Quantitative Imaging in Magnetic Resonance Imaging

Abstract

Magnetic resonance imaging (MRI) offers superior soft tissue contrast due to its unique dependence on tissue water magnetization and the access to user-defined variables. As such, MRI contrast can also made dependent on water diffusion rates, a capability unique to MRI, from which quantitative estimates of tissue water diffusion can be derived. Diffusion-weighted MRI (DWI) and diffusion tensor imaging MRI (DTI) MRI are the two primary methods available for this purpose, but many newer options are emerging. MRI contrast can be further enhanced by administration of MRI contrast agents, which are routinely used for the clear identification of disease. When dynamic MR images are acquired during the administration of exogenous MRI contrast agents, a perfusion-dependent MRI signal will result, from which tissue perfusion parameters can be derived. The two primary approaches used for this purpose are dynamic contrast-enhanced (DCE)-MRI and dynamic susceptibility contrast (DSC)-MRI. While qualitative assessment of structural, diffusion, and perfusion MRI images has positioned MRI solidly at the center of diagnostic imaging, the benefits of quantifying this information is becoming increasingly clear. This chapter describes the basic principles, applications to cancer, and challenges for quantification of structural MRI, diffusion-weighted imaging MRI, and perfusion-weighted imaging MRI techniques.