Magnetic Resonance Imaging Parameters in Predicting the Treatment Outcome of High-intensity Focused Ultrasound Ablation of Uterine Fibroids With an Immediate Nonperfused Volume Ratio of at Least 90

Machine learning models for prediction of NPVR ≥80% with HIFU ablation for uterine fibroids

BACKGROUND

Currently high-intensity focused ultrasound (HIFU) is widely used to treat uterine fibroids (UFs). The aim of this study is to develop a machine learning model that can accurately predict the efficacy of HIFU ablation for UFs, assisting the preoperative selection of suitable patients with UFs.

METHODS

This study collected data from 1,000 patients with UFs who underwent ultrasound-guided high-intensity focused ultrasound. The least absolute shrinkage and selection operator (LASSO) regression was used for multidimensional feature screening. Five machine learning algorithms such as logistic regression, random forest, extreme gradient boosting (XGBoost), artificial neural network, and gradient boosting decision tree were utilized to predict ablation efficacy. The efficacy was quantified by the non-perfused volume ratio (NPVR), which was classified into two categories: NPVR <80% and NPVR ≥80%.

RESULTS

The XGBoost model proved to be the most effective, showing the highest AUC of 0.692 (95% CI: 0.622-0.762) in the testing data set. The four key predictors were T2 weighted image, the distance from ventral side of UFs to skin, platelet count, and contrast-enhanced T1 weighted image.

CONCLUSIONS

The machine learning prediction model in this study showed significant potential for accurately predicting the preoperative efficacy of HIFU ablation for UFs. These insights were important for clinicians in the preoperative assessment and selection of patients, which could enhance the precision of treatment planning.

A Dual-Sequence MRI-Based Radiomics Model for Predicting High-Intensity Focused Ultrasound Ablation Efficacy in Adenomyosis Treatment

Purpose

The aim of this study is to develop a predictive model for the therapeutic efficacy of high-intensity focused ultrasound (HIFU) ablation in the treatment of adenomyosis, utilizing dual-sequence MRI radiomics.

Methods

A retrospective analysis was conducted on 114 patients diagnosed with adenomyosis who underwent ultrasound-guided HIFU ablation under conscious sedation between July 2021 and July 2023. Patients were randomly allocated into a training set and a test set at a ratio of 7:3. The study aimed to evaluate the distribution of clinical characteristics among patients experiencing effective versus ineffective ablation at two distinct classification thresholds (0.7 and 0.5). Multiple models were developed to explore the combination of effective radiomic features derived from dual-sequence MRI and clinical data. Radiomic features were extracted from the MRI images of adenomyosis lesions in the training set. This process included feature extraction, selection, model construction, and evaluation. Logistic regression was used to construct the predictive model, and its performance was assessed on the test set using the receiver operating characteristic (ROC) curve. The Delong test, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were used to compare the predictive accuracy of the models.

Results

The predictive model showed better alignment with actual ablation outcomes, particularly for predicting ablation success rates exceeding 50%. The combination of radiomic features from the two MRI sequences achieved an AUC of 0.84 in the test set. Decision curve analysis demonstrated that the combined model provided greater net benefit than the single-sequence radiomics model across a broader range of risk thresholds. For the prediction of 70% efficacy, the combined model achieved an AUC of 0.804 in the test set, slightly lower the 50% efficacy prediction task.

Conclusion

The model, based on dual-sequence MRI radiomics, emerges as a promising tool for predicting the efficacy of HIFU ablation, potentially aiding clinicians in anticipating the outcomes of HIFU ablation procedures.

Ablation of symptomatic uterine fibroids with the Mirabilis system for rapid noninvasive ultrasound-guided high-intensity focused ultrasound (HIFU): a prospective observational clinical study

OBJECTIVES

Uterine fibroids often lead to symptoms that negatively impact health-related quality of life (HRQOL). High-intensity focused ultrasound (HIFU) has emerged as a promising noninvasive treatment for reducing fibroid size and symptoms. The Mirabilis system for ultrasound (US)-guided HIFU introduces a novel technique known as 'shell ablation'. This study evaluates the feasibility and efficacy of Mirabilis in a clinical setting, focusing on clinical outcomes.

MATERIALS AND METHODS

Sixteen patients with 23 uterine fibroids were treated with the Mirabilis system. Follow-up assessments included US and MRI at baseline, 6 weeks, 3, 6 and 9 months, and 1 year after HIFU. Changes in symptoms and QOL were evaluated using the Uterine Fibroid Symptom and HRQOL Questionnaire.

RESULTS

A significant reduction in fibroid volume was observed after HIFU (baseline 182.1 ± 49.3 ml; 1 year: 76.0 ± 37.9 ml, p < 0.001). The symptom severity score significantly declined (baseline 57.2 ± 3.8; 1 year: 30.2 ± 4.9, p < 0.001), correlating with a significant improvement in HRQOL (baseline 47.0 ± 3.9, 1 year: 71.8 ± 5.3, p < 0.001).

CONCLUSION

HIFU with the portable Mirabilis system is a feasible and safe noninvasive treatment for symptomatic uterine fibroids in an outpatient setting. This approach allows efficient and rapid ablation even for large fibroids, significantly reducing fibroid volume and symptoms.

Magnetic Resonance-Guided Focused Ultrasound Surgery for Gynecologic Indications

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) appears to be an effective and safe treatment for uterine fibroids and adenomyosis, particularly in women who wish to preserve fertility. In abdominal wall endometriosis and painful recurrent gynecologic malignancies, MRgFUS can relieve pain, but more research is needed. There is no widespread reimbursement due to the lack of large prospective or randomized controlled trials comparing MRgFUS with standard therapy.

Effect of "T2-rim sign" related parameters on high-intensity focused ultrasound ablation of uterine fibroids

PURPOSE

To investigate the effect of "high-signal-intensity peripheral rim on T2-weighted MR images (T2-rim sign)" related parameters on non-perfused volume ratio (NPVR) after high-intensity focused ultrasound (HIFU) ablation of uterine fibroids.

METHODS

Data from 616 patients with uterine fibroids treated with HIFU were retrospectively analyzed. Univariate and multivariate logistic regression was used to analyze the factors influencing the ablation effect. The effect of T2-rim sign on ablation parameters and results was also analyzed. Spearman correlation analysis was used to compare the correlation between coverage ratio, average thickness of T2-rim sign and NPVR in 207 cases of fibroids with T2-rim sign.

RESULTS

The presence of T2-rim sign was an independent risk factor affecting the ablation effect. The coverage ratio of T2-rim sign was negatively correlated with treatment efficiency (r = -0.174, p = 0.012) and NPVR (r = -0.186, p = 0.007), and positively correlated with energy efficiency factor (EEF) (r = 0.156, p = 0.024). The average thickness of T2-rim sign was positively correlated with treatment intensity (r = 0.203, p = 0.003) and negatively correlated with NPVR (r = -0.363, p < 0.001). There was a negative correlation between the average thickness of the T2-rim sign and NPVR in isointense fibroids (r = -0.484, p < 0.001).

CONCLUSION

The presence of T2-rim sign increases the difficulty of ablation and reduces the ablation effect. In clinical practice, the presence and related parameters of T2-rim sign should be fully considered when screening for HIFU indications and formulating treatment plans.

An Updated Review of Thermal Ablation Technology for Uterine Fibroids and Adenomyosis: Focusing on Protecting Fertility

There is a growing trend towards minimally invasive or noninvasive alternatives for gynecological disorders due to their rapid alleviation of symptom, expedited recovery, and minimal risks of postoperative complications. Thermal ablation technology has been commonly advocated as a minimally invasive therapeutic methods in recent years, including microwave ablation, radiofrequency ablation, and high-intensity focused ultrasound. The increasing application scenarios require updated and systematic research, and more evidence to promote their appropriate use. The objective of this review is to summarize the latest views of ablation from a prospective of fertility protection, endeavor to clarify the clinical value of thermal ablation technology in protecting fertility by assessing parameters such as ablation rates, alleviation of disease symptoms, re-intervention rates and post-treatment pregnancy rates. We review the clinical studies of ablation for uterine fibroids and adenomyosis treatment in the past 10 years, summarize the limitation and the prospects of its development in the treatment process, so as to provide clinicians with advice on the best practice. In the management of uterine fibroids and adenomyosis, thermal ablation technology offers improved fertility preservation and minimizes normal tissue injury compared to traditional surgical approaches for patients pursuing reproductive goals. In the future, thermal ablation technology will play a significantly enhanced role in preserving fertility for individuals requiring treatment for uterine fibroids and adenomyosis, guided by indications. But further research is still needed in the form of more extensive randomized prospective trials to provide stronger evidence supporting this perspective.

