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In the context of developing boiling histotripsy (BH) as a potential clinical approach for non-invasive mechanical ablation of kidney tumors, the concept of BH dose (BHD) was quantitatively investigated in porcine and canine kidney models in vivo and ex vivo. Volumetric lesions were produced in renal tissue using a 1.5-MHz 256-element HIFU-array with various pulsing protocols: pulse duration t p = 1–10 ms, number of pulses per point ppp = 1–15. Two BHD metrics were evaluated: BHD1 = ppp, BHD2 = t p × ppp. Quantitative assessment of lesion completeness was performed by their histological analysis and assignment of damage score to different renal compartments (i.e., cortex, medulla, and sinus). Shear wave elastography (SWE) was used to measure the Young's modulus of renal compartments in vivo vs ex vivo , and before vs after BH treatments. In vivo tissue required lower BH doses to achieve identical degree of fractionation as compared to ex vivo. Renal cortex (homogeneous, low in collagen) was equal or higher in stiffness than medulla (anisotropic, collagenous), 5.8–12.2 kPa vs 4.7–9.6 kPa, but required lower BH doses to be fully fractionated. Renal sinus (fatty, irregular, with abundant collagenous structures) was significantly softer ex vivo vs in vivo , 4.9–5.1 kPa vs 9.7–15.2 kPa, but was barely damaged in either case with any tested BH protocols. BHD1 was shown to be relevant for planning the treatment of renal cortex (sufficient BHD1 = 5 pulses in vivo and 10 pulses ex vivo), while none of the tested doses resulted in complete fractionation of medulla or sinus. Post-treatment SWE imaging revealed reduction of tissue stiffness ex vivo by 27–58%, increasing with the applied dose, and complete absence of shear waves within in vivo lesions, both indicative of tissue liquefaction. The results imply that tissue resistance to mechanical fractionation, and hence required BH dose, are not solely determined by tissue stiffness but also depend on its composition and structural arrangement, as well as presence of perfusion. The SWE-derived reduction of tissue stiffness with increasing BH doses correlated with tissue damage score, indicating potential of SWE for post-treatment confirmation of BH lesion completeness. [ABSTRACT FROM AUTHOR]

Abstract The primary purpose of high-intensity focused ultrasound (HIFU), a non-invasive medical therapy, is to precisely target and ablate tumors by focusing high-frequency ultrasound from an external power source. A series of ablations must be performed in order to treat a big volume of tumors, as a single ablation can only remove a small amount of tissue. To maximize therapeutic efficacy while minimizing adverse side effects such as skin burns, preoperative treatment planning is essential in determining the focal site and sonication duration for each ablation. Here, we introduce a machine learning-based approach for designing HIFU treatment plans, which makes use of a map of the material characteristics unique to a patient alongside an accurate thermal simulation. A numerical model was employed to solve the governing equations of HIFU process and to simulate the HIFU absorption mechanism, including ensuing heat transfer process and the temperature rise during the sonication period. To validate the accuracy of this numerical model, a series of tests was conducted using ex vivo bovine liver. The findings indicate that the developed models properly represent the considerable variances observed in tumor geometrical shapes and proficiently generate well-defined closed treated regions based on imaging data. The proposed strategy facilitated the formulation of high-quality treatment plans, with an average tissue over- or under-treatment rate of less than 0.06%. The efficacy of the numerical model in accurately predicting the heating process of HIFU, when combined with machine learning techniques, was validated through quantitative comparison with experimental data. The proposed approach in cooperation with HIFU simulation holds the potential to enhance presurgical HIFU plan.

The primary purpose of high-intensity focused ultrasound (HIFU), a non-invasive medical therapy, is to precisely target and ablate tumors by focusing high-frequency ultrasound from an external power source. A series of ablations must be performed in order to treat a big volume of tumors, as a single ablation can only remove a small amount of tissue. To maximize therapeutic efficacy while minimizing adverse side effects such as skin burns, preoperative treatment planning is essential in determining the focal site and sonication duration for each ablation. Here, we introduce a machine learning-based approach for designing HIFU treatment plans, which makes use of a map of the material characteristics unique to a patient alongside an accurate thermal simulation. A numerical model was employed to solve the governing equations of HIFU process and to simulate the HIFU absorption mechanism, including ensuing heat transfer process and the temperature rise during the sonication period. To validate the accuracy of this numerical model, a series of tests was conducted using ex vivo bovine liver. The findings indicate that the developed models properly represent the considerable variances observed in tumor geometrical shapes and proficiently generate well-defined closed treated regions based on imaging data. The proposed strategy facilitated the formulation of high-quality treatment plans, with an average tissue over- or under-treatment rate of less than 0.06%. The efficacy of the numerical model in accurately predicting the heating process of HIFU, when combined with machine learning techniques, was validated through quantitative comparison with experimental data. The proposed approach in cooperation with HIFU simulation holds the potential to enhance presurgical HIFU plan. [ABSTRACT FROM AUTHOR]

High intensity focused ultrasound (HIFU) is a non-invasive therapy that induces heat in a small, localized volume of cancerous tissue without damaging neighbouring vital structures and cells. Precise targeting and treatment monitoring is typically achieved by pairing HIFU with an imaging modality such as magnetic resonance imaging (MRI). The most commonly used MRI pulse sequence for detecting HIFU thermal lesions is the T2-weighted fast spin echo (T2W-FSE) pulse sequence as it provides good contrast between normal and coagulated tissue. The drawbacks of the T2W-FSE pulse sequence are the manifestation of ringing artifacts and the loss of spatial resolution due to the signal modulation in k-space caused by the T2 decay. The inverse Fourier transform (IFT) multiplication scheme aims to remove the signal modulation by incorporating an inverse filter, which is an inverse of the signal modulation trend present in the k-space, to reduce the effects of T2 decay and improve image quality. In this study, four inverse filters (named as regular, narrow, wide, and compound) were developed and implemented on T2W-FSE MR images of ex vivo porcine muscle tissue with HIFU induced thermal lesion using a 0.55 T benchtop MRI research system (Pure Devices, Rimpar, Germany). Offline processing and enhancement of MR images of ex vivo porcine muscle tissue with HIFU induced thermal lesion using the narrow filter yielded the largest improvements of 13.8 ± 2.5 %, 17.0± 2.3 %, and 14.4± 1.1 % in lateral and axial spatial resolutions, and lesion signal-to-noise ratio (SNR), respectively, compared to the original images. Our results indicate an amplification of the signals in k-space and a reduction in the exponential signal modulation caused by T2 decay. These results also indicate the potential of the IFT multiplication scheme as an image processing method to improve thermal lesion detectability in MR-guided HIFU procedures.

