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Ultrasound Physics
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Portable ultrasound machines and “pocket” handheld devices are increasingly attractive to non-imaging specialists (such as emergency physicians and GPs) who want to use ultrasound for a specific imaging purpose. For example, guided insertion of a chest drain or biopsy needle, or targeted anaesthesia (Figure 3.1). Ultrasound equipment can range from specialist medical equipment, such as bladder scanners and foetal heart-rate monitors, to versatile ultrasound scanners, offering full diagnostic imaging. At higher energies, ultrasound can be used therapeutically for physiotherapy, brain stimulation and tumour ablation. For example, High-Intensity Focused Ultrasound (HIFU) can be used to treat localised prostate cancer as an alternative to surgery. Ultrasound physics training and safety and QA processes therefore need to cover a wide range of clinical applications.
Nanomaterials for Theranostics: Recent Advances and Future Challenges *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Eun-Kyung Lim, Taekhoon Kim, Soonmyung Paik, Seungjoo Haam, Yong-Min Huh, Kwangyeol Lee
Xia et al. prepared porous AuNCs covered by temperature-dependent volume-changing smart polymers [839]. For pure PNIPAAm, its low critical solution temperature (LCST) is about 32°C. Below 32°C, the polymer is hydrophilic and soluble in water. When the temperature is raised above 32°C, the polymer undergoes a phase transition to a hydrophobic state accompanied by volume contraction. By incorporating acrylamide (AAm) into the polymer chain they obtained PNIPAAm-co-pAAm copolymers with LCSTs tuned to the range of 32–50°C. Upon NIR irradiation, AuNC produced heat as expected, the elevated temperature led to a volume contraction of the polymer, and then the pores of AuNCs, originally blocked by polymer shell, were revealed to release anticancer drug DOX. Upon turning off the NIR laser, the pores were resealed to stop the release of therapeutic contents (Fig. 16.40). They further remodeled the nanocomposite by changing the polymer to phase-change materials for encapsulating hydrophobic and hydrophilic drugs into AuNC [840]. They also demonstrated a drug-release process induced by high-intensity focused ultrasound.
A Perspective of Ultrasound-Related Micro/Nano Cancer Therapy
Published in Hala Gali-Muhtasib, Racha Chouaib, Nanoparticle Drug Delivery Systems for Cancer Treatment, 2020
Tingting Zheng, Yun Chen, Jiao Peng, Yu Shi, Jun Zhang, Haitao Xiao, Xiangmei Chen, Yongcan Huang, Tao Pei, Zhuxia Zhang, Xue Zhang, Xiaohe Bai, Li Liu, Jinrui Wang
Ultrasound (US) is currently identified not only as a noninvasive diagnosis tool but also as a promising mineral- and/or non-invasive therapeutic tool in hospitals. According to ultrasound adjustability, which includes adjusting frequency, intensity, mode, and waveform, theranostic treatment can be performed in different parameter combinations, of which high-intensity focused ultrasound and low-intensity focused ultrasound are two frequently performed treatments, especially for cancer treatment. Most important traits of cancer theranostic focused ultrasound among others are sonothermal effect, ultrasonic cavitation effect, sonoporation effect, sonodynamic effect, and ultrasound targeted drug delivery. To date, high-intensity focused ultrasound (HIFU) ablation has already been applied clinically; however, low-intensity focused ultrasound (LIFU) targeted cancer therapy is still in preclinical study phase. One of the main challenges for its clinical transition ascribes to its low therapeutic efficiency. Scientists therefore induce hybrid micro-/nanoparticles, which play a role as contrast and/or drug delivery carriers in a microscopic scale. In assistance of hybrid micro-/nanobubbles and correlative smart nanoparticles, ultrasound (e.g., LIFU)-related cancer therapy has been verified as a promising choice with minimal side effects or non-trauma. In this chapter, we will discuss the use of HIFU and LIFU approaches to cancer therapy in combination with micro-/nanoparticles to maximize therapeutic effects.