A systematic review of the side effects of high-intensity focused ultrasound ablation of uterine fibroids

Background

A new intervention called high-intensity focused ultrasound (HIFU) targets fibroids with high-intensity ultrasound pulses using ultrasound probes. This noninvasive method, which can be carried out with either magnetic resonance imaging or ultrasound guidance, results in immediate coagulated necrosis within a clearly defined area a few millimeters in diameter.

Methods

This systematic review evaluated the safety of HIFU in the treatment of uterine fibroids regardless of site or size. We specifically aimed to determine the incidence of side effects that can occur during and after HIFU. We searched the PubMed, Scopus, ScienceDirect, and Mendeley archive using only the terms HIFU and fibroid. After identifying 1077 studies of different types from 2014 to March 2024, 300 studies were screened and 60 included.

Results

According to Society of Interventional Radiology guidelines, class A adverse events (AEs) showed no significant results, and individuals with these AEs required no treatment and had no long-term consequences. Similarly, there were no class B significant results. However, 3943 of 10,204 patients (38%) complained of lower abdominal pain after the procedure, a class B AE, which resolved by analgesics. Further, 153 of 24,700 patients (0.6%) had skin burns, blisters, or nodules, and these issues resolved with conservative treatment. Additionally, 74 of 23,741 patients (0.3%) had hematuria; 882 of 5970 patients (14.7%) had abnormal vaginal discharge; 414 of 23,449 (1.7%) had vaginal bleeding; and 267 of 7598 (3.5%) had leg paresthesia. Major AEs (class C and D) were almost nonexistent, and the incidence of death in our study was zero.

Conclusion

HIFU ablation of uterine fibroids is generally safe, causing mostly mild side effects and very few severe complications. The relative safety of HIFU compared to other minimally invasive techniques, such as uterine artery embolization, still needs further evaluation.

A novel scoring system based on magnetic resonance imaging for the prediction of the difficulty of ultrasound-guided high-intensity focused ultrasound ablation for uterine fibroids

OBJECTIVE

To develop a novel scoring system based on magnetic resonance imaging (MRI) for predicting the difficulty of ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation for uterine fibroids.

MATERIALS AND METHODS

A total of 637 patients with uterine fibroids were enrolled. Sonication time, non-perfused volume ratio (NPVR), and ultrasound energy delivered for ablating 1 mm3 of fibroid tissue volume (E/V) were each classified as three levels and assigned scores from 0 to 2, respectively. Treatment difficulty level was then assessed by adding up the scores of sonication time, NPVR and E/V for each patient. The patients with score lower than 3 were categorized into low difficulty group, with score equal to or greater than 3 were categorized into high difficulty group. The potential predictors for treatment difficulty were compared between the two groups. Multifactorial logistic regression analysis model was created by analyzing the variables. The difficulty score system was developed using the beta coefficients of the logistic model.

RESULTS

Signal intensity on T2WI, fibroid location index, largest diameter of fibroids, abdominal wall thickness, homogeneity of the signal of fibroids, and uterine position were independent influencing factors for the difficulty of USgHIFU for uterine fibroids. A prediction equation was obtained: difficulty score = 17 × uterine position (anteverted =0, retroverted =1)+71 × signal intensity (hypointense = 0, isointense/hyperintense = 1) +8 × enhancement (homogenous = 0, heterogeneous = 1)+25×(largest diameter of fibroids-20) +35 × (fibroid location index -0.2) +1×(abdominal wall thickness -5).

CONCLUSIONS

This scoring system established based on MRI findings can be used to reliably predict the difficulty level of USgHIFU treatment of uterine fibroids.

Achieving NPVR ≥ 80% as technical success of high-intensity focused ultrasound ablation for uterine fibroids: a cohort study

OBJECTIVE

To report the long-term re-intervention of patients with uterine fibroids after ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation and to analyse the influencing factors of re-intervention in patients in the NPVR ≥ 80% group.

MATERIALS AND METHODS

Patients with a single uterine fibroid who underwent USgHIFU at our hospital from January 2012 to December 2019 were enrolled. The patients were divided into four groups according to different nonperfusion volume ratio (NPVR). Kaplan-Meier survival curve was used to analyse long-term re-intervention in different NPVR groups, and Cox regression was used to analyse the influencing factors of re-intervention in the NPVR ≥ 80% group.

MAIN RESULTS

A total of 1,257 patients were enrolled, of whom 920 were successfully followed up. The median follow-up time was 88 months, and the median NPVR was 85.0%. The cumulative re-intervention rates at 1, 3, 5, 8 and 10 years after USgHIFU were 3.4%, 11.8%, 16.8%, 22.6% and 24.1%, respectively. The 10-year cumulative re-intervention rate was 37.3% in the NPVR < 70% group, 31.0% in the NPVR 70-79% group, 18.2% in the NPVR 80-89% group and 17.8% in the NPVR ≥ 90% group (P < 0.05). However, no difference was found between the group of NPVR 80-89% and the group of NPVR ≥ 90% (P = 0.499). Age of patients and signal intensity on T2-weighted imaging (T2WI) of tumours were found to be independent risk factors for long-term re-intervention in the NPVR ≥ 80% group. A younger age and greater signal intensity on T2W images corresponded to a greater risk of re-intervention.

CONCLUSION

USgHIFU, an alternative treatment for uterine fibroids, has reliable long-term efficacy. NPVR ≥ 80% can be used as a sign of technical success, which can reduce re-intervention rates. However, an important step is to communicate with patients in combination with the age of patients and the signal intensity on T2WI of fibroids.

TRIAL REGISTRATION

This retrospective study was approved by the ethics committee at our institution (Registration No. HF2023001; Date: 06/04/2023). The Chinese Clinical Trial Registry provided full approval for the study protocol (Registration No. CHiCTR2300074797; Date: 16/08/2023).

Prediction of non-perfusion volume ratio for uterine fibroids treated with ultrasound-guided high-intensity focused ultrasound based on MRI radiomics combined with clinical parameters

BACKGROUND

Prediction of non-perfusion volume ratio (NPVR) is critical in selecting patients with uterine fibroids who will potentially benefit from ultrasound-guided high-intensity focused ultrasound (HIFU) treatment, as it reduces the risk of treatment failure. The purpose of this study is to construct an optimal model for predicting NPVR based on T2-weighted magnetic resonance imaging (T2MRI) radiomics features combined with clinical parameters by machine learning.

MATERIALS AND METHODS

This retrospective study was conducted among 223 patients diagnosed with uterine fibroids from two centers. The patients from one center were allocated to a training cohort (n = 122) and an internal test cohort (n = 46), and the data from the other center (n = 55) was used as an external test cohort. The least absolute shrinkage and selection operator (LASSO) algorithm was employed for feature selection in the training cohort. The support vector machine (SVM) was adopted to construct a radiomics model, a clinical model, and a radiomics-clinical model for NPVR prediction, respectively. The area under the curve (AUC) and the decision curve analysis (DCA) were performed to evaluate the predictive validity and the clinical usefulness of the model, respectively.

RESULTS

A total of 851 radiomic features were extracted from T2MRI, of which seven radiomics features were screened for NPVR prediction-related radiomics features. The radiomics-clinical model combining radiomics features and clinical parameters showed the best predictive performance in both the internal (AUC = 0.824, 95% CI 0.693-0.954) and external (AUC = 0.773, 95% CI 0.647-0.902) test cohorts, and the DCA also suggested the radiomics-clinical model had the highest net benefit.

CONCLUSIONS

The radiomics-clinical model could be applied to the NPVR prediction of patients with uterine fibroids treated by HIFU to provide an objective and effective method for selecting potential patients who would benefit from the treatment mostly.

What predicts durable symptom relief of uterine fibroids treated with MRI-guided focused ultrasound? A multicenter trial in 8 academic centers

OBJECTIVE

To identify variables predictive of durable clinical success after MRI-guided focused ultrasound (MRgFUS) treatment of uterine fibroids.

MATERIALS AND METHODS

In this prospective, multicenter trial, 99 women with symptomatic uterine fibroids were treated using MRgFUS. Pelvic MRI was obtained at baseline and treatment day. The Uterine Fibroid Symptom-Quality of Life questionnaire was used to calculate a symptom severity score (SSS) at baseline and 6, 12, 24, and 36 months following treatment. Clinical, imaging, and treatment variables were correlated with symptom reduction sustained through the 12- and 24-month time points using univariable and multivariable logistic regression analyses. A novel parameter, the ratio of non-perfused volume to total fibroid load (NPV/TFL), was developed to determine association with durable outcomes.

