Interventional radiology plays a large role in treating hepatic malignancies that are not resectable. In common, interventions are loco-regional therapies, and are imaging-guided. It is important to stress that these treatments are palliative, and not for curative intent. This article will discuss two interventional techniques: transarterial chemoembolisation and radiofrequency ablation of liver tumours.

Transarterial chemoembolisation (TACE)
TACE combines hepatic artery embolisation with simultaneous infusion of a concentrated dose of chemotherapeutic drugs. Embolisation deprives the tumour of blood supply and renders it ischaemic. This also prevents rapid washout of cytotoxic agents. Second, by delivering chemotherapy drugs locally, tumour drug concentrations can be higher than in systemic intravenous delivery, thus reducing systemic side effects.

Patient selection

	Disease limited to liver
	Clinically insignificant metastases with symptomatic liver lesion

Contraindications

	portal vein thrombosis (relative contraindication)
	presence of hepatic encephalopathy
	biliary obstruction or jaundice (absolute contraindication)

Procedure
Patients are admitted to the hospital the evening prior to the procedure and they have to fast for 8 hours prior to intervention. Prophylactic intravenous antibiotics (cephazolin 1-2 gram, metronidazole 500 mg) are administered.

Via a groin puncture into the femoral artery, a catheter is then advanced superselectively into the right or left hepatic artery. The chemoembolic mixture comprising 10 mg doxorubicin and 10 mg mitomycin-C is dissolved in 5-10 mL of radiographic contrast and emulsified with 5-10 mL of iodised oil. Gelfoam particles (for embolisation) is injected until nearly complete stasis of blood flow is achieved. Intravenous pain control agents are routinely administered.

The procedure usually takes about one hour, and only one lobe of the liver is embolised at a time.

Most patients are discharged 2 days after embolisation and have a triphasic CT scan of the liver a month after treatment to assess for interval improvement.

Complications
Up to 80% to 90% of patients suffer from “postembolisation syndrome”, characterised by pain, fever, and nausea and vomiting. The severity varies from patient to patient, but it is usually self-remitting (lasting a few hours to several days).

Major complications of hepatic embolisation have a low incidence at 3-4% and include hepatic insufficiency or infarction, hepatic abscess, tumour rupture, and non-target embolisation to the gut.

Results
Response rates in published series (as measured by decreased tumour volume and decreased serum alpha-fetoprotein levels) were 60% to 83%. Cumulative probability of survival ranged from 54% to 88% at 1 year, 33% to 64% at 2 years, and 18% to 51% at 3 years. Survival varies directly with iodised oil uptake and retention, and inversely with tumour volume, stage, and Child's class.

Radiofrequency ablation (RFA)
RFA uses the principle of microwaves to generate heat within target tissue. It does not distinguish between tumour or normal tissue. Different devices exist for RFA, and each uses 15- to 18-gauge needles with either multiple parallel needles or a radial array to disperse the energy over a larger volume. The needle is placed into the lesion under imaging guidance. Both CT and ultrasound work well for this technique (we often combine both).

Using current technology, 3cm to 4cm tumours can usually be ablated using overlapping burns. Each burn usually requires 12 to 40 minutes.

Other than pain, side effects are minimal. Careful placement of the grounding pads is important to avoid thermal injury to the skin.

Immediate success with radiofrequency ablation is high at 60-90%. Local recurrence rates have been reported to be as low as 2% to as high as 40% within one year. However, the occurrence of new lesions is high, up to 65% of patient in one year. This is the commonest cause of treatment failure in patients with HCC.

In all cases, interventional radiologists work very closely with hepatobiliary surgeons, hepatologists and oncologists. The cases are usually discussed at radiology meetings. The aim is to achieve adequate palliation for patients in as safe a manner as possible and to allow them to continue their follow-up consultations with their referring doctors.

By Drs K Sheah, BS Tan, KH Tay and R Lo

Dept of Diagnostic & Interventional Radiology

Singapore General Hospital