Clinical presentation and the role of diagnostic imaging
In clinical practice of interventional radiology, the assessment of hepatic vasculature is often performed against the background of concomitant severe pathology, such as viral hepatitis C and biopsy-proven liver cirrhosis (cirrhosis). The diagnostic workup often begins with the detection of hypervascular lesions showing intense contrast enhancement.
The baseline imaging modality is three-phase computed tomography (CT) with arterial contrast enhancement. Magnetic resonance imaging (MRI) is used for additional confirmation of findings—on T1-weighted images in the arterial phase, the hypervascularity of the lesion is clearly verified. Angiography (Angiography) is a crucial diagnostic step. It allows for the evaluation of typical mesenteric anatomy and confirmation of portal vein patency (patent portal vein). On arterial phase angiograms, a specific "tumor blush" sign (tumour arterial blush) may be detected, which directly indicates intensive local blood supply.
Technique of selective embolization
In patient instability due to active arterial bleeding or pseudoaneurysm rupture (which may occur, for example, as a complication after liver biopsy or biliary drainage), emergency transcatheter embolization is indicated. The technical aspects of this procedure are largely similar to transarterial chemoembolization or radioembolization.
A key factor for a successful intervention is clear anatomical visualization using digital subtraction angiography (DSA) with automated contrast injectors. The use of a microcatheter selectively placed in the target branch (e.g., the right hepatic artery) and flat-panel CT guidance (DynaCT) makes it possible to achieve opacification exclusively of the target tissue (tumour contrast opacification). The strict absence of nontarget contrast accumulation (no nontarget enhancement) confirms the correct and safe position of the catheter.
Various agents are used to occlude the injured vessel: metal coils (coils), microparticles (particles), or liquid embolic materials (surgical glue). The main goal of the intervention is rapid anatomical diagnosis and the most reliable hemostasis.
Portosystemic shunting (TIPS): indications and limitations
For bleeding of other origins—specifically from varices refractory to endoscopic therapy—transjugular intrahepatic portosystemic shunting (TIPS) is used. The method consists of creating a transhepatic artificial communication between a large intrahepatic branch of the portal vein and a hepatic vein. The patency of the created channel is maintained using a covered metal stent.
The procedure aims at effectively reducing portal venous pressure. The main indications include refractory ascites, hepatic hydrothorax, Budd-Chiari syndrome (Budd-Chiari syndrome), as well as severe hepatorenal and hepatopulmonary syndromes.
Absolute contraindications to TIPS include heart failure (due to inevitable sharp hemodynamic shifts after shunt opening), systemic sepsis, and biliary obstruction. A critical clinical prerequisite is that any coagulopathy in the patient must be completely corrected before the intervention begins. For preoperative prognostic assessment in elective TIPS, the MELD (Model for End-Stage Liver Disease) score is used. Three-month mortality directly correlates with the score: at MELD < 17 it is 16%, at MELD > 18 it is 35%, and at critical values exceeding 24 it reaches 65%.
Access and stages of TIPS creation
The intervention is traditionally performed under general anesthesia. Vascular access is achieved via the right internal jugular vein: a special introducer is advanced into the right atrium, after which the right hepatic vein is selectively catheterized.
For reliable visualization of the portal vein, the specialist's choice may include:
- Percutaneous introduction of a guidewire directly into the portal vein;
- Aortoportography with delayed visualization after contrast injection into the superior mesenteric artery;
- Wedged portography from a hepatic vein.
The process of shunt creation itself involves several strict stages. The transhepatic trocar is advanced from the hepatic vein toward the portal vein. The needle is withdrawn, and aspiration is performed while pulling back the catheter. Upon obtaining venous blood, a small volume of contrast is injected to verify position. Next, a guidewire is advanced into the portal vein, after which pressure in the portal vein and right atrium must be measured. Using a calibrated catheter, the exact length of the future tract from the portal vein to the junction of the hepatic vein with the inferior vena cava is measured. At the final stage, the tract is dilated with an angioplasty balloon, and a covered stent is implanted into it.
Briefly: answers to topical questions
What specific complications may occur in a patient after transcatheter arterial embolization of the liver?
Following transcatheter arterial interventions on the liver, the following complications are described in sources:
- Post-embolization syndrome (PES) after chemoembolization: associated with cell death and cytokine release; manifests as nausea, vomiting, pain, fever, and general malaise; lasts 2–7 days.
- Nontarget embolisation (nontarget embolisation) during yttrium-90 radioembolization: dangerous due to radiation damage to healthy tissues; gastrointestinal bleeding and pancreatitis are indicated for the GI tract.
- With intrahepatic arteriovenous shunts, attempts at arterial embolization usually exacerbate the process; liver necrosis and liver failure are possible.
What direct and indirect imaging signs indicate active arterial bleeding during digital subtraction angiography?
During angiography, direct and indirect signs of active arterial bleeding are distinguished. A direct sign is extravasation (escape) of contrast medium into the intestinal lumen or beyond the vascular bed. Indirect signs indicating the source of bleeding include:
- Pseudoaneurysm (pseudoaneurysm) — formation of a false aneurysm.
- Vessel truncation (vessel truncation) — stump of the damaged artery.
- Early venous return (early venous return) — premature opacification of veins.
- Vascular lakes (vascular lakes) — pools of contrast.
- Tumor circulation (tumour circulation) — abnormal vascular network.
- Wall irregularity — contour defects of the vessel.
What types of surgical portosystemic anastomoses are used when endovascular TIPS cannot be performed?
For the surgical treatment of portal hypertension, sources indicate the creation of:
- splenorenal anastomoses;
- portacaval anastomoses.
Transjugular intrahepatic portosystemic shunt (TIPS/TIPSS) is also widely used for the palliative treatment of portal hypertension.
Class and exam questions
What is the primary imaging modality when active arterial bleeding from the liver is suspected?
The main method of primary non-invasive diagnostics is three-phase contrast-enhanced computed tomography (CT) of the liver.
How is the safety of radioembolization confirmed?
Before therapeutic use of yttrium-90 (90Y), radionuclide scanning with macroaggregated albumin is mandatory. It must confirm only minimal, safe shunting of the drug into the lungs.
What is the role of flat-panel CT (DynaCT) during the intervention?
DynaCT examination, performed through an inserted microcatheter, allows the physician to verify opacification exclusively of the target lesion tissue and guarantee the absence of nontarget drug accumulation.
What else to study on this topic
- Digital subtraction angiography (DSA) protocols in interventional radiology.
- Comparative characteristics of embolic agents: coils, microspheres, and liquid glue.
- MELD score assessment in patients with cirrhosis: calculation and clinical significance.
- Pathophysiology of hemodynamic changes following portosystemic shunt formation.
- Budd-Chiari syndrome: imaging features and indications for stenting.
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