P846

P846 is an experimental, intermediate-sized, macrocyclic gadolinium-based contrast agent (GBCA) developed by Guerbet for use in magnetic resonance imaging (MRI). It is characterized by high longitudinal relaxivity (r1) and a molecular weight of approximately 3.5 kDa, which classifies it as a "low-diffusible" agent. Unlike standard low-molecular-weight GBCAs such as gadoterate meglumine (Gd-DOTA), P846 does not bind to plasma proteins but exhibits prolonged intravascular retention due to its size. This property makes it particularly suitable for magnetic resonance angiography (MRA) and the assessment of vascular permeability in tumors or myocardial injury. Preclinical studies indicate that P846 can provide superior lesion enhancement and contrast-to-noise ratios at significantly lower gadolinium doses (up to a 4-fold reduction) compared to conventional agents. It has been evaluated in various animal models for applications in neuro-oncology, cardiology, and pancreatic cancer imaging.