Daeho Lee1, Adam Bruce Kerr1, Juan Manuel Santos2, Bob Sueh-Chien Hu3, John Mark Pauly1
1Electrical Engineering, Stanford University, Stanford, CA, United States; 2HeartVista, Inc., Palo Alto, CA, United States; 3Cardiology, Palo Alto Medical Foundation, Palo Alto, CA, United States
The pressure gradient across cardiac valves is commonly utilized to evaluate the severity of valvular stenosis. Peak velocity is often used to derive the pressure-gradient, and more accurate estimation is possible with a localized velocity spectrum. MR Doppler has been shown to effectively acquire a spatially resolved velocity spectrum in real-time without cardiac gating thanks to resolving flow along a cylindrical pathway restricted by pencil beam excitation. The fidelity of velocity estimation is especially critical for diagnosing stenotic flow in the range of 2~3 m/s. However, off-resonance, inflow effect, and flow acceleration during readout incurs signal drop and spurious dispersion in the velocity spectrum, degrading the velocity estimation. We present a circular k-space echo-shifted interleaved acquisition method to improve the reliability of velocity estimation, especially for imaging high-velocity jets.