Characterization of Signal Ehnacement following the Intraperitoneal Injection of Gadolinium Based Contrast Agents

Introduction: The intravenous (IV) administration of Gadolinium is routinely used in both human and animal imaging for the diagnosis of lesions that compromise the blood-brain barrier (BBB). Although it is relatively trivial in humans and larger animals, gaining IV access in the mouse turns out to be challenging (1). Mouse IV injections are most commonly administered via one of the two tail veins. Not only is considerable skill required in locating these veins, they cannot be probed multiple times due to sclerosis (1,2). This limits the usefulness of IV Gadolinium administration in longitudinal investigations, and in high-throughput imaging of large numbers of mice, where individual tail vein injections can significantly increase the preparation overhead time. Intraperitoneal (IP) injection has been proposed as a simpler alternative for Gadolinium administration (1). Since IP administered Gadolinium must gain venous access by absorption through the intraperitoneal cavity, it stands to reason that the dosage requirements in mice and the time-course of signal enhancement would differ from what is currently known for IV injected Gadolinium. The objective of this investigation is therefore to determine the enhancement time-course and dosage requirements for intraperitoneally administered Gadolinium.