RESULTS

Post-treatment, mean symptom severity decreased at the 6-, 12-, 24-, and 36-month follow-ups (p < 0.001, all time points). In univariable analysis, three variables predicted treatment success (defined by ≥ 30-point improvement in SSS) sustained at both the 12-month and 24-month time points: increasing ratio of NPV/TFL (p = 0.002), decreasing total fibroid load (p = 0.04), and the absence of T2-weighted Funaki type 2 fibroids (p = 0.02). In multivariable analysis, the NPV/TFL was the sole predictor of durable clinical success (p = 0.01). Patients with ratios below 30% had less improvement in SSS and lacked durable clinical response compared with those between 30-79 (p = 0.03) and ≥ 80% (p = 0.01).

CONCLUSION

Increased non-perfused volume relative to total fibroid volume was significantly associated with durable reduction of symptoms of abnormal uterine bleeding and bulk bother.

CLINICAL RELEVANCE STATEMENT

Patient selection for sustained clinical benefit should emphasize those with likelihood of achieving high ablation ratios, as determined by imaging (e.g., device access, Funaki type) and by considering the total fibroid load, not just the primary symptomatic fibroid.

TRIAL REGISTRATION

Clinical trial ID: NCT01285960.

KEY POINTS

• Patient selection/treatment approach associated with durable symptom relief in MRI-guided focused ultrasound ablation of uterine fibroids remains unclear. • The ablation ratio, non-perfused volume/total fibroid volume, was positively associated with sustained symptom relief in both bleeding and bulk bother at 1- and 2-year follow-ups. • Selecting patients with imaging features that favor a high ratio of ablation to total fibroid load (including non-targeted fibroids) is the main factor in predicting durability of symptom relief after uterine fibroid treatment.

MRI parameters for predicting the effect of ultrasound-guided high-intensity focused ultrasound in the ablation of uterine fibroids

AIM

To study the value of magnetic resonance imaging (MRI) parameters in predicting the efficacy of ultrasonic ablation of fibroids.

MATERIALS AND METHODS

A total of 91 patients were divided into groups based on non-perfused volume (NPV) ratio and blood supply type. The preoperative MRI parameters were measured and analysed. A correlation analysis between the MRI parameters and the NPV ratio was performed. Receiver operating characteristic (ROC) curves were used to analyse and determine the cut-off value of MRI parameters to predict the ablation rate of fibroids.

RESULTS

The uterine fibroids group with an NPV ratio <80% and the group with an NPV ratio of ≥80% had significant differences in signal intensity (SI) at MRI T2-weighted imaging (WI), fibroid-to-rectus abdominis SI ratio (SIR) at T2WI, and blood supply type (p<0.05). There were no significant differences in fibroid volume, T2WI signal uniformity, and apparent diffusion coefficient (ADC) values. The ADC value and SI and SIR at MRI T2WI in the group with poor blood supply were lower than those in the group with a rich blood supply (p<0.05). SI at MRI T2WI correlated negatively with the NPV ratio. The cut-off values for SI and SIR at MRI T2WI of fibroids whose NPV ratio exceeds 80% were 220.58 and 1.315, respectively.

CONCLUSION

SI at MRI T2WI and blood supply type could be predictors of the efficacy of ablation. Ultrasonic ablation of fibroids with MRI T2WI hyperintensity and a rich blood supply had poor efficacy.

Therapeutic dose and long-term efficacy of high-intensity focused ultrasound ablation for different types of uterine fibroids based on signal intensity on T2-weighted MR images

OBJECTIVE

To investigate the therapeutic dose and long-term efficacy of high-intensity focused ultrasound (HIFU) ablation for different types of uterine fibroids based on signal intensity on T2-weighted MR images (T2WI).

MATERIALS AND METHODS

Four hundred and one patients with a solitary uterine fibroid treated with HIFU were classified into four groups consisting of extremely hypointense, hypointense, isointense and hyperintense fibroids. Each group was further classified into two subtypes: homogeneous and heterogeneous, based on signal homogeneity of fibroids. The therapeutic dose and long-term follow-up results were compared.

RESULTS

There were significant differences in treatment time, sonication time, treatment intensity, total treatment dosage, treatment efficiency, energy-efficiency factor (EEF) and non-perfused volume (NPV) ratio among the four groups (p<.05). The average NPV ratio achieved in patients with extremely hypointense, hypointense, isointense and hyperintense fibroids was 75.2 ± 14.6%, 71.1 ± 15.6%, 68.2 ± 17.3% and 67.8 ± 16.6%, respectively; the re-intervention rates at 36 months after HIFU were 8.4%, 10.3%, 12.5% and 6.1%, respectively. Sonication time, treatment intensity and total energy for heterogeneous fibroids were greater than that for homogeneous fibroids in patients with extremely hypointense fibroids (p<.05). The treatment time for heterogeneous fibroids was significantly longer than that for homogeneous fibroids in patients with isointense fibroids (p<.05). Multivariate ordered logistic regression analysis showed that the ablation volume of fibroids and treatment time were related to NPV ratio (p<.05).

CONCLUSION

Every group of patients obtained satisfactory long-term results. Hyperintense fibroids are difficult to treat by HIFU. Heterogeneous fibroids are more difficult to treat with HIFU than homogeneity fibroids.

High-intensity focused ultrasound as a pretreatment combined with hysteroscopic resection for gestational trophoblastic neoplasia with chemotherapy intolerance: a case report

BACKGROUND

Due to resistance and intolerance to chemotherapy, localized lesion resection may be required in some patients with Gestational trophoblastic neoplasia (GTN), which may lead to massive bleeding. In this case report, we describe the successful use of high-intensity focused ultrasound (HIFU) as an effective pretreatment method for surgical procedure in a patient with GTN to reduce the perioperative risk and the impact on fertility.

CASE PRESENTATION

A 26-year-old woman was diagnosed with high-risk GTN (FIGO Stage III: 12 prognostic scores) after a hydatidiform mole. The fifth chemotherapy cycle was interrupted due to severe chemotherapy toxicity. However, the uterine lesion was still present and the beta-human chorionic gonadotropin (β-hCG) level was not restored to normal. Therefore, ultrasound-guided HIFU was performed as a pretreatment method to shrink the lesion and prevent massive bleeding during localized lesion resection. The effectiveness of ablation was evaluated immediately using contrast-enhanced ultrasound and Color Flow Doppler ultrasonography. One month after HIFU treatment, the uterine lesion was completely resected under hysteroscopic surgery. During the surgery, HIFU was found to have shrunk the lesion and there was minimal bleeding (5 mL). The uterine cavity morphology and menstruation returned to normal after surgery. The patient has showed no signs of recurrence as of one-year follow-up.

CONCLUSION

Ultrasound-guided HIFU ablation may be a new choice for high-risk GTN patients with chemoresistance or chemo-intolerance. As a noninvasive pretreatment method, HIFU can shrink the uterine lesion, and reduce the risk of bleeding with no obvious effect on fertility.

Factors influencing USgHIFU ablation for adenomyosis with NPVR ≥ 50

OBJECTIVE

To investigate the influencing factors of ultrasound-guided HIFU (USgHIFU) ablation for adenomyosis with a non-perfused volume ratio (NPVR)≥50%.

METHODS

A total of 299 patients with adenomyosis who underwent USgHIFU ablation were enrolled. Quantitative signal intensity (SI) analysis was performed on T2WI and dynamic enhancement type. The energy efficiency factor (EEF) was defined as the ultrasound energy delivered for ablating 1 mm³ of tissue. NPVR ≥ 50% was used as the criterion for technical success. Adverse effects and complications were recorded. Logistic regression analyses of variables were conducted to identify the factors affecting NPVR ≥ 50%.

RESULTS

The median NPVR was 53.5% (34.7%). There were 159 cases in the NPVR ≥ 50% group and 140 cases in the NPVR < 50% group. The EEF in NPVR < 50.0% group was significantly higher than that in NPVR ≥ 50% group (p < 0.05). The incidence of intraoperative adverse effects and postoperative adverse events in the NPVR < 50% group were higher than those in the NPVR ≥ 50% group (p < 0.05 for both). Logistic regression analysis showed that abdominal wall thickness, SI difference on T2WI between adenomyosis and rectus abdominis, and enhancement type on T1WI were protective factors for NPVR ≥ 50% (p < 0.05), while the history of childbirth was an independent risk factor (p < 0.001).

