Non-invasive magnetic resonance-guided high intensity focused ultrasound ablation of a vascular malformation in the lower extremity: a case report

Johanna M. M. van Breugel, Robbert J. Nijenhuis, Mario G. Ries, Raechel J. Toorop, Evert-Jan P. A. Vonken, Joost W. Wijlemans, Maurice A. A. J. van den Bosch

Therapy of choice for symptomatic vascular malformations consists of surgery, sclerotherapy, or embolization. However, these techniques are invasive with possible complications and require hospitalization. We present a novel non-invasive technique, i.e., magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation, for the treatment of a vascular malformation in a patient. This technique applies high-intensity sound waves transcutaneously to the body and is fully non-invasive. MRI guidance is the novel aspect of HIFU treatments and is used for exquisite delineation and localization of the lesion and accurate real-time temperature monitoring during tissue ablation. MR-HIFU is a well-established treatment option for uterine fibroids and is currently being investigated for, e.g., bone tumors, breast cancer, prostate cancer, and liver cancer. MR-HIFU of vascular malformations has not been a topic of research yet. Volumetric MR-HIFU ablation of a vascular malformation in the lower extremity of an 18-year-old male patient was performed. Temperatures of 62-80 °C were reached in the target lesion with sonications of 4 × 4 × 8 mm using powers of 200 W for <20 s. At 1-month follow-up, the patient reported qualitatively sustained reduction of pain and normal motor function. Three-month follow-up imaging indicated successful nidus destruction, which resulted in reduction of >30 % of the tumor volume. After 13 months, pain score was reduced to <2 after extreme exertion for several hours and to 0 for daily activities. Radiofrequency ablation and cryoablation are minimally invasive techniques that have been tried on low-flow vascular malformations with inconsistent results. Furthermore, both techniques require probe insertion, which is associated with risks of wound infection and hospitalization. Since MR-HIFU is truly non-invasive, these risks are negligible. In conclusion, we reported a successful non-invasive treatment of a vascular malformation with MR-HIFU in a clinical patient including long-term follow-up data for the first time. The patient reported qualitatively sustained pain reduction up to 13 months post treatment.