Peri-intraprocedural imaging: US, CT, and MRI

Abstract

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.

Image-guided Treatment in the Hepatobiliary System: Role of Imaging in Treatment Planning and Posttreatment Evaluation

“…In patients with HCC or liver metastases, dynamic multiphasic contrast-enhanced CT and dynamic gadolinium-enhanced MR imaging (including arterial, portal venous. and delayed phases) are accepted options for initial diagnostic evaluation, regardless of the type of therapy that will be selected (1,7). Success of ablative techniques is influenced by accurate definition of hepatic tumor burden and tumor relationship to surrounding critical structures and vessels; for this reason, MR imaging may be preferred because of its superior contrast resolution (37).…”

“…In fact, optimal imaging evaluation before treatment initiation has been shown to change management strategies in nearly 30% of patients with liver metastases from colorectal cancer who were treated at tertiary care centers (28). The imaging protocol for staging of hepatic malignancies should be tailored to the individual tumor type (7). In patients with HCC or liver metastases, dynamic multiphasic contrast-enhanced CT and dynamic gadolinium-enhanced MR imaging (including arterial, portal venous.…”

“…Transarterial embolization techniques are Imaging is integral to the care of patients undergoing targeted therapy and is used to select patients, guide treatment delivery, and assess treatment effectiveness (2,7,(26)(27)(28)(29). Pretreatment imaging is essential to define tumor burden and stage, determine the relationship of tumor to critical structures, select appropriate therapeutic options, and plan treatment delivery (2,7,(26)(27)(28)(29).…”

“…Modalities commonly applied in the liver include ethanol injection, RFA, and microwave ablation, while irreversible electroporation, cryoablation, and laser ablation are less commonly performed in the liver because of limited clinical experience (Table 1). Among the various ablative techniques, collective experience with RFA is much higher, and RFA is considered a standard treatment option for local tumor control (7,14,32,(34)(35)(36).…”

“…Pretreatment imaging is essential to define tumor burden and stage, determine the relationship of tumor to critical structures, select appropriate therapeutic options, and plan treatment delivery (2,7,(26)(27)(28)(29). Postprocedural imaging is required to monitor therapeutic success and detect residual or recurrent disease to guide future therapy (7,(26)(27)(28)(29). Technical advancements in cross-sectional imaging techniques such as computed tomography (CT) and magnetic resonance (MR) imaging, coupled with innovations in postprocessing capabilities, have not only facilitated reliable morphologic assessment of hepatobiliary tumors but also enabled functional evaluation.…”