A Comparison of Quality of Life, Cosmesis and Cost-Utility of Open Surgery, Vacuum-Assisted Breast Biopsy and High Intensity Focused Ultrasound for Breast Fibroadenoma

RATIONALE AND OBJECTIVES

To compare the quality of life (QOL), cosmesis and cost-utility of open surgery (OS), vacuum-assisted breast biopsy (VABB) and high intensity focused ultrasound (HIFU) for fibroadenoma (FA).

MATERIALS AND METHODS

A total of 162 patients with 267 FAs were enrolled. Baseline characteristics and treatment information were recorded. Patients were followed up at 3-, 6- and 12-month post-treatment. QOL was evaluated by health survey. Breast cosmesis was evaluated by self-rating survey and Harvard Scale. A decision-analytic model was established and incremental cost was calculated for cost-utility analysis.

RESULTS

For QOL evaluation, there was no difference of physical component summary (PCS) score in three groups (P > 0.05), while the mental component summary (MCS) score was significantly higher in HIFU group than the other two groups at 3- and 6-month post-treatment (P < 0.05). The proportion of patients satisfied with breast cosmesis was significantly higher in HIFU group (96.49%) than in VABB group (54.90%) and OS group (49.99%) (P < 0.05). By Harvard Scale, 27.78%, 78.42% and 100.00% of patients were rated as excellent and good in OS group, VABB group and HIFU group, respectively (P < 0.05). To acquire a quality-adjusted life year (QALY), cost of OS, VABB and HIFU was 1034.31 USD, 1776.96 USD and 1277.67 USD, respectively. When compared to OS, incremental cost analysis showed HIFU was cost-effective, while VABB was not.

CONCLUSION

OS, VABB and HIFU were all effective and safe for FA, but among these three treatments, HIFU had the best QOL improvement, breast cosmesis and cost-effectiveness.

High intensity focused ultrasound in treating great saphenous vein incompetence: Perioperative and 1-year outcomes

BACKGROUND

To investigate the use of high intensity focused ultrasound (HIFU) for great saphenous vein (GSV) incompetence.

MATERIAL AND METHODS

Patients with GSV incompetence underwent HIFU. The primary endpoint was the rate of GSV target segment shrinkage or closure after 1 year.

RESULTS

Out of 188 limbs treated, the GSV treated segment shrinkage/closure rate at 1 week, 3 months, 6 months, and 12 months was 93.3%, 98.2%, 97.6%, and 98.3%, respectively.

CONCLUSION

These preliminary results suggest that HIFU holds promise for the treatment of GSV incompetence. Further trials are needed to compare it with other techniques and assess long-term outcomes.

Effectiveness and complication rates of high intensity focused ultrasound treatment for abdominal wall endometriosis: A systematic review

In this review, a systematic literature search on the effectiveness and complication rates of ultrasound-guided and magnetic resonance-guided high-intensity focused ultrasound (USg-/MRgHIFU) for abdominal wall endometriosis (AWE) was conducted in six databases in May/June 2023. Original articles of (non)randomized trials, cohort studies, case-control studies and case series published in peer-reviewed journals were included. Of the included studies the level of evidence (LoE) and methodological quality using the ROBINS-I and IHE-QAT was assessed. Primary outcomes were non-perfused volume ratio (NPV%), lesion size, pain scores, side effects and complication rates according to Society of Interventional Radiology (SIR) guidelines. Secondary outcomes were recurrence and re-intervention rates. Seven cohort studies (one of good methodological quality) (LoE 3) on USgHIFU were included (n = 212, AWE lesions = 240-245). Six months after USgHIFU treatment, pain scores were reduced with 3.3-5.2 points (baseline: 5.1-6.8, n = 135). Self-limiting side effects were pain (85.7 % (114/133)) and swelling (34.6 % (46/133)) in the treatment area. Complications occurred in 17.7 % (32/181), all of which were minor. Recurrence occurred in 12.8 % (11/86). Three of these seven cohort studies compared USgHIFU (n = 61) with surgical excision (n = 74). Pooled results showed no significant differences in pain scores, complications (resp. 26.3 % (10/38) vs. 32.6 % (15/46) (p = 0.53)) and recurrences (resp. 4.9 % (3/61) vs. 5.4 % (4/74) (p = 0.90)). This systematic review suggests that HIFU is an effective and safe treatment option for AWE. USgHIFU treatment led to reduced pain scores and lesion size, was free of major complications and had a pooled recurrence rate of 12.8 %. Compared to surgical excision pooled results showed no significant differences in pain scores, complications and recurrences after USgHIFU. However, many of the included studies had limitations in their methodological quality and therefore the results should be interpreted with caution. Well-structured high-quality randomized controlled trials comparing HIFU to standard care should be conducted to provide more conclusive evidence.

Inducing cavitation within hollow cylindrical radially polarized transducers for intravascular applications

Thrombotic occlusions of large blood vessels are increasingly treated with catheter based mechanical approaches, one of the most prominent being to employ aspiration to extract clots through a hollow catheter lumen. A central technical challenge for aspiration catheters is to achieve sufficient suction force to overcome the resistance of clot material entering into the distal tip. In this study, we examine the feasibility of inducing cavitation within hollow cylindrical transducers with a view to ultimately using them to degrade the mechanical integrity of thrombus within the tip of an aspiration catheter. Hollow cylindrical radially polarized PZT transducers with 3.3/2.5 mm outer/inner diameters were assessed. Finite element simulations and hydrophone experiments were used to investigate the pressure field distribution as a function of element length and resonant mode (thickness, length). Operating in thickness mode (∼5 MHz) was found to be associated with the highest internal pressures, estimated to exceed 23 MPa. Cavitation was demonstrated to be achievable within the transducer under degassed water (10 %) conditions using hydrophone detection and high-frequency ultrasound imaging (40 MHz). Cavitation clouds occupied a substantial portion of the transducer lumen, in a manner that was dependent on the pulsing scheme employed (10 and 100 μs pulse lengths; 1.1, 11, and 110 ms pulse intervals). Collectively the results support the feasibility of achieving cavitation within a transducer compatible with mounting in the tip of an aspiration format catheter.

Histology-based quantification of boiling histotripsy outcomes via ResNet-18 network: Towards mechanical dose metrics

This work was focused on the newly developed ultrasonic approach for non-invasive surgery - boiling histotripsy (BH) - recently proposed for mechanical ablation of tissues using pulsed high intensity focused ultrasound (HIFU). The BH lesion is known to depend in size and shape on exposure parameters and mechanical properties, structure and composition of tissue being treated. The aim of this work was to advance the concept of BH dose by investigating quantitative relationships between the parameters of the lesion, pulsing protocols, and targeted tissue properties. A HIFU focus of a 1.5 MHz 256-element array driven by power-enhanced Verasonics system was electronically steered along the grid within 12 × 4 × 12 mm volume to produce volumetric lesions in porcine liver (soft, with abundant collagenous structures) and bovine myocardium (stiff, homogenous cellular) ex vivo tissues with various pulsing protocols (1-10 ms pulses, 1-15 pulses per point). Quantification of the lesion size and completeness was performed through serial histological sectioning, and a computer vision approach using a combination of manual and automated detection of fully fractionated and residual tissue based on neural network ResNet-18 was developed. Histological sample fixation led to underestimation of BH ablation rate compared to the ultrasound-based estimations, and provided similar qualitative feedback as did gross inspection. This suggests that gross observation may be sufficient for qualitatively evaluating the BH treatment completeness. BH efficiency in liver tissue was shown to be insensitive to the changes in pulsing protocol within the tested parameter range, whereas in bovine myocardium the efficiency increased with either increasing pulse length or number of pulses per point or both. The results imply that one universal mechanical dose metric applicable to an arbitrary tissue type is unlikely to be established. The dose metric as a product of the BH pulse duration and the number of pulses per sonication point (BHD1) was shown to be more relevant for initial planning of fractionation of collagenous tissues. The dose metric as a number of pulses per point (BHD2) is more suitable for the treatment planning of softer targets primarily containing cellular tissue, allowing for significant acceleration of treatment using shorter pulses.

Noninvasive magnetic resonance-guided focused ultrasound for tendon disruption: an in vivo Animal study

PURPOSE

Surgical resection of the tendon is an effective treatment for severe contracture. Magnetic Resonance-guided Focused Ultrasound (MRgFUS) is a non-invasive ultrasonic therapy which produces a focal increase in temperature, subsequent tissue ablation and disruption. We evaluated MRgFUS as a clinically translatable treatment modality to non-invasively disrupt in vivo porcine tendons.

MATERIAL AND METHODS

In vivo Achilles tendons (n = 28) from 15-20kg Yorkshire pigs (n = 16) were randomly assigned to 4 treatment groups of 600, 900, 1200 and 1500 J. Pretreatment range of motion (ROM) of the ankle joint was measured with the animal under general anesthesia. Following MRgFUS treatment, success of tendon rupture, ROM increase, temperature, thermal dosage, skin burn, and histology analyses were performed.

RESULTS

Rupture success was found to be 29%, 86%, 100% and 100% for treatment energies of 600, 900, 1200 and 1500 J respectfully. ROM difference at 90° flexion showed a statistically significant change in ROM between 900 J and 1200 J from 16° to 27°. There was no statistical significance between other groups, but there was an increase in ROM as more energy was delivered in the treatment. For each of the respective treatment groups, the maximal temperatures were 58.4 °C, 63.3 °C, 67.6 °C, and 69.9 °C. The average areas of thermal dose measured were 24.3mm2, 53.2mm2, 77.8mm2 and 91.6mm2. The average areas of skin necrosis were 5.4mm2, 21.8mm2, 37.2mm2, and 91.4mm2. Histologic analysis confirmed tissue ablation and structural collagen fiber disruption.

CONCLUSIONS

This study demonstrated that MRgFUS is able to disrupt porcine tendons in vivo without skin incisions.

