A review of design criteria for cancer-targeted, nanoparticle-based MRI contrast agents

Magnetic resonance imaging (MRI) has become an essential tool for the diagnosis and prognosis of various medical conditions, including cancer. Despite its widespread use, MRI's ability to distinguish between healthy and diseased tissues is limited in some cases, necessitating the use of exogenous contrast agents. While paramagnetic-based chelates are commonly used as MRI contrast agents, they have several limitations that compromise their diagnostic efficacy. Shortcomings include a short circulation time, suboptimal sensitivity, lack of specificity, and the potential for toxicity, which ultimately lead to unsatisfactory diagnostic outcomes. Thanks to the rapid advances of nanotechnology in the biomedical field, paramagnetic-based nanostructures have emerged as a promising alternative to conventional chelates, receiving significant attention among researchers and practitioners. These innovative nanostructures hold the potential to revolutionize MRI imaging, improving its accuracy, sensitivity, and specificity, and ultimately leading to better patient outcomes. Achieving this goal requires a comprehensive understanding of the rational design of nanostructures in terms of their pharmacokinetics, contrast enhancing properties, and safety profiles, which is the primary focus of this review paper.