Meeting Banner
Abstract #0115

In Vivo Correction of Non-Linear Phase Patterns for Diffusion-Weighted FSE Imaging Using Tailored RF Excitation Pulses

Rita G. Nunes1, 2, Shaihan J. Malik3, Joseph V. Hajnal3

1Institute of Biophysics and Biomedical Engineering, Faculty of Sciences, University of Lisbon, Lisbon, Portugal; 2Robert Steiner MRI Unit, Imaging Sciences Department, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, London, United Kingdom; 3Robert Steiner MRI Unit, Imaging Sciences Department, MRC Clinical Sciences Centre,, Hammersmith Hospital, Imperial College London, London, United Kingdom

Unlike Echo-planar imaging, single-shot fast spin-echo is insensitive to field inhomogeneities but it requires precise control of the phase of the magnetization prior to the start of the refocusing train (CPMG condition). Due to motion, this is very difficult to achieve when diffusion-weighting is applied in vivo. Previously it has been shown that linear phase errors can be measured and corrected for in real time using gradients. The remaining non-linear phase modulations can be prospectively corrected using tailored RF excitation pulses as demonstrated on phantoms. Here the method is further developed and shown to be effective for in vivo imaging.

Abstract PDF Presentation Video

Keywords

account achieve achieved acquisitions allow appealing application applied approximately artifacts avoid biomedical blip blips body brain calibrate calibrations cardiac challenging coil commonly compensate component components condition constant contribution control cooperative correct corrected correcting correction cost coverage delay deposition described designed developments diastole diffusion distortions duration eddies eddy effective encoding ensuring errors evolution excitation exploration field flat fluctuations fulfill full gradient gradients healthy idea imperial in vivo induced inhomogeneities instructed interfaces interval introduced introducing lead limitations linear loss magnet meant measured minimized module motion navigator navigators next nonlinear object occurs option parallel particularly pattern patterns peak period phantom placed power presence prior processing produced project prolonging pulse pulses radians readout real reduction refocusing related remain repeats residual retain rigid satisfied scanned scanner sciences selective sensitive shorten shot shots slice space spacing spatial spin spiral stage steiner still sufficiently suggested tailored terms theory train trajectory triggering true uncorrected unfortunately uniform variable variants vibrations volunteer whole