Diffusion-Weighted Whole-Body Imaging: Tumor Staging Applications

Diffusion-weighted imaging (DWI) is a method of magnetic resonance imaging that reflects thermal molecular motion of water molecules in tissues. Unlike random molecular motion in unrestricted states, molecular diffusion in human tissue is affected by its structural nature and other biochemical factors, e.g., motion is limited by cell membranes. These effects measurably impact the magnetic resonance signal. Images thus generated impart information about healthy and diseased tissues in a noninvasive, in vivo modality that does not rely on the use of contrast agents. DWI magnetic resonance images are widely used to provide important indicators of possible prostate cancer and to monitor efficacy of ablative treatments. This technology is finding wide application for whole-body diagnosis for metastases in place of bone and PET/CT scans for staging prostate, breast, thyroid, lung, pancreas, colon, and melanoma skin cancers.