May-Thurner syndrome (MTS) traditionally refers to compression of the left common iliac vein between the right common iliac artery and the vertebral body. However, iliac vein compression is common in asymptomatic individuals, and the contemporary concept of nonthrombotic iliac vein lesions (NIVLs) emphasizes that anatomic compression alone does not constitute an indication for treatment. Successful endovascular therapy depends on appropriate patient selection and accurate assessment of clinically significant venous outflow obstruction. Intravascular ultrasound is valuable for lesion characterization, assessment of stenosis severity, stent sizing, selection of landing zones, and confirmation of final stent expansion. Durable reconstruction requires complete coverage of the diseased segment, appropriate stent sizing and expansion, adequate proximal outflow with minimal unnecessary coverage of the contralateral common iliac vein ostium, and adequate distal inflow. In post-thrombotic obstruction, reconstruction may need to extend across the inguinal ligament into the common femoral vein when required to reach a satisfactory inflow segment. This review provides a practical framework for the evaluation and endovascular management of MTS and NIVLs, with emphasis on procedural decision-making relevant to interventional radiologists.

<b>Purpose</b><br/>This study aimed to evaluate the clinical efficacy and patency of stents placed for symptomatic iliac vein or IVC obstruction caused by malignant tumors. <br/><b>Materials and Methods</b><br/>A total of 34 consecutive patients with malignant iliac vein or IVC obstruction underwent stent placement. We reviewed their electronic medical records, pre- and post-procedural CT scans, and angiograms retrospectively, and evaluated technical success, clinical success, and patient-based and vessel-based reocclusion rates confirmed by follow-up cross-sectional images. The reocclusion rate difference between IVC and iliac stents was also assessed. <br/><b>Results</b><br/>All patients complained of leg and/or trunk edema. The stents were placed in the following locations: IVC (n = 9); iliac veins (n = 19); and both IVC and iliac veins (n = 6). Technical success rate was 100% and the clinical success rate was 87.5% during hospitalization. Cross-sectional area of the affected thigh was significantly decreased after stent placement (mean 11.7%, p = 0.003). The median follow-up period was 65 days (Q1–Q3, 28.5–227.3; IQR, 198.8). The patient-based reocclusion rate was 42.8%. The vessel- based reocclusion rates for IVC (12.5%) tended to be lower than those of iliac veins (45.0%), though the difference was not statistically significant (p = 0.194). <br/><b>Conclusion</b><br/>Stent insertion for iliac vein or IVC obstruction secondary to malignancy is technically feasible and can help to improve patients’ symptoms. IVC stents tend to achieve a higher rate of patency than iliac vein stents.