Gadolinium(III) ion (Gd³⁺) (Gd³⁺)

The Gadolinium(III) ion (Gd³⁺) within the gadopiclenol chelate is a trivalent lanthanide metal ion that serves as the active paramagnetic core of this high-relaxivity contrast agent (FDA, 2022). Characterized by seven unpaired electrons, the Gd³⁺ ion generates a strong magnetic moment that interacts with nearby water protons, significantly shortening their longitudinal (T1) relaxation times (PubChem, CID 165514). In gadopiclenol (brand name Elucirem), the ion is sequestered within a macrocyclic ligand designed to provide high thermodynamic stability and kinetic inertness, preventing the release of free gadolinium which is toxic (Robic et al., 2019). The unique structure of the gadopiclenol chelate allows for two inner-sphere water molecules to interact with the Gd³⁺ ion, resulting in a relaxivity approximately two to three times higher than that of conventional gadolinium-based contrast agents (Bustros et al., 2022). This enhanced relaxivity improves the visualization of lesions in the central nervous system and other tissues during magnetic resonance imaging (MRI). While the Gd³⁺ ion is not a biological target such as a receptor or enzyme, it is the functional diagnostic moiety responsible for signal enhancement in clinical imaging. Safety considerations associated with the Gd³⁺ ion include the risk of Nephrogenic Systemic Fibrosis (NSF) in patients with impaired renal function and the potential for long-term gadolinium deposition in various tissues (NIH, 2023).

Other names

Gadolinium ionGd(III)Gadolinium(3+)Paramagnetic gadolinium center

The Gd³⁺ ion acts as a paramagnetic center that shortens the longitudinal (T1) and transverse (T2) relaxation times of nearby water protons, enhancing MRI signal contrast.