Real-time geometric distortion correction for interventional imaging with Echo-planar imaging (EPI)

Many MR-guided interventional procedures rely on fast imaging sequences for providing images in real-time with a precise relation between the target position in the image and its true position. Echo-planar imaging (EPI) methods are very fast but prone to geometric distortions. Here, we propose a correction method designed for real-time conditions, adapting existing approaches based on dual EPI acquisition with varying echo times. The method is demonstrated with MR-thermometry for guiding thermal therapies. The proposed approach imposes a small penalty in acquisition speed but adds negligible latency to data processing, an important element for interventions of mobile organs. Magn Reson Med 61:994-1000, 2009.