Differences in the therapeutic effects of high-intensity focused ultrasound (HIFU) ablation on uterine fibroids with different shear wave velocity (SWV): a study of histopathological characteristics.

OBJECTIVE: To explore correlations between the therapeutic effect of high intensity focused ultrasound (HIFU) and histopathological characteristics of uterine fibroids with different Shear Wave Velocity (SWV) values. METHODS: A retrospective study was conducted on 36 women (43 fibroids) who had undergone high intensity focused ultrasound (HIFU) uterine fibroids ablation between January 2019 and January 2020. Preoperative fibroids tissue sections were obtained for histopathological examination. The pathological sections were stained with Masson-trichrome, and were observed and imaged under a Low-power microscope (4 × 10), while the smooth muscle cell (SMC) and collagen fiber content were semi-quantitatively measured. Preoperative fibroid SWV was measured using the Virtual Touch tissue quantification (VTQ) technique. Within one month after HIFU ablation, all patients had undergone a pelvic cavity MRI examination, which measured the size, volume, and non-perfused volume (NPV) of the fibroids. The formula: the ablation rate = NPV/target fibroid volume × 100% was used to calculate the ablation rate of the uterine fibroids. Correlation analysis of SWV values, HIFU ablation rate, along with the smooth muscle cell (SMC) and collagen fiber content, were conducted using the Spearman's correlation test. RESULTS: The collagen fiber and SMC content of the preoperative fibroids were 32.09 ± 15.90%/view and 37.61 ± 15.32%/view, respectively. Preoperative fibroid SWV value was 3.56 ± 0.71 m/s. Preoperative fibroid SWV was negatively correlated with SMC content (r = -0.445, p = 0.003), but positively correlated with collagen fiber content (r = 0.454, p = 0.002). The ablation rate was negatively correlated with collagen fiber content (r = -0.377, p = 0.013), but positively correlated with SMC content (r = 0.402, p = 0.007). CONCLUSION: Differences in histopathological characteristics may be important factors that induce differences in the therapeutic effects of HIFU ablation on uterine fibroids with different SWV values.

The value of acoustic radiation force impulse imaging in preoperative prediction for efficacy of high-Intensity focused ultrasound uterine fibroids ablation.

Objective: To investigate the application value of acoustic radiation force impulse imaging in preoperative prediction for efficacy of High-Intensity Focused Ultrasound uterine fibroids ablationMethods: A prospective study was conducted on 32 women (41 fibroids) undergoing HIFU uterine fibroids ablation between January 2019 and September 2019. The virtual touch tissue quantification (VTQ) technique was used for the preoperative determination of uterine fibroids shear wave velocity (SWV). The stiffness of the preoperative uterine fibroids was graded on a virtual touch tissue image (VTI). All uterine fibroids were ablated with a single point ablation acoustic power of 400 W. All patients underwent pelvic cavity MRI examination for the measurement of the size, volume and non-perfused volume (NPV) of fibroids within the first month after HIFU ablation. The ablation rate of uterine fibroids was calculated according to the formula: ablation rate = NPV × 100/target fibroid volume. The patients were divided into two groups based on the postoperative ablation rate: ≥70% ablation rate group, and＜70% ablation rate group. The preoperative SWV and VTI grade of uterine fibroids were compared between the two groups. The correlation of preoperative uterine fibroids' SWV and VTI grade with HIFU ablation rate were analyzed using the Spearman's correlation coefficient. The optimal cutoff points in preoperative uterine fibroids SWV of 70% ablation rate were determined by receiver operating curve (ROC) analysis.Results: A total of 30 patients (73.17%, 30/41) showed ablation rate ≥70%, with preoperative uterine fibroids' SWV values of (3.42 ± 0.71) m/s. Of these, 24 patients (80%, 24/30) had VTI grades II-III. On the other hand, 26.83% (11/41) showed ablation rate <70%, with preoperative uterine fibroids' SWV values of (4.02 ± 0.69) m/s; of these, 63.6% (7/11) had VTI grade IV. The SWV values and VTI grades of preoperative uterine fibroids were significantly different in the two groups (p < 0.05). Interestingly, postoperative ablation rate was negatively correlated with preoperative uterine fibroids' SWV values (r= -0.536, p = 0.0003) and VTI grades (r= -0.511, p = 0.001). The area under the ROC curve of preoperative uterine fibroids' SWV values with ablation rate <70% was 0.75 at a cutoff value of 3.915 m/s (p < 0.05). Specificity was 72.7% and sensitivity was 80.1%; the positive predictive value was 72.7%, and the negative predictive value was 80%.Conclusion: ARFI technique is an effective and feasible noninvasive ultrasound technique for the preoperative prediction of the efficacy of HIFU uterine fibroids ablation.