2.1. Management

transplantation, or percutaneous ablation [5]. In the intermediate stage (BCLC-B), patients are managed with image-guided catheter based therapies such as transarterial embolization or chemoembolization (TAE/TACE). However, intra-arterial locoregional therapies are palliative and most patients experience disease progression. In 2017, several new therapeutic options have become available for advanced HCC although this is beyond the scope of this chapter where

Percutaneous ablation is a curative intent procedure reserved for patients with early stage disease HCC. It involves accessing the tumor percutaneously under ultrasound or CT guidance with probes. Three broad categories of percutaneous ablation exist: chemical, thermal,

Chemical ablation induces cellular dehydration, protein denaturation, and blood vessel thrombosis causing coagulation necrosis via ethanol administration into the tumor. The ethanol has an unpredictable distribution in the surrounding tissue, leading to a high rate of tumor recurrence. This technique has largely been replaced by thermal ablation though still finds its uses where

Thermal ablation can be classified into three modalities: radiofrequency, microwave ablation,

Radiofrequency ablation (RFA) is the most commonly performed procedure for hepatic tumors. There is an alternating electrical current within the device that causes agitated ions to generate heat and induce coagulative necrosis. This technique is reserved for tumors less than

Microwave ablation (MWA) uses electromagnetic waves to induce an alternating electrical field that produces heat. This has the ability to reach higher temperatures to overcome perfusionmediated tissue cooling when compared to RFA, making ablation of larger tumors possible along with faster ablation times. This technique is preferred for tumors near major vessels, such

Cryoablation consists of pumping high-pressure argon into a probe, which escapes at the very tip and causes rapid expansion of the gas leading to intense cooling and formation of an ice ball around the needle tip. This causes intracellular ice crystals and disrupts the cell membrane and cellular metabolism. The low temperature also causes vascular thrombosis. Multiple cycles of freezing and thawing are performed. The advantage of cryoablation is the ability to see the ice ball during the procedure on CT, which allows the physician to determine adequate ablation. The technique was historically not used because of reported cryoshock. Recent

Non-thermal ablation is performed through irreversible electroporation (IRE). This technique involves high voltage electrical impulses between parallel electrodes. The high voltage causes

as the inferior vena cava or main hepatic veins, due to the attenuated heat sink effect [6].

thermal ablation is risky such as in tumors in close proximity to vital organs.

3 cm due to the techniques poor conductive heating over greater distances.

reports have demonstrated that hepatic cryoablation is feasible and safe.

locoregional therapies will be reviewed.

52 Medical Imaging and Image-Guided Interventions

2. Percutaneous ablation

and non-thermal.

and cryoablation.

Based on the BCLC, percutaneous ablation is reserved for patients with very early disease or early stage HCC that are not amenable to surgical resection or transplantation. The criteria for very early stage include a single tumor less than 2 cm. The criteria for early stage include a single tumor less than 5 cm or 3 nodules less than 3 cm each.

Absolute contraindications include intrahepatic biliary ductal dilatation, uncorrectable bleeding diathesis, or decompensated liver failure. Relative contraindications include tumor burden to be greater than five lesions, tumors larger than 3 cm, or tumors in close proximity to vital structures such as the portal vein, biliary tree, or gastrointestinal tract.

Patients are usually monitored for a few hours post-procedure. If vital signs and lab values are not significantly changed, patients can be discharged the same day or the day after the procedure. Follow up imaging with CT or MRI is obtained 4–8 weeks post procedure.
