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Objectives: To compare the clinical and radiographic outcomes of two sinus floor elevation techniques: the conventional lateral window technique versus the transalveolar approach using a hydrodynamic ultrasonic device. Materials and methods: The study was designed as a randomized controlled clinical trial, and participants were randomly allocated to the control group (lateral window: LW) or to the test group (hydrodynamic transalveolar approach: HTA). The intraoperative and postoperative data, including procedure duration and patient-reported outcome measures (PROMs), were collected during the surgery and up to 1 year post-surgery. Additionally, qualitative assessment of gained bone volumes and implant survival rates was recorded. Results: Twenty-two patients were included in the study. The mean surgical time was significantly longer in the HTA compared to the LW group (48.1 ± 11.2 min vs. 35.2 ± 9.1 min, P = 0.0011). Perforation of the Schneiderian membrane occurred in 2/11 and 5/11 patients in the LW and the HTA group, respectively (P = 0.36). Postoperatively, higher morbidity and consumption of nonsteroidal anti-inflammatory drugs (NSAIDs) were associated with the LW group. However, self-reported satisfaction with surgical procedures was similar in the two groups. At 1 year, implant survival rates of 80% in the HTA group and 100% in the LW group were recorded (P = 0.12). Conclusions: Although the new transalveolar approach seems to reduce postoperative morbidity, an increased risk of intraoperative complications compared to the LW approach needs to be considered when choosing a technique. Clinical relevance: Our results provide new insights regarding clinical and radiographic outcomes of HTA and may help further determine indications for its use. Trial registration: ClinicalTrivals.gov: NCT04499625 [ABSTRACT FROM AUTHOR]

Purpose: to improve the results of treatment of the obstructive complications (an urethra stenosis, a bladder neck sclerosis) caused by application of the high-intensity focused ultrasonic ablation (HIFU) concerning treatment of the localized prostate cancer. Material and Methods. An object of the research included 41 patients, with the infravesical obstruction (IVO) which has arisen in the postoperative period to which elimination the holmium laser is used. Results. The bladder neck was the most frequent place of obstruction. Average time before emergence of the first episode of IVO: 8.2±1.3 months. Distinctions on time before development of an episode of IVO depending on the fact of carrying out TURP before HIFU not confirmed (p=0.440). More advanced age for a moment HIFU-ablation has been associated with much higher frequency of IVO (p=0.021). Considerably smaller frequency repeated was observed by IVO at a larger ratio transurethral resection to the initial volume of a prostate (p=0.031). Duration of a laser endoscopic ure-throtomy was 27 [10-70] minutes, serious perioperative or postoperative complications were not determined. Average term before removal of a catheter of Foley: 3 [1-5] days, hospitalization duration included 4 [3-6] days. After treatment considerable improvement on indicators of the maximum speed of a stream of urine (Qmax) and volume of residual urine was observed. The total score according to the questionnaires of IPSS and QoL has considerably improved, significant changes on symptoms of accumulation are noted. After the first holmium laser urethrotomy of 80.4% of patients have noted satisfactory results without recurrence of IVO; 19.6% of patients were required a repeated laser endoscopic urethrotomy. Recurrence term after the first laser urethrotomy is on average equal to 2.5 months. Conclusion. The endoscopic urethrotomy by means of the holmium laser is safe, effective and minimum invasive type of treatment of a stenosis of a neck of the bladder / urethra after ablative cancer therapy of prostate. The advantages are the minimum of traumas of surrounding tissues and preservation of the mechanism of deduction of urine.