CONCLUSIONS

Compared with NPVR < 50%, NPVR ≥ 50% did not increase the intraprocedural and postprocedural adverse reactions. The possibility of NPVR ≥ 50% was higher in patients with thinner abdominal walls, showed slight enhancement of adenomyosis on T1WI, with a history of childbirth, or in whom the SI difference on T2WI between adenomyosis and rectus abdominis was more minor.

Tissue specific considerations in implementing high intensity focussed ultrasound under magnetic resonance imaging guidance

High-intensity focused ultrasound can ablate a target permanently, leaving tissues through which it passes thermally unaffected. When delivered under magnetic resonance (MR) imaging guidance, the change in tissue relaxivity on heating is used to monitor the temperatures achieved. Different tissue types in the pre-focal beam path result in energy loss defined by their individual attenuation coefficients. Furthermore, at interfaces with different acoustic impedances the beam will be both reflected and refracted, changing the position of the focus. For complex interfaces this effect is exacerbated. Moreover, blood vessels proximal to the focal region can dissipate heat, altering the expected region of damage. In the target volume, the temperature distribution depends on the thermal conductivity (or diffusivity) of the tissue and its heat capacity. These are different for vascular tissues, water and fat containing tissues and bone. Therefore, documenting the characteristics of the pre-focal and target tissues is critical for effective delivery of HIFU. MR imaging provides excellent anatomic detail and characterization of soft tissue components. It is an ideal modality for real-time planning and monitoring of HIFU ablation, and provides non-invasive temperature maps. Clinical applications involve soft-tissue (abdomino-pelvic applications) or bone (brain applications) pre-focally and at the target (soft-tissue tumors and bone metastases respectively). This article addresses the technical difficulties of delivering HIFU effectively when vascular tissues, densely cellular tissues, fat or bone are traversed pre-focally, and the clinical applications that target these tissues. The strengths and limitations of MR techniques used for monitoring ablation in these tissues are also discussed.

ACR Appropriateness Criteria® Fibroids

Uterine fibroids (leiomyomas or myomas) are the most common neoplasm of the uterus. Though incompletely understood, fibroid etiology is multifactorial, a combination of genetic alterations and endocrine, autocrine, environmental, and other factors such as race, age, parity, and body mass index. Black women have greater than an 80% incidence of fibroids by age 50, whereas White women have an incidence approaching 70%. Fibroid symptoms are protean, and menorrhagia is most frequent. The societal economic burden of symptomatic fibroids is large, 5.9 to 34.3 billion dollars annually. There are a variety of treatment options for women with symptomatic fibroids ranging from medical therapy to hysterectomy. Myomectomy and uterine fibroid embolization are the most common uterine sparing therapies. Pelvic ultrasound (transabdominal and transvaginal) with Doppler and MRI with and without intravenous contrast are the best imaging modalities for the initial diagnosis of fibroids, the initial treatment of known fibroids, and for surveillance or posttreatment imaging. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Ultrasound-guided percutaneous microwave ablation for uterine fibroids: mid-term local treatment efficiency and associated influencing factors

OBJECTIVE

To investigate the mid-term local treatment efficiency of ultrasound-guided percutaneous microwave ablation (MWA) for uterine fibroids (UFs) and the associated influencing factors.

METHODS

From July 2020 to October 2021, a total of 28 patients with 52 UFs who had undergone ultrasound-guided MWA were retrospectively included in this study. Pre-treatment clinical characteristics, conventional ultrasound and contrast-enhanced ultrasound (CEUS) features were analyzed to explore their correlation with volume reduction ratios (VRRs) of sufficient ablation (i.e. a VRR of at least 50% at the 3 month follow-up). The patients were assessed at 1-, 3-, 6 month follow-up after MWA treatment and the assessment included VRR, adverse events, uterine fibroid symptom (UFS) and quality of life (QoL) scores, and clinical symptoms.

RESULTS

The procedures of percutaneous MWA for UFs were tolerated well and no major complications occurred in all patients. At the 1-, 3-, 6 month follow-up, the median VRRs of UFs were 30.1%, 46.9%, and 65.8%, respectively. At the 3 month follow-up, 44.4% of fibroids obtained sufficient ablation while the remaining 55.6% obtained partial ablation (i.e. a VRR of <50%). Non-enhancing area during the early phase (i.e. within 30 s after injecting contrast agent) on pre-treatment CEUS was present in 22.2% UFs, which was associated with sufficient ablation at the 3 month follow-up (p < 0.05). In addition, the relevant clinical symptoms of all patients were alleviated or removed. The UFS and QoL score after MWA decreased significantly in comparison with those after MWA (p = 0.04 and p = 0.057, respectively), indicating a remarkable improvement of clinical symptom and QoL.

CONCLUSION

Ultrasound-guided MWA is an effective and safe method to treat patients with UFs. Non-enhancing area during the early phase on pretreatment CEUS is associated with mid-term local treatment efficiency, which might be used to predict treatment outcome.

ADVANCES IN KNOWLEDGE

Non-enhancing area during the early phase on pretreatment CEUS is an important factor associated with mid-term local treatment efficiency. This is the first study finding that CEUS feature can be used as a marker for the prediction of mid-term local treatment response.

Ultrasound-guided HIFU for uterine fibroids of hyperintense on T2-weighted MR imaging with or without GnRH-analogue-pretreated: A propensity score matched cohort study

Objective

To compare the therapeutic effect of high-intensity focused ultrasound (HIFU) ablation and HIFU pretreated with gonadotropin-releasing hormone analogue (GnRH-a) in the treatment of hyperintense uterine fibroids on T2-weighted magnetic resonance imaging (T2WI) by using propensity score matching.

Materials and methods

339 women with 368 hyperintense uterine fibroids on T2WI who underwent single-session HIFU ablation were enrolled, including 283 patients with 303 fibroids in the single-session HIFU (sHIFU) group and 56 patients with 65 fibroids in the HIFU pretreated with GnRH-a (Gn-HIFU) group. The signal intensity (SI) value and standard deviation (SD) value were measured based on T2WI, and the fibroids were further subdivided into heterogeneous hyperintense fibroids, slightly homogeneous hyperintense fibroids and markedly homogeneous hyperintense fibroids as 3 subgroups (HHF, sHHF and mHHF group respectively). Treatment time, sonication time, dose, non-perfused volume (NPV), NPV per sonication time, non-perfused volume ratio (NPVR), energy effect ratio (EEF) and adverse events were recorded.

Results

Out of 339 patients, the median NPVR was 75.2% (interquartile range,31.5%). After propensity score matching, the matched cohort included 91 (64.5%) patients in the sHIFU group and 48 (34.5%) patients in the Gn-HIFU group. The NPVR of sHHF in the Gn-HIFU group had significantly smaller than that in the sHIFU group (60.2% versus 74.9%, p = 0.005), and the NPVR of HHF in the Gn-HIFU group was higher than those in the sHIFU group (87.4% versus 72.9%, p = 0.002).

Conclusions

Compared with HIFU alone, the therapeutic efficacy of the heterogeneous hyperintense fibroids may be enhanced by GnRH-a pretreated with HIFU, however it is important to rule out the slightly homogeneous hyperintense fibroids.

Tolerance and efficacy of HIFU ablation for uterine fibroids NPVR ≥ 90%: a nested case-control study

OBJECTIVE

To investigate the tolerance and efficacy of HIFU ablation for uterine fibroids with a non-perfused volume ratio (NPVR) ≥ 90%.

METHODS

A prospective cohort study of 2411 patients from 20 clinical centers was available. Contrast-enhanced MRI was used to assess the non-perfused volume ratio (NPVR). The International Society of Interventional Radiotherapy (SIR) complication grading system was used as the tolerance index. Uterine Fibroids-related Symptoms-Quality of Life (UFS-QoL) was used to evaluate the efficacy.

RESULTS

A total of 1352 patients underwent USgHIFU ablation treatment enrolled, NPVR was median 91.9% (IQR, 81.4%,100.0%). There was 761 case (56.3%) in the NPVR ≥ 90% group in which 17.5% case experienced SIR-B abdominal pain, 591 cases (43.7%) in NPVR < 90% group in which 9.3% case had SIR-B abdominal pain. There were statistically differences in the improvement degree of UFS at 12 months among the four subgroups (NPVR < 70%, 70%-80%, 80%-90%, 90%-100%) (all p < 0.05).

CONCLUSIONS

Patients with NPVR ≥ 90% had a higher incidence of SIR-B lower abdominal pain. NPVR was positively correlated with the degree of symptom relief at 12 months, and NPVR ≥ 90% was more likely to obtain better clinical symptom relief.

