Magnetic resonance-guided focused ultrasound surgery (MRgFUS) treatment for uterine fibroids

Advanced software for MRgFUS treatment planning

BACKGROUND AND OBJECTIVES

Herein, a user-friendly software platform for 3-dimensional Focused Ultrasound treatment planning based on Magnetic Resonance Imaging (MRI) images is presented.

METHODS

The software directly retrieves and loads MRI images. Various design tools can be used on the MRI images to define the treatment area and the sonication parameters. Based on the treatment plan, the software controls the robotic motion and motion pattern of Magnetic Resonance guided Focused Ultrasound (MRgFUS) robotic systems to execute the treatment procedure. Real-time treatment monitoring is achieved through MRI images and thermometry. The software's functionality and performance were evaluated in both laboratory and MRI environments. Different treatment plans were designed on MRI images and sonications were executed on agar-based phantoms and polymer films.

RESULTS

Magnetic Resonance (MR) thermometry maps were acquired in the agar-based phantoms. An exceptional agreement was observed between the software-planned treatment area and the lesions produced on the polymer films.

CONCLUSIONS

The developed software was successfully integrated with the MRI and robotic system controls for performing accurate treatment planning and real-time monitoring during sonications. The software provides an extremely user-friendly interface, while in the future it could be enhanced by providing dynamic modulation of the ultrasonic parameters during the treatment process.

Military Contributions to the Field of Medical Ultrasound

Medical ultrasound is based on the same principle of the piezoelectric effect as sound navigation and ranging, used by the world's navies and maritime industry. Many of the early advances in sound navigation and ranging technology influenced landmark discoveries in diagnostic ultrasound made by military officers and defense department researchers.

Minimally Invasive Interventional Procedures for Metastatic Bone Disease: A Comprehensive Review

Metastases are the main type of malignancy involving bone, which is the third most frequent site of metastatic carcinoma, after lung and liver. Skeletal-related events such as intractable pain, spinal cord compression, and pathologic fractures pose a serious burden on patients’ quality of life. For this reason, mini-invasive treatments for the management of bone metastases were developed with the goal of pain relief and functional status improvement. These techniques include embolization, thermal ablation, electrochemotherapy, cementoplasty, and MRI-guided high-intensity focused ultrasound. In order to achieve durable pain palliation and disease control, mini-invasive procedures are combined with chemotherapy, radiation therapy, surgery, or analgesics. The purpose of this review is to summarize the recently published literature regarding interventional radiology procedures in the treatment of cancer patients with bone metastases, focusing on the efficacy, complications, local disease control and recurrence rate.

MRI guided focused ultrasound (MRgFUS) treatment for uterine fibroids among women with and without abdominal scars

INTRODUCTION

MRI guided focused ultrasound (MRgFUS) is a noninvasive technique for treating uterine fibroids. The presence of abdominal scars can limit the number of women eligible for the procedure, due to absorbance of beam energy. The goals of this study were to assess the number of women that fit the procedure and to compare outcomes among women with or without abdominal scars.

MATERIAL AND METHODS

A prospective cohort study of all women that were interested in MRgFUS in a single University-Affiliated Hospital between November 2012 and December 2019. Rates of women that were referred to further screening, fulfilled selection criteria and underwent the procedure were compared between patients with or without abdominal scars. We evaluated the treatment parameters of the two groups and used linear regression model predict non-perfused volume (NPV) at the end of the process.

RESULTS

Out of 701 patients, 21.8% were suitable for MRgFUS. Women with scars had significant lower NPV compared with women without scars (60% versus 82.4%, p = 0.021). No serious adverse events were reported in both groups. Linear regression models showed that fibroids' volume, stopping the treatment due to severe pain and the presence of abdominal scars had a statistically significantly negative effect on NPV (betas: -11.51, -6.96, and -6.29, p-values: <0.001, 0.003, and 0.007 respectively), while number of sonication had a statistically significantly positive effect on NPV (beta = 5.98, p = 0.011).

CONCLUSION

Regardless of strict inclusion criteria, MRgFUS treatment is less efficient among women with abdominal scars, although still feasible for those who are interested in noninvasive option.

