Interventional Oncology · IR Playbook

Transarterial Embolization and Chemoembolization of Liver Tumors (TAE/TACE)

Transarterial embolization and chemoembolization treat hypervascular primary or secondary liver tumors by selective catheterization of their arterial supply followed by delivery of embolic material, with or without chemotherapy. The principal techniques are conventional TACE using a chemotherapy–iodized-oil emulsion followed by embolization, drug-eluting bead TACE, and bland transarterial embolization. Careful patient selection, superselective treatment and preservation of non-tumorous liver perfusion are central to achieving tumor necrosis without precipitating liver failure.

Learning objectives

• Select appropriate patients using tumor stage, liver reserve, performance status, portal venous patency and multidisciplinary treatment intent.
• Differentiate conventional TACE, drug-eluting bead TACE and bland embolization.
• Identify hepatic arterial variants, extrahepatic tumor feeders and arteries responsible for non-target embolization.
• Perform superselective embolization using an appropriate embolic endpoint while preserving major hepatic arteries.
• Recognize postembolization syndrome, liver failure, infection, biliary injury and non-target embolization.

Indications

• Unresectable, liver-confined or liver-dominant hepatocellular carcinoma with preserved liver function, particularly intermediate-stage multinodular HCC when selective arterial treatment is feasible.
• Bridging to liver transplantation by controlling tumor growth while the patient remains on the waiting list.
• Downstaging HCC to accepted transplantation or curative-treatment criteria after multidisciplinary review.
• Selected early-stage HCC unsuitable for resection, transplantation or thermal ablation because of tumor size, location or patient comorbidity.
• Symptomatic, hormonally functional or radiologically progressive liver-dominant neuroendocrine tumor metastases.
• Selected unresectable intrahepatic cholangiocarcinoma or liver-dominant metastases, including chemotherapy-refractory colorectal metastases, within a tumor-specific multidisciplinary protocol.
• Bland embolization when ischemic tumor control is desired and chemotherapy provides no established additional benefit, is contraindicated or is not appropriate for the tumor type.

Absolute contraindications

• Refusal of treatment or absence of a defensible multidisciplinary oncological indication.
• Decompensated liver disease or severely impaired hepatic reserve in which embolization is likely to precipitate irreversible liver failure, including uncontrolled ascites, active encephalopathy or marked jaundice.
• Uncorrectable coagulopathy or thrombocytopenia that makes arterial access unsafe.
• Uncontrolled systemic infection, active cholangitis or untreated hepatic abscess.
• No safe arterial route to the tumor or unavoidable perfusion of critical non-target organs.
• Severe unmanageable iodinated-contrast hypersensitivity or renal dysfunction when no safe alternative strategy is possible.

Relative contraindications

• Main portal-vein occlusion, hepatofugal portal flow or extensive tumor thrombus; risk depends on collateral portal perfusion, liver reserve and whether highly selective treatment is possible.
• Child–Pugh B8 or worse, high ALBI grade, rising bilirubin or recent hepatic decompensation.
• Tumor replacement exceeding approximately 50% of liver volume, particularly when treatment cannot be staged.
• Transjugular intrahepatic portosystemic shunt because diversion of portal perfusion increases ischemic risk.
• Segmental or subsegmental portal-vein thrombosis.
• ECOG performance status 2 or greater unless symptoms are predominantly tumor-related and potentially reversible.
• Bilioenteric anastomosis, biliary sphincterotomy, biliary stent or pneumobilia because of substantially increased hepatic-abscess risk.
• Clinically important renal impairment, severe cardiopulmonary disease or prior cumulative anthracycline exposure.
• Extensive extrahepatic disease without a clear liver-directed palliative objective.