The paper presents the results of a numerical experiment comparing the rates of volumetric thermal ablation of bovine liver tissue ex vivo, generated by a multielement ultrasound array Sonalleve V1 3.0T (Philips Healthcare) using various exposure protocols. Pulsed sonications with the same time-average, but different peak power and duty cycle were modeled. The treatment trajectory consisted of a discrete set of single foci located at the center and along two concentric circles. Beam focusing in tissue was modeled using the Westervelt equation, the temperature field was calculated using the bioheat equation, and the threshold of tissue damage was determined according to the thermal dose formulation. It is shown that pulsed shock-wave exposures can provide up to three times faster volumetric ablation of tissue as compared to continuous quasi-harmonic wave treatments. [ABSTRACT FROM AUTHOR]

A novel numerical algorithm based on the wide-angle parabolic approximation is developed for modeling linear and nonlinear fields generated by axially symmetric ultrasound transducers. An example of a strongly focused single-element transducer is used to compare the results of ultrasound field simulations based on the Westervelt equation, Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation with differently modified boundary condition, and nonlinear wide-angle parabolic equation. It is demonstrated that having a computational speed comparable to modeling the KZK equation, the use of wide-angle parabolic approximation makes it possible to obtain solutions for highly focused ultrasound beams that are closer in accuracy to solutions based on the Westervelt equation. [ABSTRACT FROM AUTHOR]

Research objective: Creation of mathematical prognosis of model of local relapsing tumors in patients with prostate cancer after treatment by high-intensive focused ultrasound (HIFU). Objects and Research Methods: Results of treatment are estimated at 102 patients with morphologically localized prostate cancer proved at biopsy. For the purpose to analyze interrelation of prognostic factors and postoperative morphological research of prostate control biopsies after HIFU ablation with frequent development of relapses comparative statistical research of received data has been conducted. For construction of mathematical models of relapse prognosis after HIFU of prostates two methods of mul-tifactorial analysis of the data have been used: the discriminant analysis and logistical regress. Results: While planning treatment of patients after HIFU ablation of prostates it has been necessary to estimate morphological risk factors of local relapse of a neoplasm such as preoperative level of serum PSA, the sum of Gleason, severity of disease, presence of lymphovascular and perineural invasion. The offered formulas are worth while using in revealing of probability of development of relapses. The comparative analysis of mathematical models has showed that accuracy of prognosis of results of HIFU of prostates is high enough.

Research objective: To study the role of prognostic factors in the estimation of risk development of recurrent prostate cancer after treatment by high-intensive focused ultrasound (HIUF). Objects and Research Methods: The research has included 102 patients with morphologically revealed localized prostate cancer by biopsy. They have been on treatment in Clinic of Urology of the Saratov Clinical Hospital n.a. S. R. Mirotvortsev. 102 sessions of initial operative treatment of prostate cancer by the method of HIFU have been performed. The general group of patients (n=102) has been subdivided by the method of casual distribution into two samples: group of patients with absent recurrent tumor and group of patients with the revealed recurrent tumor, by morphological research of biopsy material of residual prostate tissue after HIFU. The computer program has been used to study the signs of outcome of patients with prostate cancer. Results: Risk of development of recurrent prostate cancer has grown with the PSA level raise and its density. The index of positive biopsy columns

Hypothesis: Wide awake local anesthesia with no tourniquet (WALANT) and office-based procedures are used in hand surgery. There are limited literature data on patient satisfaction when comparing methods of anesthesia and location of surgery., Methods: We conducted a retrospective single-surgeon study with patient reported satisfaction in three groups. We compared patient impressions of anesthesia type; WALANT vs locoregional anesthesia plus sedation. We also compared satisfaction in three surgery settings; office surgery vs hospital ambulatory minor procedure room vs main operating room. Group 1 office surgery patients had ultrasound guided surgery with WALANT. Group 2 main operating room surgery patients also had ultrasound guided surgery with WALANT. Group 3 main operating room patients had endoscopic surgery with sedation and a tourniquet. Each group had 30 patients with a minimum follow up of 2 months. We measured overall satisfaction, satisfaction with the organization of care, satisfaction with the administration of anesthesia, and satisfaction with the quality of anesthesia. We also collected secondary data on the resolution of the neuropathic symptoms., Results: Procedures performed in an office-based setting showed higher rates of patient satisfaction when compared to the ambulatory day surgery setting. WALANT anesthesia also showed significantly higher rates of patient satisfaction on a numerical analog scale when compared to sedation based on, irrespective of the surgical setting. All patients had resolution of their neuropathic symptoms regardless of the technique performed., Conclusion: We found that carpal tunnel releases performed in an office-based setting produces superior patient satisfaction. WALANT anesthesia also provides improved patient satisfaction when compared to sedation and monitoring techniques, irrespective of the surgical setting and location. Carpal tunnel release with WALANT in an office-based setting is better for patient comfort and satisfaction, with no evidence of lesser clinical outcomes at a short term follow-up., Level of Evidence: III., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