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.

MRI-based pictorial review of the FIGO classification system for uterine fibroids

Uterine fibroids are the most common gynecologic neoplasm and contribute to significant morbidity, particularly when submucosal in location or large enough to cause bulk symptoms. Correctly classifying fibroids is essential for treatment planning and prevention of complications. Ultrasound is the first-line imaging modality for characterizing uterine fibroids. However, MRI allows for high-resolution, multiplanar visualization of leiomyomata that affords a more accurate assessment than ultrasound, particularly when fibroids are numerous. The FIGO system was developed in order to more uniformly and consistently describe and classify uterine fibroids. In this article, we review the MRI appearance of each of the FIGO classification types, detailing key features to report. Additionally, we present a proposed template for structured reporting of uterine fibroids based on the FIGO classification system.

Improved PRF-based MR thermometry using k-space energy spectrum analysis

PURPOSE

Proton resonance frequency (PRF) thermometry encodes information in the phase of MRI signals. A multiplicative factor converts phase changes into temperature changes, and this factor includes the TE. However, phase variations caused by B₀ and/or B₁ inhomogeneities can effectively change TE in ways that vary from pixel to pixel. This work presents how spatial phase variations affect temperature maps and how to correct for corresponding errors.

METHODS

A method called "k-space energy spectrum analysis" was used to map regions in the object domain to regions in the k-space domain. Focused ultrasound heating experiments were performed in tissue-mimicking gel phantoms under two scenarios: with and without proper shimming. The second scenario, with deliberately de-adjusted shimming, was meant to emulate B₀ inhomogeneities in a controlled manner. The TE errors were mapped and compensated for using k-space energy spectrum analysis, and corrected results were compared with reference results. Furthermore, a volunteer was recruited to help evaluate the magnitude of the errors being corrected.

RESULTS

The in vivo abdominal results showed that the TE and heating errors being corrected can readily exceed 10%. In phantom results, a linear regression between reference and corrected temperatures results provided a slope of 0.971 and R² of 0.9964. Analysis based on the Bland-Altman method provided a bias of -0.0977°C and 95% limits of agreement that were 0.75°C apart.

CONCLUSION

Spatially varying TE errors, such as caused by B₀ and/or B₁ inhomogeneities, can be detected and corrected using the k-space energy spectrum analysis method, for increased accuracy in proton resonance frequency thermometry.

Long-term outcome of MR-guided focused ultrasound treatment and laparoscopic myomectomy for symptomatic uterine fibroid tumors

BACKGROUND

Fibroid tumors are the most common benign tumors in women of reproductive age. Treatment is usually indicated for those who are symptomatic, with different techniques being used.

OBJECTIVE

The purpose of this study was to compare the long-term outcome of laparoscopic myomectomy with magnetic resonance-guided focused ultrasound for symptomatic uterine fibroid tumors.

STUDY DESIGN

A cohort study was conducted on all patients with symptomatic uterine fibroid tumors who were admitted to a single tertiary care center and treated operatively with laparoscopic myomectomy or treated conservatively with magnetic resonance-guided focused ultrasound from January 2012 until January 2017. Assessment for further interventions and sustained fibroid-associated symptoms was performed, with the use of the Uterine Fibroid Symptom and Quality of Life symptom severity score.

RESULTS

One hundred fifty-four women met the inclusion criteria. Complete follow-up evaluation was achieved for 64 women who underwent laparoscopic myomectomy and for 68 women who were treated by magnetic resonance-guided focused ultrasound. Follow-up time was similar for the 2 groups (median, 31 months [interquartile range, 17-51 months] vs 36 months [interquartile range, 24-41]; P=.95). The rate of additional interventions was 5 (7.8%) and 9 (13.2%), respectively (P=0.312). Similarly, the Uterine Fibroid Symptom and Quality of Life symptom severity score questionnaire score at follow-up interviews revealed comparable median scores of 17 (interquartile range, 12-21) vs 17 (interquartile range, 13-22) for laparoscopic myomectomy and magnetic resonance-guided focused ultrasound, respectively (P=.439). Analysis of each of the symptoms separately (bleeding, changes in menstruation, abdominal pain, bladder activity, nocturia, fatigue) did not change these findings, nor did a multivariate analysis.