Increased MR-guided high intensity focused ultrasound (MR-HIFU) sonication efficiency of uterine fibroids after carbetocin administration

Purpose

We investigated whether administration of the long-acting uterus stimulant carbetocin increased intra-subject sonication efficiency during Magnetic Resonance image guided High Intensity Focused Ultrasound (MR-HIFU) treatment of uterine fibroids.

Method

In this prospective cohort study, thirty women with symptomatic uterine fibroids undergoing MR-HIFU treatment were included between January 2018 and January 2019. Treatment started with three sonications on one side of the uterine fibroid. Subsequently, one ampoule of 1 mL carbetocin (100 µg/mL) was administered intravenously and treatment continued with three sonications on the other side of the uterine fibroid. We compared the intra-subject sonication efficiency, in terms of Energy Efficiency Factor (EEF), thermal dose volume and sonication time to ablate one cm3 of fibroid tissue, before and after carbetocin administration. Adverse events that occurred within 30 min after carbetocin administration were recorded.

Results

Sonication efficiency improved after carbetocin administration as indicated by a significant decrease in EEF and sonication time (p = 0.006 and p = 0.001 respectively), and a significant increase in thermal dose volume reached (p = <0.001). Five women (16.7%) experienced temporary tachycardia, one women in combination with headache, within 30 min after carbetocin administration.

Conclusion

Administration of the long-acting uterus stimulant carbetocin improved the MR-HIFU treatment intra-subject sonication efficiency in women with symptomatic uterine fibroids.

The predictive value of conventional MRI combined with radiomics in the immediate ablation rate of HIFU treatment for uterine fibroids

OBJECTIVE

This study aimed to assess the predictive value of conventional magnetic resonance imaging (MRI) combined with radiomics in determining the nonperfused volume ratio (NPVR) following high-intensity focused ultrasound (HIFU) ablation for uterine fibroids.

METHODS AND MATERIALS

A total of 216 symptomatic uterine fibroids in 216 women were subjected to HIFU ablation from October 2015 to March 2020. Baseline clinical and MR parameters acquired before and after HIFU ablation were analyzed, and the NPVR was calculated accordingly. Radiomics features were extracted using A.K. software on T2-weighted imaging (T2WI). The minimum redundancy and maximum relevancy (mRMR) method were used to refine the selected radiomics features. Then, multiple linear regression models, the Wilcoxon signed-rank test, and Spearman's rank correlation and Bland-Altman analyses were conducted.

RESULTS

Conventional MRI combined with radiomics revealed the signal intensity on T2WI (X₉), enhancement degree on T1-weighted imaging (T1WI) (X₁₁), uterine fibroid location (X₄), wavelet_glszm_SizeZoneNonUniformity first order (X₁₂) and wavelet_HHH_firstorder_Skewness (X₁₃) negatively affected the NPVR. The resulting regression equation was NPVR = 104.030 - 11.886 × X₉ - 5.459 × X₁₁ - 2.776 × X₄ - 0.20 × X₁₂ - 16.913 × X₁₃. The adjusted R² values of the conventional MRI model and combined model were 0.385 and 0.408, respectively, and the two fitted models were statistically significant (p < 0.05). No significant differences were observed between the predicted NPVR value [81 (71, 91) %] of the combined model and the actual NPVR value [89 (77, 97) %] (p > 0.05). In addition, the predicted NPVR was correlated with the actual NPVR (r = 0.655, p < 0.001).

CONCLUSIONS

The efficiency of the combined model was better than that of the conventional MRI model in predicting the NPVR following HIFU ablation for uterine fibroids. Radiomics is an important supplemental modality to conventional MRI.

Physician Experience in Technical Success of Achieving NPVR ≥ 80% of High-Intensity Focused Ultrasound Ablation for Uterine Fibroids: A Multicenter Study

Objective

To evaluate the experience of the physician of the technical success in high-intensity focused ultrasound (HIFU) ablation of uterine fibroids with a nonperfused volume ratio (NPVR) of at least 80%.

Methods

Patients from a 20-center prospective study were enrolled in this study. In this study, among the 20 clinical centers, five centers had physician with >3 years of HIFU experience, and the other 15 centers initiated HIFU therapy <3 years, were defined as the experienced group and the inexperienced group, respectively. Technical success was defined as achieving NPVR ≥ 80% of uterine fibroids with no major complications and it was defined as the successful group; otherwise, it was defined as the unsuccessful group.

Results

A total of 1,352 patients were included at the age of 41.32 ± 5.08 years. The mean NPVR (87.48 ± 14.91%) was obtained in the inexperienced group (86.50 ± 15.76%) and in the experienced group (89.21 ± 13.12%), respectively. The multivariate analysis showed that the volume of uterus, location of fibroids, and physician experience were significantly correlated with technical success (p < 0.05). In the experienced group, 82.20% of uterine fibroids obtained NPVR ≥ 80%, compared with 75.32% in the inexperienced group, and the difference was significant (p = 0.003). The technical success rate of the experienced group was 82.00% which was higher than 75.20% of the inexperienced group (p = 0.004).

Conclusion

In technical success of achieving NPVR ≥ 80%, experience of the physician was positively correlated with technical success; NPVR and major complications for the inexperienced group were comparable to those of the experienced group from a clinical perspective; inexperienced physicians could reach NPVR ≥ 80% of sufficient ablation and were trustworthy in efficacy. Smaller uterus and fibroids of anterior wall were correlated with better technical success; experienced physicians still have better technical success when choosing patients with larger uterus, contributing to clinical decision-making and patient referral.

Comparison of two invasive non-surgical treatment options for uterine myomas: uterine artery embolization and magnetic resonance guided high intensity focused ultrasound-systematic review

BACKGROUND

Uterine Artery Embolization (UAE) and Magnetic Resonance guided High Intensity Focused Ultrasound (MRgHIFU) are two noninvasive treatments for uterine leiomyoma.

METHODS

This systematic review, following PRISMA guidelines, analyzed the effectiveness of two treatments by comparing percent fibroid volume shrinkage immediately after the procedure and after 3, 6, 12 and 24 months of follow-up and also assessed and compared common complications following treatment. The search utilized Science Direct, PubMed, MEDLINE, Google Scholar and BioMed Central databases, selecting manuscripts published during the period 2000 and 2020. Studies with premenopausal patients with previous treatments for uterine leiomyoma and/or with other pelvic diseases were excluded.

RESULTS

Twenty-nine papers satisfied inclusion and exclusion criteria. Results were pooled and stratified by treatment and follow-up time. Weighted fibroid volume percent shrinkage after UAE was statistically significantly greater than MRgHIFU at 6, 12, and 24 months follow-up times. However, UAE had statistically significantly more complications, such as pain, nausea and vomiting. However, this study cannot conclude that UAE is more effective than MRgHIFU due to confounding factors.

Comparison of Dose and Effectiveness of a Single-Session Ultrasound-Guided High-Intensity Focused Ultrasound Ablation of Uterine Fibroids With Different Sizes

PURPOSE

This study aimed to compare the dose and effectiveness of ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation of uterine fibroids with different sizes and explore the effect of uterine fibroid size on dose, which provided dose evaluation for clinicians in accordance with the size of uterine fibroids.

MATERIALS AND METHODS

A total of 1,000 patients with symptomatic uterine fibroids who received a single-session USgHIFU treatment were enrolled in this study. The size of fibroids was divided into seven groups: 3-4 cm, 4-5 cm, 5-6 cm, 6-7 cm, 7-8 cm, 8-9 cm, and 9-11 cm. The dose was expressed on the basis of the energy efficiency factor (EEF) as the energy required for ablation per unit volume of tissue, and the non-perfused volume ratio (NPVR) was used to assess the effect of HIFU ablation.

RESULTS

The median NPVR of 88.3% (IQR: 80.3%-94.8%) was obtained, and no significant difference was observed among the seven groups. The classification of T2-weighted image signal intensity fibroids in the 4-5 cm group was compared with that in the 6-7 cm and 8-9 cm groups, and the difference was significant (p < 0.05). However, the proportion of T2WI hyperintense signal fibroids had no significant difference among the seven groups (p > 0.05). The median EEF was 3.88 J/mm³, and a significant difference was observed among the seven groups of EEF (p < 0.05). The EEF of groups with a fibroid size less than 6 cm was more than double the EEF of groups with a fibroid size above 6 cm. In addition, the EEF of groups with a fibroid size of 4-5 cm and 3-4 cm was 3-4 times higher than those with a fibroid size above 7 cm (p < 0.05).

CONCLUSIONS

A single-session HIFU ablation for uterine fibroids of 3-11 cm can obtain an NPVR of more than 80%. The EEF decreased with the increase of the size of uterine fibroids. A fibroid size of 6.5 cm was considered as a clinical meaningful point affecting EEF.

