Pelvic applications of MR-guided high intensity focused ultrasound

Treatment of adenomyosis, abdominal wall endometriosis and uterine leiomyoma with interventional radiology: A review of current evidences

Interventional radiology shows promises in the field of women's health, particularly in pelvic interventions. This review article discusses the latest advancements in interventional radiology techniques for pelvic conditions affecting women including adenomyosis, abdominal wall endometriosis and uterine leiomyoma. Extraperitoneal endometriosis involving the abdominal wall may be treated by percutaneous thermal ablation, such as cryoablation, whereas uterine leiomyoma and adenomyosis can be managed either using percutaneous thermal ablation or using uterine artery embolization. Continued research and development in interventional radiology will further enhance the minimally-invasive interventions available for women's health, improving outcomes and quality of life for this large patient population of women.

Role of Interventional Procedures in Obstetrics and Gynecology

Radiological guided intervention techniques are discussed in obstetric and gynecologic patients. Fallopian tube recanalization, postpartum hemorrhage control, techniques of treating uterine leiomyomas, pelvic congestion treatment, and the use of percutaneous and transvaginal ultrasonography-guided aspirations and biopsy are covered. These techniques use basic radiological interventional skills and show how they are adapted for use in the female pelvis.

Updates on MR-Guided Focused Ultrasound for Symptomatic Uterine Fibroids

Magnetic-resonance-guided focused ultrasound (MRgFUS), also called high-intensity focused ultrasound (HIFU) is an effective, noninvasive uterine-preserving treatment for symptomatic uterine fibroids. As the use of this therapeutic modality is not yet widespread, it may remain unfamiliar to many interventional radiologists. The purpose of this review is to discuss MRgFUS, including technology, patient selection, technique, outcomes, complications, and recent data on fertility and comparative effectiveness.

Image-guided thermal ablation with MR-based thermometry

Thermal ablation techniques such as radiofrequency, microwave, high intensity focused ultrasound (HIFU) and laser have been used as minimally invasive strategies for the treatment of variety of cancers. MR thermometry methods are readily available for monitoring thermal distribution and deposition in real time, leading to decrease of incidents of normal tissue damage around targeted lesion. HIFU and laser-induced thermal therapy (LITT) are the two widely accepted tumor ablation techniques because of their compatibility with MR systems. MRI provides multiple temperature dependent parameters for thermal imaging, such as signal intensity, T1, T2, diffusion coefficient, magnetization transfer, proton resonance frequency shift (PRFS, including phase imaging and spectroscopy) as well as frequency shift of temperature sensitive contrast agents. Absolute temperature mapping techniques, including both spectroscopic imaging using metabolites as a reference and phase imaging using fat as a reference, are immune to susceptibility effects and are not dependent on phase differences. These techniques are intrinsically more reliable than relative temperature measurement by phase mapping methods. If the limitation of low temporal and spatial resolution could be overcome, these methods may be preferred for MR-guided thermal ablation systems. As of today, the most popular MR thermal imaging method applied in tumor thermal ablation surgery is, however, still PRFS based phase mapping technique, which only provides relative temperature change and is prone to motion artifacts.

Uterine fibroid therapy using interventional radiology mini-invasive treatments: current perspective

Uterine fibroids are common benign tumors of unclear etiopathology that affect the female reproductive tract. They are responsible for considerable morbidity and deterioration of life quality, and may have a negative impact on the reproductive system as well. Besides surgery aided by uterus-saving techniques, several minimally invasive procedures are now available within the field of interventional radiology that represent a valid solution for women who desire pregnancy and relief from disease-specific symptomatology. The main advantages offered by these techniques are low grade of invasiveness and short times of hospitalization. The most diffuse techniques are uterine artery embolization (UAE) and magnetic resonance-guided high-intensity focused ultrasound (MRgFUS). UAE is an endovascular procedure whose goal is obtained by provoking ischemia of the uterine vessels. MRgFUS is a thermoablation procedure that selectively ablates the symptomatic fibroids. In this review study, both procedures will be described, including a description of technical details, indications, contraindications, complications, and outcomes.

