High Ultrasound Frequencies Research Articles

Frequency dependence of ultrasonic effects on the kinetics of hen egg white lysozyme fibrillation

Our study aimed to investigate the effects of ultrasound on the fibrillation kinetics of HEWL (hen egg white lysozyme) and its physicochemical properties. Ultrasound, a mechanical wave, can induce conformational changes in proteins. To achieve this, we developed an ultrasound exposure system and used various biophysical techniques, including ThT fluorescence spectroscopy, ATR-FTIR, Far-UV CD spectrophotometry, Fluorescence microscopy, UV-spectroscopy, and seeding experiments. Our results revealed that higher frequencies significantly accelerated the fibrillation of lysozyme by unfolding the native protein and promoting the fibrillation process, thereby reducing the lag time. We observed a change in the secondary structure of the sonicated protein change to the β-structure, but there was no difference in the Tm of native and sonicated proteins. Furthermore, we found that higher ultrasound frequencies had a greater seeding effect. We propose that the effect of frequency can be explained by the impact of the Reynolds number, and for the Megahertz frequency range, we are almost at the transition regime of turbulence. Our results suggest that laminar flows may not induce any significant change in the fibrillation kinetics, while turbulent flows may affect the process.

Contrast Agent-Free 3D Renal Ultrafast Doppler Imaging Reveals Vascular Dysfunction in Acute and Diabetic Kidney Diseases.

To combat the irreversible decline in renal function associated with kidney disease, it is essential to establish non-invasive biomarkers for assessing renal microcirculation. However, the limited resolution and/or vascular sensitivity of existing diagnostic imaging techniques hinders the visualization of complex cortical vessels. Here, a 3D renal ultrafast Doppler (UFD) imaging system that uses a high ultrasound frequency (18MHz) and ultrahigh frame rate (1KHz per slice) to scan the entire volume of a rat's kidney in vivo is demonstrated. The system, which can visualize the full 3D renal vascular branching pyramid at a resolution of 167µm without any contrast agent, is used to chronically and noninvasively monitor kidneys with acute kidney injury (AKI, 3 days) and diabetic kidney disease (DKD, 8 weeks). Multiparametric UFD analyses (e.g., vessel volume occupancy (VVO), fractional moving blood volume (FMBV), vessel number density (VND), and vessel tortuosity (VT)) describe rapid vascular rarefaction from AKI and long-term vascular degeneration from DKD, while the renal pathogeneses are validated by in vitro blood serum testing and stained histopathology. This work demonstrates the potential of 3D renal UFD to offer valuable insights into assessing kidney perfusion levels for future research in diabetes and kidney transplantation.

Assessment and Monitoring of Nail Psoriasis with Ultra-High Frequency Ultrasound: Preliminary Results.

Psoriatic onychopathy is one of the clinical presentations of psoriasis and a well-known risk factor for the development of psoriatic arthritis. High-frequency ultrasounds (HFUS > 20 MHz) have recently been used to evaluate the nail apparatus of healthy and psoriatic subjects. The aim of our study was to detect by means of ultra-high-frequency ultrasound (UHFUS 70-100 MHz) alterations of the nail bed and matrix in patients with psoriatic onychopathy and to monitor these parameters during the treatment with monoclonal antibody (mAb). We enrolled 10 patients with psoriatic onychopathy and naive to previous biologic therapies. Patients were evaluated at baseline, after 1 month and after 3 months from the beginning of mAb therapy by a complete clinical assessment and US evaluation. A UHFUS examination with a 70 MHz probe was performed on the thumbnail (I), the index fingernail (II) and the nail with greater clinical impairment (W). The following measurements were analyzed: nail plate thickness (A), nail bed thickness (B), nail insertion length (C), nail matrix length (D) and nail matrix thickness (E). Among the various parameters analyzed, some measures showed a statistically significant decrease with p-value < 0.05 (t0 WA = 0.52 mm vs. t2 WA = 0.42 mm; t0 WB = 2.8 mm vs. t2 WB = 2.4 mm; t0 WE = 0.76 mm vs. t2 WE = 0.64 mm; t0 IIA = 0.49 mm vs. t2 IIA = 0.39 mm). In conclusion, UHFUS could represent a viable imaging technique for the real-time evaluation and monitoring of psoriatic onychopathy, thus supporting the clinical parameters and revealing any subclinical signs of early drug response.

