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. Author manuscript; available in PMC: 2016 Aug 1.
Published in final edited form as: J Magn Reson. 2015 Jun 15;257:102–109. doi: 10.1016/j.jmr.2015.05.011

Fig. 2.

Fig. 2

Schematic of Ultra FastEXchange SpectroscopY (UF-EXSY) reconstruction. Using conventional EXSY the 2D spectra can be reconstructed from the magnitude of the 1D spectrum but requires many τ repetitions. Using the UF-EXSY reconstruction the entire 2D spectra can be reconstructed from a few echoes with high spectral resolution in the indirect frequency direction equal to that of the direct frequency direction. For each frequency, fi, with a signal greater than the noise threshold in the direct frequency direction the cross peaks are calculated using Eq. (6) or with linear least squares based on the phase accrual and frequency difference between every other frequency with a signal also greater than the noise threshold. 2D spectra can be reconstructed from a single acquisition as long as he number of echoes is greater than the number of concomitant exchange pathways at a single resonance.