The Role of High Intensity Focused Ultrasound in the Treatment of Fibroadenomas: A Systematic Review

Introduction

Fibroadenomas are solid, mobile, and non-tender benign breast lumps, with highest prevalence amongst young women aged between 15 and 35. Symptoms can include discomfort, and they can become problematic, particularly when they enlarge, resulting in many referrals for biopsies, with fibroadenomas accounting for 30-75% of the cases. Diagnosis is based on triple assessment that involves a clinical examination, ultrasound imaging, and mammography, as well as core needle biopsies. Current management includes observation for 6-12 months, with the indication of definitive surgery, in cases that are older than 35 years or with fibroadenoma persistence. Serious adverse effects of surgery might include nipple areolar distortion, scarring, and damage to the breast tissue, as well as the risks associated with surgery and anesthesia, making it a non-feasible option.

Methods

A literature search was performed on the databases Embase, MEDLINE/PubMed, Google Scholar, and Ovid for English language papers published between January 1, 2000, and March 17, 2021. A structured protocol was employed to devise a comprehensive search strategy with keywords and Boolean operators defined by the research question. The keywords used for the search were "HIFU", "High Intensity Focused Ultrasound," "Fibroadenoma," "Breast," "Lesion." This review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Results

Recently, a thermal ablative technique, high intensity focused ultrasound (HIFU), was found to be a safe, noninvasive, and technically successful alternative, having displayed promising outcomes in reducing the volume of fibroadenomas, pain experienced by patients, and the length of hospitalization. Quality of life improvement was also evidenced, exhibited by the disappearance of symptoms, and enhanced physical activity post-intervention, in addition to patients' satisfaction with the cosmetic results and future recommendation of the procedure to other patients.

Conclusion

Overall, HIFU is a well-tolerated treatment associated, with low risk of complications, that can potentially include erythema, skin discoloration, and bruising with the majority of these self-resolving shortly after the procedure.

Sonothrombolysis with an acoustic net-assisted boiling histotripsy: A proof-of-concept study

Whilst sonothrombolysis is a promising and noninvasive ultrasound technique for treating blood clots, bleeding caused by thrombolytic agents used for dissolving clots and potential obstruction of blood flow by detached clots (i.e., embolus) are the major limitations of the current approach. In the present study, a new sonothrombolysis method is proposed for treating embolus without the use of thrombolytic drugs. Our proposed method involves (a) generating a spatially localised acoustic radiation force in a blood vessel against the blood flow to trap moving blood clots (i.e., generation of an acoustic net), (b) producing acoustic cavitation to mechanically destroy the trapped embolus, and (c) acoustically monitoring the trapping and mechanical fractionation processes. Three different ultrasound transducers with different purposes were employed in the proposed method: (1) 1-MHz dual focused ultrasound (dFUS) transducers for capturing moving blood clots, (2) a 2-MHz High Intensity Focused Ultrasound (HIFU) source for fractionating blood clots and (3) a passive acoustic emission detector with broad bandwidth (10 kHz to 20 MHz) for receiving and analysing acoustic waves scattered from a trapped embolus and acoustic cavitation. To demonstrate the feasibility of the proposed method, in vitro experiments with an optically transparent blood vessel-mimicking phantom filled with a blood mimicking fluid and a blood clot (1.2 to 5 mm in diameter) were performed with varying the dFUS and HIFU exposure conditions under various flow conditions (from 1.77 to 6.19 cm/s). A high-speed camera was used to observe the production of acoustic fields, acoustic cavitation formation and blood clot fragmentation within a blood vessel by the proposed method. Numerical simulations of acoustic and temperature fields generated under a given exposure condition were also conducted to further interpret experimental results on the proposed sonothrombolysis. Our results clearly showed that fringe pattern-like acoustic pressure fields (fringe width of 1 mm) produced in a blood vessel by the dFUS captured an embolus (1.2 to 5 mm in diameter) at the flow velocity up to 6.19 cm/s. This was likely to be due to the greater magnitude of the dFUS-induced acoustic radiation force exerted on an embolus in the opposite direction to the flow in a blood vessel than that of the drag force produced by the flow. The acoustically trapped embolus was then mechanically destructed into small pieces of debris (18 to 60 μm sized residual fragments) by the HIFU-induced strong cavitation without damaging the blood vessel walls. We also observed that acoustic emissions emitted from a blood clot captured by the dFUS and cavitation produced by the HIFU were clearly distinguished in the frequency domain. Taken together, these results can suggest that our proposed sonothrombolysis method could be used as a promising tool for treating thrombosis and embolism through capturing and destroying blood clots effectively.

Single-center, prospective phase 2 trial of high-intensity focused ultrasound (HIFU) in patients with unilateral localized prostate cancer: good functional results but oncologically not as safe as expected

PURPOSE

Focal therapy (FT) for localized prostate cancer (PCa) is only recommended within the context of clinical trials by international guidelines. We aimed to investigate oncological follow-up and safety data of focal high-intensity focused ultrasound (HIFU) treatment.

METHODS

We conducted a single-center prospective study of 29 patients with PCa treated with (focal) HIFU between 2016 and 2021. Inclusion criteria were unilateral PCa detected by mpMRI-US-fusion prostate biopsy and maximum prostate specific antigen (PSA) of 15 ng/ml. Follow-up included mpMRI-US fusion-re-biopsies 12 and 24 months after HIFU. No re-treatment of HIFU was allowed. The primary endpoint was failure-free survival (FFS), defined as freedom from intervention due to cancer progression.

RESULTS

Median follow-up of all patients was 23 months, median age was 67 years and median preoperative PSA was 6.8 ng/ml. One year after HIFU treatment PCa was still detected in 13/ 29 patients histologically (44.8%). Two years after HIFU another 7/29 patients (24.1%) were diagnosed with PCa. Until now, PCa recurrence was detected in 11/29 patients (37.93%) which represents an FFS rate of 62%.One patient developed local metastatic disease 2 years after focal HIFU. Adverse events (AE) were low with 70% of patients remaining with sufficient erectile function for intercourse and 97% reporting full maintenance of urinary continence.

CONCLUSION

HIFU treatment in carefully selected patients is feasible. However, HIFU was oncologically not as safe as expected because of progression rates of 37.93% and risk of progression towards metastatic disease. Thus, we stopped usage of HIFU in our department.

The histotripsy spectrum: differences and similarities in techniques and instrumentation

Since its inception about two decades ago, histotripsy - a non-thermal mechanical tissue ablation technique - has evolved into a spectrum of methods, each with distinct potentiating physical mechanisms: intrinsic threshold histotripsy, shock-scattering histotripsy, hybrid histotripsy, and boiling histotripsy. All methods utilize short, high-amplitude pulses of focused ultrasound delivered at a low duty cycle, and all involve excitation of violent bubble activity and acoustic streaming at the focus to fractionate tissue down to the subcellular level. The main differences are in pulse duration, which spans microseconds to milliseconds, and ultrasound waveform shape and corresponding peak acoustic pressures required to achieve the desired type of bubble activity. In addition, most types of histotripsy rely on the presence of high-amplitude shocks that develop in the pressure profile at the focus due to nonlinear propagation effects. Those requirements, in turn, dictate aspects of the instrument design, both in terms of driving electronics, transducer dimensions and intensity limitations at surface, shape (primarily, the F-number) and frequency. The combination of the optimized instrumentation and the bio-effects from bubble activity and streaming on different tissues, lead to target clinical applications for each histotripsy method. Here, the differences and similarities in the physical mechanisms and resulting bioeffects of each method are reviewed and tied to optimal instrumentation and clinical applications.

Long-term outcome of ultrasound-guided focused ultrasound ablation for gestational trophoblastic neoplasia in the cesarean scar: a case report

BACKGROUND

The treatment of gestational trophoblastic neoplasia (GTN) is one of the success stories in medical oncology. GTN in the cesarean scar is a rare entity, but most cases need to be treated with hysterectomy or localized uterine lesion resection because of chemoresistant lesions and/or massive bleeding. We present a patient with post-molar GTN in the cesarean scar who was non-invasively treated with ultrasound-guided high intensity focused ultrasound (HIFU) to preserve the uterus and fertility.

CASE PRESENTATION

A 32-year-old woman was diagnosed with low-risk GTN (FIGO Stage I: 2 prognostic score) after partial hydatidiform mole. The 5th cycle of chemotherapy was interrupted because of persistent hepatic toxicity and impaired ovarian reserve function. However, the uterine lesion persisted (diameter of residual uterine lesion in the cesarean scar: 2.0 cm). Therefore, ultrasound-guided HIFU treatment was performed. A significant gray-scale change was observed during the HIFU treatment. Color Doppler ultrasonography and contrast-enhanced ultrasound (CEUS) was performed to evaluate the ablation effectiveness. Color Doppler ultrasonography showed disappearance of the signal of vascularity and CEUS showed no perfusion in the lesion located in the cesarean scar. The uterine lesion was obviously shrunken one month after HIFU treatment. Menstrual cycle resumed 48 days after HIFU. HIFU treatment decreased the number of chemotherapy cycles and there was complete disappearance of the GTN lesion at 4-month follow-up. The patient has shown no signs of recurrence as of 58-month follow-up.

CONCLUSION

Ultrasound-guided HIFU may be a useful alternative to lesion resection for GTN in the cesarean scar in patients who show chemoresistance or are not suitable for chemotherapy. It has the potential to ablate the residual uterine lesion noninvasively to preserve the uterus and fertility, avoiding perioperative risks of lesion resection, especially acute bleeding.

