MHz Transducer Research Articles

Comprehensive evaluation of lens and planar circular ultrasonic transducer combinations to enhance C-scan imaging: a phantom study at 10 and 15 MHz

Abstract Objective. To evaluate the imaging capabilities of four polydimethylsiloxane-based acoustic lenses with subsonic refractive indices, focusing on a spherical lens and three designed aspherical lenses with varying focus. Approach. We investigated a spherical lens with a radius curvature of 8 mm (SL-R8), two aspherical lenses with focal lengths of 15 mm and 10 mm (AL15 and AL10), and an aspherical folding lens with a focal length of 10 mm (AFL10). The equation cross-section profile of an aspherical lens is calculated using the assumption that all trajectories passing through the lens have the same flight duration when they reach the focal point. Furthermore, we observed that we can fold this aspherical lens without greatly diminishing its focusing capability. Utilizing circular planar ultrasonic transducers at frequencies of 10 MHz and 15 MHz, we examined the reflected waveforms via pulse-echo tests and measured focal points and beam widths using a needle hydrophone in the acoustic intensity measurement system. The target resolution was assessed using a C-Scan imaging system. Main results. Analysis of the axial and lateral beam profiles revealed that AFL10 and AL10 lenses exhibited narrower beam widths at the focal point. We evaluate the AFL10 and AL10 lenses combined with a 15 MHz transducer for preclinical testing using standard medical phantoms containing microparticles in gelatin- and agar-based matrices. In conclusion, using these twocombinations, C-Scan imaging successfully formed a 25 µm backscatter inside the phantom image. Significance. Due to their high-resolution capabilities, applying cross-sectional profile equations in the lateral plane of the lens surface in linear ultrasonic array probes offers promises for early-stage medical diagnostics.

Birth Weight, Current Weight, and Weight Dynamism from Birth to Adulthood as Measure of Outcome in Heart Failure

Objectives: Among the non-communicable disease, the cardiovascular disease is major cause of mortality worldwide. The risk factors include the hypertension, diabetes mellitus increasing age and gender, and dyslipidemia. Recently, much attention has been paid to impact of weight in determining the cardiovascular events and it’s role in development of chronic disease. Studies have been published for fetal origin for adult disease; one among them is barker’s hypothesis. Furthermore, epidemiological study proposes decremental effects of birth weight outside the normal range. Our study focuses on significance of birth weight, weight dynamism from birth to adulthood for correlation with heart failure (HF) in adults. Materials and Methods: Imaging studies were done with echocardiography (ECHO) of 2.5–3.5 Mhz transducers. Patients were grouped as Group A and B. Group A is asymptomatic, healthy population. Group B patients have failure signs and symptoms. Both group undergone to 2D ECHO, necessary tests, and body mass index measured. Results: In our study, we collected data from 100 subjects. Out of 50 patients in case, group age of patient ranges from 50 to 60 years. Among the control group, age of patients ranges from 50 to 60 years. Mean age of patient in case group is 58.4 ± 3.36 year. Mean age of patients in Group A is 56.6 ± 3.02 years. Birth weight among the patients with HF ranges from 1.5 to 3.5 kg. Total number of patients having low birth weight (LBW) is 44 among case group. None of patients were having LBW in control group and was statistically significant (P < 0.001). Thus indicating, there is higher incidence of HF in patients having LBW. Mean birth weight among patients with HF was 2.14 ± 0.267 kg and among control group was 3.01 ± 0.276 kg. Incidence of HF was more among women than men group. Conclusion: The LBW associated HF and has inverse relationship with cardiovascular function; also, adult obese population have increased risk of HF. similarly, severe left ventricular dysfunction had high present weight and women had high risk of HF compared to men group.

Pressure estimation of ultra-high frequency ultrasound using gas vesicles.

