Prediction of early response to uterine artery embolization in fibroids: Value of MR signal intensity ratio

Uterine Artery Embolization of Uterine Leiomyomas: Predictive MRI Features of Volumetric Response

OBJECTIVE. The purpose of this article was to evaluate MRI features of uterine leiomyomas that predict volumetric response after uterine artery embolization (UAE). MATERIALS AND METHODS. This retrospective study included 75 patients with 212 uterine leiomyomas who were successfully treated between August 2013 and December 2018. To predict uterine volumetric response, age, number of lesions, and baseline uterine volume were assessed. To predict leiomyoma volumetric response, a multivariate regression analysis was performed to evaluate six predictive factors: location, baseline leiomyoma volume, signal intensity on T1-weighted and T2-weighted MRI, heterogeneity of signal intensity on T2-weighted MRI, and vascularity on subtraction imaging (SI). A five-variable predictive ROC model was developed to evaluate the diagnostic accuracy of the signal intensity ratio on T2-weighted MRI, enhancement ratio, heterogeneity ratio on T2-weighted MRI, location, and baseline leiomyoma volume in predicting at least 40% leiomyoma volumetric response. RESULTS. Age, number of leiomyomas, and baseline uterine volume were not predictive of uterine volumetric response. A submucosal location was the best predictive factor of leiomyoma volumetric response, and it showed 32.2% more leiomyoma volumetric response compared with a nonsubmucosal location (p < .001). Hyperintensity on T2-weighted MRI was the second best predictive factor of leiomyoma volumetric response, and it showed 16.9% more volumetric response compared with hypointense leiomyomas (p = .013). A small baseline leiomyoma volume (< 58 cm³) was associated with 10.2% more leiomyoma volumetric response compared with larger leiomyomas (p = .01). Leiomyomas that were hyperintense on SI showed 7.9% more leiomyoma volumetric response compared with those that were hypointense (p = .014). The five-variable ROC model showed high diagnostic accuracy with an AUC of 0.85, sensitivity of 82%, and specificity of 71%. CONCLUSION. A submucosal location, hyperintensity on T2-weighted MRI, small baseline leiomyoma volume (< 58 cm³), and hyperintense leiomyoma on subtraction imaging are the main independent favorable predictors of leiomyoma volumetric response after UAE. An accurate predictive ROC model was developed that may help in selecting patients suitable for UAE. Quantitative assessment of heterogeneity on T2-weighted MRI showed promising results as a predictor of volumetric response, and further research in this area using texture analysis and radiomics is suggested.

The utility of apparent diffusion coefficients for predicting treatment response to uterine arterial embolization for uterine leiomyomas: a systematic review and meta-analysis

PURPOSE

Apparent diffusion coefficient (ADC) values, which are derived from diffusion-weighted imaging, have a potential role for predicting treatment response. A systematic review was conducted to examine the value of baseline ADC values for predicting leiomyoma size reduction after uterine arterial embolization (UAE).

METHODS

Study selection, quality appraisal and data extraction were conducted independently by two authors. Statistical analyses included the calculation of weighted means and summary correlation coefficients (under the random effects model).

RESULTS

Eleven studies consisting of a total of 258 patients (age, weighted mean±standard deviation [SD], 43.1±10.1 years) were included. The weighted mean±SD ADC value was 1.2±1.5 ×10-3 s/mm2 at baseline (ten studies) and 1.3±2.8 ×10-3 s/mm2 at approximately 6 months after embolization (six studies). The weighted mean percentage leiomyoma volume reduction (VR) at 6 months was 47.1%±35.6% (seven studies). Based on four studies, the weighted summary correlation coefficient for the correlation between baseline ADC and leiomyoma VR at approximately 6 months was not significant (r=0.40; 95% CI, -0.07 to 0.72; I2=69.7%). No associations were found in three of the four studies that examined changes in ADC values as a predictor.

CONCLUSION

Due to high heterogeneity, it is unclear whether ADC may be useful for predicting treatment responses to UAE.

Susceptibility weighted MRI after uterine artery embolization for leiomyoma

PURPOSE

To evaluate whether susceptibility-weighted MR imaging (SWI) findings are associated with tumor infarction on contrast-enhanced MRI (CE-MRI) after uterine artery embolization (UAE) for leiomyoma.