Deep learning prediction of non-perfused volume without contrast agents during prostate ablation therapy

The non-perfused volume (NPV) is an important indicator of treatment success immediately after prostate ablation. However, visualization of the NPV first requires an injection of MRI contrast agents into the bloodstream, which has many downsides. Purpose of this study was to develop a deep learning model capable of predicting the NPV immediately after prostate ablation therapy without the need for MRI contrast agents. A modified 2D deep learning UNet model was developed to predict the post-treatment NPV. MRI imaging data from 95 patients who had previously undergone prostate ablation therapy for treatment of localized prostate cancer were used to train, validate, and test the model. Model inputs were T1/T2-weighted and thermometry MRI images, which were always acquired without any MRI contrast agents and prior to the final NPV image on treatment-day. Model output was the predicted NPV. Model accuracy was assessed using the Dice-Similarity Coefficient (DSC) by comparing the predicted to ground truth NPV. A radiologist also performed a qualitative assessment of NPV. Mean (std) DSC score for predicted NPV was 85% ± 8.1% compared to ground truth. Model performance was significantly better for slices with larger prostate radii (> 24 mm) and for whole-gland rather than partial ablation slices. The predicted NPV was indistinguishable from ground truth for 31% of images. Feasibility of predicting NPV using a UNet model without MRI contrast agents was clearly established. If developed further, this could improve patient treatment outcomes and could obviate the need for contrast agents altogether. Trial Registration Numbers Three studies were used to populate the data: NCT02766543, NCT03814252 and NCT03350529.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13534-022-00250-y.

Evaluation of post-ablation mpMRI as a predictor of residual prostate cancer after focal high intensity focused ultrasound (HIFU) ablation

PURPOSE

To evaluate the performance of multiparametric magnetic resonance imaging (mpMRI) and PSA testing in follow-up after high intensity focused ultrasound (HIFU) focal therapy for localized prostate cancer.

METHODS

A total of 73 men with localized prostate cancer were prospectively enrolled and underwent focal HIFU followed by per-protocol PSA and mpMRI with systematic plus targeted biopsies at 12 months after treatment. We evaluated the association between post-treatment mpMRI and PSA with disease persistence on the post-ablation biopsy. We also assessed post-treatment functional and oncological outcomes.

RESULTS

Median age was 69 years (Interquartile Range (IQR): 66-74) and median PSA was 6.9 ng/dL (IQR: 5.3-9.9). Of 19 men with persistent GG ≥ 2 disease, 58% (11 men) had no visible lesions on MRI. In the 14 men with PIRADS 4 or 5 lesions, 7 (50%) had either no cancer or GG 1 cancer at biopsy. Men with false negative mpMRI findings had higher PSA density (0.16 vs. 0.07 ng/mL², P = 0.01). No change occurred in the mean Sexual Health Inventory for Men (SHIM) survey scores (17.0 at baseline vs. 17.7 post-treatment, P = 0.75) or International Prostate Symptom Score (IPSS) (8.1 at baseline vs. 7.7 at 24 months, P = 0.81) after treatment.

CONCLUSIONS

Persistent GG ≥ 2 cancer may occur after focal HIFU. mpMRI alone without confirmatory biopsy may be insufficient to rule out residual cancer, especially in patients with higher PSA density. Our study also validates previously published studies demonstrating preservation of urinary and sexual function after HIFU treatment.

Evaluating the learning curve of high intensity focus ultrasound for breast fibroadenoma by CUSUM analysis: a multi-center study

OBJECTIVE

To explore the learning curve of high intensity focus ultrasound (HIFU) treatment for breast fibroadenoma.

METHODS

A database of 110 patients with 255 breast fibroadenomas who underwent HIFU treatment at two different clinical centers (Center 1 and 2) were retrospectively analyzed. The learning curves of HIFU treatment for breast fibroadenoma were drawn by CUSUM analysis in two centers, respectively. According to the inflection point of the learning curves, the treatment was divided into two groups: initial phase and consolidation phase. HIFU treatment parameters were compared between two groups. The effectiveness and safety results were also evaluated.

RESULTS

The inflection points of the learning curves were the 60^th treatment in Center 1 and the 65^th treatment in Center 2. The screening time, treatment time, sonication time and hyperechoic scale change time were significantly shorter in consolidation phase than those in initial phase of the two centers (p < 0.05). There were no differences in non-perfused volume (NPV) ratio and energy effect factor (EEF) between the two groups in Center 1, while in Center 2, these above-mentioned results in consolidation phase led to a greater improvement than those in initial phase. There was no difference of Visual Analogue Scale (VAS) scores and no adverse event observed in both centers.

CONCLUSION

HIFU treatment for breast fibroadenoma was effective and safe. The learning curve of HIFU treatment for breast fibroadenoma can be completed after treating 60-65 tumors without increasing the safety risk.

Investigating atherosclerotic plaque phantoms for ultrasound therapy

PURPOSE

The aim of the proposed study was to conduct a feasibility study using a flat rectangular (2 × 10 mm2) transducer operating at 4.0 MHz for creating thermal lesions in an arterial atherosclerotic plaque phantom. The proposed method can be used in the future for treating atherosclerotic plaques in human arteries.

MATERIALS AND METHODS

The flat rectangular transducer was firstly assessed in agar/silica evaporated milk phantom, polyacrylamide phantom and freshly excised turkeytissue phantom. Then, the same transducer was assessed in an arterial atherosclerotic plaque phantom which was created in the laboratory with a very low cost. The recipe of the atherosclerotic plaque phantom was 4% w/v agar, 1% w/v gypsum, 2% w/v butter and 93% water. The amount of plaque removal was evaluated visually and using an X-Ray system.

RESULTS

It was shown that the flat rectangular transducer can create thermal lesions on the agar/silica evaporated milk phantom, polyacrylamide phantom and in excised tissue. The size of the lesions matches the geometry of the transducer. Moreover, this transducer destroyed 27.1% of the atherosclerotic plaque phantom with 8 W acoustical power and 30 s duration.

CONCLUSIONS

This feasibility study demonstrated that atherosclerotic plaque can be destroyed using a very small flat rectangular (2 × 10 mm2) transducer in a very small time interval of 30 s. In future clinical trials the transducer will be incorporated in a catheter which will be inserted intravascular (1-3 mm) wide and can be used to treat atherosclerotic plaques in the coronary arteries.

Clinical efficacy and safety of high-intensity focused ultrasound (HIFU) ablation in treatment of cesarean scar pregnancy (CSP) I and II

Objective

To investigate the safety and feasibility of high intensity focused ultrasound (HIFU) ablation followed by ultrasound-guided dilation and curettage (USg-D&C) for two types patients with cesarean scar pregnancy (CSP-I and CSP-II).

Materials and methods

This study was a retrospective analysis of 101 CSP-I patients and 52 CSP-II patients who received HIFU ablation followed by USg-D&C from Jun 2014 to Oct 2020. The diameter of gestational sac/mass, thickness of the intervening myometrium, intraoperative blood loss, operation time, length of hospital stays, adverse effects and β-HCG level in the two groups were compared.

Results

All patients successfully received HIFU ablation under conscious sedation. The median total treatment time of HIFU ablation and median USg-D&C time in the CSP-I group were statistically longer than those in the CSP-II group (P < 0.05). The average intraoperative median blood loss was 39 ml in the CSP-I group and 65 ml in the CSP-II group (P < 0.05). The duration of hospitalization was 7.07 ± 1.83 days in the CSP-I group and 7.18 ± 1.72 days in the CSP-II group (P > 0.05). The average time needed for β-HCG return to normal levels was 26.08 ± 5.02. and 28.15 ± 4.99 days for CSP-I and CSP-II, respectively (P > 0.05). The percentage of adverse effects and complications was not significantly different between the two groups (P > 0.05).

Conclusions

HIFU ablation followed by USg-D&C was safe and effective in treating the CSP-I patients and CSP-II patients, which may be a potential noninvasive therapeutic option for patients with CSP.

High intensity focused ultrasound in the therapy of benign thyroid nodules-first German bicentric study with long-term follow-up

PURPOSE

The study evaluated high-intensity-focused ultrasound (HIFU) for benign thyroid nodules in terms of efficiency, complication rate, influence of preablative nodule size, parameters influencing the therapeutic success and hormonal-thyroid-function.

METHODS

Seventy-two patients with 75 nodules were treated with HIFU at 2 centers from 2014-2019. Median nodule volume was 4.4 ml (range 0.33-53). The therapeutic ultrasound probe (EchoPulse THC900888-H) generated 80-90 °C in the target tissue with 87.6-320.3 J per sonication. Nodal volume was measured at baseline and over 12 months after therapy in a retrospective bicentric-study with long-term follow-up. Hormonal-thyroid function (TSH, T3, T4) was measured before and after ablation. Complications were assessed.

RESULTS

Significant volume reduction (p < 0.05 Wilcoxon-signed-rank test) of thyroid nodules was 38.98% at 3 months, 37.32% at 6 months, 61.54% at 9 months and 60.66% at 12 months. Volume reduction of nodules <3 ml did not differ significantly from nodules >3 ml (p > 0.05 Mann-Whitney test). At 3 months solid nodules had a significant volume reduction of 52.08%, complex nodules of 32.57%, nodules treated under regional anesthesia of 33.07% and under general anesthesia of 49.47%. Hormonal-thyroid function was not influenced significantly by HIFU therapy (p > 0.05 Wilcoxon-signed-rank test). Complication rate was 3.8%. No long-term complications occurred.

CONCLUSION

Significant volume reduction of thyroid nodules up to 12 months after HIFU was shown. All complications were reversible. Therapy was more efficient in solid than complex nodules and in nodules treated under general anesthesia than with regional anesthesia. Hormonal-thyroid-function was not affected.

TRIAL REGISTRAFTION NUMBER

2020-1728-evBO. Date of registration: 16.06.2020. Agency: Ethik-Kommission bei der Landesäztekammer Hessen.

Outcomes of partial gland ablation using high intensity focused ultrasound for prostate cancer

BACKGROUND

To evaluate the clinical and oncological outcomes of partial gland ablation (PGA) using high intensity focused ultrasound (HIFU) technique for the clinically unilateral prostate cancer.

