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Accelerated water–fat imaging using restricted subspace field map estimation and compressed sensing



Water–fat separation techniques play an important role in a variety of clinical and research applications. In particular, multiecho separation methods remain a topic of great interest due to their ability to resolve water and fat images in the presence of B0-field inhomogeneity. However, these methods are inherently slow as they require multiple measurements. An accelerated technique with reduced k-space sampling is desirable to decrease the scan time. This work presents a new method for water–fat separation from accelerated multiecho acquisitions. The proposed approach does not require the region-growing or region-merging schemes that are typically used for field map estimation. Instead, the water, fat, and field map signals are estimated directly from the undersampled k-space measurements. In this work, up to 2.5×-acceleration is demonstrated in a water–fat phantom, ankle, knee, and liver. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.