Impact of target depth on safety and efficacy outcomes in MR-guided focused ultrasound thalamotomy for tremor patients

OBJECTIVE

Target depth, defined by the z-coordinate in the dorsoventral axis relative to the anterior commissure-posterior commissure axial plane of the MR-guided focused ultrasound (MRgFUS) lesion, is considered to be critical for tremor improvement and the occurrence of side effects such as gait impairment. However, although different z-coordinates are used in the literature, there are no comparative studies available with information on optimal lesion placement. This study aimed to compare two different MRgFUS lesion targets (z = +2 mm vs z = 0 mm) regarding efficacy and safety outcomes.

METHODS

The authors conducted a retrospective analysis of 52 patients with pharmacoresistant tremor disorders who received unilateral MRgFUS thalamotomy in the ventral intermediate nucleus for the first time between 2017 and 2022 by one neurosurgeon, with two different z-coordinates, either z = +2 mm (+2-mm group; n = 17) or z = 0 mm (0-mm group; n = 35), but otherwise identical parameters. Standardized video-recorded assessments of efficacy (including the Washington Heights-Inwood Genetic Study of Essential Tremor scale) and safety (using a standardized grading system) outcomes at baseline and at 6 months posttreatment were reviewed and compared. Moreover, overall patient satisfaction was extracted as documented by the examiner at 6 months.

RESULTS

Based on a multiple logistic regression analysis, the authors found that a more dorsal target with a z-coordinate of +2 mm as compared with 0 mm was associated with a higher incidence of any persistent side effect at 6 months (p = 0.02). Most consistently, sensory disturbances, although mild and nondisturbing in most cases, occurred more frequently in the +2-mm group (35% vs 11%, p = 0.007), while no significant differences were found for gait impairment (29% vs 35%) and arm ataxia (24% vs 11%). On the other hand, average tremor suppression was similar (63.6% vs 60.2%) between the groups. Here, higher efficacy was associated with a higher side effect burden in the 0-mm group but not in the +2-mm group. Despite the occurrence of side effects, general patient satisfaction was high (87% would undergo MRgFUS again) as most patients valued tremor suppression more.

CONCLUSIONS

A more ventral MRgFUS target of z = 0 mm seems to be associated with a more favorable safety and a comparable efficacy profile as compared with a more dorsal target of z = +2 mm, but prospective studies are warranted.

Optimized treatment parameter by computer simulation for high-intensity focused ultrasound treatment of uterine adenomyosis: Short-term and long-term results

This study aimed to investigate the efficacy and safety of using optimized parameters obtained by computer simulation for ultrasound-guided high-intensity focused ultrasound (HIFU) treatment of uterine adenomyosis in comparison with conventional parameters. We retrospectively assessed a single-institution, prospective study that was registered at Clinical Research Information Service (CRiS) of Republic of Korea (KCT0003586). Sixty-six female participants (median age: 44 years) with focal uterine adenomyosis were prospectively enrolled. All participants were treated with a HIFU system by using treatment parameters either for treating uterine fibroids (Group A, first 20 participants) or obtained via computer simulation (Group B, later 46 participants). To assess the treatment efficacy of HIFU, qualitative indices, including the clinically effective dysmenorrhea improvement index (DII), were evaluated up to 3 years after treatment, whereas quantitative indices, such as the nonperfused volume ratio and adenomyosis volume shrinkage ratio (AVSR), on MRI were evaluated up to 3 months after treatment. Quantitative/qualitative indices were compared between Groups A and B by using generalized linear mixed effect model. A safety assessment was also performed. Results showed that clinically effective DII was more frequently observed in Group B than in Group A (odds ratio, 3.69; P = 0.025), and AVSR were higher in Group B than in Group A (least-squares means, 21.61; P = 0.001). However, two participants in Group B developed skin burns at the buttock and sciatic nerve pain and required treatment. In conclusion, parameters obtained by computer simulation were more effective than the conventional parameters for treating uterine adenomyosis by using HIFU in terms of clinically effective DII and AVSR. However, care should be taken because of the risk of adverse events.

Efficacy and influencing factor analysis of high-intensity focused ultrasound therapy for abdominal wall endometriosis: a case series

OBJECTIVE

The aim of this retrospective study was to investigate the short-term and long-term efficacy of high-intensity focused ultrasound (HIFU) therapy for abdominal wall endometriosis (AWE) and explore its potential influencing factors.

MATERIALS AND METHODS

A total of 80 patients with AWE who underwent HIFU therapy were retrospectively analyzed. Follow-ups were also conducted to evaluate the changes in lesion size and pain relief. Multivariate logistic regression analysis was applied to investigate factors influencing HIFU therapy for AWE.

RESULTS

Among the 80 patients with AWE who received HIFU therapy, the effective rates were 76.3%, 80.5%, and 90.5% after 3, 12 and 24 months of follow-up, respectively. Multivariate logistic regression analysis revealed that the AWE lesion diameter and sonication intensity had statistically significant effects on the 3-month and 12-month efficacy of HIFU therapy for AWE, while age, BMI, disease duration, average sonication power and grey-scale changes did not have statistically significant effects. Four patients with AWE experienced recurrence after HIFU therapy, for a three-year cumulative recurrence rate of 6.3%. Furthermore, ten patients required reintervention after treatment, for a five-year cumulative reintervention rate of 13.9%.

CONCLUSIONS

This study further confirmed the safety and effectiveness of HIFU therapy for AWE. Factors such as AWE lesion diameter and sonication intensity have been identified as key influencers affecting the short-term and long-term efficacy of HIFU therapy for AWE. The first two years following HIFU therapy constitute crucial periods for observation, and judiciously extending follow-up intervals during this timeframe is advised.

Systematic review and meta-analysis of reproductive outcomes after high-intensity focused ultrasound (HIFU) treatment of adenomyosis

High-intensity focused ultrasound (HIFU) has emerged as a promising uterus-sparing and possibly fertility-sparing treatment modality for women with adenomyosis, especially those who desire to conceive. We conducted this systematic review and performed a meta-analysis on clinical studies aimed to improve reproduction in women with adenomyosis. After extensive search of PubMed and CNKI, we identified 10 studies published in English and Chinese involving a total of 557 patients with adenomyosis who desired to conceive after HIFU treatment. We found a pooled estimate of pregnancy rate of 53.4% and of the live birth rate of 35.2%, and there was a substantial heterogeneity among these studies. While there is a potential for HIFU treatment to improve fertility for patients with adenomyosis who desired to conceive, such evidence is very weak as of now. Comparative studies with much higher methodological rigor, preferably randomized clinical trials, are badly needed to further illuminate this issue.

Factors associated with thermal injury of abdominal skin in focused ultrasound ablation of uterine fibroids

OBJECTIVE

To investigate the factors which may cause thermal injury of abdominal skin in patients with uterine fibroids (UFs) who underwent ultrasound-guided focused ultrasound ablation surgery (FUAS).

METHOD

A total of 123 patients were enrolled in the injury group. In contrast, 246 patients without thermal injury were assigned to the non-injury group. The relationship between patient and treatment parameters and injury were explored using univariate analysis and multiple logistic regression analyses. In addition, the factors influencing the degree of thermal injury were analyzed using Kruskal-Wallis H.

RESULTS

(1) Abdominal scars (p = .007, OR = 2.187, 95% CI: 1.242-3.849), abdominal wall thickness (p < .001, OR = 1.042, 95% CI: 1.019-1.067), fundus fibroids (p = .038, OR = 1.790, 95% CI: 1.033-3.100), UFs with hyperintense/mixed T2-weighted imaging (T2WI) signals (p = .022, OR = 1.843, 95% CI: 1.091-3.115), average sonication power (AP) (p = .025, OR = 1.021, 95% CI: 1.003-1.039), and treatment time (TT) (p < .001, OR = 1.017, 95% CI: 1.011-1.023) were independent risk factors for thermal injury, while treatment volume (TV) (p = .002, OR = 0.775, 95% CI: 0.661-0.909) was a protective factor for injury. (2) Four groups were subdivided according to the degree of thermal injury(Group A: without skin injury. Group B: with changed T2WI signal in the abdominal wall, Group C: mild skin injury, Group D: severe skin injury), comparison of each with every other showed that the abdominal wall in Groups A and D was thinner than Groups B and C, with statistically significant differences (PAB<0.05, PAC<0.01, PDC<0.05, PDB<0.05); Group A was slightly thicker than D, however, without statistical difference. The ratio of sonication time (ST) to TV in Group A was the lowest of all (PAB, PAC, PAD all < 0.05). And as the level of thermal injury rose, the ratio gradually increased, however, without statistical difference.

CONCLUSIONS

Based on our limited results, the following conclusion was made. (1) Abdominal scars, abdominal wall thickness, fundus fibroids, UFs with T2WI hyperintense/mixed signals, AP and TT were independent risk factor. (2) Neither too thick nor too thin abdominal walls would be recommended, as both might increase the risk of skin injury. (3) Noticeably, the risk of skin injury might increase considerably when the ST was longer and the sonication area was more fixed.

High-intensity focused ultrasound ablation combined with systemic therapy for unresectable colorectal cancer liver metastasis: A propensity score-matched analysis

OBJECTIVE

Unresectable colorectal cancer liver metastasis (CRLM) remains a challenging obstacle that often prevents curative treatment. In this study, we retrospectively analyzed the efficacy and safety of high-intensity focused ultrasound (HIFU) as a local adjuvant therapy for systemic chemotherapy for patients with unresectable CRLM. HIFU is a noninvasive method previously demonstrated as efficacious for various solid malignancies.