An equivalent source model is developed for setting boundary conditions on the parabolic diffraction equation in order to simulate ultrasound fields radiated by strongly focused medical transducers. The equivalent source is defined in a plane; corresponding boundary conditions for pressure amplitude, aperture, and focal distance are chosen so that the axial solution to the parabolic model in the focal region of the beam matches the solution to the full diffraction model (Rayleigh integral) for a spherically curved uniformly vibrating source. It is shown that the proposed approach to transferring the boundary condition from a spherical surface to a plane makes it possible to match the solutions over an interval of several diffraction maxima around the focus even for focused sources with F-numbers less than unity. This method can be used to accurately simulate nonlinear effects in the fields of strongly focused therapeutic transducers using the parabolic Khokhlov-Zabolotskaya equation. [ABSTRACT FROM AUTHOR]

Certain modern applications of high-intensity focused ultrasound (HIFU) in medicine use the nonlinear effect of shock front formation in the focal waveform. However, an important problem remains unsolved: determination of transducer parameters that provide the given pressure levels of the shock wave field at the focus required for a specific application. In this paper, simulations based on the Khokhlov-Zabolotskaya equation are performed to test and confirm the hypothesis that angular aperture of the transducer is the main parameter that determines the characteristic amplitude of the shock front and corresponding values for the peak positive and negative pressures at the focus. A criterion for formation of a developed shock in the acoustic waveform, as well as a method for determining its amplitude is proposed. Quantitative dependences of the amplitude of the developed shock and the peak pressures in the wave profile on the angular aperture of the transducer are calculated. The effects of saturation and the range of changes of the shock waveform parameters at the focus are analyzed for a typical HIFU transducer. [ABSTRACT FROM AUTHOR]

The paper presents an analytical method for calculating and analyzing the quality of 3-D acoustic fields of multielement phased arrays used in noninvasive ultrasound surgical devices. An analytical solution for the far field of each of its elements is used when calculating the array field. This method significantly accelerates calculations while preserving the high accuracy of results as compared to conventional direct numerical integration. Radiation from typical phased arrays is calculated using this approach, and the quality of their dynamic focusing is analyzed. Undesired diffraction effects caused by electronic focus steering are considered: an amplitude decrease in the main maximum and the appearance of grating lobes. The quality of dynamic focusing of the acoustic fields of two practically interesting arrays with a quasi-random element distribution (256 and 1024 elements, respectively), as well as of the regular array consisting of 256 elements is compared. In addition as well, a study is made of how the dimensions of the array elements and their spatial distributions affect the dimensions of the areas in which dynamic focusing is possible without occurrence of strong grating lobes and significant decrease in pressure amplitude at the main focus. [ABSTRACT FROM AUTHOR]

Two devices are currently available for the treatment of prostate cancer with HIFU: Sonablate® and Ablatherm®. The outcomes achieved for primary-care patient are very promissing with mid- and long-term progression-free survival rates around 70%, negative postoperative prostate biopsies almost 85%, and an excellent morbidity profile. Moreover, HIFU has a considerable potential for local recurrence after radiation failure. Recently, some early experiences on focal therapy suggest that HIFU could be an excellent option for highly selected patient. [ABSTRACT FROM AUTHOR]