Towards High-Resolution Ultrasound Neuromodulation With Crossed-Beam Phased Arrays.

Transcranial focused ultrasound stimulation (tFUS) has emerged as a potential noninvasive therapeutic technology. Due to skull attenuations at high ultrasound (US) frequencies, successful tFUS with sufficient penetration depth requires sub-MHz US waves, leading to relatively poor stimulation specificity particularly in the axial direction (perpendicular to the US transducer). This shortcoming can potentially be overcome by utilizing two individual US beams properly crossed in time and space. For large-scale tFUS, a phased array is also required to dynamically steer focused US beams at desired neural targets. This article presents the theoretical foundation and optimization (through a wave-propagation simulator) of crossed-beam formation using two US phased arrays. It also experimentally validates crossed-beam formation with two custom-made 32-element phased arrays (operating at 555.5 kHz) positioned relatively at different angles. In measurements, the sub-MHz crossed-beam phased arrays achieved 0.8/3.4 mm lateral/axial resolution at a focal distance of ∼ 46 mm, compared to the lateral/axial resolution of 3.4/26.8 mm of the individual phased array at 50 mm focal distance (∼ 28.4-fold improvement in reducing the main focal zone area). The crossed-beam formation in the presence of a rat skull and a tissue layer was also validated in the measurements.

Sonic disruption of wood pulp fibres aided by hydrophobic cavitation nuclei

For paper manufacturing and biofuel production, the controlled deformation of wood pulp is of interest, provided that the integrity of the fibre structure remains intact. Conventional ultrasonic pretreatment in the near-audible range has been observed to cause uncontrolled inertial cavitation damage in wood pulp fibres. To prevent internal damage, we proposed to subject wood pulp mixed with hydrophobic particles to 1-MHz short pulses above the nucleation threshold of the particles but below the Blake threshold, and to observe the interaction of pulsating cavities and wood pulp fibres assisted by high-speed photography. Our 1-MHz results showed the interaction of a collapsing bubble with a wood pulp fibre wall to form a liquid jet hitting the fibre, without apparent destruction of the structure, whilst our 20-kHz controls confirmed previously observed structural destruction. This study shows the feasibility of controlled wood fibre deformation at a high ultrasound frequency.

Review of High-Frequency Ultrasounds Emulsification Methods and Oil/Water Interfacial Organization in Absence of any Kind of Stabilizer.

Emulsions are multiphasic systems composed of at least two immiscible phases. Emulsion formulation can be made by numerous processes such as low-frequency ultrasounds, high-pressure homogenization, microfluidization, as well as membrane emulsification. These processes often need emulsifiers’ presence to help formulate emulsions and to stabilize them over time. However, certain emulsifiers, especially chemical stabilizers, are less and less desired in products because of their negative environment and health impacts. Thus, to avoid them, promising processes using high-frequency ultrasounds were developed to formulate and stabilize emulsifier-free emulsions. High-frequency ultrasounds are ultrasounds having frequency greater than 100 kHz. Until now, emulsifier-free emulsions’ stability is not fully understood. Some authors suppose that stability is obtained through hydroxide ions’ organization at the hydrophobic/water interfaces, which have been mainly demonstrated by macroscopic studies. Whereas other authors, using microscopic studies, or simulation studies, suppose that the hydrophobic/water interfaces would be rather stabilized thanks to hydronium ions. These theories are discussed in this review.

Basal cell carcinoma thickness evaluated by high-frequency ultrasounds and correlation with dermoscopic features.

