Relaxivity Performance of Gadopiclenol Versus Gadobenate Dimeglumine In Vitro, and Liver and Brain Imaging

Objectives: High-relaxivity macrocyclic gadolinium-based contrast agents (GBCAs) have been introduced to reduce the administered gadolinium dose while maintaining high diagnostic performance. Gadopiclenol exhibits higher intrinsic relaxivity than conventional extracellular agents, but comprehensive evaluation of longitudinal and transverse relaxivity across biologically relevant media and in vivo applications remains limited. The purpose was to compare r1, r2, and r2* relaxivity of gadopiclenol and gadobenate dimeglumine, and to assess dose-dependent in vivo effects in dynamic liver MRI and dynamic susceptibility contrast (DSC) MRI of brain perfusion using a randomized intraindividual crossover design. Methods: Relaxivity was measured in saline, plasma, and whole blood at 1.5T and 3.0T across clinically relevant concentrations. In vivo, participants underwent 3 MRI examinations in a randomized crossover design using 0.05mmol/kg gadopiclenol, 0.1mmol/kg gadopiclenol, and 0.1mmol/kg gadobenate dimeglumine, each separated by ≥28 days. Liver imaging assessed signal enhancement, relative contrast and between-visit residual GBCA effects. DSC perfusion evaluated arterial input function (AIF) metrics and gray-to-white matter relative cerebral blood volume (GM/WM rCBV) ratios. Results: Phantom experiments demonstrated field-dependent and medium-dependent linear relaxivity for all agents and media ( R ²>0.98), with consistently higher r1, r2, and r2* for gadopiclenol. Liver imaging was performed in 10 participants with focal nodular hyperplasia (7 women; age 20 to 81 y); DSC perfusion imaging was acquired in 10 healthy participants (1 woman, 9 men; age 35 to 77 y). Overall, 60 MRI examinations were performed. Enhancement in the abdomen was comparable between 0.05mmol/kg gadopiclenol and 0.1mmol/kg gadobenate, while 0.1mmol/kg gadopiclenol produced significantly higher liver parenchymal and vascular enhancement. In DSC perfusion imaging, AIF peak and AUC were significantly reduced with 0.05mmol/kg gadopiclenol, whereas 0.1mmol/kg gadopiclenol closely matched gadobenate dimeglumine. Agreement of GM/WM rCBV ratios was high across all protocols despite attenuated first-pass effects. Discussion: 0.05mmol/kg gadopiclenol maintains T1-weighted abdominal imaging performance, supporting dose reduction, while higher dosing enhances signal and susceptibility effects. Optimal gadopiclenol dosing appears application-dependent, particularly for DSC perfusion MRI.