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. Author manuscript; available in PMC: 2014 Apr 1.
Published in final edited form as: Magn Reson Med. 2012 May 24;69(4):1044–1055. doi: 10.1002/mrm.24340

Figure 3.

Figure 3

a: Simulated echo signal for 1-pentene under spin echo (SE) and CPMG and UDD sequences with 4, 8 and 16 pulses, normalized to the FID signal. The inset regions (bottom) show the typical experimental TE regime, from 40 ms to 150 ms. J-couplings cause the signal to drop quickly (to ~10% after 45 ms), with subsequent signal oscillations. The colorbar shown across the top of each graph shows the subtraction (UDD-CPMG)/CPMG and indicates the TEs where UDD is better and where CPMG is better. The optimal signal depends on the echo time and number of pulses and is due to the complicated chemical structure of J-couplings. b: Simulated echo signal for 1-pentene under CPMG8 and UDD8 sequences using the timing of the experimental imaging sequence. The CPMG and UDD timings are calculated using the given TE (such that the echo spacing remains the same), but there is an extra π pulse after the final 180 to provide slice selection and an extra 10 ms of evolution time (2.5 ms before CPMG or UDD; 2.5 ms after CPMG or UDD; and 5 ms after the slice selective pulse). The inset region (right) shows the typical experimental TE regime, from 40 ms to 150 ms, and the colorbar indicates (UDD-CPMG)/CPMG.