Background Basal cell carcinoma (BCC) is the most common skin cancer and it can be easily treated by surgery or by various other physical modalities and topical chemotherapy. For metastatic, locally advanced BCC and for cancers that cannot be removed by surgery, sistemic drugs known as hedgehog pathway blocker are used. High-frequency ultrasound (HFUS) is a non- invasive technique used in diagnosis of some skin cancers. It has proven potentially useful for BCC management. In this study we used high frequency ultrasounds to evaluate BCCs' thickness and the correlation with dermoscopic features. Methods We examined 86 basal cell carcinomas with dermoscopy and with high frequency ultrasound. The main patterns identified by ultrasound were linear, ellipsoid and non-specific or undefined. Patients were divided by sex and age. The BCCs were grouped by anatomic location. Finally we recorded specific dermoscopic features of BCCs noting their presence/absence in lesions overall and in each of four quadrants. Then the lesions were excised and histological examination was made with definition of tumor thickness (in mm). Results In our study two main echographic patterns were described: linear, associated with superficial BCC, and ellipsoid, found primarily in nodular variants. However, a small percentage of lesions have otherwise non-specific patterns. We observed a significant correlation between echographic tumor thickness and histotype. We observed high concordance between histological tumor thickness and ultrasounds. Also dermoscopic criteria as large branching and blue ovoid nests were significantly associated with heightened histologic and echographic assessments of tumor thickness. Conclusions In our study we have confirmed the utility of ultrasound in the diagnosis of BCCs and for the first time we have correlated ultrasounds' patterns with dermoscopy and tumor thickness.

In vivo assessment of prostate cancer response using quantitative ultrasound characterization of ultrasonic scattering properties

BackgroundThe study here investigated quantitative ultrasound (QUS) parameters to assess tumour response to ultrasound-stimulated microbubbles (USMB) and hyperthermia (HT) treatment in vivo. Mice bearing prostate cancer xenografts were exposed to various treatment conditions including 1% (v/v) Definity microbubbles stimulated at ultrasound pressures 246 kPa and 570 kPa and HT duration of 0, 10, 40, and 50 min. Ultrasound radiofrequency (RF) data were collected using an ultrasound transducer with a central frequency of 25 MHz. QUS parameters based on form factor models were used as potential biomarkers of cell death in prostate cancer xenografts.ResultsThe average acoustic concentration (AAC) parameter from spherical gaussian and the fluid-filled spherical models were the most efficient imaging biomarker of cell death. Statistical significant increases of AAC were found in the combined treatment groups: 246 kPa + 40 min, 246 kPa + 50 min, and 570 kPa + 50 min, in comparison with control tumours (0 kPa + 0 min). Changes in AAC correlates strongly (r2 = 0.62) with cell death fraction quantified from the histopathological analysis.ConclusionScattering property estimates from spherical gaussian and fluid-filled spherical models are useful imaging biomarkers for assessing tumour response to treatment. Our observation of changes in AAC from high ultrasound frequencies was consistent with previous findings where parameters related to the backscatter intensity (AAC) increased with cell death.

The Role of Endoscopic Ultrasonography in the Differential Diagnosis of Polypoid Lesions of the Gallbladder: an Update

Although most gallbladder (GB) polyps are benign, some early carcinomas of the GB share the same appearance as benign polyps. Currently, GB polyps larger than 1 cm should be surgically removed because of the increased risk of malignancy. Distinguishing between nonneoplastic and neoplastic lesions is are a major diagnostic dilemma, and the therapeutic options for these lesions remain controversial. Endoscopic ultrasonography (EUS) is considered to be superior to the conventional US for imaging GB lesions since EUS can provide high-resolution images of small lesions with higher ultrasound frequencies. However, differential diagnosis remains difficult, especially for small GB polyps. Thus, various diagnostic methods using EUS have been introduced to overcome the difficulty of differential diagnosis between neoplastic and non-neoplastic polyps. Contrast-enhanced harmonic EUS is useful for observing microvascular patterns and additional enhancement images of GB polyps. This requires a post-recording analysis due to a short enhancement time. Real-time color Doppler-EUS provides the Doppler flow of vessels without a time limit. Keywords: Gallbladder, polyp; Endoscopic ultrasonography 중심 단어: ë‹´ë‚­ìš©ì¢ ; 내시경 초음파

Improved Ultrasound Microvessel Imaging Using Deconvolution with Total Variation Regularization

