Abstract #2077

Correcting diffusion weighted MR images for signal pile-up and distortions near gas pockets

Laurens D. van Buuren¹, Daniel Polders¹, Maaike T. Milder¹, Floris J. Pos¹, Stijn W. Heijmink¹, Baukelien van Triest¹, and Uulke A. van der Heide¹

¹Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, Netherlands

Echo-planar imaging is widely used to obtain diffusion images within acceptable time limits. These images suffer from geometric distortions. Additionally, the diffusion signal intensity can be obscured by signal pile-up, when strong variations of the magnetic field occur, for example near gas pockets. We demonstrate in a water phantom that both the signal pile-up and geometric distortions can be corrected by combining the information from EPI images obtained with opposite gradients and a magnetic field map. We applied this method in two patients and show a reduction in signal pile-up and geometric distortions near gas pockets in the rectum.

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