Abdominal venous system: assessment using MR.

Abstract

Patients (25) with known or suspected evidence of venous disease based on results of computed tomography, angiography or ultrasound were imaged with magnetic resonance (MR) to determine the MR characterization of venous abnormalities. MR findings were proved by laparotomy or autopsy in 18 of 25 cases. In 7 of 25 patients in whom only biopsy was performed, the MR findings were correlated with findings from other radiologic tests. On MR, the inferior vena cava (IVC), portal vein and their major tributaries were seen in all but 2 cases. In those 2, identification of collaterals led to the correct diagnosis of splenic vein thrombosis in 1 case and left renal vein thrombosis in another. MR imaging helped identify intraluminal thrombi in the IVC (12 of 12 cases), portal vein (2 of 2 cases), renal veins (7 of 7 cases), superior mesenteric vein (1 case), and iliac veins (7 of 7 cases). Intraluminal signal intensity secondary to slow blood flow seen in 5 patients was always differentiated from the thrombus. MR imaging helped identify correctly the nature of the thrombus in 11 of 16 patients. In 5 patients, the differentiation between tumor thrombus and blood clot thrombus was not possible. Involvement of the IVC wall by tumor was seen in 4 cases. MR imaging also accurately depicted slow flow in obstructed or constricted veins; encasement, compression or displacement of veins without intraluminal occlusions; and the presence of venous collaterals. The MR imaging evaluation of venous abnormalties is accurate, easily performed and will probably become an important application.