Singular value decomposition-based clutter filters can robustly reject tissue clutter, allowing for detection of slow blood flow in imaging microvasculature. However, to identify microvessels, high ultrasound frequency must be used to increase the spatial resolution at the expense of shorter depth of penetration. Deconvolution using Tikhonov regularization is an imaging processing method widely used to improve spatial resolution. The ringing artifact of Tikhonov regularization, though, can produce image artifacts such as non-existent microvessels, which degrade image quality. Therefore, a deconvolution method using total variation is proposed in this study to improve spatial resolution and mitigate the ringing artifact. Performance of the proposed method was evaluated using chicken embryo brain, ex ovo chicken embryo chorioallantoic membrane and tumor data. Results revealed that the reconstructed power Doppler (PD) images are substantially improved in spatial resolution compared with original PD images: the full width half-maximum (FWHM) of the cross-sectional profile of a microvessel was improved from 132 to 83 µm. Two neighboring microvessels that were 154 µm apart were better separated using the proposed method than conventional PD imaging. Additionally, 223 FWHMs measured from the cross-sectional profiles of 223 vessels were used to determine the improvement in FWHM with the proposed method statistically. The mean ± standard deviation of the FWHM without and with the proposed method was 233.19 ± 85.08 and 172.31 ± 75.11 μm, respectively; the maximum FWHM without and with the proposed method was 693.01 and 668.69 μm; and the minimum FWHM without and with the proposed method was 73.92 and 45.74 μm. There were statistically significant differences between FWHMs with and without the proposed method according to the rank-sum test, p < 0.0001. The contrast-to-noise ratio improved from 1.06 to 4.03 dB with use of the proposed method. We also compared the proposed method with Tikhonov regularization using ex ovo chicken embryo chorioallantoic membrane data. We found that the proposed method outperformed Tikhonov regularization as false microvessels appeared using the Tikhonov regularization but not with the proposed method. These results indicate that the proposed method is capable of providing more robust PD images with higher spatial resolution and higher contrast-to-noise ratio.

Basal cell carcinoma thickness evaluated by high-frequency ultrasounds and correlation with dermoscopic features.

Basal cell carcinoma (BCC) is the most common skin cancer, and it can be easily treated by surgery or by various other physical modalities and topical chemotherapy. For metastatic, locally advanced BCC and for cancers that cannot be removed by surgery, systemic drugs known as hedgehog pathway blocker are used. High-frequency ultrasound (HFUS) is a non- invasive technique used in diagnosis of some skin cancers. It has proven potentially useful for BCC management. In this study we used high frequency ultrasounds to evaluate BCCs' thickness and the correlation with dermoscopic features. We examined 86 basal cell carcinomas with dermoscopy and with high-frequency ultrasound. The main patterns identified by ultrasound were linear, ellipsoid and non-specific or undefined. Patients were divided by sex and age. The BCCs were grouped by anatomic location. Finally, we recorded specific dermoscopic features of BCCs noting their presence/absence in lesions overall and in each of four quadrants. Then the lesions were excised, and histological examination was made with definition of tumor thickness (in mm). In our study, two main echographic patterns were described: linear, associated with superficial BCC, and ellipsoid, found primarily in nodular variants. However, a small percentage of lesions have otherwise non-specific patterns. We observed a significant correlation between echographic tumor thickness and histotype. We observed high concordance between histological tumor thickness and ultrasounds. Also, dermoscopic criteria as large branching and blue ovoid nests were significantly associated with heightened histologic and echographic assessments of tumor thickness. Our study confirmed the utility of ultrasound in the diagnosis of BCCs and for the first time we have correlated ultrasounds' patterns with dermoscopy and tumor thickness.

A feasible strategy based on high ultrasound frequency and mass spectrometry for discriminating individuals diagnosed with bipolar disorder and schizophrenia through ionomic profile.

