Robust Data Acquisition for MR Doppler

Daeho Lee¹, Adam Bruce Kerr¹, Juan Manuel Santos², Bob Sueh-Chien Hu³, John Mark Pauly¹

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.