Multidisciplinary management to optimize outcome of ultrasound-guided high-intensity focused ultrasound (HIFU) in patients with uterine fibroids

Little is known about the specific anaesthesiological and multidisciplinary management of high-intensity focused ultrasound (HIFU) in uterine fibroids. This observational single-center study is the first reporting on an interdisciplinary approach to optimize outcome following ultrasound (US)-guided HIFU in German-speaking countries. A sample of forty patients with symptomatic uterine fibroids was treated by HIFU. Relevant treatment parameters such as total treatment time for intervention, anaesthesia, and sonication time as well as total energy, body temperature, peri-interventional medication and complications were analyzed. Interventional variables did not correlate significantly either with opioid dose or with body temperature. The average fibroid volume reduction rate was 37.8% ± 23.5%, 48.5% ± 22.0% and 70.2% ± 25.5% after 3, 6 and 12 months, respectively. No major anaesthesiological complications occurred apart from an epileptic seizure prior to HIFU treatment in one patient. Peri-procedural hyperthermia (> 37.5 °C) occurred in two patients. Post-procedural two patients experienced a sciatic nerve irritation up to one year; one patient with very large treated fibroid experienced strong short-lasting post-procedural pain. There were two complication-free pregnancies of HIFU-treated patients. Multidisciplinary management is crucial to optimize safety and outcome of US-guided HIFU for uterine fibroids. Peri-procedural pain and temperature management are critical points where an adequate collaboration between anesthesiologist and interventionalist is mandatory.

A feasibility analysis of the ArcBlate MR-guided high-intensity focused ultrasound system for the ablation of uterine fibroids

Purpose

Uterine fibroids are benign gynecologic tumors and commonly occur in women by the age of 50. Women with symptomatic uterine fibroids generally receive surgical intervention, while they do not favor the invasive therapies. To evaluate the feasibility and safety of a novel magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) modality, ArcBlate, in the treatment of uterine fibroids.

Methods

Nine patients with uterine fibroids and one patient with adenomyosis were treated with ArcBlate MRgHIFU. Tumor size and quality of life were evaluated postoperatively at 1 and 3 months by magnetic resonance imaging (MRI) and the 36-Item Short Form Survey (SF-36), respectively.

Results

All patients completed the ArcBlate MRgHIFU procedure and there were no treatment-related adverse effects either during the procedure or during the 3 months of follow-up. Despite limiting the ablation volume to under 50% of the treated fibroid volume as a safety precaution, tumor volumes were markedly reduced in four patients by 15.78–58.87% at 3-month post-treatment. Moreover, SF-36 scale scores had improved at 3 months from baseline by 2–8 points in six patients, indicating relief of symptoms and improved quality of life.

Conclusion

This study evidence demonstrates the safety and feasibility of ArcBlate MRgHIFU and suggests its potential for treating uterine fibroids.

Comparison of Clinical Performance Between Two Generations of Magnetic Resonance-guided Focused Ultrasound Systems in Treatments of Uterine Leiomyomas

OBJECTIVES

The aim of this study was to evaluate the impact of technology improvements on the outcomes of magnetic resonance-guided focused ultrasound (MRgFUS) treatments of symptomatic uterine leiomyomas (uterine fibroids). The study compared ablation volumes and incidence of adverse events in patient groups treated with two generations of MRgFUS systems from a single vendor.

METHODS

The present study describes the results of a retrospective comparative study of two groups of women with symptomatic uterine leiomyomas who were clinically treated with MRgFUS at a single institution. Group 1 (n = 130) was treated using the first-generation system between March 2005 and December 2009. Group 2 (n = 71) was treated using the second-generation between December 2013 and September 2019.

RESULTS

The second-generation MRgFUS system resulted in significantly improved nonperfused volume ratios in both dark and bright T2 fibroid categories compared with the first-generation system (dark - 80% versus46 %, p = 0.00002 and bright - 46% versus 32%, p = 0.001). There have been no recorded hospital admissions, no skins burns, and no reported major adverse events since the introduction of this second-generation ExAblate 2100 system with advanced safety and treatment planning features.

CONCLUSION

This study has demonstrated that improvements to current MRgFUS technology resulted in significantly increased efficacy and patient safety of clinical treatments of patients with symptomatic uterine leiomyomas.

Nonenhanced MRI-based radiomics model for preoperative prediction of nonperfused volume ratio for high-intensity focused ultrasound ablation of uterine leiomyomas

OBJECTIVES

To develop and assess nonenhanced MRI-based radiomics model for the preoperative prediction of nonperfused volume (NPV) ratio of uterine leiomyomas after high-intensity focused ultrasound (HIFU) treatment.

METHODS

Two hundred and five patients with uterine leiomyomas treated by HIFU were enrolled and allocated to training (N =164) and testing cohorts (N = 41). Pyradiomics was used to extract radiomics features from T2-weighted images and apparent diffusion coefficient (ADC) map generated from diffusion-weighted imaging (DWI). The clinico-radiological model, radiomics model, and radiomics-clinical model which combined the selected radiomics features and clinical parameters were used to predict technical outcomes determined by NPV ratios where three classification groups were created (NPV ratio ≤ 50%, 50-80% or ≥ 80%). The receiver operating characteristic (ROC) curve, area under the curve (AUC), and calibration and decision curve analyses were performed to illustrate the prediction performance and clinical usefulness of model in the training and testing cohorts.

RESULTS

The multi-parametric MRI-based radiomics model outperformed T2-weighted imaging (T2WI)-based radiomics model, which achieved an average AUC of 0.769 (95% confidence interval [CI], 0.701-0.842), and showed satisfactory prediction performance for NPV ratio classification. The radiomics-clinical model demonstrated best prediction performance for HIFU treatment outcome, with an average AUC of 0.802 (95% CI, 0.796-0.850) and an accuracy of 0.762 (95% CI, 0.698-0.815) in the testing cohort, compared to the clinico-radiological and radiomics models. The decision curve also indicated favorable clinical usefulness of the radiomics-clinical model.

CONCLUSIONS

Nonenhanced MRI-based radiomics has potential in the preoperative prediction of NPV ratio for HIFU ablation of uterine leiomyomas.

Efficacy of ultrasound-guided high-intensity focused ultrasound (USgHIFU) for uterine fibroids: an observational single-center study

INTRODUCTION

To evaluate treatment response of uterine fibroids after ultrasound guided high-intensity focused ultrasound (USgHIFU) with a special focus on fibroid size and characterization based on Funaki classification scheme, as well as clinical response to treatment of leading fibroid-associated symptoms.

MATERIALS AND METHODS

Uterine fibroids treated by USgHIFU were assigned to Funaki type 1-3 based on T2-w-MRI. Differences in size, non-perfused volume ratio (NPVR) and volume reduction over time were determined using T1-/T2-w MRI sequences and contrast-enhanced sonography. Treatment effects on three leading fibroid-associated symptoms were also evaluated. Measurements were compared by mixed model, Bland-Altman's plot and Spearman's correlation.

RESULTS

In this prospective single-center study, 35 patients with 44 symptomatic uterine fibroids were treated by USgHIFU (n = 22, n = 12 and n = 10 assigned to Funaki type 1, 2 and 3, respectively). NPVRs of Funaki type 1 and 2 fibroids were significantly higher compared to type 3 (p = .0023). A significant fibroid shrinkage was observed independent of Funaki type compared to baseline: 38.8 ± 26.9%, 46.7 ± 30.3% and 54.5 ± 29.3% at 3, 6 and 12 months, respectively (each p < .05). Moreover, patients experienced a significant improvement of fibroid-associated hypermenorrhea (3.9 ± 1.3 vs. 2.3 ± 1.3), pressure in the pelvic area (3.5 ± 1.3 vs. 2.1 ± 0.9) and frequent urination (2.8 ± 1.5 vs. 1.9 ± 0.8) one year post-procedure (each p < .05), regardless of fibroid Funaki type.

CONCLUSION

Following USgHIFU, a significant shrinkage of uterine fibroids and improvement of leading fibroid-associated symptoms were demonstrated regardless of the Funaki type.

High-intensity focused ultrasound (HIFU) ablation versus surgical interventions for the treatment of symptomatic uterine fibroids: a meta-analysis

OBJECTIVES

To compare the treatment success and safety of ultrasound- and MR-guided high-intensity focused ultrasound (HIFU) with surgery for treating symptomatic uterine fibroids.