METHODS

This was a single institution, retrospective study. Between February 2016 and April 2017, 27 consecutive patients underwent UAE and completed SWI and CE-MRI before and 1 week after UAE. Two blinded readers independently reviewed the MRI of 261 tumors ≥1 cm in all patients. We evaluated the relationship between the hypointense peripheral rim observed on the tumor surface on post-procedural SWI and the infarction rates (≥90%, <90%) of each tumor based on post-procedural CE-MRI. Inter-reader correlation coefficients (ICC) and the sensitivity and specificity of the rim were measured.

RESULTS

Substantial inter-reader agreement was noted in post-procedural SWI interpretations (ICC = 0.681, 95% CI; 0.547, 0.771). The rim was observed in 66.7% (174/261) of tumors by reader 1 and 55.9% (146/261) of tumors by reader 2 on post-procedural SWI. Correlations were observed between the rim and ≥90% tumor infarction by readers 1 and 2 (Spearman's coefficient = 0.474 and 0.438, p < 0.001 and p < 0.001, respectively). The sensitivity and specificity of the rim to tumor infarction were 77.2 and 82.6% (reader 1), and 65.8 and 100% (reader 2), respectively.

CONCLUSIONS

The present study demonstrated that the hypointense peripheral rim was observed on some leiomyomas on SWI immediately after UAE. The rim correlated with tumor infarction on post-procedural CE-MRI. This SWI finding was helpful for evaluating embolic effects on leiomyomas in the acute phase after UAE.

Development of a Model for the Prediction of Treatment Response of Uterine Leiomyomas after Uterine Artery Embolization

Background: Uterine artery embolization (UAE) is one of the minimally-invasive alternatives to hysterectomy for treatment of uterine leiomyomas. There are various factors affecting the outcomes of UAE, but these have only been sporadically studied. Study Objective: To identify factors associated with the efficacy of UAE for the treatment of uterine leiomyoma, and to develop a model for the prediction of treatment response of uterine leiomyomas to UAE. Study design: A retrospective cohort study (Canadian Task Force Classification II-2) Patients: One hundred ninety-eight patients with symptomatic uterine leiomyomas. Intervention: UAE Measurements and Main Results: Among 198 leiomyoma patients who were treated with UAE, 104 who underwent pelvic magnetic resonance imaging (MRI) with diffusion-weighted imaging were selected for developing prediction model. Variables that were statistically significant from the univariate analysis were: location of leiomyoma, total number of lesions, sum of leiomyomas diameters, T2 signal intensity of largest leiomyoma, and T2 leiomyoma:muscle ratio. After a logistic regression analysis, leiomyoma location and T2 signal intensity of the largest leiomyoma were found to be statistically significant variables. Using intramural myomas defined as controls, submucosal leiomyomas showed a greater response to UAE with an odds ratio of 7.6904. The odds ratio of T2 signal intensity with an increase in signal intensity of 10 was 1.093. Using these two variables, we developed a prediction model. The AUC in the prediction model was 0.833, and the AUC in the validation set was 0.791. Conclusion: We identified that submucosal leiomyomas and those leiomyomas that show high signal intensity on T2-weighted imaging will exhibit a greater response to UAE. Prediction models are clinically helpful in selecting UAE as an appropriate treatment option for managing uterine leiomyoma.

Nonsurgical Alternatives for Uterine Fibroids

Uterine leiomyomata are the direct cause of a significant health-care burden for women, their families, and society as a whole. Because of the long experience with the mode of treatment, surgical myomectomy remains the gold standard for treating reproductive-age women; however, in the recent years, the wide evolution of less invasive approaches led to a change in the options used by the clinician to treat symptomatic fibroids. Minimally invasive procedures such as uterine artery embolization (UAE) are increasingly used to treat symptomatic fibroids. Other alternative treatments are becoming more diffuse, such as magnetic resonance-guided high-frequency focused ultrasound surgery (MRgFUS), cryomyolysis, vaginal occlusion, and laparoscopic closure of the uterine arteries. Both advantages and limitations of these techniques under development must be taken into account, but this wider range of choices is being increasingly considered for a tailored treatment. This article aims to enable health-care providers with the tools to provide the latest evidence-based care in the minimally invasive or noninvasive management of this common problem.