METHODS

We performed a retrospective analysis for the 163 patients who treated by PGA for clinically unilateral prostate cancer. The PGA was performed using Focal one system with concurrent trans-urethral prostatectomy. The oncological and functional outcomes were evaluated as well as risk factors for remnant disease after PGA. Clinically significant cancer was defined as grade group ≥2.

RESULTS

Among the entire subjects, grade group 2 or greater was present at pre-treatment biopsy in 76.7%. Median follow-up time was 17 months and 60.1% of total subjects had follow-up biopsy at postoperative 1 year. There were 25 subjects (24.2%) with any cancer and 13 subjects (12.6%) with CS cancer at the follow-up biopsy. The preoperative age and number of positive cores at preoperative biopsy were significantly associated with positive results at follow-up biopsy. Incontinence which requires 2 or more pads per day was observed at 4 subjects (2.5%) postoperatively. There were no subjects who needed intensive care or experienced rectal complications.

CONCLUSION

The PGA with HIFU was safe and showed good preservation of functional outcomes as well as satisfactory oncological control. The remnant disease was observed in the 24.5% of patients who underwent follow-up biopsy in the present study. Thus, further prospective study is needed to evaluate oncological and functional outcomes of PGA with HIFU more accurately.

Evaluation of the treatment of high intensity focused ultrasound combined with suction curettage for exogenous cesarean scar pregnancy

PURPOSE

To evaluate the effectiveness of high-intensity focused ultrasound (HIFU) combined with suction curettage in the treatment of exogenous cesarean scar pregnancy (CSP).

METHODS

A retrospective single-center observational study was conducted. A total of 41 patients diagnosed with exogenous CSP were enrolled in this study. All patients received HIFU combined with suction curettage.

RESULTS

Twenty-nine patients were administered one session of HIFU ablation. In addition, the other 12 patients received 2 HIFU sessions. Suction curettage was performed in all patients after HIFU, and no patient was converted to laparoscopy or hysterectomy. The mean blood loss during suction curettage was 99 ml. Three patients received two sessions of suction curettage. The success rate of our study was 92.68%. The mean time for serum β-HCG normalization was 23.18 ± 3.13 days. The average menstruation recovery time was 29.38 ± 3.34 days. Based on the blood loss during suction curettage, 41 patients were divided into a bleeding group and a control group. The size of the gestational sac in the bleeding group (3.80 ± 0.87 cm) was larger than that in the control group (3.39 ± 0.77 cm) (P < 0.05). The thickness of the myometrium between the bladder and gestational sac in the bleeding group (2.37 ± 0.89 mm) was less than that in the control group (2.75 ± 0.75 mm) (P < 0.05).

CONCLUSION

The results suggested that HIFU combined with suction curettage could be considered an effective treatment for exogenous CSP of < 9 weeks. The size of the gestational sac and the thickness of the myometrium between the bladder and gestational sac might be high-risk factors for blood loss during this treatment.

Drug-loaded nanoparticles conjugated with genetically engineered bacteria for cancer therapy

Drug-loaded nanoparticles have been widely used as synergists in high-intensity focused ultrasound (HIFU) tumor ablation therapy. However, these synergists have certain limitations, such as poor tumor targeting and low accumulation at the tumor site, that restrict the therapeutic efficacy of HIFU. In this study, we utilized drug-loaded nanoparticles conjugated with genetically engineered bacteria which can selectively colonize the hypoxic areas of tumor to facilitate HIFU ablation. Genetically modified Escherichia coli carrying gas vesicles (GVs-E. coli), which were gas-filled protein nanostructures, had a negatively charged surface and could specifically target into the tumor. In contrast, paclitaxel (PTX) and perfluorohexane (PFH) co-loaded cationic lipid nanoparticles (PTX-CLs) had a positively charged surface, hence, GVs-E. coli was used as a vehicle by conjugating with PTX-CLs via electrostatic adsorption and subsequently attracting more PTX-CLs to the tumor site. To improve the therapeutic efficiency of HIFU, the GVs in GVs-E. coli and PFH encapsulated in PTX-CLs could act as cavitation nuclei to enhance the HIFU cavitation effect, while PTX entrapped in PTX-CLs was released at the tumor site under HIFU irradiation, enhancing the therapeutic efficacy of HIFU and chemo-synergistic therapy. This novel combination strategy has great potential for cancer treatment.

Control of the dynamics of a boiling vapour bubble using pressure-modulated high intensity focused ultrasound without the shock scattering effect: A first proof-of-concept study

Boiling histotripsy is a promising High-Intensity Focused Ultrasound (HIFU) technique that can be used to induce mechanical tissue fractionation at the HIFU focus via cavitation. Two different types of cavitation produced during boiling histotripsy exposure can contribute towards mechanical tissue destruction: (1) a boiling vapour bubble at the HIFU focus and (2) cavitation clouds in between the boiling bubble and the HIFU source. Control of the extent and degree of mechanical damage produced by boiling histotripsy is necessary when treating a solid tumour adjacent to normal tissue or major blood vessels. This is, however, difficult to achieve with boiling histotripsy due to the stochastic formation of the shock scattering-induced inertial cavitation clouds. In the present study, a new histotripsy method termed pressure-modulated shockwave histotripsy is proposed as an alternative to or in addition to boiling histotripsy without inducing the shock scattering effect. The proposed concept is (a) to generate a boiling vapour bubble via localised shockwave heating and (b) subsequently control its extent and lifetime through manipulating peak pressure magnitudes and a HIFU pulse length. To demonstrate the feasibility of the proposed method, bubble dynamics induced at the HIFU focus in an optically transparent liver tissue phantom were investigated using a high speed camera and a passive cavitation detection systems under a single 10, 50 or 100 ms-long 2, 3.5 or 5 MHz pressure-modulated HIFU pulse with varying peak positive and negative pressure amplitudes from 5 to 89 MPa and -3.7 to -14.6 MPa at the focus. Furthermore, a numerical simulation of 2D nonlinear wave propagation with the presence of a boiling bubble at the focus of a HIFU field was conducted by numerically solving the generalised Westervelt equation. The high speed camera experimental results showed that, with the proposed pressure-modulated shockwave histotripsy, boiling bubbles generated by shockwave heating merged together, forming a larger bubble (of the order of a few hundred micron) at the HIFU focus. This coalesced boiling bubble then persisted and maintained within the HIFU focal zone until the end of the exposure (10, 50, or 100 ms). Furthermore, and most importantly, no violent cavitation clouds which typically appear in boiling histotripsy occurred during the proposed histotripsy excitation (i.e. no shock scattering effect). This was likely because that the peak negative pressure magnitude of the backscattered acoustic field by the boiling bubble was below the cavitation cloud intrinsic threshold. The size of the coalesced boiling bubble gradually increased with the peak pressure magnitudes. In addition, with the proposed method, an oval shaped lesion with a length of 0.6 mm and a width of 0.1 mm appeared at the HIFU focus in the tissue phantom, whereas a larger lesion in the form of a tadpole (length: 2.7 mm, width: 0.3 mm) was produced by boiling histotripsy. Taken together, these results suggest that the proposed pressure-modulated shockwave histotripsy could potentially be used to induce a more spatially localised tissue destruction with a desired degree of mechanical damage through controlling the size and lifetime of a boiling bubble without the shock scattering effect.

MRI features and clinical outcomes of unexpected uterine sarcomas in patients who underwent high-intensity focused ultrasound ablation for presumed uterine fibroids

OBJECTIVE

To investigate the MRI features and clinical outcomes of unexpected uterine sarcomas in patients after high-intensity focused ultrasound (HIFU) ablation for presumed uterine fibroids.

MATERIALS AND METHODS

15,759 consecutive patients who came for HIFU treatment, from November 2008 to September 2019, for presumed uterine fibroids were retrospectively reviewed. All the patients had completed a pre-HIFU MRI. All MRI images were independently analyzed and interpreted by two radiologists in every center.

RESULTS

According to the T2WI MRI features of hyperintensity, accompanied by irregular margins, necrosis or cystic degeneration, multi-lobulated lesion with internal septation, 46 patients were suspected to be uterine sarcomas before HIFU. Eleven patients were histologically diagnosed as uterine sarcomas after laparotomy. Among the 15713 patients who received HIFU treatment for presumed uterine fibroids, 8 patients were found to have occult recurrence during the follow-up period, and 6 were confirmed histologically as uterine sarcomas after laparotomy. The incidence rate of uterine sarcomas was 0.108% (17/15759). Among them, 12 cases were low-grade endometrial stromal sarcoma (LG-ESS) and 5 cases were uterine leiomyosarcoma (LMS). No histological dissemination of the sarcoma was detected in patients with unexpected uterine sarcomas.

CONCLUSION

Although some MRI features of uterine sarcomas and uterine fibroids overlapped, MRI is valuable in distinguishing between uterine fibroids and uterine sarcomas. HIFU does not seem to cause histological dissemination of the sarcoma, but follow-up visits should be strictly adhered to in order to detect unexpected uterine sarcomas at an early stage and to treat them in a timely manner.

High-intensity focused ultrasound ablation of liver tumors in difficult locations

High-intensity focused ultrasound (HIFU) has been shown to be a valuable tool in the management of small liver tumors such as hepatocellular carcinoma (HCC). It has been shown to be a safe and effective means to ablate small HCC even in the presence of advanced cirrhosis. This review examines the challenges faced during HIFU ablation when the target tumors are located in difficult locations such as the liver dome, close to the rib cage, near large blood vessels or the heart, or adjacent to hollow viscera; and the special maneuvers employed to tackle such lesions.