Background: Maintaining ureteral patency is imperative to preventing renal injury and systemic infection. Ureteral stents are small conduits connecting the kidney and the bladder. They have been widely used to treat ureteral obstructions and ureteral leaks. The most problematic and frequent stent‐associated complication is stent encrustation. This occurs when mineral crystals (e.g. calcium, oxalate, phosphorus, struvite) are deposited onto the surface and internal lumen of the stent. Encrustation can lead to the obstruction of a stent and increases risk of systemic infection. As a result, ureteral stents need to be replaced typically every 2–3 months. Purpose: In this study, we present a non‐invasive, high‐intensity focused ultrasound (HIFU)‐based technique to recanalize obstructed stents. By taking advantage of the mechanical force produced by a HIFU beam, including acoustic radiation force, acoustic streaming, and cavitation, HIFU can break up encrustations, clearing the stent of obstruction. Methods: The ureteral stents for this study were obtained from patients undergoing ureteral stent removal. Under the guidance of ultrasound imaging, the encrustation in the stents were located, and then targeted by HIFU at frequencies of 0.25 and 1 MHz. The duty cycle of HIFU was 10%, and the HIFU burst repetition rate was 1 Hz, while the HIFU amplitude was varied to find the threshold pressure that would displace encrustations. The treatment duration was limited at 2 min (or 120 shots from HIFU). The treatments were carried out in two different orientations (parallel and perpendicular) of the ureteral stent with respect to the HIFU beam. For each setting, five treatments were conducted for a maximum duration of 2 min. During the entire treatment, an ultrasound imaging system was used to monitor the movement of encrustations inside the stent. The peak negative HIFU pressures needed to move the encrustations inside the stent was recorded for quantitative analysis. Results: Our results demonstrated that at both 0.25 and 1 MHz ultrasound frequencies, obstructed stents could be recanalized. At 0.25 MHz, the needed average peak negative pressure was 0.52 MPa in parallel orientation and 0.42 MPa in perpendicular orientation. At 1 MHz, the needed average peak negative pressure was 1.10 MPa in parallel orientation and 1.15 MPa in perpendicular orientation Conclusions: This first in‐vitro study has demonstrated the feasibility of non‐invasive HIFU to recanalize ureteral stents. This technology has a potential to reduce the need for ureteral stent exchange. [ABSTRACT FROM AUTHOR]

AbstractObjectives Focused ultrasound (FUS) therapy has emerged as a promising noninvasive solution for tumor ablation. Accurate monitoring and guidance of ultrasound energy is crucial for effective FUS treatment. Although ultrasound (US) imaging is a well-suited modality for FUS monitoring, US-guided FUS (USgFUS) faces challenges in achieving precise monitoring, leading to unpredictable ablation shapes and a lack of quantitative monitoring. The demand for precise FUS monitoring heightens when complete tumor ablation involves controlling multiple sonication procedures.Methods To address these challenges, we propose an artificial intelligence (AI)-assisted USgFUS framework, incorporating an AI segmentation model with B-mode ultrasound imaging. This method labels the ablated regions distinguished by the hyperechogenicity effect, potentially bolstering FUS guidance. We evaluated our proposed method using the Swin-Unet AI architecture, conducting experiments with a USgFUS setup on chicken breast tissue.Results Our results showed a 93% accuracy in identifying ablated areas marked by the hyperechogenicity effect in B-mode imaging.Conclusion Our findings suggest that AI-assisted ultrasound monitoring can significantly improve the precision and control of FUS treatments, suggesting a crucial advancement toward the development of more effective FUS treatment strategies.

Endometrial carcinoma (EC) is a type of epithelial malignancy prevalent in about 8% of the total malignancies in women. Development of new treatment methods is vital for improving the prognosis of endometrial cancer. High Intensity Focused Ultrasound (HIFU) is a safe method for oncological treatment with low complication rate. However, EC treatment by HIFU is rarely reported and its mechanism is unclear. Herein, the effects of HIFU on EC progression were detected. Data confirmed the inhibition of EC tumor growth in mice by HIFU. Moreover, HIFU inhibited the EC tumor apoptosis. It down-regulated the Treg cell production and enhanced the tumorspecific cytotoxicity. It restrained the Janus kinase/Signal transducer and activator of transcription 3 (JAK/STAT3) pathway in vivo, and suppressed the EC progression. HIFU could thus be a promising treatment for EC. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Test & Measurement Technology is the property of Publishing Center of North University of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective To investigate the tolerance and efficacy of HIFU ablation for uterine fibroids with a non-perfused volume ratio (NPVR) ≥ 90%.Methods A prospective cohort study of 2411 patients from 20 clinical centers was available. Contrast-enhanced MRI was used to assess the non-perfused volume ratio (NPVR). The International Society of Interventional Radiotherapy (SIR) complication grading system was used as the tolerance index. Uterine Fibroids-related Symptoms-Quality of Life (UFS-QoL) was used to evaluate the efficacy.Results A total of 1352 patients underwent USgHIFU ablation treatment enrolled, NPVR was median 91.9% (IQR, 81.4%,100.0%). There was 761 case (56.3%) in the NPVR ≥ 90% group in which 17.5% case experienced SIR-B abdominal pain, 591 cases (43.7%) in NPVR < 90% group in which 9.3% case had SIR-B abdominal pain. There were statistically differences in the improvement degree of UFS at 12 months among the four subgroups (NPVR < 70%, 70%–80%, 80%–90%, 90%–100%) (all p

Objective To investigate the value of the image indexes of B-mode and power Doppler sonography in predicting the therapeutic efficacy of high intensity focused ultrasound (HIFU) ablation for uterine fibroids.Materials and methods Two hundred and three patients with a solitary uterine fibroid were enrolled in this study. Every patient underwent transvaginal sonography (TVS) and magnetic resonance imaging (MRI) before HIFU. The patients were divided into hypointense, isointense and hyperintense fibroid groups based on T2 weighted MR imaging characteristics, and ultrasonic image indexes of the fibroids in different groups were compared. Multiple linear regression analysis was used to evaluate the correlation between ultrasonic image indexes and energy efficiency factor (EEF), non-perfused volume (NPV) ratio of uterine fibroids.Results Among them, 72 patients had a hypointense fibroid, 70 had an isointense fibroid and 61 had a hyperintense fibroid. Significant differences were observed in the ultrasound imaging gray scale value difference between the myometrium and uterine fibroids (GSmyo-fib), the ultrasound imaging gray scale value ratio of fibroids over the myometrium (GSfib/myo), and the ratio of power Doppler pixel area to fibroid area (PDPA/FA) among the three groups (p

Copyright of Journal of Measurement Science & Instrumentation is the property of Journal of Measurement Science & Instrumentation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Focused ultrasound is a treatment modality increasingly used for diverse therapeutic applications, and currently approved for several indications, including prostate cancers and uterine fibroids. But what about breast cancer? Breast cancer is the most common and deadliest cancer in women worldwide. While there are different treatment strategies available, there is a need for development of more effective and personalized modalities, with fewer side effects. Therapeutic ultrasound is such an option, and this review summarizes the state of the art in their use for the treatment of breast cancer and evaluate potentials of novel treatment approaches combining therapeutic ultrasound, immuno‐ and chemo‐therapies. [ABSTRACT FROM AUTHOR]

