The assessment of tumor response after intra-arterial therapy (IAT) is useful to determine treatment success, to guide future treatments, and to predict patient outcome. Changes in tumor size in the axial plane after transarterial therapies might be delayed with the traditional criteria, whereas cellular tumor changes can be detected earlier by functional metrics such as vascular enhancement and cellular integrity in the entire tumor volume. Magnetic resonance imaging has become an important tool in the evaluation of early tumor response with the introduction of new techniques, such as diffusion-weighted imaging and apparent diffusion coefficient maps, and the development of advanced software to quantify vascular enhancement after IATs. This review discusses the role of treatment response by functional volumetric imaging after IAT in patients with primary and secondary liver tumors.