METHODS

We searched studies comparing HIFU with surgery for fibroids in different databases from January 2000 to July 2020. The mean difference (MD) or relative risk (RR) with 95% confidence interval (CI) for different outcome parameters was synthesized.

RESULTS

We included 10 studies involving 4450 women. Compared with the surgery group, the decrease in uterine fibroid severity score at 6- and 12-month follow-up was higher in the HIFU group (MD - 4.16, 95% CI - 7.39 to - 0.94, and MD - 2.44, 95% CI - 3.67 to - 1.20, p < 0.05). The increase in quality-of-life (QoL) score at 6- and 12-month follow-up was higher in the HIFU group (MD 2.13, 95% CI 0.86 to 3.14, and MD 2.34, 95% CI 0.82 to 3.85, p < 0.05). The duration of hospital stay and the time to return to work was shorter in the HIFU group (MD - 3.41 days, 95% CI - 5.11 to - 1.70, and MD - 11.61 days, 95% CI - 19.73 to - 3.50, p < 0.05). The incidence of significant complications was lower in the HIFU group (RR 0.33, 95% CI 0.13 to 0.81, p < 0.05). The differences in the outcomes of adverse events, symptom recurrence, re-intervention, and pregnancy were not statistically significant (p > 0.05).

CONCLUSIONS

HIFU is superior to surgery in terms of symptomatic relief, improvement in QoL, recovery, and significant complications. However, HIFU showed comparable effects to surgery regarding the incidence of adverse events, symptom recurrence, re-intervention, and pregnancy.

KEY POINTS

• HIFU ablation is superior to surgery in terms of symptomatic relief, improvement in QoL, recovery, and significant complications. • HIFU has comparable effects to surgery in terms of symptom recurrence rate, re-intervention rate, and pregnancy rate, indicating that HIFU is a promising non-invasive therapy that seems not to raise the risk of recurrence and re-intervention or deteriorate fertility compared to surgical approaches in women with fibroids. • There is still a lack of good-quality comparative data and further randomized studies are necessary to provide sufficient and reliable data, especially on re-intervention rate and pregnancy outcome.

Oxytocin selectively reduces blood flow in uterine fibroids without an effect on myometrial blood flow: a dynamic contrast enhanced MRI evaluation

INTRODUCTION

Uterine fibroids are the most common benign neoplasms in women. The administration of intravenous oxytocin is known to increase the efficacy of a non-invasive thermal ablation method (MR-HIFU) for treating fibroids. However, it is not known whether this phenomenon is caused by the effect of the oxytocin on the myometrium or the fibroid itself. The objective of this study was to evaluate the influence of oxytocin on the blood flow of fibroids, myometrium and skeletal muscle using a quantitative perfusion MRI technique.

MATERIALS AND METHODS

17 premenopausal women with fibroids considered to be treated with MR-HIFU and 11 women with no fibroids were enrolled in the study. An extended MRI protocol of the pelvis was acquired for each subject. Later another MRI scan was performed with continuous intravenous infusion of oxytocin. The effect of oxytocin was analyzed from quantitative perfusion imaging. The study was registered in clinicaltrials.gov NCT03937401.

RESULTS

Oxytocin decreased the blood flow of each fibroid; the median blood flow of fibroid was 39.9 ml/100 g tissue/min without and 3.5 mL/100 g/min with oxytocin (p ≤ 0.0001). Oxytocin did not affect the blood flow of the myometrium in either group. Oxytocin increased the blood flow of the skeletal muscle in both groups (p = 0.04).

CONCLUSION

Oxytocin is effective in decreasing the blood flow in fibroids while having minor or no effect on the blood flow of normal myometrium. Routine use of oxytocin in HIFU therapy may make the therapy suitable to a larger group of women in a safe manner.

A Prediction of NPVR ≥ 80% of Ultrasound-Guided High-Intensity Focused Ultrasound Ablation for Uterine Fibroids

Objective: To evaluate factors in predicting the treatment outcome of ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation for uterine fibroids with a non-perfused volume ratio (NPVR) of at least 80%.

Methods: One thousand patients with uterine fibroids who received USgHIFU were enrolled. Thirty-two independent variables of four dimensions of data set, including general information of patients, clinical symptoms, laboratory tests, and fibroid imaging characteristics, were used to investigate the potential predictors of the NPVR of at least 80% by multivariate logistic regression. NPVR was the gold standard for evaluating the efficiency of HIFU ablation, and a NPVR of at least 80% was considered sufficient ablation, while partial ablation was defined as having an NPVR of <80%.

Results: Out of 1,000 fibroids, 758 obtained sufficient ablation and 242 obtained partial ablation, and the median NPVR was 88.3% (interquartile range: 80.3–94.8%). The probability of NPVR reaching 80% fibroids with a signal intensity of T2WI of hypointense, isointense, and hyperintense was 86.4, 76.5, and 62.6%, respectively; fibroids with an enhancement type of T1WI of slight, irregular, and regular was 81.5, 73.6, and 63.7%, respectively; and fibroids with uterine anteroposterior of 30–130 mm was 57.7–78.3%, respectively. In patients with a platelet count of 50 × 10⁹/L−550 × 10⁹/L, the probability of NPVR reaching 80% is from 53.4 to 80.1%, respectively.

Conclusions: In predicting NPVR ≥ 80%, the signal intensity on T2WI was the most important factor affecting ablative efficiency, followed by enhancement type on T1WI, uterine anteroposterior, and platelet count.

Volumetric MRI-guided, high-intensity focused ultrasound ablation of uterine leiomyomas: ASEAN preliminary experience

PURPOSE

We sought to present our preliminary experience on the effectiveness and safety of magnetic resonance imaging (MRI)-guided, high-intensity focused ultrasound (HIFU) therapy using a volumetric ablation technique in the treatment of Association of Asian Nations (ASEAN) patients with symptomatic uterine leiomyomas.

METHODS

This study included 33 women who underwent HIFU treatment. Tissue characteristics of leiomyomas were assessed based on T2- and T1-weighted MRI. The immediate nonperfused volume (NPV) ratio and the treatment effectiveness of MRI-guided HIFU on the basis of the degrees of volume reduction and improvement in transformed symptom severity score (SSS) were assessed.

RESULTS

The median immediate NPV ratio was 89.8%. Additionally, the median acoustic sonication power and HIFU treatment durations were 150 W and 125 min, respectively. At six-month follow-up, the median leiomyoma volume had decreased from 139 mL at baseline to 84 mL and the median transformed SSS had decreased from 56.2 at baseline to 18.8. No major adverse events were observed.

CONCLUSION

The preliminary results demonstrated that volumetric MRI-guided HIFU therapy for the treatment of symptomatic leiomyomas in ASEAN patients appears to be clinically acceptable with regard to treatment effectiveness and safety.

High-intensity focused ultrasound for treatment of recurrent uterine leiomyosarcoma: a case report and literature review

Uterine leiomyosarcoma has the characteristics of high malignancy, a poor prognosis, and a high recurrence rate. Surgery is the main treatment option, supplemented by chemotherapy and radiotherapy. We report on a patient with recurrent uterine leiomyosarcoma who was treated with high-intensity focused ultrasound combined with chemotherapy. Tumor growth was controlled and the patient's survival time was prolonged. High-intensity focused ultrasound combined with chemotherapy may thus provide a new treatment strategy for patients with recurrent and surgically difficult uterine leiomyosarcoma.

Uterine Myomas: Extravascular Treatment

Uterine fibroids are common benign tumors that affect the female reproductive tract. They are responsible for considerable morbidity and deterioration of life quality. The main advantages offered by mini invasive techniques are low grade of invasiveness and short times of hospitalization. The most diffuse technique is uterine artery embolization (UAE). Common concerns with UAE include postprocedural pain, postembolization syndrome, and risk of infection. Image-guided thermal ablation techniques like radiofrequency ablation, percutaneous microwave ablation, and imaging-guided high-intensity focused ultrasound were introduced to overcome the side effects related to UAE and surgery. The aim of this review is to briefly analyze the ablative procedures and their role in the management of symptomatic fibroids, and to describe the safety profile and outcomes of these modalities.

The role of magnetic resonance-guided focused ultrasound in fertility-sparing treatment of uterine fibroids-current perspectives

Uterine fibroids (UFs) are the most common benign tumours of the female reproductive system and the most frequent reason for hysterectomy worldwide. UFs are reported in 20%–70% of women of reproductive age depending on a study group. Although most women with UFs are asymptomatic, over 30% of them will present with different symptoms. Abnormal uterine bleeding, pain, pressure and infertility are the most common. Lesions that cause these kinds of symptoms may require medical intervention.