METHODS

Propensity score matching was used for the combination therapy group (HIFU group, n = 59) and the observation group receiving systemic therapy only (No-HIFU group, n = 59). In addition, the survival benefit, adverse effects, and factors affecting prognosis following HIFU were evaluated.

RESULTS

The disease control rate was 77.9% and 62.7%, and the objective remission rate was 18.9% and 6.8% in the HIFU and non-HIFU groups, respectively. The survival analysis showed that median progression-free survival (mPFS) was 12.0 months and 11.0 months for the HIFU and non-HIFU groups, respectively (p = 0.002). The univariate and multivariate analysis showed that pre-treatment colorectal cancer liver metastasis lesion size was significantly associated with mPFS. In addition, patients that received a combination treatment for CRLM lesions <5.0 cm had a longer mPFS when compared to those receiving systemic therapy alone (13.0 months vs. 11.0 months, p = 0.001). In the HIFU group, patients with lesions <5.0 cm had a longer mPFS than patients with lesions ≥5.0 cm (13.0 months vs. 10.0 months, p = 0.04) (Figure 3B,C). Most treatment-related adverse events observed in both groups were grade 1-2. Only four cases (6.8%) of grade 1-2 skin burns were observed in patients in the HIFU group; no other statistically significant adverse events were observed.

CONCLUSIONS

Our study showed that HIFU ablation targeting unresectable CRLM alongside systemic therapy safely and significantly improved local control rates and prolonged mPFS, especially for lesions smaller than 5.0 cm.

Risk factors for unresectable pancreatic cancer following high-intensity focused ultrasound treatment

PURPOSE

Pancreatic cancer is one of the most aggressive malignant tumors with poor prognosis. High-intensity focused ultrasound (HIFU) is an effective and safe treatment option for advanced pancreatic cancer, however, the survival time of patients after the treatment was different. So, the purpose of this study was to evaluate the relationship between the high-risk characteristics and prognosis of unresectable pancreatic cancer after HIFU treatment.

PATIENTS AND METHODS

This prospective study included 30 patients with unresectable pancreatic cancer who received HIFU at Beijing Friendship Hospital. Data on patients' tumor size, pain scores, peripheral blood lymphocyte subsets, CA19-9 and contrast enhanced ultrasound (CEUS) features were collected to assess the relationship with overall survival (OS) after HIFU.

RESULTS

The median OS from the start of HIFU treatment was 159 days, 95% confidence interval (95% CI): 108-210. The levels of pain were determined by visual analogue scale (VAS) score, and the quartile of the score decreased from 6 (2, 7) to 4 (2, 5) immediately after one session of the treatment (p = 0.001). The diagnostic model showed that high post VAS score and decreasing of peripheral CD4+ T cells were significantly correlated with poor prognosis (p < 0.05), and showed good discrimination ability (AUC = 0.848, 95% CI = 0.709-0.987).

CONCLUSION

HIFU can effectively relieve pain in patients with unresectable pancreatic cancer. Post treatment VAS and change of peripheral CD4+ T cells are independent risk factors affecting the prognosis in patients with unresectable pancreatic cancer after HIFU treatment.

Hepatic and Renal Histotripsy in an Anticoagulated Porcine Model

PURPOSE

To determine the risk of mechanical vessel wall damage resulting in hemorrhage during and after hepatic and renal histotripsy in an anticoagulated in vivo porcine model.

MATERIALS AND METHODS

Non-tumor-bearing pigs (n = 8; mean weight, 52.5 kg) were anticoagulated with warfarin (initial dose, 0.08 mg/kg) to a target prothrombin time (PT) of 30%-50% above baseline. A total of 15 histotripsy procedures were performed (kidney: n = 8, 2.0-cm sphere; liver: n = 7, 2.5-cm sphere). Treatments were immediately followed by computed tomography (CT) imaging. Animals were observed for 7 days while continuing anticoagulation, followed by repeat CT and necropsy.

RESULTS

All animals survived to complete the entire protocol with no signs of disability or distress. Three animals had hematuria (pink urine without clots). Baseline PT values (mean, 16.0 seconds) were elevated to 22.0 seconds (37.5% above baseline, P = .003) on the day of treatment and to 28.8 seconds (77.8% above baseline, P < .001) on the day of necropsy. At the time of treatment, 5 of 8 (63%) animals were at a therapeutic anticoagulation level, and all 8 animals (100%) reached therapeutic levels by the time of necropsy. There were no cases of intraparenchymal, peritoneal, or retroperitoneal hemorrhage associated with any treatments despite 5 of 7 (71%) liver and all 8 (100%) kidney treatments extending to the organ surface.

CONCLUSIONS

Liver and kidney histotripsy seems safe with no elevated bleeding risk in this anticoagulated animal model, supporting the possibility of histotripsy treatments in patients on anticoagulation.

Numerical study of high-intensity focused ultrasound (HIFU) in fat reduction

INTRODUCTION

This study aimed to investigate the effect of fat-layer thickness and focal depth on the pressure and temperature distribution of tissue.

METHODS

Computer simulations were performed for the skin-fat layer models during high-intensity focused ultrasound (HIFU) treatment. The acoustic pressure field was calculated using the nonlinear Westervelt equation and coupled with the Pennes bioheat transfer equation to obtain the temperature distribution. To investigate the effect of the thickness of the fat layer on pressure and thermal distributions, the thickness of the fat layer behind the focal point (z = 13.5 mm) changed from 8 to 24 mm by 2 mm step. The pressure and temperature distribution spectra were extracted.

RESULTS

The simulated results were validated using the experimental results with a 98% correlation coefficient (p < 0.05). There was a significant difference between the pressure amplitude and temperature distribution for the 8-14 mm thickness of the fat layer (p < 0.05). By changing the focal point from 11.5 to 13.5 mm, the maximum acoustic pressure at the focal point increased 66%, and the maximum temperature was 56%, respectively.

CONCLUSION

Considering the specific treatment plan for each patient, according to the skin and fat layer thicknesses, can help prevent side effects and optimize the treatment process of HIFU.

Mechanical damage thresholds for hematomas near gas-containing bodies in pulsed HIFU fields

Objective. Boiling histotripsy (BH) is a novel high intensity focused ultrasound (HIFU) application currently being developed for non-invasive mechanical fractionation of soft tissues and large hematomas. In the context of development of BH treatment planning approaches for ablating targets adjacent to gas-containing organs, this study aimed at investigation of the ultrasound pressure thresholds of atomization-induced damage to the tissue-air interface and correlation of the danger zone dimensions with spatial structure of nonlinear HIFU field parameters.Approach. A flat interface with air of freshly clotted bovine blood was used as anex vivomodel due to its homogenous structure and higher susceptibility to ultrasound-induced mechanical damage compared to soft tissues. Three 1.5 MHz transducers of differentF-numbers (0.77, 1 and 1.5) were focused at various distances before or beyond a flat clot surface, and a BH exposure was delivered either at constant, high-amplitude output level, or at gradually increasing level until a visible damage to the clot surface occurred. The HIFU pressure field parameters at the clot surface were determined through a combination of hydrophone measurements in water, forward wave propagation simulation using 'HIFU beam' software and an image source method to account for the wave reflection from the clot surface and formation of a standing wave. The iso-levels of peak negative pressure in the resulting HIFU field were correlated to the outlines of surface erosion to identify the danger zone around the BH focus.Main results. The outline of the danger zone was shown to differ from that of a typical BH lesion produced in a volume of clot material. In the prefocal area, the zone was confined within the 4 MPa contour of the incident peak-to-peak pressure; within the main focal lobe it was determined by the maximum BH lesion width, and in the postfocal area-by the transverse size of the focal lobe and position of the first postfocal pressure axial null.Significance. The incident HIFU pressure-based danger zone boundaries were outlined around the BH focus and can be superimposed onto in-treatment ultrasound image to avoid damage to adjacent gas-containing bodies.

Management of unresectable and recurrent intra-abdominal desmoid tumors treated with ultrasound-guided high-intensity focused ultrasound: A retrospective single-center study

To assess the efficacy and safety of ultrasound (US)-guided high-intensity focused ultrasound (HIFU) ablation for treatment of unresectable and recurrent intra-abdominal desmoid tumors. From June 2014 to March 2020, 15 patients with consecutive unresectable and recurrent diseases that pathologically proven to be intra-abdominal desmoid tumors had undergone the treatment of US-guided HIFU ablation. All patients underwent contrast-enhanced magnetic resonance imaging before and after HIFU treatment. Nonperfused volume ratio was used to evaluate the effect of HIFU therapy. Intraprocedural and postprocedural adverse effects and complications are recorded to assess the safety of the therapy. Outcome of HIFU ablation has been investigated through serial contrast-enhanced imaging examinations during follow up. Out of 15 patients 14 of them have successfully completed the whole therapy, 1 patient is ineffective and gives up further treatment. The mean nonperfused volume ratio is 71.1% (95% confidence interval, 3% to 88.2%). During a mean follow up of 29 months (range from 8 to 61 months), the mean tumor volume was reduced by 59% (95% confidence interval, +49% to -100%). No tumor spreads along the treated area in all patients except one. Complications have occurred in 5 patients (33.3%), including bowel rupture (1 case), intra-abdominal abscess (1 case), slight injury to the femoral nerve (1 case), and bone injury (2 cases), the bowel rupture patient underwent surgery; the others have been cured during the follow up. US-guided HIFU ablation is an effective treatment modality for patients suffered from unresectable and recurrent intra-abdominal desmoid tumors.