A viable and accurate method based on high-power ultrasound-assisted microextraction and inductively coupled plasma mass spectrometry was developed to determine metals in human serum from patients with bipolar disorder and schizophrenia. A simple and rapid sample preparation method using a cup-horn sonoreactor was developed. The acid concentration of HNO3 (10, 20, and 40% v/v) and HCl (1, 5, 15, and 30% v/v) of the extraction solution, the sonication time (1, 3, 6, and 10 min), and the sonication amplitude (20, 40, 60, and 80%) were evaluated. Cd, Cu, Fe, Li, Pb, and Zn were determined in serum samples from patients with bipolar disorder and schizophrenia, and from healthy controls. Quantitative metal recoveries using the proposed method were compared under the same conditions using an ultrasonic bath, magnetic stirring, and microwave-assisted digestion. Optimum extraction conditions were obtained using HNO3 (40% v/v) + HCl (30% v/v) as the extraction solution with 3 min sonication time and 60% sonication amplitude. Significant differences were observed among the methods compared. On application of the sample preparation method based on high-power ultrasound-assisted microextraction coupled with inductively coupled plasma mass spectrometry, Pb and Cd in all the studied samples were below the limit of detection of our method. Compared with healthy controls, the concentration of Cu, Li, Fe, and Zn was found to be significantly higher for the bipolar disorder group, while these metals and Li were found at a lower level for the group diagnosed with schizophrenia. Principal component analysis showed a significant separation for the groups studied based on their ionomic profiles after the application of high-power ultrasound-assisted microextraction as a sample preparation strategy.

The Role of EUS in the Differential Diagnosis of Polypoid Lesions of the Gallbladder: Update

Although most gallbladder (GB) polyps are benign, some early carcinomas of the GB share the same appearance as benign polyps. Currently, GB polyps larger than 1 cm should be surgically removed because of the increased risk of malignancy. Distinguishing between nonneoplastic, neoplastic, and potentially malignant lesions is a major diagnostic dilemma, and the therapeutic options for these lesions remain controversial. Endoscopic ultrasonography (EUS) is considered to be superior to conventional US for imaging GB lesions, because EUS can provide highresolution images of small lesions with higher ultrasound frequencies. However, differential diagnosis remains difficult, especially for small GB polyps. Thus, various diagnostic methods using EUS have been introduced to overcome difficulty for differential diagnosis between neoplastic and non-neoplastic polyps. Contrastenhanced harmonic EUS is useful for observing microvascular patterns and additional enhancement images of GB polyps. This is needed a post-recording analysis due to a short enhancement time. Real-time color Doppler-EUS provides the Doppler flow of vessels without a time limit.

Phonon Magnetochiral Effect.

The magnetochiral effect (MCE) of phonons, a nonreciprocal acoustic propagation arising due to symmetry principles, is demonstrated in the chiral-lattice ferrimagnet Cu_{2}OSeO_{3}. Our high-resolution ultrasound experiments reveal that the sound velocity differs for parallel and antiparallel propagation with respect to the external magnetic field. The sign of the nonreciprocity depends on the chirality of the crystal in accordance with the selection rule of the MCE. The nonreciprocity is enhanced below the magnetic ordering temperature and at higher ultrasound frequencies, which is quantitatively explained by a proposed magnon-phonon hybridization mechanism.

Methods of Testing of Sound Insulation Properties of Barriers Intended for High Frequency Noise and Ultrasonic Noise Protection

Abstract Two test stands for determining sound insulation in the frequency range above 5 kHz were made. One consisted of two horizontally adjacent reverberation rooms and a special source of high frequency sounds and ultrasounds. The other test stand consisted of a miniaturized test chamber and a special source of ultrasounds. The paper presents results of the preliminary measurements of sound insulation properties of different barriers in the frequency range above 5 kHz.

Validation study of ultrasound bladder wall thickness measurements.

The aim was to validate ultrasound bladder wall thickness measurements. We scanned at three frequencies (5MHz, 7MHz and 9MHz), using two techniques described in clinical practice and compared them with direct micrometre calliper measurements. Bladder dome cadaver specimens were dissected from male and female cadavers. The direct micrometre calliper measurement under direct vision was used as the gold standard. We imaged using a Voluson E8 ultrasound scanner at three frequencies, using three probes: AB27D (2-7MHz), RAB25D (2-5MHz) and RIC50D (5-9MHz). The specimens were scanned on two different occasions for intra-observer variability. A second operator, measured the samples again independently for the interobserver agreement. The specimens were gently placed onto a sheathed and gelled probe to avoid deformation. The method of scanning was the same for all the specimens, probes and operators. Twenty-five bladder dome specimens were assessed. The correlation of the ultrasound measurement to the direct measurement improved at higher ultrasound frequencies. Measuring from the inside of the serosal hyperechogenicity also increased the accuracy correlation with the direct measurement for all the frequencies tested. This is the first study validating BWT ultrasound measurements against cadaveric bladder wall calliper measurements. Technology and technique affect accuracy, which is important in clinical practice. The use of 5-MHz probes is not recommended. The most accurate measurement was obtained using high-frequency ultrasound, where the measurement did not include the serosal brightness. These data suggest that high-frequency ultrasound should be used to assess BWT.

