From the Guidelines
The best CT scan protocol for diagnosing portal vein thrombosis is a multiphasic contrast-enhanced CT scan with arterial, portal venous, and delayed phases, as recommended by the most recent and highest quality study 1.
Key Components of the Protocol
- Intravenous contrast (typically 100-150 mL of iodinated contrast medium) injected at a rate of 3-5 mL/second
- Arterial phase acquired at approximately 25-30 seconds post-injection
- Portal venous phase at 60-70 seconds
- Delayed phase at 180 seconds
- Thin-slice acquisition (1-3 mm) with multiplanar reconstructions for optimal visualization
- Patient should be fasting for 4-6 hours prior to the examination to reduce bowel peristalsis and improve image quality
Importance of the Multiphasic Approach
- Portal vein thrombosis appears as a filling defect within the portal vein that is best appreciated during the portal venous phase when the surrounding normal vein enhances with contrast
- The arterial phase helps identify any associated arterial abnormalities or hypervascular tumors that might be causing the thrombosis
- The delayed phase can help differentiate between acute and chronic thrombosis, as the latter may show cavernous transformation or collateral vessels
Additional Considerations
- Oral contrast is generally not necessary and may actually obscure visualization of the portal venous system
- The protocol should be performed without delay in any patient with suspicion for acute mesenteric ischemia, as delay in diagnosis is the dominant factor that accounts for high mortality rates 1
From the Research
CT Scan Protocol for Diagnosing Portal Vein Thrombosis
The best CT scan protocol for diagnosing portal vein thrombosis involves the use of dynamic contrast-enhanced CT, which is considered the best means of diagnosis and evaluation of various causative diseases 2.
Key Features of Portal Vein Thrombosis on CT
The findings of portal vein thrombosis on dynamic CT include:
- Filling defect partially or totally occluding the vessel lumen
- Rim enhancement of the vessel wall 2
Importance of Imaging in Clinical Decision-Making
Imaging plays a crucial role in clinical decision-making for portal vein thrombosis, particularly in differentiating between benign and malignant thrombosis 3, 4.
- Contrast-enhanced ultrasound (CEUS) has been shown to be helpful in discriminating between benign and malignant portal vein thrombi 5, 4
- Dynamic contrast-enhanced CT is essential for evaluating the extent of thrombosis and guiding treatment decisions 2, 3
Treatment and Management
Anticoagulation treatment is an important non-invasive strategy for patients with cirrhosis and portal vein thrombosis, and can be effective in recanalizing the portal vein 6.
- Low molecular weight heparin (LMWH) medications, such as enoxaparin, can be used to treat portal vein thrombosis in patients with cirrhosis awaiting liver transplantation 6