Magnetic Resonance Imaging and Its Molecular Probes in Evaluating the Response to Tumor Treatment

Morphological imaging techniques are very limited in their ability to evaluate the early efficacy of tumor therapies, with the limitation of being more reflective and lagging. Many of the newer therapies are cytostatic, and tumor necrosis or lack of tumor progression is associated with a good response to treatment even in the absence of tumor shrinkage; therefore, there is an increasing need to develop techniques for the assessment of tumor efficacy. Magnetic resonance imaging (MRI), with the help of a variety of contrast mechanisms and probes, provides excellent soft-tissue imaging, high-quality anatomical signals as well as reflecting certain functional states of the tumor and molecular biological information. It can be used to differentiate between cancer and normal tissue, to noninvasively monitor tumor growth, and to identify changes in the tumor and its microenvironment in response to treatment. This review will discuss the role of magnetic resonance imaging in the assessment of tumor efficacy, with a focus on presenting research advances in magnetic resonance molecular imaging and its probes in the assessment of tumor efficacy.