Effectiveness of High-intensity Focused Ultrasound (HIFU) Therapy of Solid and Complex Benign Thyroid Nodules - A Long-term Follow up Two-center Study

PURPOSE

To investigate the effectiveness of high-intensity focused ultrasound (HIFU) of solid and complex benign thyroid nodules.

METHODS

Fifty-eight patients with benign thyroid nodules were treated with HIFU at two centers from 2014-2019. The device, EchoPulse (Teraclion, Malakoff, France), heats the nodes to 80-90 °C. Nodal volumes were measured by ultrasound at regular intervals before and up to 12 months after therapy. In a retrospective long-term two-center study, average volume reductions in relation to baseline volume were statistically analyzed by the Wilcoxon signed-rank test. Side effects were documented.

RESULTS

In solid nodules, the average percent volume reductions at the 3, 6, 9, and 12-months follow-up were 49.98%, 46.40%, 65.77%, and 63.88%, respectively. The results were significant with p<0.05 in the Wilcoxon signed-rank test at the 3, 6, and 9-months follow-up. In complex nodules, the average percent volume reduction was 35.2% at 3 months, 36.89% at 6 months, and 63.64% at twelve months follow up. The results were significant with p<0.05 in the Wilcoxon signed-rank test at the 3- and 6-months follow-up. The complication rate was 5.2%. All complications occurred in patients with solid nodules.

CONCLUSION

The study showed that HIFU is an effective treatment method for both solid and complex nodules. The complication rate is relatively high at 5.2%. No long-term complications occurred. The solid nodules responded better to HIFU than complex nodules.

[Clinical effect and influencing factors of focused ultrasound ablation surgery combined with suction curettage for the treatment of mass-type cesarean scar pregnancy]

Objective: To investigate the clinical effect of focused ultrasound ablation surgery (FUAS) combined with suction curettage for mass-type cesarean scar pregnancy (CSP) and to analyze the influencing factors of vaginal bleeding and readmission. Methods: From January 2014 to December 2020, 88 patients with mass-type CSP were treated by FUAS combined with suction curettage in the Third Xiangya Hospital of Central South University. The clinical results and the influencing factors of bleeding and readmission for mass-type CSP were analyzed. Results: All the patients underwent one time FUAS treatment successfully. Immediately after FUAS treatment, color Doppler ultrasound showed obvious necrosis and no perfusion area in all lesions, and the blood flow in the mass-type CSP tissue significantly decreased. The median volume of blood loss in the procedure was 20 ml (range: 5-950 ml). Thirteen patients (15%, 13/88) had vaginal bleeding≥200 ml, and 15 patients (17%, 15/88) were hospitalized again. The average time for menstruation recovery was (28±8) days (range: 18-66 days). The average time needed for serum human chorionic gonadotropin-beta subunit to return to normal levels was (22±6) days (range: 7-59 days). The risk of large vaginal bleeding of patients were related to the blood supply of the mass (OR=5.280, 95%CI: 1.335-20.858, P=0.018) and the largest diameter of the mass (OR=1.060, 95%CI: 1.010-1.120, P=0.030). The risk of readmission were related to the largest diameter of the mass (OR=1.055, 95%CI: 1.005-1.108, P=0.030) and the depth of the uterus cavity (OR=1.583, 95%CI: 1.015-2.471, P=0.043). No serious complications such as intestinal and nerve injury occurred during and after FUAS treatment. Conclusions: FUAS combined with suction curettage is safe and effective in treating patients with mass-type CSP through this preliminary study. The volume of vaginal bleeding are associated with the blood supply of the mass and the largest diameter of the mass, the risk of readmission are related to the largest diameter of the mass and the depth of the uterus cavity.

[Clinical efficacy of focused ultrasound ablation surgery in the treatment of internal adenomyosis]

Objective: To investigate the relationship between the clinical efficacy and the ablated area of endometrium in patients with internal adenomyosis treated with focused ultrasound ablation surgery (FUAS). Methods: From January 2015 to December 2018, 122 patients in Chongqing Haifu Hospital who were diagnosed as internal adenomyosis through history, clinical symptoms and enhanced magnetic resonance imaging (MRI) and treated with FUAS were enrolled in this study. According to the patient's wishes, patients were given whether to ablate the adenomyotic lesion alone or ablate the adenomyotic lesion and the endometrium that involved in adenomyotic lesions together. The ablated area of adenomyotic lesions and endomitrium were evaluated by post-FUAS enhanced MRI. The adverse events and the changes of dysmenorrhea and menstrual volume at different follow-up points within 24 months were recorded. Results: Among the 122 patients, 32 patients chose to ablate adenomyotic lesion alone, and 90 patients chose to ablate the adenomyotic lesion and the endometrium during FUAS. No major complications such as bowel injury and nerve injury occurred after FUAS. The median non-perfused volume ratio of adenomyotic lesions was 31.7% in the group without endometrial ablation and it was 60.0% in the group with endometrium ablation (P<0.01). The improvement of dysmenorrhea in the group with endometrium ablation was significantly better than the group without endometrial ablation (P<0.01). The average menstrual volume score (3.4±0.9) before FUAS in the group with endometrial ablation was higher than that in the group without endometrial ablation (2.5±0.6; P<0.01), but it decreased significantly after FUAS treatment, reaching the similar menstrual volume score of the group without endometrial ablation (P>0.05). The proportions of abnormal vaginal discharge (34.4%, 31/90) and bleeding (16.7%, 15/90) were significantly higher in the group with endometrium ablation than those in the group without endometrial ablation (all P<0.01). Conclusions: FUAS could be safely and effectively used in the treatment of patients with internal adenomyosis. It seems that ablation of adenomyotic lesion and endometrium together could obtain better therapeutic effects.

The efficacy and safety of high-intensity focused ultrasound in the treatment of benign thyroid nodules: A systematic review and meta-analysis from 1990 to 2021

INTRODUCTION

To date, there have only been 2 systematic reviews, and 1 systematic review and meta-analysis on high-intensity focused ultrasound (HIFU) for benign thyroid nodules. The present systematic review and meta-analysis seeks to evaluate the efficacy and safety of HIFU in the treatment of benign thyroid nodules.

METHODS

Pubmed, Embase and Cochrane databases were searched for relevant studies from 1990 to 2021. Nine studies were included in the systematic review and 6 in the meta-analysis. Pooled volume reduction rates (VRRs) at 3, 6 and 24 months after HIFU were assessed.

RESULTS

This systematic review and meta-analysis showed that pooled VRRs at 3, 6, and 24 months after HIFU were 42.14 (95% confidence interval [CI] 28.66-55.62, I2=91%), 53.51 (95% CI 36.78-70.25, I2=97%) and 46.89 (95% CI 18.87-74.92, I2=99%), respectively. There was significant heterogeneity in the pooled VRRs at 3, 6 and 24 months after HIFU. No studies recorded complete disappearance of the nodules. Common side effects included pain, skin changes and oedema. There were no major complications except for transient vocal cord paralysis and voice hoarseness (0.014%) and transient Horner syndrome (0.5%).

CONCLUSION

HIFU may be an effective and safe alternative treatment modality for benign thyroid nodules. Larger clinical trials with longer follow-up are needed to evaluate the effectiveness of HIFU in treating benign thyroid nodules.

The efficacy and safety of high-intensity focused ultrasound in the treatment of benign thyroid nodules: A systematic review and meta-analysis from 1990 to 2021

INTRODUCTION

To date, there have only been 2 systematic reviews, and 1 systematic review and meta-analysis on high-intensity focused ultrasound (HIFU) for benign thyroid nodules. The present systematic review and meta-analysis seeks to evaluate the efficacy and safety of HIFU in the treatment of benign thyroid nodules.

METHODS

Pubmed, Embase and Cochrane databases were searched for relevant studies from 1990 to 2021. Nine studies were included in the systematic review and 6 in the meta-analysis. Pooled volume reduction rates (VRRs) at 3, 6 and 24 months after HIFU were assessed.

RESULTS

This systematic review and meta-analysis showed that pooled VRRs at 3, 6, and 24 months after HIFU were 42.14 (95% confidence interval [CI] 28.66-55.62, I2=91%), 53.51 (95% CI 36.78-70.25, I2=97%) and 46.89 (95% CI 18.87-74.92, I2=99%), respectively. There was significant heterogeneity in the pooled VRRs at 3, 6 and 24 months after HIFU. No studies recorded complete disappearance of the nodules. Common side effects included pain, skin changes and oedema. There were no major complications except for transient vocal cord paralysis and voice hoarseness (0.014%) and transient Horner syndrome (0.5%).

CONCLUSION

HIFU may be an effective and safe alternative treatment modality for benign thyroid nodules. Larger clinical trials with longer follow-up are needed to evaluate the effectiveness of HIFU in treating benign thyroid nodules.

Prospective clinical trial on the learning curve of high-intensity-focused ultrasound for the treatment of breast fibroadenoma

INTRODUCTION

High-intensity-focused ultrasound (HIFU) is a safe and feasible treatment option for breast fibroadenoma. However, its learning curve has not been described in the medical literature.

