Research articleUterine fibroids: Influence of “T2-Rim sign” on immediate therapeutic responses to magnetic resonance imaging-guided high-intensity focused ultrasound ablation

- Uterine fibroids with a T2-rim sign showed significantly poorer therapeutic responses.
- Higher percent coverage of a T2-rim sign lowered ablation efficiency and quality.
- T2-rim sign is an essential criterion in treatment planning.

ObjectivesTo investigate the influence of a high-signal-intensity peripheral rim on T2-weighted MR images (i.e., T2-rim sign) on the immediate therapeutic responses of MR-guided high intensity focused ultrasound (MR-HIFU) ablation of uterine fibroids.MethodsThis retrospective study was approved by the institutional review board, and patient informed consent was obtained for MR-HIFU ablation. In total, 196 fibroids (diameter 6.2 ± 2.6 cm) in 123 women (age 43.4 ± 5.0 years) who underwent MR-HIFU ablation from January 2013 to April 2016 were included. The effects of a T2-rim sign on the immediate therapeutic responses (non-perfused volume [NPV] ratio, ablation efficiency [NPV/treatment cell volume], ablation quality [grade 1-5, poor to excellent]) were investigated with univariable and multivariable analyses using generalized estimating equation (GEE) analysis. In multivariable analysis, T2 signal intensity ratio of fibroids-to-skeletal muscle, relative peak enhancement of fibroids, and subcutaneous fat thickness were also considered.ResultsThe presence of a T2-rim sign significantly lowered the NPV ratio (54.0 ± 28.0% vs. 83.7 ± 17.7%), ablation efficiency (0.6 ± 0.5 vs. 1.3 ± 0.6), ablation quality (3.1 ± 1.2 vs. 4.2 ± 0.8), (P < 0.0001). GEE analysis showed that the presence of a T2-rim sign was independently significant for ablation efficiency and ablation quality (P < 0.05).ConclusionUterine fibroids with a T2-rim sign showed significantly poorer immediate therapeutic responses to MR-HIFU ablation.