Peri-intraprocedural imaging: US, CT, and MRI

Imaging in liver interventional oncology plays a key role in the entire process starting from patient selection, leading to patient treatment and continuing with patient follow-up. Pre-procedural imaging evaluation is aimed to determine the indication for interventional therapies according to the size, number, and location of hepatic lesions, to the presence of major vascular invasion, nodal disease, and distant metastases, and to choose the most suitable approach according to tumor histology. Ideal qualities of a targeting technique include clear delineation of the tumor tissue and the surrounding anatomy, coupled with real-time imaging, multiplanar, and interactive capabilities. Moreover, the modality of image guidance should visualize therapy effects during the intervention to assess coverage of the targeted tissue and to prevent unintended thermal injury to critical structures in the surroundings of the target. Post-treatment imaging is then imperative to evaluate response to therapy by assessing for residual or recurrent disease, revising prognosis, and guiding future therapy. In this article, the role of imaging in patient selection and treatment planning will be discussed. Recently amended RECIST (mRECIST) for evaluation of tumor response in hepatocellular carcinoma and specific treatment-related findings after thermal ablation, trans-arterial chemoembolization, and radioembolization will be reviewed.