METHODS

All patients with biopsy-proven fibroadenoma considered indicated for HIFU were screened for eligibility for HIFU treatment. A total of 60 patients were recruited according to the pre-defined sample size calculation.

RESULTS

Sixty consecutive patients were divided into three cohorts in chronological order. The mean tumor volume shrinkage rates in cohorts 1, 2, and 3 at 6 months post-HIFU ablation were 38%, 34%, and 59%, respectively. Significant tumor shrinkage was observed from case 41 onward (p < 0.0001). Similarly, the mean tumor volume shrinkage rates in cohorts 1, 2, and 3 at 12 months post-HIFU ablation were 45%, 51%, and 71%, respectively. Significant tumor shrinkage was observed from case 41 onwards (p < 0.0473). The mean procedure time for the first 20 patients was 48.5 (range 45-75) minutes, while that in the second 20 patients was 39.7 (range 20-60) minutes, and that in the last 20 patients was 28.9 (range 15-45) minutes. The treatment time was significantly shorter from case 41 onwards (p = 0.0481).

CONCLUSION

Treatment outcomes and treatment time improved significantly after performing approximately 40 HIFU procedures.

Novel Therapeutic Method for Unresectable Pancreatic Cancer-The Impact of the Long-Term Research in Therapeutic Effect of High-Intensity Focused Ultrasound (HIFU) Therapy

High-intensity focused ultrasound (HIFU) is a novel advanced therapy for unresectable pancreatic cancer (PC). HIFU therapy with chemotherapy is being promoted as a novel method to control local advancement by tumor ablation. We evaluated the therapeutic effects of HIFU therapy in locally advanced and metastatic PC. PC patients were treated with HIFU as an optional local therapy and systemic chemotherapy. The FEP-BY02 (Yuande Bio-Medical Engineering) HIFU device was used under ultrasound guidance. Of 176 PC patients, 89 cases were Stage III and 87 were Stage IV. The rate of complete tumor ablation was 90.3%, while that of symptom relief was 66.7%. The effectiveness on the primary lesions were as follows: complete response (CR): n = 0, partial response (PR): n = 21, stable disease (SD): n = 106, and progressive disease (PD): n = 49; the primary disease control rate was 72.2%. Eight patients underwent surgery. The median survival time (MST) after diagnosis for HIFU with chemotherapy compared to chemotherapy alone (100 patients in our hospital) was 648 vs. 288 days (p < 0.001). Compared with chemotherapy alone, the combination of HIFU therapy and chemotherapy demonstrated significant prolongation of prognosis. This study suggests that HIFU therapy has the potential to be a novel combination therapy for unresectable PC.

Technique Success, Technique Efficacy and Complications of HIFU Ablation for Palliation of Pain in Patients With Bone Lesions: A Meta-Analysis of 28 Feasibility Studies

Several feasibility studies have reported that high-intensity focused ultrasound (HIFU) ablation can be applied to ease patients' bone pain. However, the effect of HIFU ablation to palliate bone pain remains unclear. To evaluate the technique's success, efficacy, minor complication and major complication on patients suffering from bone pain, we searched the PubMed, MEDLINE, EMBASE and Cochrane Library databases from January 1998 to March 2019. Clinical studies that have assessed the association between bone pain and HIFU ablation were involved. We filtered out 28 feasibility studies, which reported the association between HIFU ablation and bone pain, including a total of 717 patients and 736 bone lesions. Overall, our results indicate that the rate of technique success of HIFU ablation was 93% (95% confidence interval [CI] 89%-96%) for patients with bone lesions. The technique efficacy rate of HIFU ablation for palliation of pain from bone lesions was 80% (95% CI 74%-87%) in all the patients, 96% (91%-100%) in the subgroup of retrospective studies and 77% (69%-85%) in the subgroup of prospective studies. In regard to HIFU ablation treatment safety, the hazard ratio for minor complication was 12% (95% CI 7%-17%), and the hazard ratio for major complication was 2% (95% CI 1%-3%). In conclusion, the summary rates for various considerations of using HIFU ablation for the palliation of bone pain are as follows: technique success is 93%, technique efficacy is 77%, minor complication is 12% and major complication is 2%. Our results suggest that extracorporeal HIFU ablation is a promising method for palliation of pain in bone lesions, with high technique success and efficacy, but low adverse events.

Tolerability and Feasibility of X-ray Guided Non-Invasive Ablation of the Medial Branch Nerve with Focused Ultrasound: Preliminary Proof of Concept in a Pre-clinical Model

Four to six million patients a year in the United States suffer from chronic pain caused by facet joint degeneration. Thermal ablation of the affected facet joint's sensory nerve using radiofrequency electrodes is the therapeutic standard of care. High-intensity focused ultrasound (HIFU) is a novel technology enabling image-guided non-invasive thermal ablation of tissue. Six pigs underwent fluoroscopy-guided HIFU of the medial branch nerve and were followed up for 1 wk (two pigs), 1 mo (two pigs) and 3 mo (two pigs). At the end of each follow-up period, the animals were sacrificed, and targeted tissue was excised and evaluated with computed tomography scans as well as by macro- and micropathology. No significant adverse events were recorded during the procedure or follow-up period. All targets were successfully ablated. X-Ray-guided HIFU is a feasible and promising alternative to radiofrequency ablation of the lumbar facet joint sensory nerve.

Systematic review of the role of high intensity focused ultrasound (HIFU) in treating malignant lesions of the hepatobiliary system

BACKGROUND

High Intensity Focused Ultrasound (HIFU) is an emerging non-invasive, targeted treatment of malignancy. The aim of this review was to assess the efficacy, safety and optimal technical parameters of HIFU to treat malignant lesions of the hepatobiliary system.

METHODS

A systematic search of the English literature was performed until March 2020, interrogating Pubmed, Embase and Cochrane Library databases. The following key-words were input in various combinations: 'HIFU', 'High intensity focussed ultrasound', 'Hepatobiliary', 'Liver', 'Cancer' and 'Carcinoma'. Extracted content included: Application type, Exposure parameters, Patient demographics, and Treatment outcomes.

RESULTS

Twenty-four articles reported on the clinical use of HIFU in 940 individuals to treat malignant liver lesions. Twenty-one studies detailed the use of HIFU to treat hepatocellular carcinoma only. Mean tumour size was 5.1 cm. Across all studies, HIFU resulted in complete tumour ablation in 55% of patients. Data on technical parameters and the procedural structure was very heterogeneous. Ten studies (n = 537 (57%) patients) described the use of HIFU alongside other modalities including TACE, RFA and PEI; 66% of which resulted in complete tumour ablation. Most common complications were skin burns (15%), local pain (5%) and fever (2%).

CONCLUSION

HIFU has demonstrated benefit as a treatment modality for malignant lesions of the hepatobiliary system. Combining HIFU with other ablative therapies, particularly TACE, increases the efficacy without increasing complications. Future human clinical studies are required to determine the optimal treatment parameters, better define outcomes and explore the risks and benefits of combination therapies.

Randomized Trial of Focused Ultrasound Subthalamotomy for Parkinson's Disease

BACKGROUND

The subthalamic nucleus is the preferred neurosurgical target for deep-brain stimulation to treat cardinal motor features of Parkinson's disease. Focused ultrasound is an imaging-guided method for creating therapeutic lesions in deep-brain structures, including the subthalamic nucleus.

METHODS

We randomly assigned, in a 2:1 ratio, patients with markedly asymmetric Parkinson's disease who had motor signs not fully controlled by medication or who were ineligible for deep-brain stimulation surgery to undergo focused ultrasound subthalamotomy on the side opposite their main motor signs or a sham procedure. The primary efficacy outcome was the between-group difference in the change from baseline to 4 months in the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor score (i.e., part III) for the more affected body side (range, 0 to 44, with higher scores indicating worse parkinsonism) in the off-medication state. The primary safety outcome (procedure-related complications) was assessed at 4 months.

RESULTS

Among 40 enrolled patients, 27 were assigned to focused ultrasound subthalamotomy (active treatment) and 13 to the sham procedure (control). The mean MDS-UPDRS III score for the more affected side decreased from 19.9 at baseline to 9.9 at 4 months in the active-treatment group (least-squares mean difference, 9.8 points; 95% confidence interval [CI], 8.6 to 11.1) and from 18.7 to 17.1 in the control group (least-squares mean difference, 1.7 points; 95% CI, 0.0 to 3.5); the between-group difference was 8.1 points (95% CI, 6.0 to 10.3; P<0.001). Adverse events in the active-treatment group were dyskinesia in the off-medication state in 6 patients and in the on-medication state in 6, which persisted in 3 and 1, respectively, at 4 months; weakness on the treated side in 5 patients, which persisted in 2 at 4 months; speech disturbance in 15 patients, which persisted in 3 at 4 months; facial weakness in 3 patients, which persisted in 1 at 4 months; and gait disturbance in 13 patients, which persisted in 2 at 4 months. In 6 patients in the active-treatment group, some of these deficits were present at 12 months.

CONCLUSIONS

Focused ultrasound subthalamotomy in one hemisphere improved motor features of Parkinson's disease in selected patients with asymmetric signs. Adverse events included speech and gait disturbances, weakness on the treated side, and dyskinesia. (Funded by Insightec and others; ClinicalTrials.gov number, NCT03454425.).

