PURPOSE: To evaluate the feasibility of magnetic resonance (MR) imaging-guided percutaneous sclerotherapy of venous malformations (VMs) by using a clinical 1.5-T MR unit and the safety and therapeutic outcome of the performed procedures. MATERIALS AND METHODS: This is a prospective pilot study with ethical approval and written informed patient consent. Ten MR imaging-guided percutaneous sclerotherapy treatments were performed in 10 patients (one male and nine female patients; age range, 16-47 years; mean age, 30.3 years) with a VM in the foot and/or ankle (n = 5), calf (n = 2), thigh and/or knee (n = 2), and elbow (n = 1). MR imaging was used for needle insertion guidance and real-time monitoring of the injection process by using three-dimensional fast spoiled gradient-echo MR sequences (repetition time msec/echo time msec = 3.7-5.2/1.1-1.6, flip angle = 35 degrees) and meglumine gadoterate/ethanol solutions as the sclerosing agent. The technical success (ie, absence of technical problems, number of needle position corrections) was systematically evaluated along with safety aspects (ie, absence of complications) and the therapeutic outcome (eg, VM volume decrease, relief of symptoms) during a 1-year follow-up period. RESULTS: MR imaging-guided sclerotherapy was technically successful in all patients. A mean of 2.5 +/- 1.85 (range, 1-6) needle position corrections were needed for correct needle placement. The distribution of the sclerosing agent (mean amount, 10.5 mL; range, 0.8-33.0 mL) was clearly visible with real-time MR monitoring. One patient developed a compartment syndrome, which was managed with surgery. No other complications were observed. VM volumes significantly decreased by 53% (range, 24%-86%; P = .02) 12 weeks after therapy. Nine of the 10 patients (90%) noted an improvement of symptoms. CONCLUSIONS: In this limited preliminary series, 1.5-T MR imaging-guided percutaneous sclerotherapy for the treatment of VMs was feasible with a high degree of technical success, was relatively safe, and had a good therapeutic outcome after 1 year.