Echo-Planar Imaging Hardware

Abstract

Single shot echo-planar imaging is the fastest magnetic resonance imaging method existing on every human MRI scanner. This is one of the reasons why it is so heavily used in functional magnetic resonance imaging as it allows acquiring images of an entire brain in a matter of a few seconds. Another reason is that echo-planar imaging easily allows susceptibility weighting, the key to measure the blood oxygenation level-dependent signal, the essence for performing functional magnetic resonance imaging. MR perfusion imaging, in brain tumors for example, is another method benefitting enormously from echo-planar imaging. Quantitative blood flow measurement can be exploited also with echo-planar imaging. Due to its fast acquisition scheme EPI is also the key to measure diffusion of spins, which is essential for early stroke and tumor detection, as well as neuronal fiber tracking in the brain and spinal cord. In the last 5–10 years methods to further accelerate Echo-planar imaging acquisition time have been developed allowing scanning the entire brain in a time shorter than a second. This is especially helpful for resting state functional magnetic resonance imaging and high resolution fiber tracking using diffusion imaging. Echo-planar imaging therefore provides functional and anatomical information beyond pixel brightness of classical magnetic resonance imaging.