Ultrafast three-dimensional microbubble imaging in vivo predicts tissue damage volume distributions during nonthermal brain ablation

Transcranial magnetic resonance imaging (MRI)-guided focused ultrasound (FUS) thermal ablation is under clinical investigation for non-invasive neurosurgery, though its use is restricted to central brain targets due primarily to skull heating effects. The combination of FUS and contrast agent microbubbles greatly reduces the ultrasound exposure levels needed to ablate brain tissue and may help facilitate the use of transcranial FUS ablation throughout the brain. However, sources of variability exist during microbubble-mediated FUS procedures that necessitate the continued development of systems and methods for online treatment monitoring and control, to ensure that excessive and/or off-target bioeffects are not induced from the exposures. Methods: Megahertz-rate three-dimensional (3D) microbubble imaging in vivo was performed during nonthermal ablation in rabbit brain using a clinical-scale prototype transmit/receive hemispherical phased array system. Results:In-vivo volumetric acoustic imaging over microsecond timescales uncovered spatiotemporal microbubble dynamics hidden by conventional whole-burst temporal averaging. Sonication-aggregate ultrafast 3D source field intensity data were predictive of microbubble-mediated tissue damage volume distributions measured post-treatment using MRI and confirmed via histopathology. Temporal under-sampling of acoustic emissions, which is common practice in the field, was found to impede performance and highlighted the importance of capturing adequate data for treatment monitoring and control purposes. Conclusion: The predictive capability of ultrafast 3D microbubble imaging, reported here for the first time, will enable future microbubble-mediated FUS treatments with unparalleled precision and accuracy, and will accelerate the clinical translation of nonthermal tissue ablation procedures both in the brain and throughout the body.

Ultrasound-Guided Focused Ultrasound Treatment for Painful Bone Metastases: A Pilot Study

Focused ultrasound (FUS) for palliation of bone metastases has typically been performed under magnetic resonance guidance. To address limitations of this approach, this pilot study evaluated a stand-alone, portable FUS device guided by diagnostic ultrasound alone (ultrasound [US]-guided FUS). Nine patients were treated; safety and efficacy were assessed for 10 d after the procedure, and medical charts were evaluated to assess durability of pain response. The procedure was safe and tolerable, with four patients reporting minor skin-related irritations. Average pain score decreased from 6.9 at baseline to 3.2 at day 10; analgesic use on average also decreased from baseline to day 10. Six patients had durable pain relief as assessed after the follow-up period. Our study provides evidence that US-guided FUS is a safe, tolerable and versatile procedure. It appears to be effective in achieving durable pain response in patients with painful bone metastases. Further research is required to refine the technology and optimize its efficacy.

HIFU for the treatment of difficult colorectal liver metastases with unsuitable indications for resection and radiofrequency ablation: a phase I clinical trial

BACKGROUND

The goal of this study is to evaluate the safety and efficacy of high intensity focused ultrasound (HIFU) for patients with colorectal liver metastases (CRLM) but were contraindicated for resection and radiofrequency ablation.

METHODS

Patients between 20 and 80 years of age with 1-3 liver metastases from colorectal cancer were selected. Included patients have had their primary lesions removed with no evidence of extrahepatic metastasis prior to the study. Ultrasound-guided HIFU was employed and target regions' ablation was achieved with repeated sonications from the deep to shallow regions of the tumors section by section.

RESULTS

Thirteen patients were enrolled. The most common adverse events (AEs) were pain (n = 8), followed by fatigue (n = 7), increased aspartate aminotransferase (AST) (n = 7), increased alanine aminotransferase (ALT) (n = 5), and skin edema (n = 4). No grade ≥ 3 AEs occurred and while most patients (76.9%) achieved a complete response, three patients achieved a partial response. The objective response rate was 100% after the first HIFU treatment. Nine patients relapsed but the tumors were mostly isolated to the liver (8/9). The median follow-up period was 25 months. The 2-year progression-free survival (PFS) was 16.7%, and the median PFS was 9 months. Notably, the 2-year overall survival (OS) was 77.8%, and the median OS was 25 months.

CONCLUSION

This study indicates that the HIFU treatment is safe, is able to achieve a good tumor response rate and long-term prognosis even when the foci were in high-risk locations, and should be considered for patients who were considered unsuitable for other local treatments.

An experience-based review of HIFU in functional interventional neuroradiology: transcranial MRgFUS thalamotomy for treatment of tremor

Tremor is a common and very disabling symptom in patients with essential tremor and Parkinson's disease. In the recent years, transcranial ablation of thalamic nuclei using magnetic resonance guided high-intensity focused ultrasound has emerged as a minimally invasive treatment for tremor. The aim of this review is to discuss, in the light of our single-center experience, the technique, current applications, results, and future perspectives of this novel technology.

Systematic review and meta-analysis of safety and efficacy of high-intensity focused ultrasound (HIFU) for face and neck rejuvenation

High-intensity focused ultrasound (HIFU) is widely used for skin rejuvenation and tightening. The aim of this study was to determine the safety and efficacy of HIFU for face and neck rejuvenation. A systematic search of peer reviewed articles published before December 2017 was performed using Medline, Web of Science, and Scopus databases. Retrieved studies were screened, and clinical trials or follow-up studies which were evaluated the effect of HIFU on rejuvenation treatments of face and neck area were included. Risk of bias for each study was assessed and was reported. Safety and efficacy variables, which were reported more often in papers, were included in meta-analysis. Seventeen studies involving 477 participants were included in the analysis. Meta-analysis showed moderate improvement as scores of 2.74 (95% CI 2.06-3.43) and 2.68 (95% CI 1.92-3.45), out of 5 maximum score, for objective improvement score and subjective satisfaction score, respectively. Meta-analysis of mean pain score, assessed by a 0-10 Likert score, was 4.2 (95% CI 4.27-5.19). Edema and erythema showed considerable heterogeneity, and no hyperpigmentation was reported by included studies. Included studies used multiple and different outcome variables with different scoring at various time points. Long follow-up was not reported by majority of studies. HIFU is safe procedure in short term and has a moderate effect on rejuvenation of face and neck areas.

How noninvasive treatment of uterine fibroids affects endometrial receptivity: a prospective cohort study

OBJECTIVE

To investigate the effect of the ultrasonic energy during MRI-guided high-intensity focused ultrasound ablation (HIFU) of uterine fibroids on molecular and tissue markers of endometrial receptivity in women of reproductive age.

MATERIAL AND METHODS

A prospective cohort study of 60 women of reproductive age was conducted. The main group consisted of 32 patients suffering from the symptomatic course of uterine fibroids who received treatment with HIFU ablation of uterine fibroids. The control group consisted of 28 healthy fertile women examined voluntarily. The endometrium obtained with pipelle biopsy on days 20-22 of the cycle was examined by scanning electron microscopy and immunohistochemistry before and three months after the treatment. The results were processed by the method of variation statistics using the SPSS 22.0.

RESULTS

The focused ultrasound rays passing through the endometrium did not cause any change in the maturation rate or the state of intercellular contacts. At the same time, a significant increase in the frequency of asynchronous maturation of pinopodia was found to be 14.28% before HIFU versus 50.00% after HIFU; p = .021 and the number of heteromorphic secretory cells 5.88% before HIFU versus 53.33% after HIFU; p = .002 in implantation endometrium. A significant decrease in the stromal expression of CD95^+bright in the endometrium to the level comparable with control values was observed after HIFU (from 70.22 ± 9.77 c/s to 48.81 ± 5.47 c/s; p < .001; the control level - 47.80 ± 2.13 c/s). The ratio and expression of steroid receptors, proliferation markers, p53-dependent apoptosis and its blockers, regulators and markers of angiogenesis, LIF and LIF-R signaling molecules in the stroma and endometrial glands did not change significantly after treatment.

CONCLUSION

This study did not reveal any significant negative effects of HIFU ablation of uterine fibroids on endometrial receptivity in women of reproductive age.

Transient choroidal detachment after ultrasonic circular cyclocoagulation

Two patients with refractory glaucoma followed in our ophthalmology department registered progression on left eyes (OS) despite best practice. Best corrected visual acuity (BCVA) was 9/10 and 8/10 and intraocular pressure (IOP) was above 20 mm Hg while under maximal hypotensive therapy. The procedure was performed under retrobulbar anaesthesia with second-generation EyeOp1probes. In follow-up, OS were hypotonic with registered IOP ≤5 mm Hg and revealed a 3/10 BCVA. The funduscopy showed one temporal and superior and another nasal and temporal choroidal detachments. The patients started oral steroids and interrupted all ocular hypotensive medication. After therapy, patients returned with normal rising OS IOPs and with totally reapplied choroids, accompanied by normalised BCVA. These two cases are proof of the possibility of transient choroidal detachment after a ultrasonic circular cyclocoagulation. While a very rare major vision-threatening complication, every ophthalmologist should remind it when sudden BCVA reductions occur after this procedure.

The Efficacy and Safety of High-Intensity Focused Ultrasound (HIFU) Therapy for Benign Thyroid Nodules-A Single Center Experience from Singapore

BACKGROUND

High-intensity focused ultrasound (HIFU) is a recent noninvasive technique of treating thyroid nodules. Our study aims to investigate the efficacy and safety of HIFU in treating benign thyroid nodules.