Focused ultrasound (FUS) therapy has emerged as a promising noninvasive solution for tumor ablation. Accurate monitoring and guidance of ultrasound energy is crucial for effective FUS treatment. Although ultrasound (US) imaging is a well-suited modality for FUS monitoring, US-guided FUS (USgFUS) faces challenges in achieving precise monitoring, leading to unpredictable ablation shapes and a lack of quantitative monitoring. The demand for precise FUS monitoring heightens when complete tumor ablation involves controlling multiple sonication procedures. To address these challenges, we propose an artificial intelligence (AI)-assisted USgFUS framework, incorporating an AI segmentation model with B-mode ultrasound imaging. This method labels the ablated regions distinguished by the hyperechogenicity effect, potentially bolstering FUS guidance. We evaluated our proposed method using the Swin-Unet AI architecture, conducting experiments with a USgFUS setup on chicken breast tissue. Our results showed a 93% accuracy in identifying ablated areas marked by the hyperechogenicity effect in B-mode imaging. Our findings suggest that AI-assisted ultrasound monitoring can significantly improve the precision and control of FUS treatments, suggesting a crucial advancement toward the development of more effective FUS treatment strategies. [ABSTRACT FROM AUTHOR]

A polyacrylamide polysaccharide hydrogel (PASG) containing a nonionic surfactant of the polyoxyethylene nonylphenyl ethers series (NP14) has been adapted to the fabrication of a reusable cost-effective ultrasonic tissue-mimicking phantom for real-time visualization of the thermal lesions by high intensity focused ultrasound (HIFU) irradiation. The constructed NP14 (40% in w/v) PASG is optically transparent at room temperatures, and it turns out to be opaque white as heated over the clouding points of about 55 °C and returns to its original transparent state after cooling. The acoustic property of the proposed phantom is similar to those of human liver tissues, which includes the acoustic impedance of 1.68 Mrayls, the speed of sound of 1595 ± 5 m/s, the attenuation coefficient of 0.52 ± 0.05 dB cm−1 (at 1 MHz), the backscatter coefficient of 0.21 ± 0.09 × 10−3 sr−1 cm−1 (at 1 MHz), and the nonlinear parameter B/A of 6.4 ± 0.2. The NP14-PASG was tested to assess the characteristic information (sizes, shapes, and locations) of the thermal lesions visualized when exposed to typical HIFU fields (1.1 MHz, focal pressure up to 20.1 MPa, focal intensity 4075 W/cm2). The proposed NP14-PASG is expected to replace the existing costly BSA-PASG used for more effective testing of the performance of therapeutic ultrasonic devices based on thermal mechanisms. [ABSTRACT FROM AUTHOR]

Boiling histotripsy (BH) is a mechanical tissue liquefaction method that uses sequences of millisecond-long high intensity focused ultrasound (HIFU) pulses with shock fronts. The BH treatment generates bubbles that move within the sonicated volume due to acoustic radiation force. Since the velocity of the bubbles and tissue debris is expected to depend on the lesion size and liquefaction completeness, it could provide a quantitative metric of the treatment progression. In this study, the motion of bubble remnants and tissue debris immediately following BH pulses was investigated using high-pulse repetition frequency (PRF) plane-wave color Doppler ultrasound in ex vivo myocardium tissue. A 256-element 1.5 MHz spiral HIFU array with a coaxially integrated ultrasound imaging probe (ATL P4-2) produced 10 ms BH pulses to form volumetric lesions with electronic beam steering. Prior to performing volumetric BH treatments, the motion of intact myocardium tissue and anticoagulated bovine blood following isolated BH pulses was assessed as two limiting cases. In the liquid blood the velocity of BH-induced streaming at the focus reached over 200 cm/s, whereas the intact tissue was observed to move toward the HIFU array consistent with elastic rebound of tissue. Over the course of volumetric BH treatments tissue motion at the focus locations was dependent on the axial size of the forming lesion relative to the corresponding size of the HIFU focal area. For axially small lesions, the maximum velocity after the BH pulse was directed toward the HIFU transducer and monotonically increased over time from about 20–100 cm/s as liquefaction progressed, then saturated when tissue was fully liquefied. For larger lesions obtained by merging multiple smaller lesions in the axial direction, the high-speed streaming away from the HIFU transducer was observed at the point of full liquefaction. Based on these observations, the maximum directional velocity and its location along the HIFU propagation axis were proposed and evaluated as candidate metrics of BH treatment completeness. [ABSTRACT FROM AUTHOR]

Background Chemotherapy is the main treatment strategy for gestational trophoblastic neoplasia (GTN). Surgical resection is crucial to deal with chemoresistance and recurrence following chemotherapy. The aim of this study was to explore if high-intensity focused ultrasound (HIFU) can be used as a complementary technique to surgical procedures in the management of GTN. Case report This case report described two females who previously developed chemoresistance or recurrence during chemotherapy and then underwent HIFU as an adjuvant surgical salvage procedure. For high-risk GTN patients with chemoresistance, HIFU treatment decreased the risk of chemoresistance and shortened the course of chemotherapy. It also reduced the dosage of chemotherapeutic agents used for the patient who suffered a recurrence. Conclusion For patients with GTN who desire to preserve their uterus, HIFU may be used as a complementary technique to surgical resection in the management of GTN.

Thermal monitoring during focused ultrasound (FUS) transcranial procedures is mandatory and commonly performed by MRI. Transcranial ultrasonic thermal monitoring is an attractive alternative. Furthermore, using the therapeutic FUS transducer itself for this task is highly desirable. Nonetheless, such application is challenged by massive skull-induced signal attenuation and aberrations. This study examined the feasibility of implementing the Golay-coded excitations (CoE) for temperature monitoring in bovine brain samples in the range of 35 °C–43 °C (hyperthermia). Feasibility was assessed using computer simulations, water-based phantoms, and ex vivo bovine brain white-matter samples. The samples were gradually heated to about 45 °C and sonicated during cool down with a 1-MHz therapeutic FUS implementing Golay CoE. Initially, a calibration curve correlating the normalized time-of-flight (TOF) changes and the temperature was generated. Next, a bovine bone was positioned between the FUS and the brain samples, and the scanning process was repeated for different fresh samples. The calibration curve was then used as a mean for estimating the temperature, which was compared to thermocouple measurements. The simulations demonstrated a substantial improvement in signal-to-noise ratio (SNR) and suggested that the implementation of 4-bit sequences is advantageous. The experimental measurements with bone demonstrated good temperature estimation with an average absolute error for the water phantoms and brains of 1.46 °C ± 1.22 °C and 1.23 °C ± 0.99 °C, respectively. In conclusion, a novel noninvasive method utilizing the Golay CoE for ultrasonic thermal monitoring using a therapeutic FUS transducer is introduced. This method can lead to the development of an acoustic tool for brain thermal monitoring. [ABSTRACT FROM AUTHOR]

