2D TTE and CMR. A. Acquisition of PISA radius and continuous wave Doppler of the MR jet allows calculation of the effective regurgitant orifice. The PISA radius is measured at mid-systole using the first aliasing with a reduced Nyquist limit (15–40 m/s). B. The anatomic regurgitant orifice can be measured by planimetry on a slice parallel to the valvular plane obtained by cardiovascular magnetic resonance.