Abstract #4066

Echo Planar Diffusion-Weighted MRI of the Abdomen and Pelvis: Comparison of Free-Breathing Monopolar and Bipolar Spin-Echo Sequences in Image Quality and Geometric Distortions

Stavroula Kyriazi¹, Veronica A. Morgan², David J. Collins², Nandita M. deSouza²

¹Cancer Research UK Clinical Magnetic Resonance Group, Institute of Cancer Research and Royal Marsden NHS Foundation Trust , Sutton, Surrey, UK; ²Cancer Research UK Clinical Magnetic Resonance Group, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK

Single-shot spin-echo echo planar diffusion weighting imaging (ssEPI-DWI)suffers from geometric distortion due to eddy currents generated by the strong gradient pulses. The application of a bipolar technique with alternating polarity diffusion sensitising gradients has been proposed to counteract these magnetic field inhomogeneities. In this study on seven healthy volunteers we compare the monopolar (conventional Steskal and Tanner) with the bipolar sequence in free-breathing abdominal and pelvic diffusion imaging, in terms od signal-to-noise ratio (SNR), apparent diffusion coefficient values (ADC), efficiency of fat saturation, and visual image quality. Our results suggest that despite their lower SNR, bipolar acquisitions provide improved image quality primarily due to reduced sensitivity to distortion artifacts.