METHODS

This is a retrospective analysis of consecutive patients who underwent HIFU of benign thyroid nodules at our institution from July 2017-2018. All procedures were performed by a single surgeon. Patients were evaluated immediately post-procedure, and at subsequent intervals of 1 week, 1 month, 3 months, and 6 months. The primary endpoint was thyroid nodule volume reduction at 6 months posttreatment. Secondary endpoints were post-procedure local complications.

RESULTS

Ten patients with 13 thyroid nodules were included. The median follow-up period was 426 days (range 238-573). Mean maximum diameter reduced from 2.6 cm (±0.8) pretreatment to 1.4 cm (±0.7, P < 0.05) 6 months posttreatment. Mean nodule volume reduced from 5.2 cm³ (±4.2) pretreatment to 1.5 cm³ (±1.3, P = 0.01) 6 months posttreatment. Mean volume reduction ratio (VRR) at 6 months posttreatment was 63.2% (±22.5, P < 0.05), with volume reduction of ≥50% in 10 of 13 (76.9%) nodules. Two nodules (15.4%) showed size increases from 4 months posttreatment. No patients experienced local skin burns or hematomas. Mean pain scores were 1.5 (±1.2) immediate post-procedure, 0.8 (±1.5) at 1 week, and 0.6 (±1.2) at 1 month post-procedure, respectively, with no reports of pain beyond 1 month. Only two (20.0%) patients had early, temporary posttreatment voice hoarseness.

CONCLUSION

Our study shows HIFU ablation to be efficacious and safe-with significant thyroid nodule volume reductions, and no significant or prolonged local complications.

Robotically-Assisted Sonic Therapy for Renal Ablation in a Live Porcine Model: Initial Preclinical Results

PURPOSE

To demonstrate the feasibility of Robotically Assisted Sonic Therapy (RAST)-a noninvasive and nonthermal focused ultrasound therapy based on histotripsy-for renal ablation in a live porcine model.

MATERIALS AND METHODS

RAST ablations (n = 11) were performed in 7 female swine: 3 evaluated at 1 week (acute) and 4 evaluated at 4 weeks (chronic). Treatment groups were acute bilateral (3 swine, 6 ablations with immediate computed tomography [CT] and sacrifice); chronic single kidney (3 swine, 3 ablations; CT at day 0, week 1, and week 4 after treatment, followed by sacrifice); and chronic bilateral (1 swine, 2 ablations). Treatments were performed using a prototype system (VortxRx; HistoSonics, Inc) and targeted a 2.5-cm-diameter sphere in the lower pole of each kidney, intentionally including the central collecting system.

RESULTS

Mean treatment time was 26.4 minutes. Ablations had a mean diameter of 2.4 ± 0.3 cm, volume of 8.5 ± 2.4 cm3, and sphericity index of 1.00. Median ablation volume decreased by 96.1% over 4 weeks. Histology demonstrated complete lysis with residual blood products inside the ablation zone. Temporary collecting system obstruction by thrombus was observed in 4/11 kidneys (2 acute and 2 chronic) and resolved by 1 week. There were no urinary leaks, main vessel thromboses, or adjacent organ injuries on imaging or necropsy.

CONCLUSIONS

In this normal porcine model, renal RAST demonstrated complete histologic destruction of the target renal tissue while sparing the urothelium.

Ultrasound-guided high-intensity focused ultrasound in the treatment of uterine fibroids

The aim of the present study was to investigate factors affecting ablation effect and safety of ultrasound-guided high-intensity focused ultrasound (USgHIFU) for uterine fibroids (UFs).A retrospective analysis of 346 patients with symptomatic UFs who were treated with USgHIFU was performed. All UFs was grouped based on magnetic resonance imaging (MRI) characteristics before HIFU; all adverse events and treatment data were recorded during and after HIFU. One-way analysis of variance and multiple linear regression analysis were used to evaluate the effect of USgHIFU treatment and affecting factors.The results showed that the mean age of patients was 38.3 ± 6.1 years, with the mean nonperfusion volume rate of 74.4 ± 14.7% and the mean energy efficiency factor (EEF) of 7.2 ± 4.8 J/mm. Except for the size group, the ablation rate was significantly different (P < .001); and the anterior, intramural, hypointense (T2WI), and mild enhancement (T1WI contrast enhancement) UFs had the highest ablation rate. The EEF of the anterior, intramural, hypointense (T2WI), mild enhancement (T1WI contrast enhancement), and >5 cm UFs had minimum value, with a statistically significant difference (P < .01). According to multiple linear regression model, the distance from the UFs ventral side to the skin, enhancement type on T1WI, size of UFs, signal intensity on T2WI, location of UFs, type and volume of fibroids all had a line relationship with EEF, and the enhancement type on T1WI was the greatest factor affecting the ablation effect. Some patients (37.6%) had thermal injury of the sacrum on MRI, but no serious adverse events were observed.Our results suggest that USgHIFU can be safely used and have a promising prospect for treating UFs, even though its effect may be affected by anatomical features, tissue characteristics, and blood supply.

Full Modeling of High-Intensity Focused Ultrasound and Thermal Heating in the Kidney Using Realistic Patient Models

OBJECTIVE

High-intensity focused ultrasound (HIFU) therapy can be used for noninvasive treatment of kidney (renal) cancer, but the clinical outcomes have been variable. In this study, the efficacy of renal HIFU therapy was studied using a nonlinear acoustic and thermal simulations in three patients.

METHODS

The acoustic simulations were conducted with and without refraction in order to investigate its effect on the shape, size, and pressure distribution at the focus. The values for the attenuation, sound speed, perfusion, and thermal conductivity of the kidney were varied over the reported ranges to determine the effect of variability on heating. Furthermore, the phase aberration was studied in order to quantify the underlying phase shifts using a second order polynomial function.

RESULTS

The ultrasound field intensity was found to drop on average 11.1 dB with refraction and 6.4 dB without refraction. Reflection at tissue interfaces was found to result in a loss less than 0.1 dB. Focal point splitting due to refraction significantly reduced the heating efficacy. Perfusion did not have a large effect on heating during short sonication durations. Small changes in temperature were seen with varying attenuation and thermal conductivity, but no visible changes were present with sound speed variations. The aberration study revealed an underlying trend in the spatial distribution of the phase shifts.

CONCLUSION

The results show that the efficacy of HIFU therapy in the kidney could be improved with aberration correction.

SIGNIFICANCE

A method is proposed by that patient specific pre-treatment calculations could be used to overcome the aberration and therefore make ultrasound treatment possible.

HIFU treatment for fibroadenoma - a clinical study at National Scientific Research Centre, Astana, Kazakhstan

This randomized controlled study evaluated effect of low frequency high intensity focused ultrasound (HIFU) in 80 women with breast fibroadenomas randomly and evenly divided into main and control groups, treated with HIFU and sectoral resection accordingly. In- vitro trial of fibroadenoma samples exposed to different power levels:100 Watt (W), 200 W and 300 W, analysis of results shown that optimal ablation power 200W was enough for coagulation necrosis of tumour, while 300W ablation caused complete destruction of tissues. Results showed that 20% of control group (surgically treated) patients had post-operative complications and 12.5% - postponed recurrences, as opposed to zero incidence of either in the main group (HIFU treated). The average hospital stay following HIFU reduced by 52%. Both in-vitro and morphological studies showed that HIFU caused high precision coagulation necrosis of fibroadenoma and preservation of the surrounding tissues. HIFU enabled to avoid early postoperative complications and long-term recurrences. This technique can significantly improve quality of life by reducing pain intensity and enabling sooner activity..

Development of an MRI-Compatible High-Intensity Focused Ultrasound Phased Array Transducer Dedicated for Breast Tumor Treatment

High-intensity focused ultrasound (HIFU) under magnetic resonance imaging (MRI) guidance can achieve a noninvasive and precise ablation of the solid tumor. In the study, an MRI-compatible 1-MHz 16-channel ring-shaped transducer was developed to minimize the burn risk of breast skin and perform volumetric ablation for short treatment time. The measured electroacoustic conversion efficiency of the transducer was 50.90% ± 5. The transducer could produce a point and a quasi-hollow-cylinder lesion in a thermal-sensitive phantom or an ex vivo pork by tuning the phase of each element. It may achieve volumetric ablation of 1.5 cm³ when the point lesion is located inside the hollow lesion. Ex vivo ablation experiments showed that the transducer could cause a coagulative necrosis in the pork from the surrounded subcutaneous fat by 5 mm without fat damage. The temperature and region of the pork ablation were quantified by MRI technique. There was no MRI interference from HIFU and vice versa while both systems operated concurrently.

Numerical and Experimental Evaluation of High-Intensity Focused Ultrasound-Induced Lesions in Liver Tissue Ex Vivo

OBJECTIVES

Recent advances in the field of acoustics and piezoelectric and ultrasound transducers have led to new approaches to the diagnosis and treatment of certain diseases. One method of treatment with ultrasonic waves is high-intensity focused ultrasound (HIFU) treatment, which is a thermal therapeutic method used to treat malignant tumors. Although a variety of treatment-planning strategies using ultrasonic waves have been investigated, little clinical success has been achieved. Computational modeling is a powerful tool for predicting device performance.

