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This study was aimed at evaluating the feasibility, safety and therapeutic effects of high-intensity focused ultrasound ablation (HIFUA) in the treatment of post-operative recurrent desmoid tumors. From September 2017 to May 2020, 42 consecutive patients with pathologically proven desmoid tumors treated with HIFUA for the first time were enrolled. These were divided into two groups: post-operative recurrent group (30 cases) and non-surgery group (12 cases). The basic characteristics, treatment parameters, ablation efficacy, tolerance and adverse events were recorded and compared between groups. The minimum distance between the tumor and skin surface in the post-operative recurrent group was significantly smaller than that in the non-surgery group (6.9 mm vs. 10.8 mm, p = 0.011), but there was no significant difference in the other basic characteristics (p > 0.05). The average acoustic power and intensity of treatment in the post-operative recurrent group were significantly lower than those in the non-surgery group (p = 0.006 and 0.036, respectively), but there was no significant difference in the remaining parameters or in ablation efficacy between groups (p > 0.05). HIFUA was successfully performed, and a large volume of coagulation necrosis was obtained from all patients without serious or life-threatening adverse events. Furthermore, there was no significant difference in the incidence of moderate adverse events and average length of stay between groups (p > 0.05). The average power and intensity of HIFUA treatment were adversely affected by surgical scar and tumor infiltration along the surgical path. However, HIFUA can still be used as an effective minimally invasive therapy for the local control of post-operative recurrent desmoid tumors. [ABSTRACT FROM AUTHOR]

Abstract: Objective: It has long been known that high intensity focused ultrasound (HIFU) can kill tissue through coagulative necrosis. However, it is only in recent years that practical clinical applications are becoming possible. Since the ribs have strong reflections to ultrasonic beams, they may affect the deposition of ultrasound energy, decreasing the efficacy of HIFU treatment and increasing the chance of adverse events when the intra-abdominal tumours concealed by ribs are treated. The aim of this study was to evaluate the influence of partial rib resection on the efficacy and safety of HIFU treatment. Methods: This prospective study was approved by the ethics committee at Chongqing University of Medical Sciences. An informed consent form was obtained from each patient and family member. A total of 16 patients with hepatocellular carcinoma (HCC), consisting of 13 males and 3 females, were studied. All patients had the successful HIFU treatment. To create a better acoustic pathway for HIFU treatment, all of the 16 patients had the ribs that shield the tumour mass to be removed. Magnetic resonance imaging (MRI) was used to evaluate the efficacy of HIFU treatment. Results: Sixteen cases had 23 nodules, including 12 cases with a single nodule, 1 case with 2 nodules, 3 cases with 3 nodules. The mean diameter of tumours was 7.0±2.1cm (5–10cm). According to TNM classification, 9 patients were diagnosed as stage II, 4 patients were stage III, and 3 patients were stage IV. Follow-up imaging showed an absence of tumour blood supply and shrinkage of all treated lesions. The survival rates at 1, 2, 3, 4, and 5 years were 100%, 83.3%, 69.4%, 55.6%, and 55.6%, respectively. No serious complications were observed in the patients treated with HIFU. Conclusion: Partial rib resection can create a better acoustic pathway of HIFU therapy. Even though it is an invasive treatment, this measure offers patients an improved prospect of complete tumour ablation when no other treatment is available. [Copyright &y& Elsevier]

The aim of this study was to explore a law of energy deposition of high-intensity focused ultrasound (HIFU) in various tissues and the expression of such a law. A focused ultrasound (US) tumor therapeutic system was used to apply a focused US beam to tissues both in vivo and in vitro. The formation of individual ellipsoid-shaped regions of coagulative necrosis has been observed. Results showed that the volume of the ellipsoid-shaped coagulative necrosis region was different from that of the acoustic focal region (AFR), both in vitro and in vivo. Acoustic intensities ranging from 7 × 103 W/cm2 to 27.7 × 103 W/cm2 and exposure times from 1 to 20 s gave volumes of ellipsoid-shaped coagulative necrosis of 0.2 to 2000 mm3. Although the HIFU doses applied were identical, the volumes of individual ellipsoid-shaped coagulative necrotic regions varied with the structures of tissues, their functional status and the irradiation depths. Individual ellipsoid-shaped regions of coagulative necrosis induced by HIFU can be added to produce coagulative necrosis of an entire tumor. We define the individual ellipsoid-shaped coagulative necrosis produced by the US energy deposition of a single exposure as the “biological focal region” (BFR) of HIFU. This serves as the basic unit for HIFU ablation of tumors, and is plotted as a function of AFR, acoustic intensity, exposure time, irradiation depth, the tissue structure and its functional status. (E-mail: wangzhibiao@netease.com) [Copyright &y& Elsevier]