Acoustic microscopy uses ultra-high frequency (UHF) ultrasound transducers over 80 MHz to perform high-resolution imaging. The pressure output of these transducers is unknown, as commercial calibrated hydrophones can measure pressure for transducers with frequencies only up to 80 MHz. This study used gas vesicle nanostructures (GVs) that collapse at 571 kPa to estimate the pressure of UHF transducers at 40, 80, 200, and 375 MHz. Agarose phantoms containing GVs were made, and a baseline ultrasound image was performed at low pressure to prevent GV collapse. Sections within the phantom were scanned at varying voltage to determine the GV collapse threshold. The pressure at full driving voltage was then calculated, assuming a linear relation between transducer voltage and pressure. The pressure calculated for the 40 MHz transducer was 2.2 ± 0.1 MPa at 21 °C. Using a hydrophone, the measured pressure was 2.1 ± 0.3 MPa, a difference of <2%, validating the method at this frequency. The pressure calculated for the other transducers was 2.0 ± 0.1 MPa (80 MHz), 1.2 ± 0.1 (200 MHz), and 1.05 ± 0.17 (375 MHz at 37 °C). This study addresses the challenge of estimating pressure output from UHF ultrasound transducers, demonstrating that the pressure output in the 40-400 MHz frequency range can be quantified.

Thyroid Ultrasonography Screening of a Cohort of Male University Students

Objective: To assess thyroid ultrasonographic (US) findings from a male cohort of asymptomatic Saudi Arabian university students. Materials and Methods: Sixty-three university students were enrolled in a quantitative prospective study from February 2024 to April 2024. They were conveniently selected, excluding females. A MyLab40 US equipment system was used with a 7 MHz transducer. The thyroid was evaluated with US for size, echotexture, and abnormalities. The chi-square test, correlations, and descriptive statistics were applied for the data analysis. Results: The mean age of the participants was 21.5 ± 1.1 years, and the mean body mass index (BMI) was 27.03 ± 6.6. 95.2% of participants had normal findings; positive findings were found in 4.8 % of the participants. Of these, 1.6 % had multiple nodules, and 3.2 % had signs of thyroiditis. The statistical analysis revealed no significant association between right and left thyroid lobe lengths compared to BMI ( p = .7 right and left 0.3). Moreover, there was no association between the thyroid echo pattern and the BMI ( p = .4). Conclusion: This cohort study concluded that the thyroid US findings were very limited. There was no statistical correlation between the thyroid lobe length, thyroid echo pattern, compared to participants’ BMI.

EXTH-39. A BENCH-TOP MODEL FOR THE OPTIMIZATION OF ULTRASOUND PARAMETERS FOR SONODYNAMIC THERAPY OF GLIOBLASTOMA

Abstract BACKGROUND In-vitro studies have demonstrated that low frequency sound waves can interact with hemo-porphyrin molecule to induce the production of reactive oxygen species. This biophysical phenomenon can induce tumour cell death in glioblastoma cells in-vitro. The purpose of this study was to evaluate the production of reactive oxygen species and expression of apoptotic markers in glioblastoma cells in response to varying total treatment time and ultrasound power using a bench-top focused ultrasound (FUS) device. METHODS U251 cells were exposed to 5-Aminolevulenic Acid (5-ALA) at varying concentrations for up to 24 hours. The time point with peak proto-porphyrin IX (PPIX) fluorescence was established using fluorescence activated cell sorting (FACS). A transducer utilized at 0.91MHz was placed on an inverted stage with the focus targeted to the bottom of a standard 96-well cell culture plate. Pressure wave delivery was confirmed using a hydrophone. GBM cells were treated with 5-ALA alone, FUS alone, or 5-ALA + FUS and the cells were incubated for 24 hours prior to measuring ROS induction and cell death. ROS was measured using FACS with the CellROX Green Kit for Oxidative Stress Detection and Annexin-V was measured using the Dead Cell Stain Kit. RESULTS Peak fluorescence intensity for PPIX in the U251 cell line was found to be induced through incubation with 5-ALA for 24 hours with a concentration 200mg/mL. The fluorescence intensity of PPIX was found to be 313% greater in the treated group compared to the control group. Peak ROS was observed using a 0.91MHz transducer frequency for a total time of 120s with 6W average power. ROS was 61% and 66% greater in the SDT group compared to the FUS and 5-ALA group respectively. CONCLUSION Using this bench-top set up we successfully induced ROS and apoptosis in U251 cells. Establishing a reliable in-vitro model will allow us to further investigate the effects of other sonication parameters such as burst length.

