Water protons in the hydration sphere of the gadopiclenol complex

Water protons in the hydration sphere of the gadopiclenol complex serve as the physical substrate for signal enhancement in magnetic resonance imaging (MRI). Gadopiclenol is a macrocyclic gadolinium-based contrast agent (GBCA) that exhibits high relaxivity due to its ability to coordinate two water molecules in its inner sphere (q=2), compared to the single water molecule (q=1) coordinated by most conventional GBCAs (Robic et al., Invest Radiol, 2019). The paramagnetic gadolinium ion (Gd3+) within the complex interacts with these nearby water protons, significantly shortening their longitudinal (T1) relaxation time. This physical interaction results in increased signal intensity on T1-weighted images, facilitating the detection and visualization of lesions in the central nervous system and other body tissues (FDA Label, Elucirem, 2022). Because this interaction is a physical phenomenon used for diagnostic purposes rather than a biochemical interaction with a protein or pathway, these protons are not classified as a traditional therapeutic target. The high relaxivity of gadopiclenol allows for effective imaging at lower gadolinium doses, potentially reducing the risk of gadolinium retention in patients (Bendszus et al., Invest Radiol, 2023).

Other names

Inner-sphere water protonsHydration sphere waterBulk water protonsGadopiclenol-bound water

Paramagnetic relaxation enhancement (PRE) of water protons through dipole-dipole interaction with the Gd3+ ion