Imaging modalities

Doppler Ultrasound (US) is the first-line modality for diagnosing and monitoring PVA due to its non-invasive nature and accessibility. It evaluates aneurysm size and morphology, blood flow characteristics, and thrombus formation. 

• Gray-scale US: PVA appears as an anechoic structure continuous with the portal vein system. [4,5]
• Color Doppler: may reveal a characteristic “yin-yang” sign, indicating turbulent flow.
• Spectral Doppler: confirms a monophasic, non-pulsatile venous flow pattern. [2,4]
• Thrombosed PVA: exhibits variable echogenicity, mimicking solid masses, and typically appears hyperechoic without intraluminal flow on color Doppler. [3,4]
  

  Fig 1: A young patient, with no significant medical history, presents with the sudden onset of vomiting and severe abdominal pain in the epigastric and periumbilical regions. Doppler ultrasound demonstrates the dilatation of the portal vein (4,1x4 cm) and an occlusive endoluminal thrombus.

Despite its advantages, US is operator-dependent and limited by acoustic window constraints and a restricted field of view. When findings are inconclusive, contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) provide superior spatial and contrast resolution.

• CT Angiography (CTA) offers detailed anatomical and vascular assessment, essential for diagnosis and treatment planning. The portal venous phase is the most informative, showing PVA as a well-defined, contrast-enhanced focal dilation of the portal venous system. The arterial phase helps exclude arterial abnormalities, while the delayed phase is useful in detecting partially organized thrombi. CTA provides high-resolution cross-sectional imaging but is limited by radiation exposure and potential nephrotoxicity in patients with renal impairment. [5]
  

  Fig 2: Abdominal CT scan showing the dilatation of the portal venous system associated with an occlusive endoluminal thrombotic material within the portal vein at the confluence with the superior mesenteric vein.
  

  Fig 3: Coronal multiplanar reconstruction (MPR) allows better evaluation of the portal vein aneurysm and the occlusive endoluminal thrombus within the portal vein, the common portal trunk, and the superior mesenteric vein.
  

  Fig 4: Sagittal multiplanar reconstruction (MPR) shows the endoluminal thrombotic material also involving the intrahepatic branches.
• Magnetic Resonance Angiography (MRA) is an alternative for patients with renal insufficiency or iodine contrast allergy. Contrast-enhanced MRI sequences offer high-resolution vascular imaging, while time-of-flight (TOF) and phase-contrast techniques assess vascular patency without contrast agents. Diffusion-weighted imaging (DWI) and T2-weighted sequences help differentiate acute from chronic thrombi. Despite superior soft tissue contrast and detailed vascular imaging, MRI’s longer acquisition time, higher cost, and limited emergency availability make it a second-line option after CT.

Digital Subtraction Angiography (DSA) remains the gold standard for vascular assessment and endovascular treatment. This invasive imaging technique provides real-time visualization of the portal venous system, enabling accurate evaluation of aneurysm morphology, blood flow dynamics, and complications such as thrombosis or stenosis. Unlike non-invasive modalities, DSA allows direct portal hemodynamic assessment and vascular pressure measurement, which is particularly valuable in portal hypertension cases. A major advantage of DSA is its dual diagnostic and therapeutic capability. Catheter-based contrast injection enhances vascular evaluation, while interventional procedures—such as embolization, stent placement, or thrombolysis—can be performed simultaneously. However, as an invasive procedure, DSA carries risks, including bleeding, vascular injury, contrast-induced nephropathy, and radiation exposure. Thus, DSA is typically reserved for cases requiring therapeutic intervention or when non-invasive imaging is inconclusive.

Fig 5: Digital Subtraction Angiography (DSA) after endovascular thrombolysis and thromboaspiration of the common portal trunk, the confluence of the splenic vein, and the superior mesenteric vein, documenting minimal residual thrombosis.

Management of PVA

The management of PVA depends on several factors, including symptomatology, aneurysm size, location, rupture risk, and associated complications such as portal hypertension, thrombosis, or compression of adjacent structures. Due to the rarity of PVA, no standardized guidelines exist, with most evidence based on case reports. However, an imaging-guided strategy allows for tailored intervention. [3]

• Asymptomatic patients without portal hypertension or cirrhosis and small aneurysms (<3 cm) are typically managed conservatively with regular follow-up.
• Interventions may be required if imaging reveals aneurysm growth or complications. [6]

Surgical VS Endovascular Treatment

Surgical treatment is reserved for complicated cases but carries a high postoperative mortality.

• Fusiform aneurysms: treated with aneurysmectomy and grafting.
• Saccular aneurysms: managed with aneurysmorraphy to restore normal vessel diameter. [2,4]

Endovascular treatment offers a minimally invasive alternative to reduce rupture and occlusion risk.

• Percutaneous embolization excludes the aneurysm from circulation, preventing growth and complications. This involves selective catheterization and deployment of embolic agents such as coils, liquid embolics, or vascular plugs. [2]
• Stent or graft placement maintains portal vein patency and prevents further enlargement, particularly in large aneurysms (>3 cm) or cases with significant portal turbulence. Bare-metal stents provide structural support, while covered stents (stent grafts), create a new vascular pathway. [7]

In case of thrombosis associated with PVA anticoagulant therapy is the first-line treatment. Endovascular thrombolysis may be used for extensive clot burden and typically involves catheter-directed administration of thrombolytic agents such as tissue plasminogen activator (tPA), which dissolves the clot and restores normal blood flow. When a rapid mechanical resolution is needed, percutaneous aspiration thrombectomy can be performed to extract the thrombus directly using specialized aspiration catheters. Additionally, pharmaco-mechanical thrombectomy, which combines mechanical clot fragmentation with simultaneous thrombolysis, may be used in patients with extensive thrombotic burden. In cases where residual stenosis remains after thrombectomy, balloon angioplasty may be performed to improve venous flow and reduce the risk of thrombosis recurrence. [8]

For patients with portal hypertension, a transjugular intrahepatic portosystemic shunt (TIPS) can reduce portal venous pressure, creating a low-resistance shunt between the portal and hepatic veins. This approach helps prevent aneurysm growth progression, rupture, thrombosis, and variceal bleeding. However, TIPS carries the potential risk of hepatic encephalopathy, necessitating careful patient selection and post-procedural monitoring. [6]

Fig 6: Coronal volume rendering (VR) reconstruction of an abdominal CT scan after placement of a 70x10 mm transjugular intrahepatic portosystemic shunt stent (TIPS), with 50 mm of the covered section, dilatated by balloon angioplasty.

Advantages and Limitations of Interventional Radiology

Interventional radiology techniques offer significant advantages over open surgical repair:

• Minimally invasive approach, leading to faster recovery times and reduced postoperative morbidity and mortality.
• Real-time imaging guidance, ensuring increased procedural precision and safety, particularly in high-risk surgical candidates.

However, limitations include:

• Potential complications, such as stent migration, thrombosis, or non-target embolization.
• Recurrence risk, as aneurysm growth or thrombosis may reoccur, necessitating long-term follow-up.