Oxford's clinical experience in the development of high intensity focused ultrasound therapy

High Intensity Focused Ultrasound (HIFU) capably bridges the disciplines of surgery, oncology and biomedical engineering science. It provides the precision associated with a surgical tool whilst remaining a truly non-invasive technique. Oxford has been a centre for both clinical and preclinical research in HIFU over the last twenty years. Research into this technology in the UK has a longer history, with much of the early research being carried out by Professor Gail ter Haar and her team at the Institute of Cancer Research at Sutton in Surrey. A broad range of potential applications have been explored extending from tissue ablation to novel drug delivery. This review presents Oxford's clinical studies and applications for the development of this non-invasive therapy. This includes treatment of solid abdominal tumours comprising those of the liver, kidney, uterus, pancreas, pelvis and prostate. It also briefly introduces preclinical and translational works that are currently being undertaken at the Institute of Biomedical Engineering, University of Oxford. The safety, wide tolerability and effectiveness of this technology is comprehensively demonstrated across these studies. These results can facilitate the incorporation of HIFU as a key clinical management strategy.

Visualization of thermal washout due to spatiotemporally heterogenous perfusion in the application of a model-based control algorithm for MR-HIFU mediated hyperthermia

PURPOSE

This article will report results from the in-vivo application of a previously published model-predictive control algorithm for MR-HIFU hyperthermia. The purpose of the investigation was to test the controller's in-vivo performance and behavior in the presence of heterogeneous perfusion.

MATERIALS AND METHODS

Hyperthermia at 42°C was induced and maintained for up to 30 min in a circular section of a thermometry slice in the biceps femoris of German landrace pigs (n=5) using a commercial MR-HIFU system and a recently developed MPC algorithm. The heating power allocation was correlated with heat sink maps and contrast-enhanced MRI images. The temporal change in perfusion was estimated based on the power required to maintain hyperthermia.

RESULTS

The controller performed well throughout the treatments with an absolute average tracking error of 0.27 ± 0.15 °C and an average difference of 1.25 ± 0.22 °C between T10 and T90. The MPC algorithm allocates additional heating power to sub-volumes with elevated heat sink effects, which are colocalized with blood vessels visible on contrast-enhanced MRI. The perfusion appeared to have increased by at least a factor of ∼1.86 on average.

CONCLUSIONS

The MPC controller generates temperature distributions with a narrow spectrum of voxel temperatures inside the target ROI despite the presence of spatiotemporally heterogeneous perfusion due to the rapid thermometry feedback available with MR-HIFU and the flexible allocation of heating power. The visualization of spatiotemporally heterogeneous perfusion presents new research opportunities for the investigation of stimulated perfusion in hypoxic tumor regions.

Polyethylenimine (PEI)-modified poly (lactic-co-glycolic) acid (PLGA) nanoparticles conjugated with tumor-homing bacteria facilitate high intensity focused ultrasound-mediated tumor ablation

The acoustic propagation characteristic of ultrasound determines that the energy of ultrasound beam will decrease with the increase of its propagation depth in the body. Similarly, the energy of High Intensity Focused Ultrasound (HIFU) will be attenuated with the increase of HIFU propagation depth in the body. Ensuring sufficient ultrasound energy deposition in the HIFU ablation region for tumor ablation is usually achieved by increasing the ultrasound irradiation power or prolonging the ultrasound ablation time. However, these two methods may damage the normal tissue adjacent to the HIFU ablation region. Herein, we constructed the nanoparticles conjugated with tumor-homing bacteria as the biological tumor-homing synergist to facilitate HIFU-mediated tumor ablation avoiding the potential safety risk. In our strategy, Bifidobacterium bifidum (B.bifidum) was selectively colonized in the hypoxic region of solid tumors after been injected into 4T1 breast cancer bearing-BALB/c mice via the tail vein due to its anaerobic growth characteristic. The amount of B. bifidum with negative surface potential in the hypoxic region of solid tumors was increased by its anaerobic proliferation. Polyethylenimine (PEI) -modified Poly (lactic-co-glycolic) acid nanoparticles loaded sodium bicarbonate (PEI-PLGA-NaHCO₃-NPs) with positive surface potential injected into 4T1 breast cancer bearing-BALB/c mice via the tail vein displayed the tumor-homing ability by the electrostatic adsorption with B. bifidum colonized solid tumors. PEI-PLGA-NaHCO₃-NPs could release NaHCO₃ to produce carbon dioxide (CO₂) as cavitation nuclei inside the acidic microenvironment of solid tumors. When HIFU irradiated solid tumors contained with more cavitation nuclei, the ultrasound energy deposition at the tumor region was increased to destroy the tumors more effectively. Meanwhile, the improved efficiency of HIFU-mediated tumor ablation reduced the dependence of the tumor ablation on the ultrasound energy dose, which improved the safety of HIFU-mediated tumor ablation to the non-targeted ablation tissue. This tumor-homing synergist shows the potential application value on the HIFU-mediated tumor ablation in the clinical.

HIFU for the treatment of gastric cancer with liver metastases with unsuitable indications for hepatectomy and radiofrequency ablation: a prospective and propensity score-matched study

Background

The purpose of this study was to explore the efficacy and safety of high intensity focused ultrasound (HIFU) in gastric cancer with liver metastasis (GCLM) patients who were contraindicated for either hepatectomy or radiofrequency ablation (RFA).

Methods

This is a prospective, observational study on GCLM patients with 1–3 liver metastases. The primary gastric lesions were thoroughly resected and any case that exhibited extra-hepatic metastasis was excluded. A 1:2:2 propensity score-matching analysis was performed using a logistic regression model on the HIFU group, best supportive care (BSC) group, and palliative chemotherapy (PC) group. The primary endpoints include progression-free survival (PFS) and overall survival (OS).

Results

Forty patients were finally included, there were 8 cases in HIFU group, 16 cases in BSC group, and 16 cases in PC group. The median follow-up time for the entire cohort was 10 months. The median PFS was 16.5 months in HIFU group, 2 months in BSC group, and 5 months in PC group. The median OS was 27.5 months in the HIFU group, 7 months in the BSC group, and 11.5 months in the PC group. Additionally, no grade 3 or higher adverse events occurred in the HIFU group.

Conclusion

The results of this study showed that HIFU treatment could improve the long-term prognosis of GCLM patients without a significant increase in the occurrence of adverse events. Compared with PC and BSC, HIFU is the preferred treatment option when GCLM patients without extra-hepatic metastasis are unable to undergo either surgery or RFA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-021-01307-y.

Focused ultrasound ablation of a large canine oral tumor achieves efficient tumor remission: a case report

Purpose: Oral cancers are one of the commonly diagnosed tumors worldwide in human and veterinary patients. Most oral cancers are surgically resected; however, obtaining an adequate margin of safety in patients without compromising their quality of life is often challenging. Herein, we investigated the ability of non-invasive focused ultrasound (FUS) to thermally ablate a biopsy confirmed canine oral cancer. Materials and Methods: A male canine patient with a large neurilemmoma (schwannoma) mass on the left maxilla, with evidence of thinning and loss of alveolar bone and pressure necrosis, was treated with FUS ablation instead of the traditional maxillectomy procedure. FUS ablations were performed in three sessions over three weeks. Tumor remission was determined with computed tomography and histopathological examination of the treated site. Additionally, the anti-tumor immune effects of FUS were assessed by flow cytometry analysis of blood and tumor samples. Results: Complete tumor remission was noted at the treated site. Treatment related adverse events were primarily thermal burns of the buccal mucosa, which were managed with periodic hyperbaric oxygen therapy and surgical coverage of the underlying exposed bones with gingival flaps. Enhanced proliferation of adaptive immunity cells (e.g., T-cells) was observed in tumor and blood samples. Conclusion: Our limited investigation in a canine oral cancer patient suggests that FUS may avoid the need for large-scale resection of bony tissues, thus potentially improving quality of life.

High-intensity focused ultrasound (HIFU) for the treatment of uterine fibroids: does HIFU significantly increase the risk of pelvic adhesions?

OBJECTIVE

To investigate the prevalence of pelvic adhesions in patients with uterine fibroids after high-intensity focused ultrasound (HIFU) treatment, then analyze the influencing factors of pelvic adhesions.

MATERIALS AND METHODS

From October 2010 to March 2020, a total of 2619 patients with uterine fibroids underwent either hysterectomy, myomectomy, or cesarean section in Suining Central Hospital of Sichuan province. Of the 2619 patients, 810 were excluded because of a documented history of either pelvic infections, endometriosis, prior abdominopelvic surgery, or gynecological malignancies; 1809 patients were enrolled and the data were retrospectively assessed for the prevalence and patterns of pelvic adhesions. Among them, 96 patients with uterine fibroids had had prior HIFU treatment (HIFU group), 1713 patients had not had HIFU or surgical treatments (control group).

RESULTS

Among the 96 patients in the HIFU group, adhesions were detected in 42 patients, the incidence of pelvic adhesion being 43.75%; the 1713 patients in the control group, adhesions were detected in 619 patients, the prevalence of pelvic adhesion being 36.14%. No statistically significant difference in the incidence of adhesion between the two groups was observed (p = .132), no significant difference in location of pelvic adhesions between the two groups and no significant difference in the severity of adhesions between the two groups was observed (p > .05).

CONCLUSIONS

Based on our results with limited numbers, we concluded that HIFU treatment did not significantly increase the risk of pelvic adhesions.

Sorafenib blocks the activation of the HIF-2α/VEGFA/EphA2 pathway, and inhibits the rapid growth of residual liver cancer following high-intensity focused ultrasound therapy in vivo

BACKGROUND

Insufficient high-intensity focused ultrasound (HIFU) can promote the rapid progression of the residual tumor through the hypoxia inducible factor-2α +(HIF-2α)/vascular endothelial growth factor A (VEGFA)/ephrin type-A receptor 2 (EphA2) pathway. Although sorafenib has been shown to significantly improve the survival of patients with advanced liver cancer, the use of sorafenib in residual tumor tissues following HIFU has rarely been elucidated. Thus, this study aimed to investigate the potential adjuvant therapeutic effects of sorafenib following HIFU in order to reduce the relapse rate following insufficient HIFU.