Coupling Ultrasound to the Electro‐Oxidation of Methyl Paraben Synthetic Wastewater: Effect of Frequency and Supporting Electrolyte

AbstractIn this paper, electrooxidation of methyl paraben (MeP) is studied by electrolysis only and electrolysis coupled with sonolysis, using a diamond electrode. Complete mineralization of MeP was achieved for both processes, in chloride and sulfate media. Results showed that, although the oxidation of pollutant is faster in the presence of chloride, the mineralization is favored in sulfate medium. Ultrasound irradiation enhanced the removal of organic matter due to the activation of oxidant species in both supporting electrolytes. Moreover, the formation of chlorine gas in the chloride containing medium improves the ultrasound cavitation effect, promoting faster depletion of the total organic carbon in the first hour of treatment. Regarding the formation of more toxic products, all possible organochlorinated intermediates were removed, since complete mineralization was attained in less than 5 hours. Ultrasonic coupling to the electrolysis process accelerates the destruction of the intermediates and delays the formation of perchlorate, which only begins after the complete removal of the total organic carbon. Low and high ultrasound frequencies were evaluated and were found to produce different effects of cavitation, which affect the electrolysis in different ways. The final result will be a balance between these effects and thus, an optimum frequency can be established for different systems.

Bilateral Asymmetries in Ultrasound Assessments of the Rectus Femoris throughout an NCAA Division I Volleyball Preseason.

The purpose of the study was to assess glycogen content of the rectus femoris (RF) muscles utilizing high-frequency ultrasound throughout an intensive, nine-day preseason training period in NCAA division I volleyball athletes. In the morning prior to the beginning of practice, athletes (n = 13) left and right RF muscles were assessed via ultrasound to quantify muscle fuel ratings (0–100 score range). The recommended location of the RF ultrasound scans were based on manufacturer guidelines, and the same technician recorded the daily measurements. To assess daily training load, session ratings of perceived exertion (s-RPE) were utilized. A paired t-test revealed a large significant difference between left (51.7 ± 17.9) and right (32.8 ± 17.4) RF muscle fuel ratings (p < 0.001). There was also a major effect of time on s-RPE (p < 0.001) and left (dominant) RF fuel rating (p = 0.001). s-RPE decreased from the beginning to the end of the training camp. However, left RF fuel ratings increased from the first to the second day, then remained elevated all throughout the preseason. In conclusion, all athletes were left-leg dominant and had a 57.6% bilateral asymmetry between their left and right RF muscle fuel ratings despite changes in training load. High-frequency ultrasounds are a noninvasive assessment tool that can determine glycogen replenishment asymmetries in the RF.

Interface characterization at nanometer scale using very high frequency ultrasounds

ABSTRACTThe main objective of this work is to study the solid-solid interfaces using a very high frequency (3GHz) ultrasonic method in order to deduce in a non-destructive way and quantitatively the quality contact at the interface, fundamental parameter in tribology. The very high frequencies allow prospecting the state of contact at the nanometer scale. The determination of the contact surface between two polished materials (Silicon-Silica) was carried out. From the measured echoes diagram, the reflection coefficient and the elasticity of the interface were extracted and compared to the ones determined by a numerical approach presented by Greenwood and Williamson

Imaging of gall bladder by endoscopic ultrasound.

Endoscopic ultrasonography (EUS) is considered a superior investigation when compared to conventional ultrasonography for imaging gall bladder (GB) lesions as it can provide high-resolution images of small lesions with higher ultrasound frequencies. Examination of GB is frequently the primary indication of EUS imaging. Imaging during EUS may not remain restricted to one station and multi-station imaging may provide useful information. This review describes the techniques of imaging of GB by linear EUS from three different stations. The basic difference of imaging between the three stations is that effective imaging from station 1 is done above the neck of GB, from station 2 at the level of the neck of GB and from station 3 below the level of the neck of GB.