MR-guided HIFU treatment of symptomatic uterine fibroids using novel feedback-regulated volumetric ablation: effectiveness and clinical practice.

PURPOSE: To evaluate a novel feedback-regulated volumetric sonication method in MR-guided HIFU treatment of symptomatic uterine fibroids. MATERIALS AND METHODS: 27 fibroids with an average volume of 124.9 ± 139.8 cc in 18 women with symptomatic uterine fibroids were ablated using the new HIFU system Sonalleve (1.5 T MR system Achieva, Philips). 21 myomas in 13 women were reevaluated 6 months later. Standard (treatment) cells (TC) and feedback-regulated (feedback) cells (FC) with a diameter of 4, 8, 12, and 16 mm were used and compared concerning sonication success, diameter of induced necrosis, and maximum achieved temperature. The non-perfused volume ratio (NPV related to myoma volume) was quantified. The fibroid volume was measured before, 1 month, and 6 months after therapy. Symptoms were quantified using a specific questionnaire (UFS-QoL). RESULTS: In total, 205 TC and 227 FC were applied. The NPV ratio was 23 ± 15 % (2 - 55). The TC were slightly smaller than intended (-3.9 ± 52 %; range, -100 - 81), while the FC were 20.1 ± 25.3 % bigger (p = 0.02). Feedback mechanism is less diversifying in diameter (p < 0.001). Overall, the FC correlate well with the planned treatment diameter (r = 0.79), other than the TC (r = 0.38). Six months after therapy, the fibroid volume was reduced by 45 ± 21 % (5 - 100) (p = 0.001). The symptoms decreased significantly (p = 0.001). No serious adverse events were recorded. CONCLUSION: Use of volumetric sonication leads to homogenous heating and sufficient necrosis. It is a safe and effective therapy for treating symptomatic uterine fibroids. Successful sonication of feedback cells leads to more contiguous necrosis in diameter and a less diversifying temperature. KEY POINTS: ▶ MR-guided HIFU ablation of symptomatic uterine fibroids is a valuable treatment option. ▶ By non-invasive HIFU fibroid volumes can be reduced and symptoms improved. ▶ The novel feedback-regulated treatment cells offer advantages over standard treatment cells.