Study on surface waves for detection of fatigue cracks in railway joint bars

The current method of inspecting railway joint bars involves the use of high-resolution cameras to detect fatigue cracks that have undergone significant cracking exposed to the surface. The novelty of the work presented in this paper discusses the development and application of non-contact ultrasonic surface wave approach to detect and characterize near-surface fatigue cracks in the head of the railway joint bars which is not usually accessible for inspection. Simulated cracks were implanted in the head of the two different used joint bars to assess the capabilities of the ultrasonic nondestructive evaluation (NDE) surface wave approach. One of the joint bars was implanted with 3.175 mm and 6.35 mm cracks in length, while the other joint bar was implanted with 12.7 mm and 25.4 mm cracks in length. Despite the complex geometry of railway joint bars, the laboratory proof-of-concept testing conducted in an immersion water tank demonstrated that the developed non-contact surface wave approach successfully detected implanted cracks in both joint bars. The results obtained from the study indicate that a 0.5 MHz ultrasonic transducer provided the best sensitivity for detecting implanted cracks compared to 1 MHz and 2.25 MHz transducers. Similarly, test results obtained with a 0.5 MHz ultrasonic transducer, launching a surface wave from an accessible area to an inaccessible area of the joint bar (where the implanted cracks were located) yielded a significantly higher signal-to-noise ratio (SNR) than the 1 MHz and 2.25 MHz transducer.

Phrenic Nerve Sonography Alterations in Patients with ALS: Insight with Clinical and Neurophysiological Findings.

Background: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder, and although the diagnosis is primarily based on clinical criteria, ENMG, as the "gold standard", does not always show detectable changes. Therefore, our study suggests that alterations in echogenicity and heterogeneity of the phrenic nerve (PN) may serve as potential additional diagnostic tools for ALS. Methods: Our study included 32 patients in the ALS group and 64 individuals in the control group. Each participant underwent an interview and completed questionnaires to collect clinical and demographic data, including age, gender, height, body mass index (BMI), hip and waist circumference, duration of illness, ALS-FRS-R score, comorbidities, and medication use. Ultrasound examinations of the PN were performed by two authors using a high-resolution "Philips EPIQ 7" ultrasound machine equipped with a linear 4-18 MHz transducer. The ALS group participants underwent PN sonography and conduction examinations, arterial blood gas (ABG) analysis, respiratory function tests (RFT), and electroneuromyography (ENMG). Results: The study demonstrated that the phrenic nerve is significantly smaller on both sides in patients with ALS compared to the control group (p < 0.01). Changes in the homogeneity and echogenicity of the PN were also observed on both sides. On the right side, 43.8% of the nerves showed heterogeneity, 40.6% were isoechoic, and 21.9% were hyperechoic. On the left side, 59.4% of the nerves exhibited heterogeneity, 34.4% were isoechoic, and 28.1% were hyperechoic. Moreover, sonography on both sides showed significant correlation with ALS-FRS-R, COMPASS-31, and ENMG results. Conclusions: Our study highlights the importance of phrenic nerve ultrasound as a promising supplementary diagnostic tool for ALS. The significant differences in phrenic nerve size, echogenicity, and homogeneity between patients with ALS and the control group demonstrate that ultrasound imaging can detect morphological changes in the phrenic nerve. Incorporating phrenic nerve ultrasound into routine diagnostic protocols could improve early detection, enhance disease monitoring, and offer a more comprehensive understanding of the neurodegenerative processes in ALS.

Effects of Two Types of Estrogen on the Follicular Wave for in Vivo Oocyte Collection in Brown Swiss Cows

