Computed tomography findings in 10 cases of iliac vein compression (May-Thurner) syndrome.

OBJECTIVE To present the computed tomography (CT) findings for the iliac veins of 10 patients who had left-sided lower extremity deep vein thrombosis due to iliac vein compression syndrome. MATERIALS AND METHODS The CT findings for 10 cases of left-sided acute or chronic deep vein thrombosis caused by iliac vein compression syndrome were retrospectively evaluated. The patients were five women and five men (mean age+/-S.D., 49.9+/-15.6 years). In each patient with iliac vein compression syndrome, the diagnosis of the compression was established by venography performed during endovascular treatment. Diameter of the left common iliac vein was also measured in 14 control subjects without any lower extremity venous disease for comparison. RESULTS In all 10 cases, CT images in the transverse plane demonstrated the left common iliac vein being compressed by the overlying right common iliac artery. The mean diameter at the origin of the left common iliac vein (3.5 mm) in patients group was much smaller than the mean diameter of the same vein (11.5 mm) in the control group (p<0.01). The mean percent stenosis of the left common iliac vein due to compression by the artery was 68%. CONCLUSION Pelvic CT images in the transverse plane are useful for detecting iliac vein compression by the overlying right common iliac artery in patients with left-sided deep vein thrombosis. Radiologists should be aware of this imaging finding of iliac vein compression by the artery where the inferior vena cava bifurcates into the common iliac veins.