Minimizing echo and repetition times in magnetic resonance imaging using a double half‐echo k‐space acquisition and low‐rank reconstruction

• Published in: NMR in biomedicine Vol. 34; no. 4; pp. e4458 - n/a
• Main Authors: Bydder, Mark, Ali, Fadil, Ghodrati, Vahid, Hu, Peng, Yao, Jingwen, Ellingson, Benjamin M.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.04.2021
• Subjects: Biological products; Calibration; Humans; Image acquisition; Image Processing, Computer-Assisted - methods; Image reconstruction; low rank; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; partial Fourier; Polarity; Repetition; Resonance; Sampling; partial Fourier; low rank
• ISSN: 0952-3480; 1099-1492
• DOI: 10.1002/nbm.4458

Sampling k‐space asymmetrically (ie, partial Fourier sampling) in the readout direction is a common way to reduce the echo time (TE) during magnetic resonance image acquisitions. This technique requires overlap around the center of k‐space to provide a calibration region for reconstruction, which limits the minimum fractional echo to ~60% before artifacts are observed. The present study describes a method for reconstructing images from exact half echoes using two separate acquisitions with reversed readout polarity, effectively providing a full line of k‐space without additional data around central k‐space. This approach can benefit sequences or applications that prioritize short TE, short inter‐echo spacing or short repetition time. An example of the latter is demonstrated to reduce banding artifacts in balanced steady‐state free precession. This study describes a method for reconstructing images from exact half echoes using two acquisitions with reserved readout polarity to effectively provide a full line of k‐space. The approach benefits applications that prioritize short echo time, short inter‐echo spacing or short repetition time. The example shows reduced banding artifacts in balanced steady state free procession (bSSFP).