Abstract: Background: High-intensity focused ultrasound (HIFU) is an emerging treatment for select patients with localized prostate cancer (PCa). Objectives: To report the oncologic outcome of HIFU as a primary care option for localized prostate cancer from a multicenter database. Design, setting, and participants: Patients with localized PCa treated with curative intent and presenting at least a 2-yr follow-up from February 1993 were considered in this study. Previously irradiated patients were excluded from this analysis. In case of any residual or recurrent PCa, patients were systematically offered a second session. Kaplan-Meier analysis was performed to determine disease-free survival rates (DFSR). Measurements: Prostate-specific antigen (PSA), clinical stage, and pathologic results were measured pre- and post-HIFU. Results and limitations: A total of 803 patients from six urologic departments met the inclusion criteria. Stratification according to d’Amico''s risk group was low, intermediate, and high in 40.2%, 46.3%, and 13.5% of patients, respectively. Mean follow-up was 42±33 mo. Mean PSA nadir was 1.0±2.8ng/ml with 54.3% reaching a nadir of ≤0.3ng/ml. Control biopsies were negative in 85% of cases. The overall and cancer-specific survival rates at 8 yr were 89% and 99%, respectively. The metastasis-free survival rate at 8 yr was 97%. Initial PSA value and Gleason score value significantly influence the DFSR. The 5- and 7-yr biochemical-free survival rates (Phoenix criteria) were 83–75%, 72–63%, and 68–62% (p =0.03) and the additional treatment-free survival rates were 84–79%, 68–61%, and 52–54% (p <0.001) for low-, intermediate-, and high-risk patients, respectively. PSA nadir was a major predictive factor for HIFU success: negative biopsies, stable PSA, and no additional therapy. Conclusions: Local control and DFSR achieved with HIFU were similar to those expected with conformal external-beam radiation therapy (EBRT). The excellent cancer-specific survival rate is also explained by the possibility to repeat HIFU and use salvage EBRT. [Copyright &y& Elsevier]

Abstract: Minimally invasive applications of thermal and mechanical energy to selective areas of the human anatomy have led to significant advances in treatment of and recovery from typical surgical interventions. Image-guided focused ultrasound allows energy to be deposited deep into the tissue, completely noninvasively. There has long been interest in using this focal energy delivery to block nerve conduction for pain control and local anesthesia. In this study, we have performed an in vitro study to further extend our knowledge of this potential clinical application. The sciatic nerves from the bullfrog (Rana catesbeiana) were subjected to focused ultrasound (at frequencies of 0.661MHz and 1.986MHz) and to heated Ringer''s solution. The nerve action potential was shown to decrease in the experiments and correlated with temperature elevation measured in the nerve. The action potential recovered either completely, partially or not at all, depending on the parameters of the ultrasound exposure. The reduction of the baseline nerve temperature by circulating cooling fluid through the sonication chamber did not prevent the collapse of the nerve action potential; but higher power was required to induce the same endpoint as without cooling. These results indicate that a thermal mechanism of focused ultrasound can be used to block nerve conduction, either temporarily or permanently. (E-mail: khynynen@sri.utoronto.ca) [Copyright &y& Elsevier]

Abstract: This article reviews the role of cavitation in the therapeutic applications of ultrasound and laser surgery, and the cavitation effects in mechanical heart valves. Whenever laser pulses are used to ablate or disrupt tissue in a liquid environment, cavitation bubbles are produced which interact with the tissue. The interaction between cavitation bubbles and tissue during pulsed laser surgery may cause collateral damage to sensitive tissue structures in the vicinity of the laser focus, and it may also contribute in several ways to ablation and cutting. Cavitation is also one of the most exploited bioeffects of ultrasound for therapeutic advantage. In both cases, the violent implosion of cavitation bubbles can lead to the generation of shock waves, high-velocity liquid jets, free radical species, and strong shear forces that can damage the nearby tissue. Knowledge of these physical mechanisms is therefore of vital importance and would provide a framework wherein novel and improved surgical techniques can be developed. [Copyright &y& Elsevier]

Abstract: The optimal dosage of ultrasound contrast agent model for ultrasound surgery was explored. A specific ultrasound contrast agent Albunex® was chosen for simulation. The model was developed based on a dilute bubbly liquid model proposed by Ye and Ding [Z. Ye, L. Ding, Acoustic dispersion and attenuation relations in bubbly mixture, J. Acoust. Soc. Am. 98 (3) (1995) 1629–1636]. The numerical simulation suggests that 2MHz is more efficient than 1MHz to thermally treat cancer in deep tissue with the optimal dosage of 3ml. On the other hand, the simulation also suggests 3MHz center frequency with the optimal dosage of 1.6ml is adequate for prostate cancer treatment with transrectal equipment. The simulation is expected to valid up to 2MPa incident pressure due to the limitation of the linearized UCA model. Even though it is developed from a single ultrasound contrast agent, this model is expected to be useful for any ultrasound contrast agent as long as the necessary parameters are provided. [Copyright &y& Elsevier]