METHODS

Xenograft tumors were established using nude mice injected with liver cancer cells. At approximately 4 weeks after the inoculation of the tumor cells (tumors reached 1.3-1.5 cm), all mice were randomly divided into 3 groups as follows: i) The control group (no treatment); ii) the HIFU-alone group, and iii) the combination group (HIFU + sorafenib), with 6 mice per group. The residual tumor volume was determined among the different treatment groups. The protein expression levels of HIF-2α, VEGFA and EphA2 were determined by immunohistochemistry and western blotting, and the mRNA levels were detected by RT-qPCR. The microvessel density (MVD) was calculated by CD31 immunohistochemistry staining.

RESULTS

The results revealed that by comparing the control group, insufficient HIFU promoted HIF-2α, VEGFA and EphA2 expression (P < 0.05). Compared with the HIFU-alone group, the protein and mRNA levels of HIF-2α, VEGFA and EphA2 were markedly decreased in the group that received combined treatment with HIFU and sorafenib (P < 0.05). Similar results were obtained for MVD expression. Synergistic tumor growth inhibitory effects were also observed between the control group and HIFU group (P < 0.05).

CONCLUSIONS

The findings of this study demonstrate that the expression of HIF-2α, VEGFA and EphA2 can be inhibited by sorafenib, and that sorafenib is likely to provide an effective adjunct treatment for patients with HCC following HIFU ablation.

A fast full-wave solver for calculating ultrasound propagation in the body

Therapeutic ultrasound is a promising non-invasive method for inducing various beneficial biological effects in the human body. In cancer treatment applications, high-power ultrasound is focused at a target tissue volume to ablate the malignant tumour. The success of the procedure depends on the ability to accurately focus ultrasound and destroy the target tissue volume through coagulative necrosis whilst preserving the surrounding healthy tissue. Patient-specific treatment planning strategies are therefore being developed to increase the efficacy of such therapies, while reducing any damage to healthy tissue. These strategies require to use high-performance computing methods to solve ultrasound wave propagation in the body quickly and accurately. For realistic clinical scenarios, all numerical methods which employ volumetric meshes require several hours or days to solve the full-wave propagation on a computer cluster. The boundary element method (BEM) is an efficient approach for modelling the wave field because only the boundaries of the hard and soft tissue regions require discretisation. This paper presents a multiple-domain BEM formulation with a novel preconditioner for solving the Helmholtz transmission problem (HTP). This new formulation is efficient at high-frequencies and where high-contrast materials are present. Numerical experiments are performed to solve the HTP in multiple domains comprising: (i) human ribs, an idealised abdominal fat layer and liver tissue, (ii) a human kidney with a perinephric fat layer, exposed to the acoustic field generated by a high-intensity focused ultrasound (HIFU) array transducer. The time required to solve the equations associated with these problems on a single workstation is of the order of minutes. These results demonstrate the great potential of this new BEM formulation for accurately and quickly solving ultrasound wave propagation problems in large anatomical domains which is essential for developing treatment planning strategies.

The interaction of shockwaves with a vapour bubble in boiling histotripsy: The shock scattering effect

Boiling histotripsy is a High Intensity Focused Ultrasound (HIFU) technique which uses a number of short pulses with high acoustic pressures at the HIFU focus to induce mechanical tissue fractionation. In boiling histotripsy, two different types of acoustic cavitation contribute towards mechanical tissue destruction: a boiling vapour bubble and cavitation clouds. An understanding of the mechanisms underpinning these phenomena and their dynamics is therefore paramount to predicting and controlling the overall size of a lesion produced for a given boiling histotripsy exposure condition. A number of studies have shown the effects of shockwave heating in generating a boiling bubble at the HIFU focus and have studied its dynamics under boiling histotripsy insonation. However, not much is known about the subsequent production of cavitation clouds that form between the HIFU transducer and the boiling bubble. The main objective of the present study is to examine what causes this bubble cluster formation after the generation of a boiling vapour bubble. A numerical simulation of 2D nonlinear wave propagation with the presence of a bubble at the focus of a HIFU field was performed using the k-Wave MATLAB toolbox for time domain ultrasound simulations, which numerically solves the generalised Westervelt equation. The numerical results clearly demonstrate the appearance of the constructive interference of a backscattered shockwave by a bubble with incoming incident shockwaves. This interaction (i.e., the reflected and inverted peak positive phase from the bubble with the incoming incident rarefactional phase) can eventually induce a greater peak negative pressure field compared to that without the bubble at the HIFU focus. In addition, the backscattered peak negative pressure magnitude gradually increased from 17.4 MPa to 31.6 MPa when increasing the bubble size from 0.2 mm to 1.5 mm. The latter value is above the intrinsic cavitation threshold of -28 MPa in soft tissue. Our results suggest that the formation of a cavitation cloud in boiling histotripsy is a threshold effect which primarily depends (a) the size and location of a boiling bubble, and (b) the sum of the incident field and that scattered by a bubble.

Quantitative prediction of the extent of pelvic tumour ablation by magnetic resonance-guided high intensity focused ultrasound

BACKGROUND

Patient suitability for magnetic resonance-guided high intensity focused ultrasound (MRgHIFU) therapy of pelvic tumors is currently assessed by visual estimation of the proportion of tumor that can be reached by the device's focus (coverage). Since it is important to assess whether enough energy reaches the tumor to achieve ablation, a methodology for estimating the proportion of the tumor that can be ablated (treatability) was developed. Predicted treatability was compared against clinically achieved thermal ablation.

METHODS

MR Dixon sequence images of five patients with recurrent gynecological tumors were acquired during their treatment. Acousto-thermal simulations were performed using k-Wave for three exposure points (the deepest and shallowest reachable focal points within the tumor, identified from tumor coverage analysis, and a point halfway in-between) per patient. Interpolation between the resulting simulated ablated tissue volumes was used to estimate the maximum treatable depth and hence, tumor treatability. Predicted treatability was compared both to predicted tumor coverage and to the clinically treated tumor volume. The intended and simulated volumes and positions of ablated tissues were compared.

RESULTS

Predicted treatability was less than coverage by 52% (range: 31-78%) of the tumor volume. Predicted and clinical treatability differed by 9% (range: 1-25%) of tumor volume. Ablated tissue volume and position varied with beam path length through tissue.

CONCLUSION

Tumor coverage overestimated patient suitability for MRgHIFU therapy. Employing patient-specific simulations improved treatability assessment. Patient treatability assessment using simulations is feasible.

Extracorporeal Treatment with High Intensity Focused Ultrasound of an Incompetent Perforating Vein in a Patient with Active Venous Ulcers

Introduction

Endovenous techniques such as ultrasound guided foam sclerotherapy, thermal methods, or glues are generally recommended to occlude incompetent veins. However, these methods can be technically challenging and risky for patients with severe atrophic skin disorders like lipodermatosclerosis or atrophie blanche. High intensity focused ultrasound (HIFU), which has been shown to coagulate and occlude veins successfully, may offer an alternative method. This case report details ultrasound guided HIFU to occlude non-invasively a refluxing perforator vein causing active ulcers.

Report

A 95 year old man presented to the Institute for Functional Phlebology (Melk, Austria) with painful recurrent ulcers in his left medial calf. His limb was scored C2,3,4a, b,6, Ep, Ap, Pr,18 according to the Clinical, Etiology, Anatomic, Pathophysiology (CEAP) classification. Lower limb ultrasound revealed a refluxing posterior tibial perforating vein, measuring 2.7 mm in diameter at the level of the fascia. Extracorporeal HIFU pulses were delivered to this vein with the Sonovein device (Theraclion, Malakoff, France). Sonication was applied for eight seconds at a mean acoustic power of 80 W. The patient was followed up for three months post-treatment and occlusion was evaluated by duplex ultrasound. There were no complications during treatment or follow up. Three months after the treatment, reflux was abolished and the two initially active ulcers had healed.

Discussion

Although this is an early report, this study shows that HIFU can be successful in ablation of incompetent perforator veins in the treatment of venous leg ulcers.

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Endovenous methods are not suited to all patients with severe skin disorders.

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High intensity focused ultrasound can treat venous leg disorders non-invasively.

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Treatments have been performed on a refluxing perforator vein causing active ulcers.

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Short-term results showed that this technique is as good as other thermal therapies.

High intensity focused ultrasound responsive release behavior of metallo-supramolecular block PPG-PEG copolymer micelles

An amphiphilic metallo-supramolecular poly(propylene glycol)-block-poly(ethylene glycol) block copolymer containing a bis(2,2':6',2″-terpyridine) ruthenium (II) complex as a supramolecular connection between the two constituting blocks was used to prepare stable aqueous micelles which displayed a high intensity focused ultrasound (HIFU) triggered release behavior. By adjusting the HIFU time and intensity, the novel modality of HIFU triggered release allows for fine-tuning of the release kinetics of the encapsulants from the micelles in a remote and controlled way. Nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, and matrix-assisted laser desorption/ionization-time of flight mass spectrometry confirmed that the degradation of the micelles was due to the cleavage of the ether bond connected to the pyridine ring. This well controlled HIFU-copolymer micelle drug delivery system has considerable potential in targeted therapy.

Focused ultrasound and prostate cancer

Focused ultrasound (FUS) has been utilized for the treatment of localized prostate cancer. Initially, FUS was performed as a whole-gland treatment comparable to radical prostatectomy or radiation therapy. However, after overall downward stage migration due to health screening programs involving prostate-specific antigen testing, as well as advances in conservative or observative strategies such as active surveillance, FUS has evolved from a whole-gland treatment to a focal treatment. This new treatment technique aims to ablate tumors while preserving the normal prostate tissue, thereby ensuring better preservation of urinary and erectile function. In this article, we review the mechanism and clinical outcomes of the FUS procedure.

