Main portal vein thrombosis: Its CT patterns and related etiology

Thrombosis of the main portal vein (MPVT) is usually a complication of preexisting conditions such as malignant tumors, liver cirrhosis, infection, or stasis blood flow, or else it is idiopathic. No conclusive evidence of CT findings of MPVT in relation to etiology could be found in the literature. In fact, different mechanisms may cause different types of MPVT. Two hundred and twenty patients with MPVT who received CT scans without and with contrast in our series were analyzed with respect to the relationship of the CT pattern to the MPVT and its etiology. We identified five types of MPVT patterns in the CT scans. Malignancy with intravascular invasion may be present as breach type (83.1%) and floating type (16.9%) of MPVT, and the size of the portal vein is usually larger than 2 cm (79%), which is evident in CT scans and is less subject to misinterpretation. Tracing the break area of the portal wall can help in finding a subtle tumor. Mural thrombus is specific to portal hypertension (69.8%); the picture and mechanism may be similar to an atherosclerotic plug in systemic hypertension. The floating, ring, and obliteration types may not be specifically related to etiology; however, rim enhancement of a vasa vasorum may intensify in infective conditions. The obliteration type is probably the late phase of a blood clot thrombus in MPVT; it is seen in cases with silent clinical symptoms and signs in the period of MPVT formation, such as in stasis blood flow. Familiarity with image patterns may improve the diagnosis of an MPVT and discovery of its related etiology.