Diffusion magnetic resonance imaging in cancer patient management.

Diffusion-weighted MRI (DW-MRI) is able to detect and characterize tissues because it incorporates sensitivity to water content and water movements into the images that are produced. Compared with other imaging modalities used in oncologic assessments, DW-MRI does not expose patients to ionizing radiations, and no injection of isotopes or any other contrast medium is necessary. Regional or whole-body examinations are possible in reasonably short examination times, allowing DW-MRI to be incorporated into oncologic imaging practice. The information obtained can be quantified and displayed as parametric maps, thus enabling spatial heterogeneity of tissues/tumors to be analyzed. Clinical applications for DW-MRI include lesion detection, characterization, and response assessments. DW-MRI has the potential to direct radiation therapy planning. In the response assessment setting, DW-MRI observations appear to reflect interactions between the mechanism of action of treatments and the underlying structural biology of tissues.