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. Author manuscript; available in PMC: 2016 Apr 15.
Published in final edited form as: Mol Imaging Biol. 2015 Apr;17(2):177–184. doi: 10.1007/s11307-014-0784-6

Figure 2.

Figure 2

Respiration-gated CEST-FISP MRI. a the respiration gated CEST-FISP MRI pulse sequence is triggered to start at initial inspiration. The initial CEST saturation period ends shortly after the end of expiration, followed by the FISP MR acquisition. An additional CEST saturation period at the next saturation frequency is then applied. A variable time TB occurs before the next inspiration triggers the start of the next pulse sequence. b Non-gated vs. gated Images show the improvement in image quality with gating. c Because respiration-gated CEST- FISP MRI has a variable time TB, a simulation of the two CEST effects was performed to show that the % CEST at 4.2 ppm (top line) and % CEST at 5.6 ppm (middle line) both decay during TB, but this decay does not affect the CEST ratio (bottom line) and therefore did not affect pH measurements.