Magnetic resonance imaging: utility as a molecular imaging modality

Significant scientific effort has gone into the deconvolution and understanding of complex biological systems. These efforts have yielded much information about the molecular changes that are causative or arise as a result of disease. Molecular imaging is a relatively newer field that is attempting to use these molecular data to generate images that report on changes in gene expression. It has been demonstrated that generating images based on molecular differences rather than anatomical differences between tissues has resulted in more sensitive detection of diseased tissues and has allowed imaging of drug efficacy against particular drug targets. This chapter discusses the application of magnetic resonance imaging (MRI) to molecular imaging. It begins with a review of the basis for magnetic resonance image generation and how manipulation of different parameters of the system can be applied to molecular imaging. It then specifically reviews some of the problematic areas for magnetic resonance application to molecular imaging and how these can be resolved by manipulating the magnetic resonance system, altering magnetic resonance probe characteristics, or exploiting the biology to be imaged. It concludes with several examples demonstrating the utility of MRI to generate high-resolution, noninvasive images of molecular events occurring in vivo.