• The work evaluates endothelial cell layer delamination and impregnation enhancement. • The ultrasound combines thermal, mechanical, and chemical mechanisms of action. • Ultrasound has benefits for vein ablation at oscillations amplitude above 40 μm. • The results demonstrate uniform irreversible damage to the venous wall. • Endovenous ultrasound treatment can increase the depth of impregnation of sclerosant up to 600 µm. The article describes the research of a new treatment method of lower limb varicose vein using low-frequency ultrasound. To study the effectiveness of this method we analyzed the interaction between the ultrasound instrument and the venous wall and defined the mechanisms of action during endovenous ultrasound treatment (EUT): thermal, mechanical, and chemical. We developed three models to study the impact of different combinations of mechanisms of action on varicose venous wall. The first model describes the endothelial cell layer delamination during mechanical mechanism. Other models investigate the two main modes of EUT. The EUT mode 1 models mechanical and thermal mechanisms of action, while the EUT mode 2 also studies the impregnation process of sclerosant. During the finite element analysis of both EUT modes, the instrument with an axisymmetric tip was inserted inside the vein with varying blood flow velocity. The amplitude of ultrasound oscillations required for the endothelial cell layer delamination was equal to 40 µm. The ultrasound exposure induced the impregnation enhancement of sclerosant up to 6 times. The temperature distribution and the necrotic tissue fraction of the venous wall were also evaluated. The results of the study demonstrate uniform irreversible damage to the venous wall for both EUT modes. [ABSTRACT FROM AUTHOR]

BACKGROUND. The potential applications of the high-intensity focused ultrasound (HIFU) as a minimally invasive therapy of the localized prostate cancer explain the growing interest of the urologic community towards this technique. HIFU has been assessed for its role in the treatment of localized prostate cancer in patients who otherwise would not have benefited from surgery, and in local recurrences after radiation failure. Methods. Relevant information on HIFU treatment was identified through a literature search of published studies. RESULTS. High biochemical efficacy, excellent tumor local control and favorable mid- and long-term oncological data with a low morbidity rate have been shown in many series of patients. CONCLUSIONS. Although HIFU is a recent and emerging technology, it has been well studied and developed to a point that HIFU will undoubtedly be an effective alternative to radiation therapy. [ABSTRACT FROM AUTHOR]

Abstract: Mitral regurgitation, when it arises from functional restriction of mitral leaflet closure, can be relieved by surgical cutting of the mitral tendineae chordae. We hypothesized that high intensity focused ultrasound (HIFU) might be useful as a noninvasive extracorporeal technique for cutting mitral chordae. As a pilot study to test this hypothesis, we examined the in vitro feasibility of using HIFU to cut calf mitral chordae with diameters from 0.2 to 1.6 mm. Sixty-seven percent of chordae were completely cut with HIFU, operated at 4.67 MHz and 45 W acoustic power, with up to 120 pulses of 0.3-s duration at 2-s intervals. Forty-five percent were completely cut when the pulse duration was reduced to 0.2 s. The average diameter of those chordae, which were completely cut, was significantly smaller than that of incompletely cut chordae (0.59 ± 0.30 versus 1.14 ± 0.30 mm with a pulse duration of 0.2 s, p < 0.0001; 0.68 ± 0.29 versus 1.32 ± 0.20 mm with a pulse duration of 0.3 s, p < 0.0001). For each pulse duration, the number of pulses required for complete cutting exhibited a strong positive correlation with the chordae diameter. In conclusion, in vitro feasibility of mitral chordal cutting by HIFU depended on the diameter of chordae but was controllable by HIFU settings. (E-mail: abeyukio@aol.com) [Copyright &y& Elsevier]

