Diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) for monitoring anticancer therapy

There is an increasing awareness that anatomical approaches based on measurements of tumor size have significant limitations for assessing therapy response. Functional imaging techniques are increasing being used to monitor response to therapies with novel mechanisms of action, often predicting the success of therapy before conventional measurements have changed. Dynamic contrast-enhanced and diffusion magnetic resonance imaging (MRI) are the most advanced in their evidence base, and in this manuscript we focus on them as response parameters. Technology, data gathering methods, and current limitations for these techniques are addressed. With few exceptions, most studies shows that successful treatment is reflected by increases in tumor water diffusion values visible as increased apparent diffusion coefficient values. Most response assessment studies also show that successful treatment results in decreases in tumor vascularization and microvessel permeability.