Chapter 5.3: MRI Contrast Agents Based on Metallofullerenes

Magnetic resonance imaging (MRI) has evolved into one of the most powerful techniques as a noninvasive diagnostic tool by providing high quality anatomical images of soft tissue; and the rapid expansion of medical MRI has prompted the development of contrast agents (CAs). These agents can shorten the relaxation time of nearby water molecules, enhancing the contrast between areas containing the contrast agent and the surrounding tissues, and increasing diagnostic confidence.The discovery of fullerenes have greatly expanded the number of known carbon allotropes, and have been the subject of intense research, both for their unique properties and for their technological applications, especially in materials science, biomedical science, electronics, and nanotechnology. As an important family of fullerenes, endohedral fullerene has exhibited unique properties of both inner clusters and carbon cage. Gadofullerenes have revealed low toxicity, high efficiency and diversity of modification as a new class of MRI contrast agents, which gives them great potential as a next generation of MRI contrast agents. The readily surface modification of carbon cage facilitates specific tissue-targeting, which in turn increase the local contrast enhancement with a limited dosage of administration. The cellular uptake of gadofullerenes will unambiguously improve the diagnosis and therapy of some disease. Herein, the latest findings on water-solubilized gadofullerene materials, such as Gd@C₈₂, Gd@C₆₀, Sc_xGd_3-x@C₈₀ (x = 0, 1, 2) and how these findings relate to their future applications in MRI are reviewed and discussed.