CONCLUSION

Satisfaction with long-term outcome and rate of reinterventions after magnetic resonance-guided focused ultrasound treatment or laparoscopic myomectomy for uterine fibroid tumors was comparable. Further larger randomized trials are needed to confirm these findings.

Alternatives to hysterectomy: The burden of fibroids and the quality of life

Uterine fibroids are the most common benign tumor in reproductive-aged women. While the majority of women are asymptomatic, those with symptoms may suffer from abnormal uterine bleeding, infertility, pelvic pain or pressure, and urinary dysfunction. Fibroids represent a significant healthcare burden for women and society as a whole. Women with fibroids have compromised overall quality of life and impairment in many specific domains including work productivity, sexuality, self-image, relationships, and social emotional and physical well-being. Many women are reluctant to ask for help and delay seeking treatment. To date, myomectomy remains the gold standard for treating fibroid-related symptoms in reproductive-aged women. However, many less invasive uterine preserving approaches have been developed. Quality of life is improved in many women following treatment for fibroids. This article aims to provide an overview of the substantial impact of fibroids on health-related quality of life.

MRI-guided coupling for a focused ultrasound system using a top-to-bottom propagation

Background

A novel magnetic resonance imaging (MRI)-conditional coupling system was developed that accommodates a focused ultrasound (FUS) transducer. With this coupling system, the transducer can access targets from top to bottom. The intended clinical application is treatment of fibroids using FUS with the patient placed in supine position.

Methods

The coupling system was manufactured using a rapid prototyping device using acrylonitrile butadiene styrene (ABS) plastic. Coupling to a gel phantom was achieved using a water bag filled with degassed water. The FUS transducer was immersed in the water bag.

Results

The coupling system was successfully tested for MRI compatibility using fast-gradient pulse sequences in a gel phantom. The robotic system with its new coupling system was evaluated for its functionality for creating discrete and multiple (overlapping) lesions in the gel phantom.

Conclusions

An MRI-conditional FUS coupling system integrated with an existing robotic system was developed that has the potential to create thermal lesions in targets using a top-to-bottom approach. This system has the potential to treat fibroid tumors with the patient lying in supine position.

Magnetic nanoparticles as a new approach to improve the efficacy of gene therapy against differentiated human uterine fibroid cells and tumor-initiating stem cells

OBJECTIVE

To study whether efficient transduction and subsequent elimination of fibroid tumor-initiating stem cells during debulking of tumor cells will aid in completely eradicating the tumor as well as decreasing the likelihood of recurrence.

DESIGN

Case control study.

SETTING

Research laboratory.

PATIENT(S)

None.

INTERVENTION(S)

Magnetic nanoparticles (MNPs) complexed to adenovirus (Ad-GFP) or (Ad-LacZ) used to transfect differentiated human fibroid cells in vitro.

MAIN OUTCOME MEASURE(S)

Rate of transduction and tumor growth inhibition.

RESULT(S)

We have developed a localized nonsurgical adenovirus-based alternative for the treatment of uterine fibroids that combines viral-based gene delivery with nanotechnology for more efficient targeting. Magnetic nanoparticles complexed to adenovirus, in the presence of an external magnetic field, accelerate adenovirus transduction. We observed a statistically significant increase in transduction efficiency among differentiated human fibroid cells at two different multiplicities of infection (MOI), 1 and 10, respectively, with MNPs as compared with adenovirus alone. Human fibroid stem cells transfected with Ad-LacZ expressed β-galactosidaze at a MOI of 1, 10, and 50 at 19%, 62%, and 90%, respectively, which were statistically significantly enhanced with MNPs.

CONCLUSION(S)

When applied with adenovirus herpes simplex thymidine kinase, magnetofection statistically significantly suppressed proliferation and induced apoptosis in both cell types. Through the use of magnetofection, we will prove that a lower viral dose will effectively increase the overall safety profile of suicide gene therapy against fibroid tumors.