METHODS

The heating induced by a concave transducer with operating powers of 85 and 135 W was studied, and the experimental results presented in this article verify its applicability. Numerical simulations of the nonlinear acoustic field were performed by using the Westervelt and Khokhlov-Zabolotskaya-Kuznetsov equations. Heat transfer was measured for the 2 operational powers, and the results were compared with ex vivo experimental results. In addition, thermal dose contours for both the simulation and experimental results were calculated to investigate the ablated area.

RESULTS

Good agreement was found between the experimental and numerical results. The results show that the average temperature deviations calculated at the focal point were 12.8% and 4.3% for transducer powers of 85 and 135 W, respectively.

CONCLUSIONS

This study provides guidance to HIFU practitioners in determining lesion size and identifying nonlinear effects that should be considered in HIFU procedures.

High-intensity focused ultrasound ablation around the tubing

High-intensity focused ultrasound (HIFU) has been emerging as an effective and noninvasive modality in cancer treatment with very promising clinical results. However, a small vessel in the focal region could be ruptured, which is an important concern for the safety of HIFU ablation. In this study, lesion formation in the polyacrylamide gel phantom embedded with different tubing (inner diameters of 0.76 mm and 3 mm) at varied flow speeds (17–339 cm/s) by HIFU ablation was photographically recorded. Produced lesions have decreased length (~30%) but slightly increased width (~6%) in comparison to that without the embedded tubing. Meanwhile, bubble activities during the exposures were measured by passive cavitation detection (PCD) at the varied pulse repetition frequency (PRF, 10–30 Hz) and duty cycle (DC, 10%-20%) of the HIFU bursts. High DC and low flow speed were found to produce stronger bubble cavitation whereas no significant influence of the PRF. In addition, high-speed photography illustrated that the rupture of tubing was produced consistently after the first HIFU burst within 20 ms and then multiple bubbles would penetrate into the intraluminal space of tubing through the rupture site by the acoustic radiation force. Alignment of HIFU focus to the anterior surface, middle, and posterior surface of tubing led to different characteristics of vessel rupture and bubble introduction. In summary, HIFU-induced vessel rupture is possible as shown in this phantom study; produced lesion sizes and shapes are dependent on the focus alignment to the tubing, flow speed, and tubing properties; and bubble cavitation and the formation liquid jet may be one of the major mechanisms of tubing rupture as shown in the high-speed photography.

Predicting Tissue Susceptibility to Mechanical Cavitation Damage in Therapeutic Ultrasound

Histotripsy is a developing focused ultrasound procedure that uses cavitation bubbles to mechanically homogenize soft tissue. To better understand the mechanics of tissue damage, a numerical model of single-bubble dynamics was used to calculate stress, strain and strain rate fields produced by a cavitation bubble exposed to a tensile histotripsy pulse. The explosive bubble growth and its subsequent collapse were found to depend on the properties of the surrounding material and on the histotripsy pulse. Stresses far greater than gigapascals were observed close to the bubble wall, but attenuated by four to six orders of magnitude within 50 μm from the bubble wall, with at least two orders of magnitude attenuation occurring within the first 10 μm from the bubble. Elastic stresses were found to dominate close to the bubble wall, whereas viscous stresses tended to persist farther into the surroundings. A non-dimensional parameter combining tissue, waveform and bubble properties was identified that dictates the dominant stress (viscous vs. elastic) as a function of distance from the bubble nucleus. In a cycle of bubble growth and collapse, characteristic times at which mechanical damage is likely to occur and dominant mechanisms acting at each time were identified.

Outcome of high-intensity focused ultrasound and uterine artery embolization in the treatment and management of cesarean scar pregnancy: A retrospective study

The aim of the study was to compare the efficacy and safety between high-intensity focused ultrasound (HIFU) treatment and uterine artery embolization (UAE) treatment; we retrospectively analyzed 152 cases with cesarean scar pregnancy (CSP). Based on our inclusion and exclusion criteria, 152 patients (average age, 31.8 ± 4.6 years old) with CSP were eligible for the HIFU group (85 patients) or the UAE group (77 patients). All patients in 2 groups received the treatment with suction curettage under hysteroscopy prior to HIFU or UAE treatment and followed up for 12 months. The assessment criteria of treatment efficacy included the success rate, intraoperative blood loss, duration of vaginal bleeding, normal menstrual function recovery time, time for β-human chorionic gonadotrophin (β-HCG) back to normal level, duration of hospital stays, and other adverse effects. Following up for 12 months, the HIFU group was of less intraoperative blood loss (76.38 ± 22.89 vs 114.42 ± 30.34 mL, P = .02), shorter duration of postoperative vaginal bleeding (11.28 ± 3.65 vs 15.77 ± 7.24 days, P = .01) and lower adverse effects rate comparing to the UAE group. However, the HIFU group have longer time for the β-HCG recovery to the normal level (35.28 ± 9.86 vs 29.91 ± 7.29, P = .03). Additionally, there were no significantly statistic differences between the 2 groups in baseline characteristics, success rate, and average time of gestational sac disappeared and menstrual recovery and hospital stay. Thus, we concluded that the method of both HIFU and UAE combined with suction curettage under hysteroscopy is safe and effective in the management of CSP. Meanwhile, HIFU is a better therapy option than UAE for those women who are seeking complete relieve of symptom to gain fertility.

Non-Invasive Liver Ablation Using Histotripsy: Preclinical Safety Study in an In Vivo Porcine Model

This study investigates the safety profile for use of histotripsy, a non-invasive ultrasonic ablation method currently being developed for the treatment of liver cancer, for liver ablation in an in vivo porcine model. Histotripsy treatments were applied to the liver and hepatic veins of 22 porcine subjects, with half of the subjects receiving systemic heparinization. Vital signs (heart rate, blood pressure, temperature, electrocardiogram and SpO₂) were monitored throughout the procedure and for 1 h post-treatment. Blood was drawn at six points during the experiment to analyze blood gases, liver function and free hemoglobin levels. All treatments were guided and monitored by real-time ultrasound imaging. After treatment, the tissue was harvested for histological analysis. Results indicated that histotripsy generated well-defined lesions inside the liver and around the treated hepatic veins of all subjects in both treatment groups. Vital signs and blood analysis revealed that animals responded well to histotripsy, with all animals surviving the treatment. One animal in the non-heparinized group had a transient increase in pH and decreases in blood pressure, heart rate and PCO₂ during the 15-min vessel treatment, with these changes returning to baseline levels soon after the treatment. Overall, the results indicate that histotripsy can safely be performed on the liver without the need for systemic heparinization, even in regions containing large hepatic vessels, supporting its future use for the treatment of liver cancer.

Safety of ultrasound-guided high-intensity focused ultrasound ablation for diffuse adenomyosis: A retrospective cohort study

OBJECTIVES

To evaluate the safety of ultrasound-guided high-intensity focused ultrasound (HIFU) ablation for patients with diffuse adenomyosis.

METHODS

This was a retrospective cohort study. The data was collected from 417 symptomatic adenomyosis patients who underwent ultrasound-guided HIFU between January 2012 and December 2015 at 1st Affiliated Hospital of Chongqing Medical University, Chongqing, China. Among them were 260 patients with diffuse adenomyosis (Group D) and 157 patients with focal adenomyosis (Group F). All patients underwent contrast-enhanced magnetic resonance imaging (MRI) one week before and the day after HIFU treatment. Successful treatment with HIFU was measured by the non-perfused volume ratio (NPVR). Intraprocedural and postprocedural adverse effects and complications were recorded to assess the safety of the procedure. Patients were followed-up for three months post-treatment. Complications were given a grade A through F according to the SIR Standards.

RESULTS

All patients successfully completed the procedure, non-perfused regions appeared in 415 (99.5%) patients. The non-perfused volume ratio (NPVR) of Group D was significantly lower than that of Group F (P<0.05). During the procedure, the odds ratio of skin-burning pain was 1.7 (OR=1.617, 95% CI: 1.103-2.532), when comparing Group D with Group F, while the odds ratio of inguinal pain was equal to 2.0 (OR=2.038, 95% CI: 1.161-3.580), when Group F was compared to Group D. 97 patients (23.3%) received nominal therapy due to complications ([Society of interventional radiology, SIR]-B grade), among them, there were 62 cases (23.8%) in Group D and 35 cases (22.3%) in Group F. No significant difference was found between the two groups (P>0.05) and neither of the reported complications of SIR-C-SIR-F occurred within the two groups.

CONCLUSIONS

Based on our results, ultrasound-guided HIFU is safe for the treatment of diffuse adenomyosis, and controlling the ablation zone is crucial to ensure patients' safety.