The manipulation of follicular waves through hormonal treatments, such as estrogen administration, plays a crucial role in optimizing in-vivo oocyte collection for assisted reproductive technologies. The present study aimed to evaluate the effect of two specific types of estrogen on follicular wave dynamics and their impact on in-vivo oocyte collection in Brown Swiss cows. Fourteen cows, in their first lactation, weighing approximately 340 kg were randomly assigned to one of two treatments including T1 (estradiol cypionate) and T2 (estradiol benzoate). Both treatments were administered at 1.2 mg of estrogen, at day 0 of the experiment. All Brown Swiss cows were provided with a diet entirely consisting of alfalfa grazing. On day 7, follicular wave dynamics were assessed using a DP-50 vet ultrasound device equipped with a 7.5 MHz transducer for transvaginal follicular aspiration guidance. Follicle counts were categorized into three size ranges including 2-4 mm (small), 4-8 mm (medium), and greater than 8 mm (large). Additionally, the quantity and quality (viable oocytes) of the collected oocytes were evaluated by the Ovum Pick Up (OPU) team for oocyte viability on day 7. The study assessed the follicular dynamics (number of follicles) and efficiency of oocyte collection (viable oocytes) in cows treated with Estradiol Cypionate (T1) and Estradiol Benzoate (T2). The average number of small, medium-sized, and large follicles size were 6.048 ± 6.037, 3.16 ± 2.01, and 0.53 ± 0.67 respectively. The total number of follicles was 9.59 ± 3.56. The mean number of viable oocytes recovered was 3.024 ± 1.66, while the mean number of non-viable oocytes was 1.47 ± 1.01. The results indicated no significant differences between treatments in the size of small, medium, and large follicles, nor in the total number of follicles and viable oocytes recovered. However, a significant difference was observed in the number of non-viable oocytes recovered, with a higher mean in T2 (1.86) compared to T1 (1.09). The results indicated an adequate follicular response and viable oocyte recovery in both treatment groups (estradiol cypionate and estradiol benzoate). However, variations in oocyte viability were observed, with estradiol cypionate showing a slight advantage.

A comparison of handheld versus cart-based ultrasound in the evaluation and diagnosis of carpal tunnel syndrome

BackgroundCarpal tunnel syndrome (CTS) is responsible for over 90 % of median nerve neuropathies. Though a clinical diagnosis, evaluation of nerve conduction via electrodiagnostic studies (EDX) and median nerve cross sectional area (CSA) through sonographic imaging provides supporting evidence and insight into disease severity. The advent of handheld ultrasound devices offers a portable, cost-effective and non-invasive method for median nerve assessment, yet its accuracy compared to traditional cart-based ultrasound has not been assessed in this setting. Methods43 consecutive patients who presented to an outpatient orthopedic clinic within a large academic institution for symptoms consistent with CTS between August 2023 and April 2024 were included. Handheld sonography was performed with the Clarius Convex L20 HD3 8–20 MHz transducer. The GE Venue Go with a 4–20 MHz linear transducer was used for conventional cart-based ultrasound evaluation. A paired t-test was performed to compare the mean cross-sectional area (CSA) measured with the GE machine to the mean CSA measured with the Clarius transducer (p < 0.05). ResultsThe average CSA measurement obtained with the GE was 14.21 ± 4.89 mm2. The average CSA measurement obtained with the Clarius handheld transducer was 13.54 ± 4.50 mm2. The mean difference between the GE and Clarius groups was 0.62 mm2 (95 % CI = −1.47 to 2.71), p = 0.55. ConclusionCSA measurements of the median nerve obtained by a handheld ultrasound transducer are comparable to those measured by a traditional cart-based ultrasound machine for carpal tunnel diagnosis. The adoption of handheld ultrasounds in clinical settings holds the potential for quicker, more precise diagnoses and broader access to imaging.

Factors associated with postprandial hypertriglyceridemia and carotid atherosclerosis in patients with type 2 diabetes mellitus

Abstract Background: As type 2 diabetic patients have significant postprandial lipid abnormalities, which have a strong and independent association with carotid atherosclerosis (CAS), carotid intima-media thickness (CIMT) is increased in patients with postprandial hypertriglyceridemia despite normal fasting triglyceride (FTG) levels. Objective: The objective of the study was to study the association of various factors with postprandial hypertriglyceridemia and CAS in patients with type 2 diabetes mellitus. Materials and Methods: A hospital-based, cross-sectional study was carried out among 50 cases of type 2 diabetes. Factors such as age, sex, duration of diabetes, complications of diabetes, lipid profile, and blood sugar were studied. Carotid artery Doppler was done by B-mode ultrasound using a 7.5 MHz transducer with an annular array ultrasound imaging system. Results: The mean duration of diabetes was significantly longer in those with high FTG and postprandial triglyceride (PPTG) levels. The mean serum total cholesterol was also significantly higher in those with high FTG and PPTG levels (P &lt; 0.05). The mean carotid artery intima-media thickness was increased in those with high FTG and PPTG levels. Other factors were not significantly associated with hypertriglyceridemia or CIMT &gt;1 mm. The mean FTGs and mean PPTG levels were significantly increased in the CIMT &gt;1 mm group compared to the CIMT &lt;1 mm group (P &lt; 0.05). Conclusion: There was a significant association between FTGs and the levels of PPTGs with CAS. The risk factors for high FTG and PPTG levels were duration of diabetes and high cholesterol levels. The only risk factor for CAS was increased FTG and PPTG levels.