To evaluate the safety and efficacy of transrectal high-intensity focused ultrasound (HIFU) in the treatment of benign prostatic hyperplasia (BPH), serial studies were conducted in 150 BPH patients before and 30 min, 1, 2, 6 and 12 month(s) after Sonablate-500™ HIFU treatment. A silicon-coated indwelling 16F latex catheter was placed during the determination of the therapy zone. Preoperative and postoperative evaluations were made by using the international prostate symptom score (IPSS), quality of life (QOL), uroflowmetric findings and transrectal ultrasound, and incidence of complications. The cystourethrography was done in 23 patients within 1 year postoperatively. The results showed that after HIFU treatment, IPSS and QOL scores were significantly decreased at 1, 2, 6 and 12 month(s) ( P<0.01). Maximum urine flow rate (6.0 to 17.2 mL/s, P<0.01), PVR (75.0 to 30.3, P<0.01) and prostatic volume (65.0 to 38.1 mL, P<0.05) were significantly improved 12 months after the operation. Recurrent urinary retention ( n=2) and urethrorectal fistula ( n=1) occurred at the 15th postoperative day. The duration of the HIFU prostate ablation was 25–90 min. The mean time for an indwelling catheter was 3–19 days. These data demonstrate that treatment of BPH with Sonablate-500™ HIFU is safe and effective. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To evaluate the results of high-intensity focused ultrasound (HIFU) treatment of localized prostate cancer with reference to disease-related prognostic factors. Materials and methods: Patients with T1–2 localized prostate cancers, prostate specific antigen (PSA) ≤15ng/ml, Gleason score ≤7, prostate volume ≤40 cc and no previous radical treatment for prostate cancer were treated with the Ablatherm HIFU device. Follow-up included PSA measurements, and prostate biopsies 3 months after HIFU and in cases of rising PSA. Failure was defined as any positive biopsy or a PSA >1ng/ml with three consecutive rises. Results: The study included 227 patients. Mean follow-up was 27±20 months (12–121 months). Eighty-six percent had negative control biopsies. Median nadir PSA was 0.10ng/ml. The actuarial 5-year disease-free survival rate (DFSR), combining pathologic and biochemical outcomes, was 66%. DFSR showed a significant decrease when stratified according to initial PSA level: 90% with PSA ≤4ng/ml versus 57% and 61% with PSA between 4.1 and 10, and between 10.1 and 15ng/ml, respectively. Incontinence and bladder neck stricture decreased with the treatment procedure standardization from 28% and 31% to 9% and 6%, respectively. Conclusions: HIFU for localized prostate cancer offered high control of local disease with low morbidity. The ability to repeat the HIFU treatment is of major interest. [Copyright &y& Elsevier]

Abstract: Histologic effects of focused ultrasound (FUS) exposures combined with an ultrasound contrast agent (Optison®) were investigated to examine whether the lesions were dominated by apoptosis or necrosis. The rabbit brains (n = 17) were sonicated (1.5 MHz, peak rarefactional pressure amplitude: 1.4 to 8.8 MPa) after Optison® was injected intravenously (IV). MRI and light microscopy were used to examine tissue effects. To detect apoptosis, TUNEL staining based on labeling of DNA strand breaks was used. The average number of apoptotic and necrotic cells in 300 × 220 μm microscopic fields were counted in 18 representative lesions. Lesions in the rabbit brains were created at lowered acoustic power levels when FUS was combined with Optison®. In histology, the lesions exhibited red blood cell extravasations and destruction of blood vessels. At 4 h after sonication, the lesions lost many cells, and the remaining cells exhibited both necrotic and apoptotic features. Overall, apoptosis dominated; there were, on average, 32.3 ± 13.2 apoptotic cells per microscopic field compared with only 5.1 ± 3.4 necrotic cells per field. In conclusion, FUS combined with Optison® could produce lesions that are dominated by apoptosis, presumably induced primarily via ischemia after cavitation-produced damage to the brain vasculature. (E-mail: Natalia@bwh.harvard.edu) [Copyright &y& Elsevier]

