Nayak, “Automatic correction of echo-planar imaging (EPI) ghosting artifacts in real-time interactive cardiac MRI using sensitivity encoding

Purpose: To develop a method that automatically corrects ghosting artifacts due to echo-misalignment in interleaved gradient-echo echo-planar imaging (EPI) in arbitrary oblique or double-oblique scan planes. Materials and Methods: An automatic ghosting correction technique was developed based on an alternating EPI ac-quisition and the phased-array ghost elimination (PAGE) reconstruction method. The direction of k-space traversal is alternated at every temporal frame, enabling lower tem-poral-resolution ghost-free coil sensitivity maps to be dy-namically estimated. The proposed method was compared with conventional one-dimensional (1D) phase correction in axial, oblique, and double-oblique scan planes in phan-tom and cardiac in vivo studies. The proposed method was also used in conjunction with two-fold acceleration. Results: The proposed method with nonaccelerated acquisi-tion provided excellent suppression of ghosting artifacts in all scan planes, and was substantially more effective than con-ventional 1D phase correction in oblique and double-oblique scan planes. The feasibility of real-time reconstruction using the proposed technique was demonstrated in a scan protocol with 3.1-mm spatial and 60-msec temporal resolution. Conclusion: The proposed technique with nonaccelerated acquisition provides excellent ghost suppression in arbitrary scan orientations without a calibration scan, and can be use-ful for real-time interactive imaging, in which scan planes are frequently changed with arbitrary oblique orientations. Key Words: echo-planar imaging (EPI); ghosting artifacts; echo-misalignment; real-time interactive MRI; sensitivity encoding (SENSE) J. Magn. Reson. Imaging 2008;27:239–245