Requirements for CEST Agents in MRI: Molarity of Exchangeable Protons Required Scales Inversely with k
| Diameter of particle containing exchangeable protons (nm) | No. of exchangeable protons (k = 104 s−1) required per particle | Required molarity of exchangeable protons within particle | Particles per (100 μm)3 voxel | Particles per cell within (100 μm)3 voxel |
|---|---|---|---|---|
| 100 | 4.8 × 105 | 750 mM | 106 | 1,000 |
| 1,000 | 4.8 × 105 | 750 μM | 106 | 1,000 |
| 1,000 | 4.8 × 108 | 750 mM | 103 | 1 |
| 10,000 | 4.8 × 105 | 0.75 μM | 106 | 1,000 |
| 10,000 | 4.8 × 108 | 750 μM | 103 | 1 |
| 10,000 | 4.8 × 1011 | 750 mM | 1 | 0.001 |