Focal HIFU therapy for anterior compared to posterior prostate cancer lesions

Objective

To compare cancer control in anterior compared to posterior prostate cancer lesions treated with a focal HIFU therapy approach.

Materials and methods

In a prospectively maintained national database, 598 patients underwent focal HIFU (Sonablate^®500) (March/2007–November/2016). Follow-up occurred with 3-monthly clinic visits and PSA testing in the first year with PSA, every 6–12 months with mpMRI with biopsy for MRI-suspicion of recurrence. Treatment failure was any secondary treatment (ADT/chemotherapy, cryotherapy, EBRT, RRP, or re-HIFU), tumour recurrence with Gleason ≥ 3 + 4 on prostate biopsy without further treatment or metastases/prostate cancer-related mortality. Cases with anterior cancer were compared to those with posterior disease.

Results

267 patients were analysed following eligibility criteria. 45 had an anterior focal-HIFU and 222 had a posterior focal-HIFU. Median age was 64 years and 66 years, respectively, with similar PSA level of 7.5 ng/ml and 6.92 ng/ml. 84% and 82%, respectively, had Gleason 3 + 4, 16% in both groups had Gleason 4 + 3, 0% and 2% had Gleason 4 + 4. Prostate volume was similar (33 ml vs. 36 ml, p = 0.315); median number of positive cores in biopsies was different in anterior and posterior tumours (7 vs. 5, p = 0.009), while medium cancer core length, and maximal cancer percentage of core were comparable. 17/45 (37.8%) anterior focal-HIFU patients compared to 45/222 (20.3%) posterior focal-HIFU patients required further treatment (p = 0.019).

Conclusion

Treating anterior prostate cancer lesions with focal HIFU may be less effective compared to posterior tumours.

Candidates to salvage therapy after external-beam radiotherapy of prostate cancer: Predictors of local recurrence volume and metastasis-free survival

PURPOSE

The purpose of this study was to assess the predictors of metastasis-free survival (MFS) and of the volume of the local recurrence in patients with rising prostate-specific antigen (PSA) serum level after radiotherapy for prostate cancer and referred for prostate magnetic resonance imaging (MRI) and biopsy in view of salvage treatment.

MATERIALS AND METHODS

A total of 132 consecutive men (median age, 70 years; IQR, 66-77 years) with rising PSA after prostate radiotherapy who underwent prostate MRI and biopsy in view of salvage treatment between January 2010 and July 2017 were retrospectively evaluated at a single center. MFS predictors were assessed with Cox models. Predictors of the volume of the local recurrence (number of invaded prostate sectors at biopsy) were assessed using Poisson regression among variables available at PSA relapse.

RESULTS

At multivariate analysis, an initial Gleason score≥8 (OR=7 [95% confidence interval (CI): 1.2-40]; P=0.03), a recent radiotherapy (OR=17 [95% CI: 3.9-72]; P<0.0001), the use of androgen deprivation therapy at PSA relapse (OR=12.5 [95% CI: 2.8-57]; P=0.001) and the number of invaded prostate sectors (OR=1.5 [95% CI: 1.1-2]; P=0.007) and maximum cancer core length (OR=0.7 [95%CI: 0.6-0.9]; P=0.002) at biopsy performed at PSA relapse were significant MFS predictors. The PSA level at relapse was significant independent predictor of the volume of local recurrence only when used as a continuous variable (P=0.0002) but not when dichotomized using the nadir+2 threshold (P=0.41).

CONCLUSION

Pathological and clinical factors can help predict MFS in patients with rising PSA after prostate radiotherapy and candidates to salvage treatment. The PSA level at relapse has strong influence on the local recurrence volume when used as a continuous variable.

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.

Deployable tessellated transducer array for ultrasound focusing and bio-heat generation in a multilayer environment

High intensity focused ultrasound (HIFU) has great potential to thermally ablate diseased tissues with minimal invasion. Yet, HIFU practice has limited cancer treatment potential since the absorption, diffusion, and reflection of ultrasound prevent HIFU from penetrating the body to deep and concealed diseased tissue. To explore a vision of deployable HIFU transducers, this research introduces an origami-inspired concept wherein a deployable tessellated acoustic array is employed to reduce the distance between the HIFU transducer and diseased tissues. A flat-foldable HIFU transducer array is considered, such that the compact shape is used to pass through the human body and then deployed into the operational form for treatment. Here a theoretical framework is developed to study the focusing and thermal heating capabilities of the tessellated array in a multilayer environment. It is observed that the wavefield and thermal elevation realized by the foldable array are functionally similar to those of an ideal arc-shaped transducer. Folding patterns that permit adequate curvature and high quality factor, and that balance slenderness and conformability are found to be beneficial for an ultrasound focusing practice. The efficacy of the analytical predictions are verified through direct numerical simulations. All together, the results encourage attention to foldable array concepts as potential means to advance in-vivo HIFU-based procedures.

The applicability and efficacy of magnetic resonance-guided high intensity focused ultrasound system in the treatment of primary trigeminal neuralgia

Primary trigeminal neuralgia is a common clinical refractory neuralgia characterized by an onset of excruciating pain that can severely affect patients' quality of life. Long-term suffering from this pain may lead to depression, anxiety, and suicide. Current treatments, however, are associated with high recurrent rates and severe complications. We hypothesize that both the applicability and efficacy of magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) treatment in primary trigeminal neuralgia can be achieved under the following conditions: a specific target focus and incident channel, a temperature measurement system that does not incur damage to surrounding tissues, and an optimal radiation dose. Successful non-invasive treatment of primary trigeminal neuralgia by MR-HIFU systems could represent a breakthrough of this technology applied to the oral and maxillofacial region.

Theranostic MRI liposomes for magnetic targeting and ultrasound triggered release of the antivascular CA4P

Theranostic nanocarriers of antivascular drug encapsulated in thermosensitive ultramagnetic liposomes can be advantageously designed to provide a locally high concentration and an active delivery, with image-guided Magnetic Resonance Imaging (MRI) so as to reliably cure tumor. We propose a novel therapeutic strategy consisting of the magnetic accumulation of Ultra Magnetic Liposomes (UML) followed by High-Intensity Focused Ultrasound (HIFU) to trigger the release of an antivascular agent monitored by MRI. For this purpose, we co-encapsulated Combretastatin A4 phosphate (CA4P), a vascular disrupting agent, in the core of UML to obtain CA4P-loaded thermosensitive Ultra Magnetic Liposomes (CA4P-UML). To assess the HIFU parameters, the CA4P release has been triggered in vitro by local heating HIFU at the lipids transition temperature. Morphology of endothelial cells was assessed to evaluate the effect of encapsulated versus non-encapsulated CA4P. The efficiency of a treatment combining the magnetic targeting of CA4P-UML with the CA4P release triggered by HIFU was studied in CT26 murine tumors. Tumor perfusion and volume regression parameters were monitored by multiparametric quantitative anatomical and dynamic in vivo MRI at 7 T. Additionally, vascularization and cellularity were evaluated ex-vivo by histology. This thorough investigation showed that the combined treatment exhibited a full benefit. A 150-fold improvement compared with the chemotherapy alone was obtained using a magnetic targeting of CA4P-UML triggered by HIFU, and was consistent with an expected effect on vascularization 24 h after treatment.

Bactericidal effects of high intensity focused ultrasound on Bacillus Calmette-Guerin in vivo and in vitro

Purpose: The objective of this study was to investigate the bactericidal effects of high intensity focused ultrasound (HIFU) on Bacillus Calmette-Guerin (BCG, a substitute for Mycobacterium tuberculosis) in vitro and in vivo, and to explore the underlying mechanisms. Materials and methods: HIFU, at a fixed frequency of 1 MHz, was applied to both BCG culture suspensions and subcutaneous BCG abscesses in rats. Results: HIFU irradiation significantly reduced the bacterial survival rate and caused temperature elevations both in vitro and in vivo. Furthermore, BCG suspensions irradiated for 15 s at 3185 and 6369 W/cm² had increased cell wall damage, which resulted in morphological changes compared to the untreated control group. Additionally, we observed histological changes in the rat subcutaneous abscesses after HIFU ablation at 6369 W/cm². H&E staining of infected lesions showed coagulative necrosis with central nucleus dissolution and increased infiltration of inflammatory cells, as well as nuclear pyknosis and nuclear fragmentation in the periphery. The volumes of the subcutaneous abscesses in the HIFU-treated group were significantly lower than those in the sham-treated group. Conclusion: HIFU has the therapeutic potential to treat BCG-infected tissues in rats. We theorize that a combination of mechanical, cavitation, and thermal effects most efficiently inactivate BCG bacteria via HIFU. This study is expected to provide a bio-plausible basis for a noninvasive and effective treatment for tuberculosis.

Focused ultrasound resolves persistent radiosurgery related change in a patient with tremor

We report on a patient who underwent magnetic resonance guided focused ultrasound (MRgFUS) thalamotomy to treat tremor 3 years after a stereotactic radiosurgery (SRS) thalamotomy. The SRS produced only limited and transient improvements and was associated with a persistent hyperintensity on T2-FLAIR MR images. The MRgFUS thalamotomy was successful, with tremor improvement at 3 months, no adverse effects, and radiological appearance of the MRgFUS lesion similar to other patients undergoing this therapy. We also observed that the SRS-related T2-FLAIR hyperintensity had increased signal intensity 1 day post-MRgFUS, but appeared completely resolved 3 months post-MRgFUS. In conclusion, the case demonstrates that MRgFUS thalamotomy may effectively control tremor in patients with a history of SRS thalamotomy. We also speculate on the potential mechanisms of the apparent resolution of radiation-related change, and discuss possible applications of MRgFUS to reduce persistent SRS-related inflammation.