High-Intensity Focused Ultrasound: Current Status for Image-Guided Therapy

Image-guided high-intensity focused ultrasound (HIFU) is an innovative therapeutic technology, permitting extracorporeal or endocavitary delivery of targeted thermal ablation while minimizing injury to the surrounding structures. While ultrasound-guided HIFU was the original image-guided system, MR-guided HIFU has many inherent advantages, including superior depiction of anatomic detail and superb real-time thermometry during thermoablation sessions, and it has recently demonstrated promising results in the treatment of both benign and malignant tumors. HIFU has been employed in the management of prostate cancer, hepatocellular carcinoma, uterine leiomyomas, and breast tumors, and has been associated with success in limited studies for palliative pain management in pancreatic cancer and bone tumors. Nonthermal HIFU bioeffects, including immune system modulation and targeted drug/gene therapy, are currently being explored in the preclinical realm, with an emphasis on leveraging these therapeutic effects in the care of the oncology patient. Although still in its early stages, the wide spectrum of therapeutic capabilities of HIFU offers great potential in the field of image-guided oncologic therapy.

[Treatment of adenomyosis (excluding pregnancy project)]

In this review we aimed to update the possibilities of adenomyosis treatment in women excluding those with a desire for pregnancy. Adenomyosis is defined as the presence of endometrial tissue within the myometrium and frequently underestimated. Over the last decades, its pathophysiology has been better known. The diagnosis is essentially based on clinical symptoms like menorrhagia and dysmenorrhea. Transvaginal ultrasound and magnetic resonance imaging are the main tools of the radiologic diagnosis. However, the definitive diagnosis is histological. The most effective treatment remains hysterectomy; however it is expensive, radical and at risk of morbidity compared with medical or surgical conservative management. The literature has reported several series of patients undergoing various treatments, thus allowing different therapeutic options. The levonorgestrel-releasing intrauterine device showed its efficacy alone or in combination with hysteroscopic treatment. Oral progestins, GnRH agonists are useful at short term or in preoperative condition. Some conservative treatments like focused ultrasound therapies or uterus-sparing operative treatment stay under evaluation and seems to be effective. Embolization has been the subject of several studies and must be outlined. Furthermore, several molecules, such as modulators of progesterone receptors and the aromatase inhibitors have been recently studied and are perhaps future treatments.

Thermal modelling using discrete vasculature for thermal therapy: A review

Reliable temperature information during clinical hyperthermia and thermal ablation is essential for adequate treatment control, but conventional temperature measurements do not provide 3D temperature information. Treatment planning is a very useful tool to improve treatment quality, and substantial progress has been made over the last decade. Thermal modelling is a very important and challenging aspect of hyperthermia treatment planning. Various thermal models have been developed for this purpose, with varying complexity. Since blood perfusion is such an important factor in thermal redistribution of energy in in vivo tissue, thermal simulations are most accurately performed by modelling discrete vasculature. This review describes the progress in thermal modelling with discrete vasculature for the purpose of hyperthermia treatment planning and thermal ablation. There has been significant progress in thermal modelling with discrete vasculature. Recent developments have made real-time simulations possible, which can provide feedback during treatment for improved therapy. Future clinical application of thermal modelling with discrete vasculature in hyperthermia treatment planning is expected to further improve treatment quality.

[MRI for monitoring of high intensity focused ultrasound: current developments]

With respect to monitoring of high intensity focused ultrasound (HIFU), synonym focused ultrasound (FUS) treatment, magnetic resonance imaging (MRI) is characterized by several advantageous properties: the precise definition and morphological characterization of the target area (before and after the intervention), the real-time visualization of the treatment effect by thermal imaging (during the intervention) and in the sense of a stereotactic system, the 3-dimensional localization of the target lesion, planning of the target volume and assessment of the achieved ablation volume (before and during the intervention). Non-enhanced T2-weighted multislice MR images are acquired for planning of the intervention. For temperature monitoring (comprising thermometry and thermodosimetry), the temperature-dependent shift of proton resonance frequency (PRFS) is most frequently employed. This method is independent of the treated tissue type or thermally induced tissue changes and facilitates a relative measurement of the temperature change based on a reference value. Future MRI applications include diffusion-weighted MRI (DWI-MRI; for the intrainterventional estimation of treatment efficacy), dynamic contrast-enhanced MRI (DCE-MRI, for the prediction of the potential and assessment of the treatment effect achieved) and motion-corrected temperature monitoring (referenceless and multibaseline thermometry).