Abstract: MRI-guided and monitored focused ultrasound thermal surgery of brain through intact skull was tested in three rhesus monkeys. The aim of this study was to determine the amount of skull heating in an animal model with a head shape similar to that of a human. The ultrasound beam was generated by a 512 channel phased array system (Exablate® 3000, InSightec, Haifa, Israel) that was integrated within a 1.5-T MR-scanner. The skin was pre-cooled by degassed temperature controlled water circulating between the array surface and the skin. Skull surface temperature was measured with invasive thermocouple probes. The results showed that by applying surface cooling the skin and skull surface can be protected, and that the brain surface temperature becomes the limiting factor. The MRI thermometry was shown to be useful in detecting the tissue temperature distribution next to the bone, and it should be used to monitor the brain surface temperature. The acoustic intensity values during the 20s sonications were adequate for thermal ablation in the human brain provided that surface cooling is used. [Copyright &y& Elsevier]

Abstract: In this paper, a two stage method is used to control the thermal dose distribution in ultrasound surgery. In the first stage, a model-based nonlinear optimal control problem is solved, leading to an optimal feedforward thermal dose distribution. The control inputs are the real and the imaginary parts of the ultrasound transducer excitations and the feedforward control give the trajectories for control input and temperature that provide the optimal thermal dose distribution in tissues. A quadratic cost criteria is used to weight the thermal dose distribution and inequality constraints are used to limit the maximum input amplitude. In the second stage, the original nonlinear system equation is linearized with respect to the feedforward trajectories and an LQG feedback controller is derived from the linearized equations. The quadratic cost function is used to weight the error between the feedforward and measured temperature trajectories. With feedback, modeling errors in feedforward control can be corrected during the sonication and numerical simulations show that the derived method leads to a feasible solution, even when large modeling errors are present. [Copyright &y& Elsevier]

This paper reviews the current status in using magnetic resonance imaging (MRI) to guide and monitor thermal coagulation of tumours using focused ultrasound. The patient treatment procedure with a second generation phased array system will be described. Several clinical trials have found that patient treatments are feasible and that MRI thermometry allows non-invasive monitoring of clinical treatments. Overall, this emerging modality holds significant potential for non-invasive tumour treatment of both benign and malignant tumours. [ABSTRACT FROM AUTHOR]

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The accuracy of high-intensity focused ultrasound (HIFU) lesion prediction modelling was evaluated for a truncated spherical transducer designed for prostate cancer treatment. The modelling adapted the bio heat transfer equation (BHTE) to take into account the activity of cavitation bubbles generated during HIFU exposure. This modelling was used to predict the lesions produced by three different transducer geometries: fixed-focus, concentric-ring and 1.5D phased-array. Lesions were predicted for different ultrasound exposure conditions close to those used in prostate cancer treatment. Twenty-one in vitro and nine in vitro experiments were performed on pig liver to validate the accuracy of the predictions. A good match was found between the predicted and experimental lesion shapes. Lesion dimensions (maximum depth and length, area at the centre of the lesion or central surface area) were measured on experimental and predicted lesions. The central surface area was predicted by the model with a range of error of O. 15-6.5% for in vitro tests and 0.97-9% in vivo. For comparison, BHTE without bubbles had a range of error of 0.4-55.5% (in vitro) and 9-25.5% (in vivo). The model should be accurate enough to predict HIFU lesions under ultrasound exposure conditions used in prostate cancer treatment. [ABSTRACT FROM AUTHOR]

Objective. – High intensity focused ultrasound (HIFU) is an effective and precise method of focal tumoral destruction since it is associated with imagery. This method is widespread for the endorectal treatment of prostatic adenocarcinomas. HIFU seem appropriate for the treatment of liver tumors but its use needs to be experimentally tested in vivo. The aim of the work is to study the feasibility, tolerance and effectiveness of the destruction of porcine liver by HIFU.Material and methods. – Ten pigs had liver destruction by HIFU after coeliotomy. Four to 5 2,3 cm3 HIFU lesions were performed per animal under ultrasonographic control. The study included biological surveillance and an autopsy was performed 4 to 24 hours later for histological examination of the liver.Results. – The destruction of the liver was feasible in all cases and the 4 lobes of the liver could be treated. The general and biological tolerance of the procedure was excellent. Ultrasonographic features of the HIFU lesions were defined. The histological examination of the lesions showed well-circumscribed necrosis areas associated with cavitation or histological deficiencies of various degrees.Conclusion. – This work demonstrated that liver destruction by HIFU is a feasible and effective method with low morbidity. A long-term experimental study is necessary before comtemplating its clinical use. [Copyright &y& Elsevier]

