Albumin-binding MR blood pool agents as MRI contrast agents in an intracranial mouse glioma model.

Intravenous MRI contrast agents are commonly used to improve the detection of intracranial tumors and other central nervous system (CNS) lesions for diagnosis and treatment planning. Two small-molecule, albumin-binding blood pool contrast agents (MP-2269 and MS-325) of potential clinical significance were evaluated at 1.5 Tesla in a mouse glioma model and compared with an extracellular contrast agent (OptiMARK). Tumor image contrast was significantly enhanced and long-lived following administration of 30 micromole/kg of the blood pool agents: specifically, contrast enhancement peaked slowly at 25-30 min following administration, remained constant for >3 hr, and returned to baseline within 20 hr. Comparable but "transient" enhancement was achieved using 100 micromole/kg OptiMARK: specifically, contrast enhancement peaked rapidly at 2-5 min following administration and then declined over 40 min. The blood pool contrast agents demonstrated an approximately threefold increased dose-effectiveness and a lengthened window of tumor contrast enhancement in comparison to commonly available extracellular contrast agents. This demonstrates the potential of alternative contrast-enhanced (CE) MRI examination protocols for tumor detection.