Magnetic resonance imaging of the liver: assessing response to treatment.

Imaging plays a critical role in evaluating tumor response to treatment. Change in tumor size on cross-sectional imaging has been widely accepted and used to guide clinical decision making. Until recently, researchers used the World Health Organization (WHO) criteria to determine tumor response. A new set of criteria recently has been adopted by the WHO, the National Cancer Institute, and the European Organization for Research and Treatment of Cancer. These criteria, called the Response Evaluation Criteria in Solid Tumors (RECIST), attempt to unify response assessment of treated lesions. Magnetic resonance imaging plays an important role in evaluating treatment response to new therapies directed toward hepatic lesion treatment. In this article, we describe the new RECIST criteria and the role of magnetic resonance imaging in assessing tumor response. We also discuss the magnetic resonance imaging findings after surgical resection, liver transplantation, and tissue ablation techniques currently available for the management of patients with liver tumors.