Sonographic Appearance of Hemodialysis Reliable Outflow Graft (HeRO Graft)

HeRO Graft (Hemodialysis Reliable Outflow Graft) consists of 3 components; an arterial graft component, a titanium connector and a venous outflow component. It is implanted under the skin of end-stage renal failure patients as a subcutaneous permanent access. It is a vascular graft that traverses central venous stenosis and has no venous anastomosis, thus providing blood flow from an artery direct into the central venous system. Ultrasound imaging of the 3 components of the HeRO graft is performed and described in this article. Equipment used include Phillips ultrasound machines CX-50, iU22, and EPIQ 7 with linear transducers of frequency 3 to 15 MHz and curvilinear transducers of frequency 1 to 5 MHz. HeRO graft is often the last hemodialysis access available for patients on long-term dialysis who would have typically exhausted all other hemodialysis options like the native arterio-venous fistula (AVF) and arterio-venous graft (AVG). As long-term dialysis patients run out of typical AVF/AVG accesses coupled with the increasing longevity of persons in countries where advanced medical technology is available, subcutaneously implanted grafts such as the HeRO graft may become more commonplace. Description of the sonographic appearance of the various components of the HeRO graft may help sonographers who are not familiar with the graft to image the components.

Diagnostic Accuracy of USG and MRI for the Detection of Rotator Cuff Injury.

Rotator cuff disease frequently causes shoulder pain and is diagnosed using various radiological methods alongside history and physical examination. Arthrography has traditionally been employed for this purpose, but newer non-invasive techniques such as ultrasonography (USG) and magnetic resonance imaging (MRI) are increasingly used. However, no single method is universally agreed upon as the best diagnostic tool, each having its own limitations. To evaluate how effectively ultrasound and MRIcan diagnose rotator cuff tears. Seventy patients suspected of having a rotator cuff tear underwent investigations at the Radiology Department of Krishna Vishwa Vidyapeeth (Deemed to be University), Karad. USG and MRI examinations were done on the same day, along with a detailed history. USG was conducted using a GE LOGIQ P9 machine with a high-frequency 3-12 MHz transducer. MRI was conducted using a 1.5T SiemensMagnetom Avanto scanner. Pain and stiffness are the most common complaints in rotator cuff tears. The predisposing factors include male predominance, increasing age, dominant hand use, and trauma history. The supraspinatus tendon is the most frequently injured, with partial tears, especially articular surface tears, being more common than full-thickness tears. Clinical examinations, USG, and MRI are valuable in diagnosing rotator cuff tears. Our findings indicate that USGmay not be as reliable in detecting rotator cuff tears as once believed. A positive ultrasound result is more trustworthy than a negative one. In contrast, MRIdemonstrates greater sensitivity and overall diagnostic accuracy compared to both ultrasonography and clinical assessment for detecting rotator cuff tears.

Use of Non-Destructive Ultrasonic Techniques as Characterization Tools for Different Varieties of Wine.

In this work, we have verified how non-destructive ultrasonic evaluation allows for acoustically characterizing different varieties of wine. For this, a 3.5 MHz transducer has been used by means of an immersion technique in pulse-echo mode. The tests were performed at various temperatures in the range 14-18 °C. The evaluation has been carried out studying, on the one hand, conventional analysis parameters (velocity and attenuation) and, on the other, less conventional parameters (frequency components). The experimental study comprised two stages. In the first, the feasibility of the study was checked by inspecting twelve samples belonging to six varieties of red and white wine. The results showed clearly higher ultrasonic propagation velocity values in the red wine samples. In the second, nine samples of different monovarietal wine varieties (Grenache, Tempranillo and Cabernet Sauvignon) were analyzed. The results show how ultrasonic velocity makes it possible to unequivocally classify the grape variety used in winemaking with the Cabernet Sauvignon variety having the highest values and the Grenache the lowest. In addition, the wines of the Tempranillo variety are those that present higher values of the attenuation coefficient, and those from the Grenache variety transmit higher frequency waves.