Effects of different hydrostatic pressure on lesions in ex vivo bovine livers induced by high intensity focused ultrasound

It is well-known that acoustic cavitation associated with the high intensity focused ultrasound (HIFU) treatment often would change the morphology and size of lesions in its treatment. In most studies reported in literature, high ambient hydrostatic pressure was used to suppress the cavitation completely. Investigation of the effects by varying the ambient hydrostatic pressure (P_stat) is still lacking. In this paper, the effects of HIFU on lesions in ex vivo bovine liver specimens under various P_stat are systematically investigated. A 1MHz HIFU transducer, with an aperture diameter of 70mm and a focal length of 55mm, was used to generate two groups US exposure of different acoustic intensities and exposure time (6095W/cm²×8s and 9752W/cm²×5s), while keeping the same acoustic energies per unit area (48760J/cm²). The peak acoustic negative pressures (p^-) of the two groups were p₁^-=9.58MPa and p₂^-=10.82MPa, respectively, with the difference p_d^-=p₂^--p₁^-=1.24MPa. A passive cavitation detection (PCD) was used to monitor the ultrasonic cavitation signal during exposure of the two groups. The US exposures were done under the following ambient hydrostatic pressures, P_stat: atmospheric pressure, 0.5MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa and3.0MPa, respectively. The result of PCD showed that there was a statistically significant increase above background noise level in broadband emissions at dose of 9752W/cm²×5s, but not at dose of 6095W/cm²×8s under atmospheric pressure; i.e., the acoustic cavitation took place for p₂^- but not for p₁^- when under atmospheric pressure. The results also showed that there was no statistically difference of the morphology and size of lesions for 6095W/cm²×8s exposure under the aforementioned different ambient hydrostatic pressures. But the lesions generated at 9752W/cm²×5s exposure under P_stat=atmospheric pressure, 0.5MPa, 1.0MPa (all of them are less than p_d^-), were larger than those under 1.5MPa, 2.0MPa, 2.5MPa and 3.0MPa (all of them are over than p_d^-) which were consistence with 6095W/cm²×8s group. It was concluded that when P_stat>p_d^-, the acoustic cavitation was suppressed and prompted that there was no need to elevate P_stat higher than p^- to suppress the acoustic cavitation in tissue, just need P_stat higher than p_d^-.

[Effekt of blood flow shutdown on the vein damage when exposed to HIFU]

The purpose. In the study we investigated the impact of the partial blood flow shutdown on structural changes in the rabbit vena cava posterior wall after exposure to high-intensity focused ultrasound (HIFU). Methods. Ultrasound Exposure: frequency of 1.65 MHz, the ultrasound intensity in the focus of 13.6 kW/cm2, the area of the focal spot 1 mm2, continuous ultrasound, exposure for 3 seconds. Results. Immediately after HIFU exposure all layers of the vein wall showed characteristic signs of thermal damage. A week after exposure structural changes in the intima, media and adventitia was minimal in the part of vessel with preserved blood flow, and after 4 weeks the changes were not revealed. A week after HIFU exposure partial endothelium destruction, destruction of myocytes, disorganization and consolidation of collagen fibers of the adventitia were observed in an isolated segment of the vessel, and in 4 weeks endothelium restored and signs of damage in media and adventitia persisted, but were less obvious than in a week after exposure. Conclusion. The shutdown of blood flow after exposure to HIFU promotes persistent changes in the vein wall. Vein compression appears to be necessary for the obliteration of the vessel, when using HIFU-technology.

A Multicenter Controlled Study to Evaluate Multiple Treatments With Nonthermal Focused Ultrasound for Noninvasive Fat Reduction

BACKGROUND

Demand for nonsurgical esthetic body procedures has led to the development of noninvasive techniques for reducing localized subcutaneous adipose tissue.

OBJECTIVE

This study assessed multiple treatments with nonthermal focused ultrasound for noninvasive abdominal treatment of excess fat deposits.

MATERIALS AND METHODS

Subjects were randomly assigned to Group 1 for a 4-week control phase before undergoing 3 abdominal fat reduction treatments, at 2-week intervals, or to Group 2 for immediate treatment. Weight, abdominal circumference, tolerability to treatment, subject satisfaction, and adverse events were recorded.

RESULTS

Weight remained stable in the 126 participants. Mean reduction in midline circumference was 2.5 ± 2.1 cm in the Group 1 and 3.5 ± 2.7 cm in the Group 2 at Week 22. The effect of multiple treatments was cumulative with a steady decrease in abdominal circumferences during the study. Erythema was observed in 28% of treatments but was mild and transient in nature. Subjects tolerated the treatments well and were satisfied with treatment outcome.

CONCLUSION

The study demonstrated the efficacy and safety of multiple nonthermal focused ultrasound treatments of excess abdominal fat deposits. Although the remodeling effect is minor compared with traditional surgical procedures, successive focused ultrasound treatments significantly reduced treatment area circumference, while avoiding invasive techniques and their associated disadvantages.

High intensity focused ultrasound ablation for atrial fibrillation: results from the National Spanish Registry

BACKGROUND

A National Spanish Registry to compile all patients treated with high intensity focused ultrasound (HIFU) energy for atrial fibrillation (AF) was created to evaluate the safety and efficacy of AF surgical ablation.

METHODS

A national Spanish registry was created, and ten hospitals using HIFU to ablate AF joined it. A total of 412 patients undergoing cardiac surgery between 2006 and February 2013 were included. AF was divided between paroxysmal AF (33%) and persistent AF (67%) with a mean AF duration of 29.3±108.2 months. Mean left atrial diameter was 51.2±6.5 mm. Mean underlying heart disease were aortic valve disease (49.3%), ischemic disease (25.2%) and mitral disease (33.2%) Clinical follow-up of patients and a 6 months postoperative echocardiogram were performed in all patients.

RESULTS

A pacemaker implantation was needed in 4.9% of patients with a perioperative stroke in 2.5%. Rhythm at discharge from hospital was sinus rhythm in 58%, AF in 35.9% and atrial flutter in 0.8% of patients. Sinus rhythm restoration at 6, 12, 24 and 36 months follow-up was achieved in 66.1%, 63.8%, 63.9% and 45.9% of patients respectively. Multivariate analysis showed paroxysmal AF and sinus rhythm restoration in the operating theatre as factors related to sinus rhythm long term restoration.

CONCLUSIONS

The Spanish national registry showed an efficacy of AF ablation with the HIFU Epicor system of 66.1%, 63.8%, 63.9% and 45.9% at 6, 12, 24 and 36 months follow-up. There were no device-related complications.

Historical ESWT Paradigms Are Overcome: A Narrative Review

Extracorporeal Shock Wave Therapy (ESWT) is a conservative treatment modality with still growing interest in musculoskeletal disorders. This narrative review aims to present an overview covering 20-year development in the field of musculoskeletal ESWT. Eight historical paradigms have been identified and put under question from a current perspective: energy intensity, focus size, anesthesia, imaging, growth plates, acuteness, calcifications, and number of sessions. All paradigms as set in a historical consensus meeting in 1995 are to be revised. First, modern musculoskeletal ESWT is divided into focused and radial technology and the physical differences are about 100-fold with respect to the applied energy. Most lesions to be treated are easy to reach and clinical focusing plays a major role today. Lesion size is no longer a matter of concern. With the exception of nonunion fractures full, regional, or even local anesthesia is not helpful in musculoskeletal indications. Juvenile patients can also effectively be treated without risk of epiphyseal damage. Further research is needed to answer the question about if and which acute injuries can be managed effectively. Treatment parameters like the number of sessions are still relying on empirical data and have to be further elucidated.

A retrospective analysis of survival factors of high intensity focused ultrasound (HIFU) treatment for unresectable pancreatic cancer

OBJECTIVE

To retrospectively evaluate possible impact factors of HIFU treatment outcome for unresectable pancreatic cancer patients.

PATIENTS AND METHODS

A total of 689 patients with unresectable pancreatic cancer were recruited in our center from December 30, 2007 to January 30, 2015. 436 patients with unresectable pancreatic cancers received HIFU treatment; the other 253 patients received non-HIFU treatment. Among these 436 patients, 345 patients received a one-time HIFU treatment, 91 patients received HIFU treatment from 2 to 5 times in the same pancreatic mass; 89 patients received HIFU treatment alone; 347 patients received HIFU-based combined therapies. Complications and overall survivals (OS) data in each group were collected.

RESULTS

The median overall survivals (mOS) in HIFU group and non-HIFU group were 7.1 vs. 5 months (P=0.005): 9.3 vs. 7.3 months (P=0.202) for patients with stage II disease, 8.3 vs. 7.3 months (P=0.783) for patients with stage III disease, and 6.4 vs. 4.2 months (P<0.0001) for patients with stage IV disease, respectively. Furthermore, there was a significant difference between repeated HIFU and one-time HIFU (mOS: 8.6 vs. 6.8 months, P=0.011). Time of HIFU treatment (P=0.0027), chemotherapy (P<0.0001), radiotherapy (P=0.0006), regional intra-arterial chemotherapy (RIAC) (P<0.0001), and stage (P<0.0001) were independent prognostic factors for the patients who received HIFU treatment. Cox analysis on the relative risk of prognostic factors showed that repeated HIFU vs. one-time HIFU (HR=0.729: 95% CI=0.576-0.924), chemotherapy vs. non-chemotherapy (HR=0.664: 95% CI=0.576-0.766), radiotherapy vs. non-radiotherapy (HR=0.580: 95% CI=0.427-0.789), RIAC vs. non-RIAC (HR=0.737: 95% CI=0.648-0.837), and stage (HR=1.386, 95% CI=1.187-1.619) were associated with significantly inferior survival. Overall, adverse events occurred in 23.2% (101/436) in the HIFU group, which included increase of serum or urinary amylase levels, incomplete intestinal obstruction, mild fever, etc. There were no severe adverse events such as skin burns or GI perforation related to HIFU therapy in any of the patients treated.

CONCLUSION

This retrospective analysis revealed that the use of a multimodal treatment approach (the combined therapy of HIFU, RIAC, and chemotherapy, with or without radiotherapy) could improve survival of patients with unresectable pancreatic cancer, and repeated HIFU presented a survival benefit and did not increase risk.