Trends in UF treatment change along with patient awareness and the introduction of new methods and techniques. Selecting an appropriate treatment option should be individualised and adjusted to the patient’s expectations as much as possible. This choice will mostly depend on the patient’s age, UF location, the size and number of lesions, severity of symptoms and, most importantly, the patient’s expectations concerning the preservation of fertility. Observations made for the past few years showed an increasing number of pre- and perimenopausal women who wish to preserve their uterus or decline surgery. In line with current trends and demands in medicine, great importance is attached to the development and upgrade of new minimally invasive or noninvasive procedures in UF therapy.

Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is not associated with severe destruction of the uterine cavity and walls. For this reason, this method may be considered as a kind of hope in fertility-sparing UF therapy and the data about its use in this indication raises future hope. In this review, we summarise the available data on the use of MR-HIFU as a fertility-sparing method in the treatment of UFs. We also indicate how it could evolve in the future.

According to the available data, MR-HIFU is a relatively safe noninvasive method which seems not to deteriorate fertility compared to the pre-treatment status. MR-HIFU may constitute an alternative solution and be chosen in patients who meet the qualification criteria and deny other methods, which also facilitates the use of other treatment options in case the procedure is ineffective. Further randomised studies are necessary to confirm the above information.

The Focused Ultrasound Myoma Outcome Study (FUMOS); a retrospective cohort study on long-term outcomes of MR-HIFU therapy

OBJECTIVES

Since 2004, uterine fibroids have been treated with MR-HIFU, but there are persevering doubts on long-term efficacy to date. In the Focused Ultrasound Myoma Outcome Study (FUMOS), we evaluated long-term outcomes after MR-HIFU therapy, primarily to assess the reintervention rate.

METHODS

Data was retrospectively collected from 123 patients treated with MR-HIFU at our hospital from 2010 to 2017. Follow-up duration and baseline (MRI) characteristics were retrieved from medical records. Treatment failures, adverse events, and the nonperfused volume percentage (NPV%) were determined. Patients received a questionnaire about reinterventions, recovery time, satisfaction, and pregnancy outcomes. Restrictive treatment protocols were compared with unrestrictive (aiming for complete ablation) treatments. Subgroups were analyzed based on the achieved NPV < 50 or ≥ 50%.

RESULTS

Treatment failures occurred in 12.1% and the number of adverse events was 13.7%. Implementation of an unrestrictive treatment protocol significantly (p = 0.006) increased the mean NPV% from 37.4% [24.3-53.0] to 57.4% [33.5-76.5]. At 63.5 ± 29.0 months follow-up, the overall reintervention rate was 33.3% (n = 87). All reinterventions were performed within 34 months follow-up, but within 21 months in the unrestrictive group. The reintervention rate significantly (p = 0.002) decreased from 48.8% in the restrictive group (n = 43; follow-up 87.5 ± 7.3 months) to 18.2% in the unrestrictive group (n = 44; follow-up 40.0 ± 22.1 months). The median recovery time was 2.0 [1.0-7.0] days. Treatment satisfaction rate was 72.4% and 4/11 women completed family planning after MR-HIFU.

CONCLUSIONS

The unrestrictive treatment protocol significantly increased the NPV%. Unrestrictive MR-HIFU treatments led to acceptable reintervention rates comparable to other reimbursed uterine-sparing treatments, and no reinterventions were reported beyond 21 months follow-up.

KEY POINTS

• All reinterventions were performed within 34 months follow-up, but in the unrestrictive treatment protocol group, no reinterventions were reported beyond 21 months follow-up. • The NPV% was negatively associated with the risk of reintervention; thus, operators should aim for complete ablation during MR-guided HIFU therapy of uterine fibroids. • Unrestrictive treatments have led to acceptable reintervention rates after MR-guided HIFU therapy compared to other reimbursed uterine-sparing treatments.

Magnetic Resonance-Guided Focused Ultrasound Surgery for Leiomyoma and Adenomyosis: An Alternative Nonvascular Approach

Magnetic resonance-guided high-intensity focused ultrasound (MRgFUS) surgery is a promisingly alternative method for the treatment of symptomatic leiomyoma and adenomyosis. In this article, we mainly aim to introduce two totally typical patients with leiomyoma and adenomyosis who underwent MRgFUS surgery successfully without any severe complications at our interventional radiology center. Our results revealed that focused ultrasound surgery is an innovatively safe and nonvascular approach which should be taken into consideration for the treatment of patients with symptomatic leiomyoma and adenomyosis.

Emerging clinical applications of high-intensity focused ultrasound

High-intensity focused ultrasound (HIFU) is a minimally-invasive and non-ionizing promising technology and has been assessed for its role in the treatment of not only primary tumors but also metastatic lesions under the guidance of ultrasound or magnetic resonance imaging. Its performance is notably effective in neurologic, genitourinary, hepato-pancreato-biliary, musculoskeletal, oncologic, and other miscellaneous applications. In this article, we reviewed the emerging technology of HIFU and its clinical applications.

Comprehensive feature selection for classifying the treatment outcome of high-intensity ultrasound therapy in uterine fibroids

The study aim was to utilise multiple feature selection methods in order to select the most important parameters from clinical patient data for high-intensity focused ultrasound (HIFU) treatment outcome classification in uterine fibroids. The study was retrospective using patient data from 66 HIFU treatments with 89 uterine fibroids. A total of 39 features were extracted from the patient data and 14 different filter-based feature selection methods were used to select the most informative features. The selected features were then used in a support vector classification (SVC) model to evaluate the performance of these parameters in predicting HIFU therapy outcome. The therapy outcome was defined as non-perfused volume (NPV) ratio in three classes: <30%, 30–80% or >80%. The ten most highly ranked features in order were: fibroid diameter, subcutaneous fat thickness, fibroid volume, fibroid distance, Funaki type I, fundus location, gravidity, Funaki type III, submucosal fibroid type and urinary symptoms. The maximum F1-micro classification score was 0.63 using the top ten features from Mutual Information Maximisation (MIM) and Joint Mutual Information (JMI) feature selection methods. Classification performance of HIFU therapy outcome prediction in uterine fibroids is highly dependent on the chosen feature set which should be determined prior using different classifiers.

MR guided high intensity focused ultrasound (MRgHIFU) for treating recurrent gynaecological tumours: a pilot feasibility study

OBJECTIVE

To assess the feasibility of targeting recurrent gynaecological tumours with MR guided high intensity focused ultrasound (MRgHIFU).

METHODS

20 patients with recurrent gynaecological tumours were prospectively scanned on a Philips/Profound 3 T Achieva MR/ Sonalleve HIFU system. Gross tumour volume (GTV) and planning target volume (PTV) were delineated on T 2W and diffusion-weighted imaging (DWI). Achievable treatment volumes that (i) assumed bowel and/or urogenital tract preparation could be used to reduce risk of damage to organs-at-risk (TVoptimal), or (ii) assumed no preparations were possible (TVno-prep) were compared with PTV on virtual treatment plans. Patients were considered treatable if TVoptimal ≥ 50 % PTV.

RESULTS

11/20 patients (55%) were treatable if preparation strategies were used: nine had central pelvic recurrences, two had tumours in metastatic locations. Treatable volume ranged from 3.4 to 90.3 ml, representing 70 ± 17 % of PTVs. Without preparation, 6/20 (30%) patients were treatable (four central recurrences, two metastatic lesions). Limiting factors were disease beyond reach of the HIFU transducer, and bone obstructing tumour access. DWI assisted tumour outlining, but differences from T 2W imaging in GTV size (16.9 ± 23.0%) and PTV location (3.8 ± 2.8 mm in phase-encode direction) limited its use for treatment planning.

CONCLUSIONS

Despite variation in size and location within the pelvis, ≥ 50 % of tumour volumes were considered targetable in 55 % patients while avoiding adjacent critical structures. A prospective treatment study will assess safety and symptom relief in a second patient cohort.

ADVANCES IN KNOWLEDGE

Target size, location and access make MRgHIFU a viable treatment modality for treating symptomatic recurrent gynaecological tumours within the pelvis.

Review of influential clinical factors in reducing the risk of unsuccessful MRI-guided HIFU treatment outcome of uterine fibroids

Magnetic resonance imaging-guided high-intensity focused ultrasound (MRI-guided HIFU) is an effective noninvasive treatment option for symptomatic uterine fibroids. However, tissue characteristics of uterine fibroids and technical limitations can limit the patient population that can benefit from this therapy. In this article, we present our literature review focusing on the influential clinical factors that might reduce the risk of an unsuccessful MRI-guided HIFU treatment outcome of uterine fibroids.