Convection-enhanced Delivery of Free Gadolinium with the

Purpose—A major obstacle in glioblastoma (GBM) therapy is the restrictive nature of the bloodbrain barrier (BBB). Convection-enhanced delivery (CED) is a novel method of drug administration which allows direct parenchymal infusion of therapeutics, bypassing the BBB. MR1-1 is a novel recombinant immunotoxin that targets the GBM tumor-specific antigen EGFRvIII and can be delivered via CED infusion. However, drug distribution via CED varies dramatically, which necessitates active monitoring. Gadolinium conjugated to diethylenetriamine penta-acetic acid (Gd-DTPA) is a commonly used MRI contrast agent which can be co-infused with therapies using CED and may be useful in monitoring infusion leak and early distribution. Experimental design—Forty immunocompetent rats were implanted with intracerebral cannulas that were connected to osmotic pumps and subsequently randomized into four groups