Molecular and functional MR imaging of cancer

Noninvasive imaging has become a powerful tool in the investigation of various disease processes, including cancer. Advances in magnetic resonance (MR), positron emission tomography (PET), single positron emission computed tomography (SPECT), ultrasound, and optical imaging techniques, as well as the development of novel imaging agents, have revolutionized our understanding of diseases. As our understanding of cancer advances, so does our recognition of the complexities of this disease, with new discoveries serving to emphasize these complexities. While a decade ago the focus in cancer research was primarily on genetic alterations, it is now apparent that the tumor’s physiological microenvironment, the interaction between host cells, including stem cells and cancer cells, the extracellular matrix (ECM), and a multitude of secreted factors and cytokines influence progression, aggressiveness, and response of the disease to treatment. Therefore, identifying central targets that act across these levels of multiplicity is essential for the successful treatment of this disease. Multiparametric molecular and functional MR methods have several key roles to play in the treatment of cancer — they can be used to (1) reveal key targets for therapy, (2) visualize delivery of the therapy, and (3) assess the outcome of treatment. Altered choline metabolism is one example of the identification of a common feature of cancer revealed by MR spectroscopy, which can be exploited for diagnosis and potentially for treatment. Similarly, the use of vascular imaging to detect the effects of antiangiogenic and antivascular drugs is another example of the applications of MR imaging (MRI) in cancer treatment. Image-guided incorporation of nano- and microdevices into tumors for slow release of therapeutic agents and gene delivery is another area of promise in cancer treatment.