The study analyzes the possibilities of compensating for aberrations when focusing an ultrasound beam through the skull bones using arrays with mosaic pattern of elements, curvature radius and aperture of F = D = 200 mm, frequency of 1 MHz, and fully populated randomized pattern of the elements. The effect of the number of elements (256, 512, and 1024) and focusing depth (25–65 mm from the inner surface of the skull) on the quality of aberration correction is considered, i.e., the sharpness of focusing, location of the focus, and the maximum pressure therein. An acoustic model of the human head is constructed from magnetic resonance imaging (MRI) data. The field and compensation for aberrations are calculated using the Rayleigh integral and wave equation in the Kelvin–Voigt model. The possibility of sharp focusing with the focal region width of about 2 mm at the level of 6 dB using the considered arrays is demonstrated within the indicated depth interval. The relative contribution of different wave effects to distortion of the ultrasound beam as it passes through the skull is analyzed. It is shown that the strongest contributions to beam attenuation come from aberrations (7.4 dB) and absorption (6.7 dB). Contributions from reflection (2.1 dB) and shear-wave generation in the skull (2 dB) are less significant. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) accounts for the vast majority of primary hepatic malignancies. The overall incidence of this disease has always been significant, but in recent years it has continued to rise, now making HCC one of the leading causes of cancer deaths worldwide. Fortunately, research into the mechanisms of carcinogenesis and treatment options for this disease has also been progressing rapidly. Although the future for new insights and therapies appears more promising than ever, it also remains important to understand both the nature of HCC and the current state-of-the-art for treating affected patients. Although surgery is often considered to be a first choice, many patients present with extensive disease and are therefore not operative candidates. Fortunately, significant clinical advances over the last decade have contributed a number of new or improved treatment options. Many of these treatments require expertise from a variety of different clinical subspecialties. Indeed, managing patients with HCC has rapidly become a multi-modality, multi-disciplinary endeavor in which the details of each individual’s circumstance can greatly impact outcomes, and strategies can be quite nuanced. The purpose of this review is to provide a perspective on the disease itself, the patients who become afflicted, the spectrum of currently available treatment options, and the strategies for their optimal implementation. Such knowledge can be critically important as new data become available on the research front.

Objective: To investigate the tolerance and efficacy of HIFU ablation for uterine fibroids with a non-perfused volume ratio (NPVR) ≥ 90%. Methods: A prospective cohort study of 2411 patients from 20 clinical centers was available. Contrast-enhanced MRI was used to assess the non-perfused volume ratio (NPVR). The International Society of Interventional Radiotherapy (SIR) complication grading system was used as the tolerance index. Uterine Fibroids-related Symptoms-Quality of Life (UFS-QoL) was used to evaluate the efficacy. Results: A total of 1352 patients underwent USgHIFU ablation treatment enrolled, NPVR was median 91.9% (IQR, 81.4%,100.0%). There was 761 case (56.3%) in the NPVR ≥ 90% group in which 17.5% case experienced SIR-B abdominal pain, 591 cases (43.7%) in NPVR < 90% group in which 9.3% case had SIR-B abdominal pain. There were statistically differences in the improvement degree of UFS at 12 months among the four subgroups (NPVR < 70%, 70%–80%, 80%–90%, 90%–100%) (all p < 0.05). Conclusions: Patients with NPVR ≥ 90% had a higher incidence of SIR-B lower abdominal pain. NPVR was positively correlated with the degree of symptom relief at 12 months, and NPVR ≥ 90% was more likely to obtain better clinical symptom relief. [ABSTRACT FROM AUTHOR]

Superheated perfluorocarbon nanodroplets are emerging ultrasound imaging contrast agents that boast biocompatible components, unique phase-change dynamics, and therapeutic loading capabilities. Upon exposure to a sufficiently high-intensity pulse of acoustic energy, the nanodroplet’s perfluorocarbon core undergoes a liquid-to-gas phase change and becomes an echogenic microbubble, providing ultrasound contrast. The controllable activation leads to high-contrast images, while the small size of the nanodroplets promotes longer circulation times and better in vivo stability. One drawback, however, is that the nanodroplets can only be vaporized a single time, limiting their versatility. Recently, we and others have addressed this issue by using a perfluorohexane core, which has a boiling point above body temperature. Thus after vaporization, the microbubbles recondense back into their stable nanodroplet form. Previous work with perfluorohexane nanodroplets relied on optical activation via pulsed laser absorption of an encapsulated dye. This strategy limits the imaging depth and temporal resolution of the method. In this study, we overcome these limitations by demonstrating acoustic droplet vaporization with 1.1-MHz high-intensity focused ultrasound (HIFU). A short-duration, high-amplitude pulse of focused ultrasound provides a sufficiently strong peak negative pressure to initiate vaporization. A custom imaging sequence was developed to enable the synchronization of a HIFU transducer and a linear array imaging transducer. We show a visualization of repeated acoustic activation of perfluorohexane nanodroplets in polyacrylamide tissue-mimicking phantoms. We further demonstrate the detection of hundreds of vaporization events from individual nanodroplets with activation thresholds well below the tissue cavitation limit. Overall, this approach has the potential to result in reliable and repeatable contrast-enhanced ultrasound imaging at clinically relevant depths. [ABSTRACT FROM AUTHOR]

Patients with localized prostate cancer (PCa) are often treated with radical prostatectomy (RP). However, more than 30% of such patients have high risk of recurrence. Salvage radiotherapy (SRT), androgen deprivation therapy (ADT) and combination of radiotherapy and ADT are the standard care for recurrent PCa. Recently, high intensity focused ultrasound (HIFU) has gradually applied in the treatment of recurrent PCa. Here, we proposed a hypothesis that combined HIFU and bicalutamide 150mg as first line salvage therapy to treat patients with local recurrent PCa with visible lesions due to the following advantages: (1) HIFU is effective in reducing local tumor load, and bicalutamide 150mg is a feasible and safety option to combine with HIFU. (2) Compared with radiotherapy, HIFU plus 150mg bicalutamide is minimal invasiveness with fewer adverse effects and better quality of life(QOL); (3) Radiotherapy can be preserved as the second-line salvage method in the cases who are failure to HIFU and 150mg bicalutamide combination. More clinical trials are warranted to confirm this hypothesis in treatment with recurrent PCa. [ABSTRACT FROM AUTHOR]

Patients with localized prostate cancer (PCa) are often treated with radical prostatectomy (RP). However, more than 30% of such patients have high risk of recurrence. Salvage radiotherapy (SRT), androgen deprivation therapy (ADT) and combination of radiotherapy and ADT are the standard care for recurrent PCa. Recently, high intensity focused ultrasound (HIFU) has gradually applied in the treatment of recurrent PCa. Here, we proposed a hypothesis that combined HIFU and bicalutamide 150mg as first line salvage therapy to treat patients with local recurrent PCa with visible lesions due to the following advantages: (1) HIFU is effective in reducing local tumor load, and bicalutamide 150mg is a feasible and safety option to combine with HIFU. (2) Compared with radiotherapy, HIFU plus 150mg bicalutamide is minimal invasiveness with fewer adverse effects and better quality of life(QOL); (3) Radiotherapy can be preserved as the second-line salvage method in the cases who are failure to HIFU and 150mg bicalutamide combination. More clinical trials are warranted to confirm this hypothesis in treatment with recurrent PCa.