Focused ultrasound-mediated blood–brain barrier opening is safe and feasible with moderately hypofractionated radiotherapy for brainstem diffuse midline glioma

BackgroundDiffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic strategies have been unsuccessful and radiotherapy (RT) remains the standard-of-care. A central impediment to treatment is the blood–brain barrier (BBB), which precludes drug delivery to the central nervous system (CNS). Focused ultrasound (FUS) with microbubbles can transiently and non-invasively disrupt the BBB to enhance drug delivery. This study aimed to determine the feasibility of brainstem FUS in combination with clinical doses of RT. We hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT.MethodsTo establish a safety timeline, we administered FUS to the brainstem of non-tumor bearing mice concurrent with or adjuvant to RT; our findings were validated in a syngeneic brainstem murine model of DMG receiving repeated sonication concurrent with RT. The brainstems of male B6 (Cg)-Tyrc-2J/J albino mice were intracranially injected with mouse DMG cells (PDGFB+, H3.3K27M, p53−/−). A clinical RT dose of 39 Gy in 13 fractions (39 Gy/13fx) was delivered using the Small Animal Radiation Research Platform (SARRP) or XRAD-320 irradiator. FUS was administered via a 0.5 MHz transducer, with BBBO and tumor volume monitored by magnetic resonance imaging (MRI).ResultsFUS-mediated BBBO did not affect cardiorespiratory rate, motor function, or tissue integrity in non-tumor bearing mice receiving RT. Tumor-bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy/13fx offered local control, though disease progression occurred 3–4 weeks post-RT.ConclusionRepeated FUS-mediated BBBO is safe and feasible concurrent with RT. In our syngeneic DMG murine model, progression occurs, serving as an ideal model for future combination testing with RT and FUS-mediated drug delivery.

Sonographic Assessment of Placental Thickness and Its Relationships with Estimated Fetal Weight and Maternal Characteristics in a Northern Nigerian Tertiary Health Institution

Background. The placenta is one of the primary factors in fetal birth weight/well-being and it’s though that, abnormalities of placental growth/perfusion may precede abnormalities in fetal growth/well-being, so its changes can be used to predict many feto-maternal complications. Objectives. To evaluate the relationship between placental thickness and estimated fetal weight (EFW) in low-risk 2nd and 3rd trimesters gestations based on gestational age and maternal characteristics. Methods. A cross sectional prospective study was conducted among 240 participants in ATBUTH Bauchi. An ultrasound machine “Toshiba-CC-15M71-MA" with 3.5MHz transducer was used. Maternal LMP, biparital diameter, head &amp; abdominal circumferences and femur lengths were measured according to practical guidelines of the international society of ultrasound in obstetrics &amp; gynecology for GA and EFW estimations. Placental thickness was measured at the level of umbilical cord insertions. Maternal characteristics were recorded prior to the study. Data obtained were analyzed using SPSS (22.0)/descriptive statistics. Results. The study revealed strong positive correlations between placental thickness and EFW(r=0.627; p=0.001), EGA(r=0.723; p=0.001), &amp; maternal BMI(r=0.263, p=0.003). No correlation was found between placental thickness and maternal gravidity(r=0.055, p=0.398). Conclusion. The results from this study suggested that placental thickness can be used a predictive parameter of EFW and therefore, overall fetal well-being across gestational ages and corresponding maternal characteristics.

Nonlinear imaging-based bubble cloud size estimates compared with histotripsy treatment zone: An in vitro study

Volterra filtering combined with subharmonic imaging was previously reported to enhance the visualization of the histotripsy bubble cloud. In this study, we compared the bubble cloud size obtained by imaging to the histotripsy ablation region using receiver operating characteristic (ROC) analysis. Histotripsy was performed in a red blood cell (RBC)-doped agarose phantom using a 1 MHz transducer. Ultrasound imaging data was acquired using a C5-2V probe and chirp-coded excitation (bandwidth: 2–5 MHz). These ultrasound acquisitions were then processed by subharmonic (SH) matched filtering alone, SH with quadratic Volterra filtering, and SH with cubic Volterra filtering. The therapy pulse and imaging sequence were interleaved (N = 100 frames), and a video camera was used to visualize the damaged region. A mean bubble cloud image was generated across all treatment sequences and co-registered with the camera image. A ROC curve was formed using binary classification of the mean bubble cloud versus the ablation zone, and the area under the ROC curve was determined. Filtering by quadratic and cubic Volterra filters reduced artifacts significantly [over 20 and 30 dB contrast-to-tissue enhancement (p &amp;lt; 0.01), respectively], along with achieving a high area under the ROC curve (0.97). These findings highlight the potential of Volterra filtering for histotripsy guidance.

