Diffusion MR imaging for monitoring of treatment response.

Functional imaging techniques are increasingly being used to monitor response to therapies, often predicting the success of therapy before conventional measurements are changed. This review focuses on magnetic resonance imaging (MRI) depicted water diffusivity as a tumor response parameter. Response assessments are undertaken by noting changes in signal intensity on high b-value images or by using measurements of apparent diffusion coefficient values. The different diffusion-weighted (DW)-MRI appearances in response to treatment of soft tissue disease and bone metastases are discussed. DW-MRI changes observed in response to cytotoxics, radiotherapy, antiangiogenics, embolization, and thermocoagulation are detailed.