A polyacrylamide polysaccharide hydrogel (PASG) containing a nonionic surfactant of the polyoxyethylene nonylphenyl ethers series (NP14) has been adapted to the fabrication of a reusable cost-effective ultrasonic tissue-mimicking phantom for real-time visualization of the thermal lesions by high intensity focused ultrasound (HIFU) irradiation. The constructed NP14 (40% in w/v) PASG is optically transparent at room temperatures, and it turns out to be opaque white as heated over the clouding points of about 55 °C and returns to its original transparent state after cooling. The acoustic property of the proposed phantom is similar to those of human liver tissues, which includes the acoustic impedance of 1.68 Mrayls, the speed of sound of 1595 ± 5 m/s, the attenuation coefficient of 0.52 ± 0.05 dB cm−1 (at 1 MHz), the backscatter coefficient of 0.21 ± 0.09 × 10−3 sr−1 cm−1 (at 1 MHz), and the nonlinear parameter B/A of 6.4 ± 0.2. The NP14-PASG was tested to assess the characteristic information (sizes, shapes, and locations) of the thermal lesions visualized when exposed to typical HIFU fields (1.1 MHz, focal pressure up to 20.1 MPa, focal intensity 4075 W/cm2). The proposed NP14-PASG is expected to replace the existing costly BSA-PASG used for more effective testing of the performance of therapeutic ultrasonic devices based on thermal mechanisms.

For accurate evaluation of high intensity focused ultrasound (HIFU) treatment effect, it is of great importance to effectively judge whether the sampled signal is the HIFU echo signal or the noise signal. In this paper, a judgment method based on an auto-regressive (AR) model and spectrum information entropy is proposed. In total, 188 groups of data are obtained while the HIFU source is on or off through experiments, and these sampled signals are judged by this method. The judgment results of this method are compared with empirical judgments. It is found that when the segment number for the power spectrum estimated by AR model is 14 to 17, the judgment results of this method have a higher consistency with empirical judgments, and Accuracy, Sensitivity and Specificity all have good values. Moreover, after comparing and analyzing this method with the classic power spectrum estimation method, it is found that the recognition rate of the two sampled signals of this method is higher than that of the classic power spectrum estimation method. Therefore, this method can effectively judge the different types of sampled signals. [ABSTRACT FROM AUTHOR]

Objective To evaluate the magnetic resonance (MR) signal intensity changes in the sacrococcygeal region of patients with uterine fibroids treated with high intensity focused ultrasound (HIFU). Materials and Methods Two hundred and sixty-seven patients with uterine fibroids treated with HIFU between January and December 2016 were retrospectively reviewed. All patients underwent enhanced pre- and post-HIFU MRI. Multivariate analysis was used to assess the relationship between the factors and the signal intensity changes in the sacrum and the soft tissue adjacent to the sacrum. Results Among the 267 patients, 122 (46%) had MR signal intensity changes in the sacrum and/or the soft tissue adjacent to the sacrum after HIFU. Multivariate analysis showed that the position of the uterus, the distance from the dorsal side of the fibroid to the sacrum, and the ablation efficiency were significantly correlated with MR signal intensity changes in the sacrum and the soft tissue adjacent to the sacrum. Further analysis showed a significant relationship between the location of the MR signal intensity changes and uterine size, the enhancement degree of the uterus. Leg pain was only seen in patients with MR signal intensity changes both in the sacrum and the soft tissue adjacent to the sacrum. Conclusions The location of the uterus, the distance between the dorsal side of the fibroids to the sacrum, and ablation efficiency have a significant relationship with the MR signal intensity changes. The size of the uterus and the degree of enhancement are related to the locations of MR signal changes.

Background Disseminated peritoneal leiomyomatosis (DPL) is a rare, generally benign disorder. With the advent of laparoscopic surgery for uterine fibroids, the reported number of cases of DPL has significantly increased since the introduction of unconfined power morcellation. Morcellation and other procedures may be associated with DPL. Methods We present the case of a 48-year-old patient with DPL who underwent uterine artery embolization (UAE), laparoscopic myomectomy and high intensity focused ultrasound (HIFU) 11 years, 6 years, and 2 years before the final diagnosis of DPL was made. A subtotal hysterectomy with bilateral salpingo-oopherectomy was performed to remove the uterus, the fallopian tube and the ovaries. We carefully excised as many visible lesions as possible. Results After the surgical treatment performed in our center the patient became free of symptoms. Conclusion In our case, the occurrence of DPL is most likely associated with laparoscopic myomectomy using power morcellation. In addition, it should be noted whether some other factors played a role in stimulating the growth of the multiple nodules.

Background: Uterine fibroids are common benign tumors among premenopausal women. High- intensity focused ultrasound (HIFU) is an emerging non-invasive intervention which uses the high-intensity ultrasound waves from ultrasound probes to focus on the targeted fibroids. However, the efficacy of HIFU in comparison with that of other common treatment types in clinical procedure remains unclear.Objective: To investigate the comparative effectiveness and safety of HIFU with other techniques which have been widely used in clinical settings.Methods: We searched the Cochrane Central Register of Controlled Trials, PubMed, EMBASE, Cumulative Index to Nursing & Allied Health Literature, Web of Science, ProQuest Nursing & Allied Health Database, and three Chinese academic databases, including randomized controlled trials (RCTs), non-RCTs, and cohort studies. The primary outcome was the rate of re-intervention, and the GRADE approach was used to interpret the findings.Results: About 18 studies met the inclusion criteria. HIFU was associated with an increased risk of re-intervention rate in comparison with myomectomy (MYO) [pooled odds ratio (OR): 4.05, 95% confidence interval (CI): 1.82–8.9]. The results favored HIFU in comparison with hysterectomy (HYS) on the change of follicle-stimulating hormone [pooled mean difference (MD): −7.95, 95% CI: −8.92–6.98), luteinizing hormone (MD: −4.38, 95% CI: −5.17−3.59), and estradiol (pooled MD: 43.82, 95% CI: 36.92–50.72)]. HIFU had a shorter duration of hospital stay in comparison with MYO (pooled MD: −4.70, 95% CI: −7.46−1.94, p < 0.01). It had a lower incidence of fever (pooled OR: 0.15, 95% CI: 0.06–0.39, p < 0.01) and a lower incidence of major adverse events (pooled OR: 0.04, 95% CI: 0.00–0.30, p < 0.01) in comparison with HYS.Conclusions: High-intensity focused ultrasound may help maintain feminity and shorten the duration of hospital stay. High-quality clinical studies with a large sample size, a long-term follow-up, and the newest HIFU treatment protocol for evaluating the re-intervention rate are suggested to be carried out. Clinical decision should be based on the specific situation of the patients and individual values.

