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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.
Application of Bioresponsive Polymers in Drug Delivery
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Manisha Lalan, Deepti Jani, Pratiksha Trivedi, Deepa H. Patel
Focused ultrasound can be used as other stimuli guided approach for drug delivery. Brain-derived neurotrophic factor (BDNF) was subjected to focused ultrasound following nasal delivery. Immunohistochemistry staining of BDNF showed that focused ultrasound enhanced drug transport by active pumping. It was hailed as a promising technique for noninvasive and localized drug delivery [89].
The efficacy and safety of secondary focused ultrasound therapy for recurrence of non-neoplastic epithelial disorders of the vulva
Published in International Journal of Hyperthermia, 2022
Focused ultrasound is a mechanical wave that has demonstrated good performance in tissue penetration, locating, and energy deposition. Previous studies have shown that the count of microvessels increased and their lumens recovered after FU therapy among women with NNEDV. Melanin cells were seen in the basal layer, and the involved tissue structures recovered normal pigmentation after FU therapy [22]. Thus, FU therapy as a local therapy has demonstrated encouraging results among patients with NNEDV. However, the recurrence rate is still high. Li et al. used FU therapy to treat 76 patients with NNEDV, and the total recurrence rate at 4 years was 36% [12]. Wu et al. found that the total recurrence rate of focused ultrasound treatment for NNEDV was 22.79% within a 5-year period. Ye et al. investigated 950 patients with pathologically confirmed NNEDV who underwent FU therapy. Of all effective cases, 89 (9.5%) recurred and most occurred within 3 years of treatment [13]. It is still unknown which treatment options should be used for relapsed patients. It is unclear whether it is effective to treat patients with FU therapy who have previously received FU therapy. For this reason, we considered it important to assess the safety and effectiveness of secondary FU therapy among women with NNEDV recurrence.
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].