Objective: To study long-term effects in patients treated with microwave ablation (MWA) for symptomatic uterine fibroids and investigate fibroid characteristics predictive of successful treatment.
Method: Women who received MWA treatment for uterine fibroids in a previous study were included. A total of 16 patients underwent contrast enhanced MRI before treatment, postoperatively at 6 months and at long-term follow-up, to assess volumes of treated fibroids (n = 42). Long-term MRI was performed between 16 and 36 months after treatment [median 22 months, interquartile range (IQR) 18.5-27]. Validated questionnaires for evaluation of uterine fibroid symptoms and menstrual bleeding (UFS-QoL and PBAC) were used to assess long-term effects on symptoms. The degree of shrinkage was correlated to vascularization and T2 signal intensity (SI) at preoperative MRI and location of fibroids according to the FIGO classification, using the Mann-Whitney U test.
Results: Most patients (82%) reported improvement up to 3 years after treatment. Out of 42 treated fibroids, 35 (83%) continued to shrink over time with median relative volume reduction of 77% (IQR 39-95). For eight fibroids (19%) which showed low vascularization on the pretreatment MRI, there was less shrinkage compared to well-vascularized fibroids (p = 0.01). Most fibroids (79%) showed iso- to hyperintense T2 signal on preoperative MRI and showed a higher grade of shrinkage than hypointense fibroids (p = 0.02).
Conclusion: After microwave treatment improvement is maintained for most patients up to 36 months and most fibroids showed continuous shrinkage. Preoperative vascularization, high T2 SI and submucosal location predicted continuous volume reduction. However, to confirm this, larger studies are needed.
Keywords: MRI; Uterine fibroids; clinical trials-thermal ablation; long-term follow-up; microwave ablation; minimally invasive treatment.