Background: Uterine fibroids are common benign tumors among premenopausal women. High- intensity focused ultrasound (HIFU) is an emerging non-invasive intervention which uses the high-intensity ultrasound waves from ultrasound probes to focus on the targeted fibroids. However, the efficacy of HIFU in comparison with that of other common treatment types in clinical procedure remains unclear. Objective: To investigate the comparative effectiveness and safety of HIFU with other techniques which have been widely used in clinical settings. Methods: We searched the Cochrane Central Register of Controlled Trials, PubMed, EMBASE, Cumulative Index to Nursing & Allied Health Literature, Web of Science, ProQuest Nursing & Allied Health Database, and three Chinese academic databases, including randomized controlled trials (RCTs), non-RCTs, and cohort studies. The primary outcome was the rate of re-intervention, and the GRADE approach was used to interpret the findings. Results: About 18 studies met the inclusion criteria. HIFU was associated with an increased risk of re-intervention rate in comparison with myomectomy (MYO) [pooled odds ratio (OR): 4.05, 95% confidence interval (CI): 1.82–8.9]. The results favored HIFU in comparison with hysterectomy (HYS) on the change of follicle-stimulating hormone [pooled mean difference (MD): −7.95, 95% CI: −8.92–6.98), luteinizing hormone (MD: −4.38, 95% CI: −5.17−3.59), and estradiol (pooled MD: 43.82, 95% CI: 36.92–50.72)]. HIFU had a shorter duration of hospital stay in comparison with MYO (pooled MD: −4.70, 95% CI: −7.46−1.94, p < 0.01). It had a lower incidence of fever (pooled OR: 0.15, 95% CI: 0.06–0.39, p < 0.01) and a lower incidence of major adverse events (pooled OR: 0.04, 95% CI: 0.00–0.30, p < 0.01) in comparison with HYS. Conclusions: High-intensity focused ultrasound may help maintain feminity and shorten the duration of hospital stay. High-quality clinical studies with a large sample size, a long-term follow-up, and the newest HIFU treatment protocol for evaluating the re-intervention rate are suggested to be carried out. Clinical decision should be based on the specific situation of the patients and individual values. [ABSTRACT FROM AUTHOR]

Real-time monitoring of tissue temperature is required during high intensity focused ultrasound (HIFU) tumor treatment to ensure safety and effectiveness. Magnetic resonance imaging (MRI) can be used to measure tissue temperature non-invasively during HIFU treatment. This paper examined the effects of coagulation necrosis-induced tissue phase transition on magnetic resonance thermometry (MRT) during HIFU tumor treatment. With a two-state rapid exchange model, the relationship between tissue longitudinal relaxation time (T1) and temperature before and after HIFU radiation-induced coagulation necrosis/tissue phase transition were analyzed theoretically. Taking the effects of tissue phase transition into account, the experimental scheme and data processing procedures for MRT were optimized, and better temperature measurements were obtained. The work demonstrated the importance of considering the effects of tissue phase transition in real-time MRT during HIFU treatment.

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.

Objective: High intensity focused ultrasound (HIFU) is a new noninvasive therapeutics that allows local treatment of solid tumors through a hyperthermal mechanism using ultrasonic energy. One promising strategy to increase the thermal efficiency of HIFU is to employ nanoparticles (NPs) as ultrasound agents for the hyperthermia procedure. However, the interaction mechanism between NPs and ultrasonic waves has not been well understood. Methods: In an effort to investigate the heating process of NPs-enhanced HIFU, we derived a set of HIFU equations governing the temperature variation during the thermal ablation based on the principle of conservation of energy for heat transfer mechanism. A numerical model was developed to solve the HIFU equations to simulate the absorption mechanism of HIFU in the presence of NPs, the consequent heat transfer process, and the temperature rise profile during the sonication period. The accuracy of numerical model was verified by performing a series of experiments on tissue-mimicking phantoms embedded with magnetic NPs (MNPs). Results: The transport processes taking place at the boundaries between NPs and surrounding medium played the major role in the temperature rise during HIFU sonication. Besides, the effects of MNPs on rising temperature were improved by amplifying the ultrasonic power and frequency as well as by increasing the MNP concentration. Conclusion: A quantitative comparison with experimental results demonstrated the potential of the numerical model to accurately predict the heating mechanism of HIFU mediated by NPs. Significance: The proposed method can help with simulation of HIFU when NPs are employed as ultrasound agents. [ABSTRACT FROM AUTHOR]

For accurate evaluation of high intensity focused ultrasound (HIFU) treatment effect, it is of great importance to effectively judge whether the sampled signal is the HIFU echo signal or the noise signal. In this paper, a judgment method based on an auto-regressive (AR) model and spectrum information entropy is proposed. In total, 188 groups of data are obtained while the HIFU source is on or off through experiments, and these sampled signals are judged by this method. The judgment results of this method are compared with empirical judgments. It is found that when the segment number for the power spectrum estimated by AR model is 14 to 17, the judgment results of this method have a higher consistency with empirical judgments, and Accuracy, Sensitivity and Specificity all have good values. Moreover, after comparing and analyzing this method with the classic power spectrum estimation method, it is found that the recognition rate of the two sampled signals of this method is higher than that of the classic power spectrum estimation method. Therefore, this method can effectively judge the different types of sampled signals.