Equipment

• Ultrasound machine, sterile probe cover, micropuncture set and 21 G access needle.
• 4–5 Fr femoral or radial arterial sheath with pressurized heparinized-saline flush.
• 0.035-inch hydrophilic guidewire and standard angled or exchange-length guidewire.
• 4–5 Fr visceral angiographic catheters such as Cobra, Simmons, reverse-curve, renal double-curve or hepatic-shaped catheter.
• 2.0–2.8 Fr microcatheter with compatible 0.014–0.021-inch microwire; use a high-flow or balloon-occlusion microcatheter when specifically required.
• Nonionic iodinated contrast medium, digital-subtraction angiography and preferably cone-beam CT with vessel-detection software.
• For conventional TACE, iodized oil, prescribed chemotherapy, Lipiodol-resistant syringes and stopcock, followed by gelatin sponge or calibrated 100–300 micrometer microspheres.
• For drug-eluting bead TACE, manufacturer-approved drug-loadable microspheres, commonly 70–150, 100–300 or 300–500 micrometers, chemotherapy and contrast-compatible suspension syringes.
• For bland embolization, calibrated microspheres commonly 100–300 or 300–500 micrometers, with larger particles selected when distal penetration is unsafe.
• 1–3 ml syringes for controlled particle administration, three-way stopcock, embolic-suspension accessories and chemotherapy personal protective equipment.
• Vascular closure device or equipment for manual compression.

Procedure steps

1. Verify tumor type, target lesions, planned technique, chemotherapy and maximum dose during the procedural time-out. Reconfirm liver function, portal-vein patency, renal function, coagulation status and biliary infection risk.Pearl: Define the maximum acceptable treated liver volume before starting; this prevents escalation to unsafe non-selective embolization when additional tumors are found.
2. Puncture the common femoral or radial artery under ultrasound guidance and insert a 4–5 Fr sheath. Administer radial vasodilator and anticoagulation medication when using radial access according to local protocol.
3. Catheterize the celiac axis and perform hepatic arteriography. Perform SMA angiography when portal flow, a replaced right hepatic artery or collateral supply requires assessment; reserve flush aortography for feeders not identified on cross-sectional imaging or selective angiography.Pearl: Compare the angiogram directly with arterial-phase CT or MRI rather than relying only on tumor blush.
4. Acquire cone-beam CT from the proper, right or left hepatic artery using a contrast rate tailored to angiographic flow. Confirm complete tumor enhancement, identify occult lesions and display arteries supplying tumor and non-target organs.
5. Advance a 2.0–2.8 Fr microcatheter coaxially into the segmental or subsegmental tumor artery while maintaining free antegrade flow. Perform a small-volume test angiogram and selective cone-beam CT when necessary.Pearl: A wedged microcatheter can redirect embolic material through collaterals and falsely simulate an embolization endpoint.
6. Confirm that the catheter tip lies distal to gastroduodenal, gastric, cystic, falciform and other non-target branches. Reposition the catheter or selectively protect a hazardous branch when embolization cannot otherwise be delivered safely.
7. For conventional TACE, prepare an extemporaneous water-in-oil chemotherapy–iodized-oil emulsion, usually using an iodized-oil-to-aqueous-drug ratio of approximately 2:1 or 3:1, and re-emulsify if separation occurs. For DEB-TACE, load and suspend beads strictly according to the manufacturer instructions; for bland embolization, select particle size according to catheter position, shunting and desired penetration.Pearl: Most conventional TACE procedures use less than 10 ml of iodized oil; keep the total below 20 ml to reduce pulmonary oil-embolism risk.
8. Inject the emulsion or particle suspension in small aliquots under continuous fluoroscopy while watching for reflux, opening of collaterals and change in arterial flow. Gently rotate or agitate particle syringes to prevent sedimentation and stop immediately if non-target flow develops.Pearl: Slow pulsatile delivery with preserved antegrade flow promotes intratumoral penetration.
9. For conventional TACE, administer the chemotherapy–iodized-oil emulsion before supplementary embolization and aim for pruning of small tumor vessels with preservation of major segmental and lobar arteries. For DEB-TACE or bland embolization, use near-stasis or stasis lasting approximately 10 cardiac beats as a guide, modified by tumor type and institutional protocol.Pearl: After calibrated microsphere delivery, wait approximately 5 minutes before judging the final endpoint because particles continue to redistribute distally.
10. Repeat selective angiography and, when useful, cone-beam CT to confirm marked reduction or absence of tumor enhancement without non-target embolization. Search for an untreated component supplied by a contralateral hepatic or extrahepatic artery.Pearl: A subcapsular missing tumor component should prompt a search for inferior phrenic, intercostal, internal thoracic or omental supply.
11. Remove the catheter and sheath after confirming access-site suitability and obtain hemostasis by manual compression or a closure device. Document treated arteries, chemotherapy and embolic doses, endpoint, residual tumor supply, contrast volume and fluoroscopic dose.

