Lipophilic Group-Modified Gd-PCTA as a High-Performance MRI Contrast Agent Featuring Kinetic Inertness, Protein...

Area of Science:

• Medical Imaging
• Radiochemistry
• Materials Science

Background:

• Gadolinium-based contrast agents (GBCAs) are essential for magnetic resonance imaging (MRI).
• There is a continuous demand for safer and more effective GBCAs with improved stability and diagnostic performance.
• Existing GBCAs face challenges related to safety profiles and efficacy.

Purpose of the Study:

• To develop a novel macrocyclic gadolinium complex, Gd-PCTA-Ach, with enhanced properties for MRI.
• To evaluate the relaxivity, kinetic inertness, and pharmacokinetic profile of Gd-PCTA-Ach.
• To assess the in vivo diagnostic utility of Gd-PCTA-Ach in preclinical tumor models.

Main Methods:

• Synthesis and characterization of the novel macrocyclic complex Gd-PCTA-Ach.
• Measurement of relaxivity (r1 and r2) and kinetic inertness.
• Evaluation of albumin binding affinity and pharmacokinetic studies.
• In vivo T₁-weighted MRI in brain and liver tumor mouse models.

Main Results:

• Gd-PCTA-Ach demonstrated superior relaxivity (r1 = 13.6, r2 = 15.8 mM^-1s^-1) and kinetic inertness compared to approved agents.
• Enhanced lipophilicity led to moderate albumin affinity (34.8%) and prolonged circulation time.
• In vivo studies confirmed primary renal clearance with partial hepatobiliary excretion (approx. 10%).
• Successful visualization of tumor lesions in both brain and liver models was achieved.

Conclusions:

• Gd-PCTA-Ach represents a highly potent and stable MRI contrast agent.
• Its favorable pharmacokinetic profile and effective tumor visualization suggest broad diagnostic utility.
• Gd-PCTA-Ach holds potential as a safer and more effective alternative to current GBCAs.