Background Nasal obstruction due to inferior turbinate hypertrophy is a common medical complaint among ENT clinic patients, which can significantly affect the patient's quality of life, and some are compelled to use topical intranasal decongestants. Conservative management is the first line of treatment; however, surgical reduction of the inferior turbinate becomes necessary if the symptoms persist after three months of treatment. The optimal surgical technique is controversial. High-intensity focused ultrasound (HIFU) is a minimally invasive surgical option that targets tissue volume precisely and minimally impacts surrounding tissue. This study aimed to assess the effectiveness and safety of HIFU in treating patients suffering from nasal obstruction due to inferior turbinate hypertrophy. Methods This prospective study was conducted from February to December 2016. The study lasted over six months. Patients with a history of allergic and non-allergic rhinitis participated in this study. It included 43 patients who had been experiencing chronic nasal obstruction due to bilateral inferior turbinate hypertrophy and had not shown improvement after three months of medical treatment. The patients underwent Ultrasound Volumetric Tissue Reduction (UVTR) surgery using the D & A Ultrasurg device (Diamant Medical Equipment Ltd., Amman, Jordan) under local anesthesia. The effectiveness, safety, and tolerance of HIFU were assessed subjectively for six months using a well-designed questionnaire utilizing a visual analog scale (VAS) and nasal endoscopy after the surgery. Results The study included 43 patients, 22 male and 21 female, aged 13 to 65 years. The study found that 40 (93%) patients showed significant improvement in nasal obstruction within a month of the surgery. However, three (7%) patients continued to experience persistent nasal obstruction even after six months of follow-up. The procedure was well-tolerated, with low rates of complications after surgery and reasonable pain control. During the surgery, 20 (46.5%) patients reported mild pain described as a pressure-like sensation, and 10 out of 43 patients (23%) required paracetamol after the procedure. Four patients (9.3%) had mild bleeding, which was treated with an ultrasound nasal probe without nasal packing. All patients experienced crusting of the nasal cavity during the first week, but no crustation was observed after the first month. There were no reported cases of synechia among the patients. Conclusion This study confirms that HIFU treatment is a reliable and effective treatment for improving short-term nasal obstruction caused by inferior turbinate hypertrophy. The procedure is easily applied and well-tolerated in outpatient clinics., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Al-Hilali et al.)

Background: The heterogeneity of uterine fibroids in magnetic resonance imaging (MRI) is complex for a subjective visual evaluation, therefore it is difficult for an accurate prediction of the efficacy of high intensity focused ultrasound (HIFU) ablation in fibroids before the treatment. The purpose of this study was to set up a radiomics model based on MRI T2-weighted imaging (T2WI) for predicting the efficacy of HIFU ablation in uterine fibroids, and it would be used in preoperative screening of the fibroids for achieving high non-perfused volume ratio (NPVR)., Methods: A total of 178 patients with uterine fibroids were consecutively enrolled and treated with ultrasound-guided HIFU under conscious sedation between February 2017 and December 2021. Among them, 96 patients with 108 uterine fibroids with high ablation efficacy (NPVR ≥80%, h&#95;NPVR) and 82 patients with 92 fibroids with lower ablation efficacy (NPVR <80%, l&#95;NPVR) were retrospectively analyzed. The transverse T2WI images of fibroids were selected, and the fibroids were delineated slice by slice using ITK-SNAP software. The radiomics analysis was performed to find the imaging biomarker for the construction of a predicting model for the evaluation of the ablation efficacy, including the feature extraction, feature selection and model construction. The prediction model was built by logistic regression and assessed by receiver operating characteristic (ROC) curve, and the prediction efficiency of the two models was compared by Delong test. The ratio of the training set to the testing set was 8:2., Results: The logistic regression model showed that the mean area under the curve (AUC) of the training set was 0.817 [95% confidence interval (CI): 0.755-0.882], and the testing set was 0.805 (95% CI: 0.670-0.941), respectively, which indicated a strong classification ability. The Delong test showed that there was no significant difference in the area under the ROC curve between the training set and testing set (P>0.05)., Conclusions: The radiomics model based on T2WI is feasible and effective for predicting the efficacy of HIFU ablation in treatment of uterine fibroids., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-23-916/coif). X.P., L.C. and X.C. are full-time employees of Shanghai United Imaging Intelligence Co., Ltd. The other authors have no conflicts of interest to declare., (2024 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

To evaluate the magnetic resonance (MR) signal intensity changes in the sacrococcygeal region of patients with uterine fibroids treated with high intensity focused ultrasound (HIFU). Two hundred and sixty-seven patients with uterine fibroids treated with HIFU between January and December 2016 were retrospectively reviewed. All patients underwent enhanced pre- and post-HIFU MRI. Multivariate analysis was used to assess the relationship between the factors and the signal intensity changes in the sacrum and the soft tissue adjacent to the sacrum. Among the 267 patients, 122 (46%) had MR signal intensity changes in the sacrum and/or the soft tissue adjacent to the sacrum after HIFU. Multivariate analysis showed that the position of the uterus, the distance from the dorsal side of the fibroid to the sacrum, and the ablation efficiency were significantly correlated with MR signal intensity changes in the sacrum and the soft tissue adjacent to the sacrum. Further analysis showed a significant relationship between the location of the MR signal intensity changes and uterine size, the enhancement degree of the uterus. Leg pain was only seen in patients with MR signal intensity changes both in the sacrum and the soft tissue adjacent to the sacrum. The location of the uterus, the distance between the dorsal side of the fibroids to the sacrum, and ablation efficiency have a significant relationship with the MR signal intensity changes. The size of the uterus and the degree of enhancement are related to the locations of MR signal changes. [ABSTRACT FROM AUTHOR]

Purpose: To develop and test in animal studies ex vivo and in vivo, an intravascular (IV) MRI‐guided high‐intensity focused ultrasound (HIFU) ablation method for targeting perivascular pathology with minimal injury to the vessel wall. Methods: IV‐MRI antennas were combined with 2‐ to 4‐mm diameter water‐cooled IV‐ultrasound ablation catheters for IV‐MRI on a 3T clinical MRI scanner. A software interface was developed for monitoring thermal dose with real‐time MRI thermometry, and an MRI‐guided ablation protocol developed by repeat testing on muscle and liver tissue ex vivo. MRI thermal dose was measured as cumulative equivalent minutes at 43°C (CEM43). The IV‐MRI IV‐HIFU protocol was then tested by targeting perivascular ablations from the inferior vena cava of 2 pigs in vivo. Thermal dose and lesions were compared by gross and histological examination. Results: Ex vivo experiments yielded a 6‐min ablation protocol with the IV‐ultrasound catheter coolant at 3‐4°C, a 30 mL/min flow rate, and 7 W ablation power. In 8 experiments, 5‐ to 10‐mm thick thermal lesions of area 0.5‐2 cm2 were produced that spared 1‐ to 2‐mm margins of tissue abutting the catheters. The radial depths, areas, and preserved margins of ablation lesions measured from gross histology were highly correlated (r ≥ 0.79) with those measured from the CEM43 = 340 necrosis threshold determined by MRI thermometry. The psoas muscle was successfully targeted in the 2 live pigs, with the resulting ablations controlled under IV‐MRI guidance. Conclusion: IV‐MRI‐guided, IV‐HIFU has potential as a precision treatment option that could preserve critical blood vessel wall during ablation of nonresectable perivascular tumors or other pathologies. [ABSTRACT FROM AUTHOR]