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.

Fertility and Pregnancy Outcome after Myoma Enucleation by Minilaparotomy under Microsurgical Conditions in Pronounced Uterus Myomatosus

Introduction: Besides the typical complaints and symptoms, myomas can cause sterility, infertility and complications during pregnancy. Laparoscopic interventions reach their limits with regard to organ preservation and the simultaneous desire to have children in the removal of multiple and larger intramural myoma nodes. The aim of this study is to examine fertility status and pregnancy outcome after myoma removal by minilaparotomy (skin incision maximal 8 cm) in women with pronounced uterus myomatosus. Materials and Methods: This retrospective study makes use of the data from 160 patients with an average age of 34.6 years. Factors analysed include number, size and localisation of the myomas, complaints due to the myoma, pre- and postoperative gravidity, mode of delivery, and complications of birth. Results: Indications for organ-sparing myoma enucleation were the desire to have children (72.5 %), bleeding disorders (60 %) and pressure discomfort (36.5 %). On average 4.95 (SD ± 0.41), maximally 46 myomas were removed. The largest myoma had a diameter of 6.64 cm (SD ± 2.74). 82.5 % of the patients had transmural myomas, in 17.5 % the uterine cavity was inadvertently opened. On average the operating time was 163 minutes (SD ± 45.47), the blood loss 1.59 g/dL (SD ± 0.955). 60.3 % of the patients with the desire to have children became pregnant postoperatively. 75.3 % of the pregnancies were on average carried through to the 38th week (28.4 % vaginal deliveries, 71.6 % Caesarean sections). In the postoperative period there was one case of uterine rupture in the vicinity of a previous scar. Discussion: By means of the microsurgical "mini-laparotomy" even extensive myomatous uterine changes can, in the majority of cases, be operated in an organ-sparing manner with retention of the ability to conceive and to carry a pregnancy through to maturity of the infant. The risk for a postoperative uterine rupture in a subsequent pregnancy and during delivery is minimal.

Alternative therapies in management of leiomyomas

Leiomyomas are benign soft-tissue neoplasms that arise from smooth muscle. Relief of symptoms (abnormal uterine bleeding, pain, pressure) is the major goal in management of women with significant symptoms. For symptomatic myomas, hysterectomy is a definitive solution; however, there are emerging less-invasive options. Magnetic resonance imaging-guided focused ultrasound surgery, cryomyolysis, and temporary occlusion of the uterine arteries are treatment options that are minimally invasive interventions with the benefit of preserving the uterus. This review summarizes procedure techniques, eligibility, complications, and outcomes of these alternate therapies.

Review of temperature dependence of thermal properties, dielectric properties, and perfusion of biological tissues at hyperthermic and ablation temperatures

The application of supraphysiological temperatures (>40°C) to biological tissues causes changes at the molecular, cellular, and structural level, with corresponding changes in tissue function and in thermal, mechanical and dielectric tissue properties. This is particularly relevant for image-guided thermal treatments (e.g. hyperthermia and thermal ablation) delivering heat via focused ultrasound (FUS), radiofrequency (RF), microwave (MW), or laser energy; temperature induced changes in tissue properties are of relevance in relation to predicting tissue temperature profile, monitoring during treatment, and evaluation of treatment results. This paper presents a literature survey of temperature dependence of electrical (electrical conductivity, resistivity, permittivity) and thermal tissue properties (thermal conductivity, specific heat, diffusivity). Data of soft tissues (liver, prostate, muscle, kidney, uterus, collagen, myocardium and spleen) for temperatures between 5 to 90°C, and dielectric properties in the frequency range between 460 kHz and 3 GHz are reported. Furthermore, perfusion changes in tumors including carcinomas, sarcomas, rhabdomyosarcoma, adenocarcinoma and ependymoblastoma in response to hyperthmic temperatures up to 46°C are presented. Where appropriate, mathematical models to describe temperature dependence of properties are presented. The presented data is valuable for mathematical models that predict tissue temperature during thermal therapies (e.g. hyperthermia or thermal ablation), as well as for applications related to prediction and monitoring of temperature induced tissue changes.