Nanocarrier mediated therapy of gliomas has shown promise. The success of systemic nanocarrier-based chemotherapy is critically dependent on the so-called leaky vasculature to permit drug extravasation across the blood–brain barrier. Yet, the extent of vascular permeability in individual tumors varies widely, resulting in a correspondingly wide range of responses to the therapy. However, there exist no tools currently for rationally determining whether tumor blood vessels are amenable to nanocarrier mediated therapy in an individualized, patient specific manner today. To address this need for brain tumor therapy, we have developed a multifunctional 100 nm scale liposomal agent encapsulating a gadolinium-based contrast agent for contrast-enhanced magnetic resonance imaging with prolonged blood circulation. Using a 9.4 T MRI system, we were able to track the intratumoral distribution of the gadolinium-loaded nanocarrier in a rat glioma model for a period of three days due to improved magnetic properties of the contrast agent being packaged in a nanocarrier. Such a nanocarrier provides a tool for non-invasively assessing the suitability of tumors for nanocarrier mediated therapy and then optimizing the treatment protocol for each individual tumor. Additionally, the ability to image the tumor in high resolution can potentially constitute a surgical planning tool for tumor resection.