Comparing the Efficacy and Safety of High-Intensity Focused Ultrasound and Uterine Artery Embolization in Caesarean Scar Pregnancy: A Meta-analysis

INTRODUCTION

High-intensity focused ultrasound (HIFU) followed by curettage and uterine artery embolization (UAE) followed by curettage are two methods of treatment for caesarean scar pregnancy (CSP). There is currently no consistent evidence concerning any difference in efficacy and safety between UAE and HIFU. Therefore, a meta-analysis was performed to compare the efficacy and safety of HIFU and UAE in the treatment of CSP.

METHODS

Studies published in PubMed, Cochrane, Embase, Web of Science, Chinese BioMedical Literature Service System, and Chinese National Knowledge Infrastructure databases were searched and the main outcomes in the studies were extracted.

RESULTS

Of 8 studies and 715 patients included in this study, 388 and 327 patients were in the HIFU group and UAE groups, respectively. Compared with the UAE group, patients in the HIFU group had less blood loss [weighted mean difference (WMD) = - 22.58 ml; 95% confidence interval (CI) - 44.45 to - 0.70; p < 0.05), lower incidence of adverse events [odds ratio (OR) = 0.17; 95% CI 0.06-0.46; p < 0.05); shorter duration of hospital stay (WMD = - 0.96 days; 95% CI - 1.88 to - 0.03; p < 0.05); and a longer β-human chorionic gonadotropin normalisation time (WMD = 9.59 days; 95% CI 1.66-17.52; p < 0.05).

CONCLUSION

Patients in the HIFU group appeared to have better outcomes than those in the UAE group; thus, HIFU may be a priority option for the early management of CSP. However, this needs to be confirmed by multi-centre, large-scale randomised controlled trials.

Mechanical damage induced by the appearance of rectified bubble growth in a viscoelastic medium during boiling histotripsy exposure

In boiling histotripsy, the presence of a boiling vapour bubble and understanding of its dynamic behaviour are crucially important for the initiation of the tissue fractionation process and for the control of the size of a lesion produced. Whilst many in vivo studies have shown the feasibility of using boiling histotripsy in mechanical fractionation of solid tumours, not much is known about the evolution of a boiling vapour bubble in soft tissue induced by boiling histotripsy. The main objective of this present study is therefore to investigate the formation and dynamic behaviour of a boiling vapour bubble which occurs under boiling histotripsy insonation. Numerical and experimental studies on the bubble dynamics induced in optically transparent tissue-mimicking gel phantoms exposed to the field of a 2.0 MHz High Intensity Focused Ultrasound (HIFU) transducer were performed with a high speed camera. The Gilmore-Zener bubble model coupled with the Khokhlov-Zabolotskaya-Kuznetsov and the Bio-heat Transfer equations was used to simulate bubble dynamics driven by boiling histotripsy waveforms (nonlinear-shocked wave excitation) in a viscoelastic medium as functions of surrounding temperature and of tissue elasticity variations. In vivo animal experiments were also conducted to examine cellular structures around a freshly created lesion in the liver resulting from boiling histotripsy. To the best of our knowledge, this is the first study reporting the numerical and experimental evidence of the appearance of rectified bubble growth in a viscoelastic medium. Accounting for tissue phantom elasticity adds a mechanical constraint on vapour bubble growth, which improves the agreement between the simulation and the experimental results. In addition the numerical calculations showed that the asymmetry in a shockwave and water vapour transport can result in rectified bubble growth which could be responsible for HIFU-induced tissue decellularisation. Strain on liver tissue induced by this radial motion can damage liver tissue while preserving blood vessels.

Robotic Assisted MRI-Guided Interventional Interstitial MR-Guided Focused Ultrasound Ablation in a Swine Model

BACKGROUND

Ablative lesions are current treatments for epilepsy and brain tumors. Interstitial magnetic resonance (MR) guided focused ultrasound (iMRgFUS) may be an alternate ablation technique which limits thermal tissue charring as compared to laser therapy (LITT) and can produce larger ablation patterns nearer the surface than transcranial MR guided focused ultrasound (tcMRgFUS).

OBJECTIVE

To describe our experience with interstitial focused ultrasound (iFUS) ablations in swine, using MR-guided robotically assisted (MRgRA) delivery.

METHODS

In an initial 3 animals, we optimized the workflow of the robot in the MR suite and made modifications to the robotic arm to allow range of motion. Then, 6 farm pigs (4 acute, 2 survival) underwent 7 iMRgFUS ablations using MRgRA. We altered dosing to explore differences between thermal dosing in brain as compared to other tissues. Imaging was compared to gross examination.

RESULTS

Our work culminated in adjustments to the MRgRA, iMRgFUS probes, and dosing, culminating in 2 survival surgeries; swine had ablations with no neurological sequelae at 2 wk postprocedure. Immediately following iMRgFUS therapy, diffusion-weighted imaging, and T1 weighted MR were accurate reflections of the ablation volume. T2 and fluid-attenuated inversion-recovery (FLAIR) images were accurate reflections of ablation volume 1-wk postprocedure.

CONCLUSION

We successfully performed MRgRA iFUS ablation in swine and found intraoperative and postoperative imaging to correlate with histological examination. These data are useful to validate our system and to guide imaging follow-up for thermal ablation lesions in brain tissue from our therapy, tcMRgFUS, and LITT.

High-intensity focused ultrasound combined procedures treatment of retained placenta accreta with marked vascularity after abortion or delivery

OBJECTIVE

To evaluate the safety and feasibility of combined procedures: HIFU combined with systemic MTX followed by ultrasound-guided curettage or hysteroscopic resection while treating placenta accreta (PA).

METHOD

This study included 21 patients diagnosed with retained PA with marked vascularity after abortion or delivery from July 2015 to December 2017. Patients with high serum β-hCG level (≥100 mIU/mL) received systemic MTX + HIFU treatment for 3 days and the ones with low β-hCG level (<100 mIU/mL) only received USgHIFU treatment for 3 days before ultrasound-guided curettage or hysteroscopic resection. All patients had completed follow-up data. The safety and feasibility of the treatment were evaluated retrospectively.

RESULT

Sixteen patients received systemic 100 mg MTX without myelosuppression. All patients received three days of HIFU ablation therapy; the median of HIFU treatment time was 60 minutes. Ultrasound-guided curettage and ovum forceps were used to extract planted placental tissue in 5 patients with one week after birth or after abortion. Sixteen patients received a hysteroscopic operation after the HIFU treatment. The median of intraoperative blood loss was 30 ml. Twenty patients had recovered normal menstruation on average 32 days (range 14-60) after the operation.

CONCLUSION

Based on the results of this study, with a relatively small number of patients, it seems that three-days' therapy of HIFU ± systemic MTX followed by ultrasound-guided curettage or hysteroscopic resection, is a safe and feasible treatment for retained PA with marked vascularity after abortion or delivery.

Spatiotemporally-controlled transgene expression in hydroxyapatite-fibrin composite scaffolds using high intensity focused ultrasound

Conventional tissue engineering approaches rely on scaffold-based delivery of exogenous proteins, genes, and/or cells to stimulate regeneration via growth factor signaling. However, scaffold-based approaches do not allow active control of dose, timing, or spatial localization of a delivered growth factor once the scaffold is implanted, yet these are all crucial parameters in promoting tissue regeneration. To address this limitation, we developed a stable cell line containing a heat-activated and rapamycin-dependent gene expression system. In this study, we investigate how high intensity focused ultrasound (HIFU) can spatiotemporally control firefly luciferase (fLuc) transgene activity both in vitro and in vivo by the tightly controlled generation of hyperthermia. Cells were incorporated into composite scaffolds containing fibrin and hydroxyapatite particles, which yielded significant increases in acoustic attenuation and heating in response to HIFU compared to fibrin alone. Using 2.5 MHz HIFU, transgene activation was observed at acoustic intensities of 201 W/cm2 and higher. Transgene activation was spatially patterned in the scaffolds by rastering HIFU at speeds up to 0.15 mm/s. In an in vivo study, a 67-fold increase in fLuc activity was observed in scaffolds exposed to HIFU and rapamycin versus rapamycin only at 2 days post implantation. Repeated activation of transgene expression was also demonstrated 8 days after implantation. No differences in in vivo scaffold degradation or compaction were observed between +HIFU and -HIFU groups. These results highlight the potential utility of using this heat-activated and rapamycin-dependent gene expression system in combination with HIFU for the controlled stimulation of tissue regeneration.

[Focal HIFU vs robot-assisted total prostatectomy: Functionnal and oncologic outcomes at one year]

OBJECTIVE

To analyse the functional and oncologic outcomes at one year of focal therapy with HIFU compared with total prostatectomy in patients with localised prostate cancer (PCa).

PATIENTS AND METHODS

Retrospective and monocentric study from 2008 to 2014 comparing 2 cohorts of patients with localised PCa (T1/T2 clinical stage, Gleason score≤3+4=7 and PSA<15ng/mL), one treated by focal therapy (HIFU-F group), one by robot-assisted total prostatectomy (RATP group). Primary outcome was a trifecta defined as: absence of urinary incontinence, erectile function with sexual relations without treatment, negative PSA with negative surgical margins (RATP group) or negative biopsy cores (HIFU-F group).

RESULTS

The 53 patients included in the "HIFU-F" group and the 66 patients in the "RATP" group were similar in terms of preoperative PSA, D'Amico risk group, erectile function but were different in terms of age, prostatic volume, length of cancer, Gleason score. Complication rate was not different. In multivariate analyse with propensity score, "HIFU-F" group achieved a better trifecta score than "RATP" group (OR=8,3, p=0,005).

CONCLUSION

In case of low or intermediate risk localised PCa, "HIFU-F" group had better functional outcomes than initial learning curse "RATP" group, at one year. A long-term evaluation by a common endpoint is necessary to judge the oncological equivalence of both techniques.

LEVEL OF EVIDENCE

3.