Background  de Quervain's syndrome is one of the main tendonitis of the wrist. The hypothesis of authors was that de Quervain's syndrome could be successfully treated with a specific ultrasound-guided percutaneous procedure, as it is for trigger finger. Surgical Technique  Identification of the subcompartmentalization of the first extensor compartment was performed first, using the Hiranuma's classification, prior to the surgery. Then, we assessed precisely the positions of the sensory branches of the radial nerve and drew the landmarks. Through a continuous ultrasound in-plane control, we performed a percutaneous retrograde section of each part of the first compartment of the extensors, using a dedicated surgical blade. Methods  In a cadaveric study, authors proposed to assess the feasibility and safety of a new and specific procedure and then assessed their first clinical cases. Fourteen specimen wrists were analyzed with ultrasound and the procedure was performed prior to an open control of the efficiency of the release, and safety for the superficial nerves. Then, we reported the results of the 22 first patients included in the clinical series. Results  In a cadaver laboratory, authors were able to identify with ultrasound the type of first compartment septation (subcompartmentalization) in 13 cases ( n  = 14). The misidentification induced one incomplete release. No damages of the superficial radial nerve were observed despite close relationship. In the small series ( n  = 22), the duration of surgery was 8 minutes (range: 4-18 minutes). It was performed in office surgery and no morbidities were noticed. All patients improved, from quickDASH preoperative score of 59 (range: 28-71) to quichDASH postoperative score of 9 (range: 0-25). Conclusion  Ultrasound-guided percutaneous release in the de Quervain's disease is a safe and reliable procedure without specific morbidity. Great care should be taken to avoid sensory nerve injuries and to identify the correct type of subcompartmentalization with a precise ultrasound evaluation., Competing Interests: Conflict of Interest None declared., (© Thieme Medical Publishers.)

The last decade has seen active development of minimally invasive (endovenous) methods of surgical removal of lower limb varicose veins (LLVV); however, the problem of increasing efficacy of these methods and improving long-term results still remains of current importance. The authors of this work propose a method of ultrasound ablation of subcutaneous veins of lower extremities. Our experimental study was aimed at determining the pattern of venous wall damage after ultrasound exposure. Samples of segments of the trunk of the great saphenous vein (GSV) were divided into 5 groups: group 1 - the control group, group 2 - treatment with a sclerosant in the amount of 0.3 ml for 30 s, group 3 - treatment with ultrasound at a frequency of 26 kHz and amplitude 40 μm and 0.3-ml sclerosant for 30 s, group 4 - exposure to ultrasound at a frequency of 26 kHz and amplitude 40 μm and 0.3-ml sclerosant for 60 s, group 5 samples were exposed to ultrasound at 26 kHz and amplitude of 40 μm for 60 s. The results of analysing the histological sections of the samples of the 2nd and 3rd groups demonstrated that the degree of alteration in the GSV wall on combined exposure to ultrasound and a sclerosant was 4.5-fold higher as compared with treatment with a sclerosant solution alone. During ultrasound exposure, the maximum temperature of the venous wall of group 5 samples was by 20 °C higher than in samples of group 4. Analysing the histological sections demonstrated a similar pattern of structural alterations of the samples of group 4 and 5, thus suggesting a possibility of controlling the temperature of the venous wall during ultrasound ablation without changing quality of structural lesions. The obtained findings showed a possibility of initiating irreversible dystrophic alterations in the venous wall on exposure to ultrasound by means of combining the mechanisms of chemical, mechanical, and thermal ablation.