Complications

• Postembolization syndrome, approximately 30%
• Hepatic decompensation or liver failure, approximately 3–5% in broad series
• Hepatic abscess, usually below 2% with an intact sphincter but markedly higher after biliary intervention
• Biliary ischemia, biloma or bile-duct necrosis, generally below 1% but higher with non-selective small-particle embolization
• Non-target gastrointestinal embolization
• Ischemic cholecystitis
• Hepatic arterial dissection, thrombosis or pseudoaneurysm
• Pulmonary iodized-oil or particle embolization, below 1%
• Access-site hematoma, pseudoaneurysm or arterial occlusion
• Contrast-associated acute kidney injury or hypersensitivity

Exam pearls

• TACE treats arterialized tumor while relying on preserved portal perfusion to protect non-tumorous liver.
• Superselective segmental or subsegmental embolization is preferred over non-selective lobar treatment whenever feasible.
• Conventional TACE means chemotherapy–iodized-oil emulsion followed by embolic material; iodized oil alone is not conventional TACE.
• The usual conventional TACE endpoint is tree-in-winter pruning with preservation of major hepatic arteries.
• For particle embolization, stop for reflux or sustained approximately 10-beat stasis even if the planned embolic volume has not been delivered.
• MRI is particularly useful after conventional TACE because dense iodized oil may obscure residual enhancement on CT.
• Loss of sphincter-of-Oddi integrity is the classic major risk factor for postembolization hepatic abscess.
• Postembolization syndrome is expected and self-limited; persistent fever, worsening pain or progressive jaundice suggests a complication.

Viva questions

What is the fundamental difference between TAE and TACE?

TAE produces tumor ischemia using embolic material without chemotherapy. TACE combines embolization with intra-arterial chemotherapy, either as a chemotherapy–iodized-oil emulsion in conventional TACE or chemotherapy loaded into drug-eluting microspheres.

Why can a hepatic artery be embolized without infarcting the entire liver?

HCC and many hypervascular metastases obtain most of their supply from the hepatic artery, whereas normal liver parenchyma receives most of its perfusion from the portal vein. This differential supply permits selective arterial tumor treatment, provided portal perfusion and hepatic reserve are adequate.

How do you prepare a conventional TACE emulsion?

A water-in-oil emulsion is favored by using more iodized oil than aqueous chemotherapy, usually a 2:1 or 3:1 ratio, and repeatedly pumping the components through a compatible stopcock. It is prepared immediately before administration and followed by particulate embolization.

What is the angiographic endpoint of conventional TACE?

The desired endpoint is pruning of small tumor-feeding radicals with a tree-in-winter appearance while preserving flow in the major lobar and segmental hepatic arteries. Complete proximal occlusion is avoided because it injures normal liver and compromises future access.

Are drug-eluting beads superior to conventional TACE?

Drug-eluting beads provide standardized embolization and lower systemic chemotherapy exposure, but randomized evidence has not shown a consistent overall-survival advantage over well-performed conventional TACE. Technique selection therefore depends on patient factors, tumor type, device availability and institutional expertise.

Is portal-vein thrombosis an absolute contraindication to TACE?

Not invariably. Main portal-vein occlusion, hepatofugal flow and poor collateral perfusion create a high risk of liver failure, whereas selected patients with limited branch thrombosis and preserved liver function may undergo highly superselective treatment. The extent of thrombosis, portal flow, liver reserve and alternatives must be reviewed together.

Which patients have the highest risk of hepatic abscess after embolization?

Risk is highest when the biliary tract is colonized after bilioenteric anastomosis, sphincterotomy, biliary stenting or other loss of sphincter-of-Oddi integrity. These patients require individualized broad-spectrum prophylaxis and close delayed follow-up.

How is response assessed after TACE for HCC?

Multiphasic CT or MRI is performed at approximately 4–6 weeks and viable arterially enhancing tumor is assessed using mRECIST. Tumor enlargement alone is unreliable because treated necrotic tissue may remain visible.

References