Nanoparticle-Based Contrast Agents for ¹²⁹Xe HyperCEST NMR and MRI Applications

Figure 5

Comparison of different MRI approaches. (a) Conventional detection operates at an individual Larmor frequency to directly detect the nuclear magnetization of each spin species and requires high spin densities. (b) HyperCEST MRI manipulates reversibly bound Xe through a selective RF pulse and detects it on the separate Larmor frequency of free Xe. One reporter can impact many Xe nuclei. (c) SPIONs impact the bulk magnetization of nearby water; the RF operates only on the water Larmor frequency.