Abstract Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel non-invasive ablation technique that uses focused sound energy to destroy focal tumors, primarily via heat deposition. It is widely used for palliation of pain from bone metastases and has also recently gained popularity as a technique for ablation of benign bone tumors and facet degenerative joint disease (rhizotomy). Clinically, in a subset of patients who have undergone MRgFUS of bone, a variety of treatment responses have been noted on follow-up imaging, including focal sclerosis within the target lesion or more exuberant proliferative changes associated with the periosteum. In this study, high resolution peripheral quantitative CT (HR-pQCT) was used to evaluate remodeling of bone following ablation in a swine model of MRgFUS and compared to samples from a control, non-treated femur. Within each treated femur, two lesions were created: a higher energy focused ultrasound dose was used for one lesion compared to a lower energy dose for the second lesion. Exuberant, extra-cortical bone formation was detected at the higher energy ablation zones, with volumes ranging from 340 mm3 to 1040 mm3. More subtle endosteal and cortical changes were detected in the lower energy ablation zones, however cortical thickness was significantly increased at these sites compared to control bone. For both high and low energy lesions, lower bone mineral density and tissue mineral density was noted in treated regions compared to control regions, consistent with the formation of newly mineralized tissue. Following HR-pQCT analysis, Fourier transform infrared (FTIR) spectroscopy was subsequently used to detect biochemical changes associated with remodeling of bone following MRgFUS, and compared to samples from the control, non-treated femur. Findings were compared with histopathologic examination following hematoxylin-eosin staining. FTIR analysis demonstrated lower mineral/phosphate ratio and increased crystallinity compared to the control samples (p = 0.013). Histopathologic review demonstrated associated areas of endosteal inflammation, scarring, fat necrosis, and new extra-cortical bone formation associated with the ablations. Overall, these findings provide novel characterization of new bone formation following MRgFUS ablation. Highlights • MRgFUS of bone can cause new bone formation associated with higher energies. • HR-pQCT is sensitive to increases in bone mineral density after MRgFUS over 6 weeks. • Changes in bone maturity after MRgFUS can be evaluated with FTIR analysis. [ABSTRACT FROM AUTHOR]

We present a back-to-back (BTB) structured, dual-mode ultrasonic device that incorporates a single-element 5.3 MHz transducer for high-intensity focused ultrasound (HIFU) treatment and a single-element 20.0 MHz transducer for high-resolution ultrasound imaging. Ultrasound image-guided surgical systems have been developed for lesion monitoring to ensure that ultrasonic treatment is correctly administered at the right locations. In this study, we developed a dual-element transducer composed of two elements that share the same housing but work independently with a BTB structure, enabling a mode change between therapy and imaging via 180-degree mechanical rotation. The optic fibers were embedded in the HIFU focal region of ex vivo chicken breasts and the temperature change was measured. Images were obtained in vivo mice before and after treatment and compared to identify the treated region. We successfully acquired B-mode and C-scan images that display the hyperechoic region indicating coagulation necrosis in the HIFU-treated volume up to a depth of 10 mm. The compact BTB dual-mode ultrasonic transducer may be used for subcutaneous thermal ablation and monitoring, minimally invasive surgery, and other clinical applications, all with ultrasound only.

Ronald H Silverman1,2 1Department of Ophthalmology, Columbia University Medical Center, 2F.L. Lizzi Center for Biomedical Engineering, Riverside Research, New York, NY, USA Abstract: The use of focused ultrasound to obtain diagnostically significant information about the eye goes back to the 1950s. This review describes the historical and technological development of ophthalmic ultrasound and its clinical application and impact. Ultrasound, like light, can be focused, which is crucial for formation of high-resolution, diagnostically useful images. Focused, single-element, mechanically scanned transducers are most common in ophthalmology. Specially designed transducers have been used to generate focused, high-intensity ultrasound that through thermal effects has been used to treat glaucoma (via cilio-destruction), tumors, and other pathologies. Linear and annular transducer arrays offer synthetic focusing in which precise timing of the excitation of independently addressable array elements allows formation of a converging wavefront to create a focus at one or more programmable depths. Most recently, linear array-based plane-wave ultrasound, in which the array emits an unfocused wavefront and focusing is performed solely on received data, has been demonstrated for imaging ocular anatomy and blood flow. While the history of ophthalmic ultrasound extends back over half-a-century, new and powerful technologic advances continue to be made, offering the prospect of novel diagnostic capabilities. Keywords: ophthalmic ultrasound, ultrasound biomicroscopy (UBM), high-intensity focused ultrasound (HIFU), ultrafast imaging, Doppler imaging

The present work is concerned with the numerical investigation of the thermal response of tissue-mimicking biological phantom(s) subjected to high intensity focused ultrasound (HIFU). Simulations have been performed on the 3-dimensional physical domain for two-layered as well as multi-layered medium consisting of water and liver tissue. Local pressure distribution within the body of the phantom has been calculated by solving the complete full-wave nonlinear form of Westervelt equation. The solution of the pressure wave equation has been coupled with Pennes bioheat transfer equation to determine the full field temperature distribution. Results in the form of pressure fields, temperature distributions and the corresponding thermal dosage in the targeted region of the tissue domain have been presented. Magnitudes of the maximum pressure (and hence the resultant temperature levels) in the focal region as obtained using the nonlinear form of Westervelt equation are found to be significantly higher than that determined based on the linear form of the equation. Compared to water, wherein the acoustic intensity is maximum, the addition of sub-layers of skin, fat, and muscle into water resulted in the reduction of the peak intensity and also shifted the intensity profiles along the direction of propagation of the acoustic waves. However, addition of liver tissue into water led to the shifting of intensity profile in the opposite direction i.e., towards the transducer. The results further reveal that due to the dependence of attenuation coefficient on the source frequency, the temperature at the focal region increases with an increase in the transducer frequency. The work is further extended from single lesion to multiple lesion generation through controlled movement of the transducer and the resultant transient full field temperature distribution has been presented. The concerned observations highlight the need of optimizing the thermal energy for each lesion, the inter spatial distance between different lesions and the delay time so as to ensure minimal thermal damage to the surrounding healthy cells as well as to reduce the total treatment duration. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Current popular cancer treatment options, include tumor surgery, chemotherapy, and hormonal treatment. These treatments are often associated with some inherent limitations. For instances, tumor surgery is not effective in mitigating metastases; the anticancer drugs used for chemotherapy can quickly spread throughout the body and is ineffective in killing metastatic cancer cells. Therefore, several drug delivery systems (DDS) have been developed to target tumor cells, and release active biomolecule at specific site to eliminate the side effects of anticancer drugs. However, common challenges of DDS used for cancer treatment, include poor site-specific accumulation, difficulties in entering the tumor microenvironment, poor metastases and treatment efficiency. In this context, non-invasive cancer treatment approaches, with or without DDS, involving the use of light, heat, magnetic field, electrical field and ultrasound appears to be very attractive. These approaches can potentially improve treatment efficiency, reduce recovery time, eliminate infections and scar formation. In this review we focus on the effects of magnetic fields and ultrasound on cancer cells and their application for cancer treatment in the presence of drugs or DDS. [ABSTRACT FROM AUTHOR]