Table 1.
T1, T2 and MTRasym measured for the triple-gel phantom containing 50 mM creatine and 3% Agarose titrated to pH values of 5.2, 6.0 and 6.4, respectively. Significant change in MTRasym at 1.9 ppm was observed. Numerical fitting using a 3-pool chemical exchange model was applied to concurrently fit three z-spectra to characterize the properties of labile protons (Fig. 2a). The derived amine proton exchange rates (ksw) were 25, 57 and 85 s-1, respectively, and the concentration relative to bulk water proton was 1:779
| pH | T1 (s) | T2 (ms) | MTRasym (%) (Δω=750Hz, B1=1 μT) | ksw (s-1) |
|---|---|---|---|---|
| 5.2 | 2.74 ± 0.05 | 40.8 ± 1.1 | 3.1 ± 1.0 | 25 |
| 6.0 | 2.76 ± 0.04 | 41.3 ± 1.2 | 9.9 ± 1.2 | 57 |
| 6.4 | 2.82 ± 0.04 | 40.9 ± 1.5 | 14.8 ± 1.1 | 85 |