Functional MR imaging as a new paradigm for image guidance.

Guidance and monitoring of locoregional minimally invasive treatment for primary or secondary liver tumor are critical to ensuring success and efficacy of therapy. In this article, we review advanced MR imaging techniques, including MR spectroscopy, diffusion and perfusion MR imaging, which can provide essential in vivo physiologic and metabolic information. These innovative imaging techniques can provide potential additional criteria to assess tumor response in addition to the accepted yet often limited Response Evaluation Criteria in Solid Tumors (RECIST) and the European Association for the Study of the Liver (EASL) criteria, which are based on decrease of tumor size and lesion enhancement, respectively. In this article, we also discuss the role of tumor size and enhancement in addition to apparent diffusion coefficient (ADC) findings after radiofrequency ablation (RFA), transarterial chemoembolization (TACE), and radioembolization.