Hydrogels for localized chemotherapy of liver cancer: a possible strategy for improved and safe liver cancer treatment
Published in Drug Delivery, 2022
Jianyong Ma, Bingzhu Wang, Haibin Shao, Songou Zhang, Xiaozhen Chen, Feize Li, Wenqing Liang
Thermal and nonthermal effects of ultrasound on biological tissues are both present. Thermal effects are the conversion of acoustic energy to thermal energy, which increases tissue temperature, disruption of cell membranes, and increases vasculature permeability (Gao et al., 2005). While nonthermal effects, known as cavitation effects, are ultrasound-mediated tiny gas bubbles acting as microreactors, causing increased pressure and permeability of cell membrane, as well as the drug release received by cells (Manouras & Vamvakaki, 2017). Hydrogels with ultrasound sensitivity have typically been used in conjunction with other gene carriers or stimuli-responsive hydrogels for years (Chen & Du, 2013). They can also be used as a distinct anticancer drug carrier because of their deep permeation and visualization. Exploration of ultrasound-sensitive gels for simultaneous diagnosis and therapy is another active research area (Kumar & Han, 2017). Ultrasound has a variety of effects on the mechanism of delivery from gels. Acoustic vibrations can produce localized high heat, as evidenced by the recent use of high-intensity focused ultrasound (HIFU) in tumor treatment (Jeong et al., 2016). The release of antitumor drugs from thermosensitive hydrogels is also regulated by this thermal effect. Furthermore, ultrasound-induced cavitation greatly improves the permeability of cell membranes in ultrasound-sensitive hydrogel carriers.
Ultrasound guided microwave ablation compared to uterine artery embolization treatment for uterine fibroids – a randomized controlled trial
Published in International Journal of Hyperthermia, 2022
Gudny Jonsdottir, Marie Beermann, Annika Lundgren Cronsioe, Klara Hasselrot, Helena Kopp Kallner
In recent years the interest in medical treatment and minimally invasive or noninvasive therapies with uterine preservation has increased. Minimally invasive treatments include uterine artery embolization (UAE), radiofrequency ablation, high intensity focused ultrasound and microwave ablation (MWA). UAE is an established method to decrease volume of fibroids and improve clinical symptoms [6], however postoperative pain and post-embolization syndrome associated with the procedure have limited its use [7]. There has been a concern that women are at increased risk of entering earlier menopause after UAE and previous studies have shown contradictory results [8–10]. Studies of MWA do not report any effects on ovarian reserve nor an elevated risk of entering premature/earlier menopause [11]. A retrospective comparison of high intensity focused ultrasound and MWA showed no difference in outcome but shorter treatment times in the MWA group [12].
Magnetic resonance imaging parameters in predicting the ablative efficiency of high-intensity focused ultrasound for uterine fibroids
Published in International Journal of Hyperthermia, 2021
Chunmei Gong, Zhenjiang Lin, Fajin Lv, Lian Zhang, Zhibiao Wang
Uterine fibroids are the most common benign gynecological tumors in women of reproductive age. The prevalence of uterine fibroids varies across races and ranges from 20% to 80% [1]. Approximately half the patients have symptoms of menorrhagia, pelvic pain or infertility. Conventional treatment for uterine fibroids includes hysterectomy, myomectomy, and uterine artery embolization (UAE) [2,3]. Hysterectomy is a definitive treatment for uterine fibroids. However, it is not suitable for patients who wish to retain their uterus. Myomectomy is a treatment of choice for patients wishing to conceive, but the reintervention rate is high [4]. Uterine artery embolization (UAE) is an alternative treatment for uterine fibroids but severe adverse effects have limited its application [5]. High-intensity focused ultrasound (HIFU) has been widely used as a noninvasive treatment in the management of uterine fibroids. Previous studies have demonstrated that this technique is safe and effective in the treatment of uterine fibroids [6–8]. However, in clinical practice, it was found that HIFU is not suitable for some patients. Therefore, optimization of these indicators is the key to achieving better results.