Characterization of Receiver Demodulation for Correcting Off-axis MR Imaging Degradation
Jung Y, Jashnani Y, Block W, Kijowski R
University of Wisconsin-Madison
Improper alignment of the gradient coil and the real-time frequency demodulation reference signal, necessary in off-axis imaging, may be one source of the inconsistency of non-Cartesian imaging. As the system delay parameter varies with imaging bandwidth and between scanners, many non-Cartesian imaging methods require trial and error tuning for off-axis imaging. We present an automatic per-patient-based method to precisely measure the timing error in the frequency demodulation reference signal in less than 0.5 s. Off-axis image quality is significantly improved when compensation for demodulation phase errors due to the delay is applied to radial and spiral reconstructions.