Contrast-enhanced Ultrasonography Assessment of Therapeutic Efficacy for Ultrasound-guided High-intensity Focused Ultrasound Ablation of Uterine Fibroids: Comparison with Contrast-enhanced Magnetic Resonance

Methods of monitoring thermal ablation of soft tissue tumors - A comprehensive review

Thermal ablation is a form of hyperthermia in which oncologic control can be achieved by briefly inducing elevated temperatures, typically in the range 50-80°C, within a target tissue. Ablation modalities include high intensity focused ultrasound, radiofrequency ablation, microwave ablation, and laser interstitial thermal therapy which are all capable of generating confined zones of tissue destruction, resulting in fewer complications than conventional cancer therapies. Oncologic control is contingent upon achieving predefined coagulation zones; therefore, intraoperative assessment of treatment progress is highly desirable. Consequently, there is a growing interest in the development of ablation monitoring modalities. The first section of this review presents the mechanism of action and common applications of the primary ablation modalities. The following section outlines the state-of-the-art in thermal dosimetry which includes interstitial thermal probes and radiologic imaging. Both the physical mechanism of measurement and clinical or pre-clinical performance are discussed for each ablation modality. Thermal dosimetry must be coupled with a thermal damage model as outlined in Section 4. These models estimate cell death based on temperature-time history and are inherently tissue specific. In the absence of a reliable thermal model, the utility of thermal monitoring is greatly reduced. The final section of this review paper covers technologies that have been developed to directly assess tissue conditions. These approaches include visualization of non-perfused tissue with contrast-enhanced imaging, assessment of tissue mechanical properties using ultrasound and magnetic resonance elastography, and finally interrogation of tissue optical properties with interstitial probes. In summary, monitoring thermal ablation is critical for consistent clinical success and many promising technologies are under development but an optimal solution has yet to achieve widespread adoption.

Contrast-Enhanced Ultrasound Imaging of Uterine Disorders: A Systematic Review

Uterine disorders are often presented with overlapping symptoms. The microvasculature holds specific information important for diagnosing uterine disorders. Conventional sonography is an established diagnostic technique in gynecology, but is limited by its inability to image the microvasculature. Contrast-enhanced ultrasound (CEUS), is capable of imaging the microvasculature by means of intravascular contrast agents; that is, gas-filled microbubbles. We provide a literature overview on the use of CEUS in diagnosing myometrial and endometrial disorders, that is, fibroids, adenomyosis, leiomyosarcomas and endometrial carcinomas, as well as for monitoring and enhancing the effectiveness of minimally invasive therapies. A systematic literature search with quality assessment was performed until December 2020. In total 34 studies were included, published between 2007 and 2020.The results entail a description of contrast-enhancement patterns obtained from healthy tissue and from malignant and benign tissue; providing a first base for potential diagnostic differentiation in gynecology. In addition it is also possible to determine the degree of myometrial invasion in case of endometrial carcinoma using CEUS. The effectiveness of minimally invasive therapies for uterine disorders can safely and accurately be assessed with CEUS. In conclusion, the abovementioned applications of CEUS are promising and it is worth further exploring its full potential for gynecology by designing innovative and methodologically high-quality clinical studies.

Use of Contrast-Enhanced Ultrasound in the Assessment of Uterine Fibroids: A Feasibility Study

Contrast-enhanced ultrasound (CEUS) is an innovative ultrasound technique capable of visualizing both the macro- and microvasculature of tissues. In this prospective pilot study, we evaluated the feasibility of using CEUS to visualize the microvasculature of uterine fibroids and compared CEUS with conventional ultrasound. Four women with fibroids underwent gray-scale ultrasound, sonoelastography and power/color Doppler scans followed by CEUS examination. Analysis of CEUS images revealed initial perfusion of the peripheral rim, that is, a pseudo-capsule, followed by enhancement of the entire lesion through vessels traveling from the exterior to the interior of the fibroid. The pseudo-capsules exhibited slight hyper-enhancement, making a clear delineation of the fibroids possible. The centers of three fibroids exhibited areas lacking vascularization, information not obtainable with the other imaging techniques. CEUS is a feasible technique for imaging and quantifying the microvasculature of fibroids. In comparison with conventional ultrasound imaging modalities, CEUS can provide additional diagnostic information based on the microvasculature.

High-Intensity Focused Ultrasound (HIFU) and the Clinical Applications for the Female Pelvis

High-intensity focused ultrasound (HIFU) is a noninvasive, nonionizing means to therapeutically treat various medical conditions. Although HIFU has proven useful in the treatment of a variety of conditions, in recent years, more research has been conducted on how HIFU treatments can be used to treat conditions related to the female pelvis. Some of the medical conditions being researched are uterine fibroids, adenomyosis, cervicitis, and polycystic ovaries. Clinical studies have demonstrated the effectiveness of HIFU in the treatment of these medical conditions unique to the female pelvis. This literature review will be used to introduce the technology of HIFU, present an overall analysis of HIFU, provide a review on the latest clinical research concerning HIFU clinical applications for pathologic conditions of the female pelvis, and identify the impact of HIFU on patients and the ultrasound community.