Ultrasound jetting and atomization of sessile and impacting droplets

We present the results of our experimental and theoretical study of the jetting and atomization of a sessile and an impacting droplet subject to an ultrasonic surface vibration with a frequency of 2.5 MHz and piezoceramic transducer (PZT) surface velocity of 0.2–1.5 ms−1. Such high-frequency vibrations result in the formation of a liquid jet shooting outwardly from the surface of the droplet, which eventually breaks up into droplets. Part of the liquid remains on the surface, which eventually goes through ultrasonic atomization. We have divided this process into three categories of (i) jetting, (ii) jet breakup and liquid layer formation, and (iii) liquid layer atomization, and characterized jetting and jet breakup separately. For impacting droplets, jetting occurs immediately and at relatively low surface vibration velocities as compared to those for sessile droplets. We have developed a model to predict the PZT surface velocity for the onset of jetting, the jet diameter, jet velocity, and spreading diameter based on momentum, force, and energy balances. The liquid jet may break up into droplets due to Rayleigh–Plateau breakup (ejecting droplets on the order of jet diameter, λa) and acoustic breakup of the jet (ejecting both few hundred micrometer and few micrometer droplets).

Skeletal Muscle Echo Intensity Values Differ Significantly across Ultrasound Parameter Settings.

Echo intensity determined by muscle ultrasound has been proposed as an efficient method for the assessment of muscle quality. The influence of changing ultrasound parameter settings on echo intensity values was assessed using a standardized approach. In this repeated measures cross-sectional study, sixteen repeated scans of rectus femoris, gracilis, and rectus abdominis were taken in 21 middle-aged persons with a portable Mindray M7 premium ultrasound machine equipped with a linear 5.0-10.0 MHz transducer. The settings of three parameters were fixed: gain, depth, and frequency. The settings of the following adjustable parameters were changed over their entire range: dynamic range, gray map, line density, persistence, and IClear. Repeated measures analyses were performed to evaluate the effect of changing the settings on echo intensity values. In all three muscles, dynamic range, gray map, and IClear correlated significantly (rrm-values ranging between -0.86 and 0.45) with echo intensity. In all three muscles, the echo intensity values differed significantly across the dynamic range (p < 0.013), gray map (p < 0.003), and IClear (p < 0.003). In middle-aged subjects, echo intensity values of lower limb and trunk muscles are significantly related to ultrasound parameters and significantly differ across their respective setting range. For the assessment of muscle quality through ultrasound, it is suggested to fix parameter settings within their midrange in order to minimize the effect of setting-dependent factors on EI values.

Craniocaudal spread and clinical translation for combined erector spinae plane block and retrolaminar block in soft embalmed cadavers: a randomised controlled equivalence study

BackgroundErector spinae plane (ESP) block spread can be unpredictable. We previously improved the spread of ESP injection by addition of retrolaminar (RL) injection. However, it is not clear whether spread at high thoracic levels is similar to spread at midthoracic levels. Our primary objective was to demonstrate that craniocaudal dye spread was equivalent after combined ESP and RL injection using a 19 G Tuohy needle at the third (T3) and sixth (T6) vertebrae in soft embalmed Thiel cadavers. MethodsWe randomised 20 combined ESP and RL injections to the T3 and T6 vertebral levels on both sides of 10 prone Thiel cadavers. A 3–8 MHz transducer was placed in the paramedian sagittal plane and a single anaesthetist injected 10 ml dye onto the transverse process, then 10 ml dye onto the laminae of T3 or T6. Cadavers were dissected 24 h later. ResultsMean (sd) craniocaudal spread of dye after combined ESP + RL injection at T3 and T6 vertebral levels was equivalent: 8.6 (1.8) vs 8.7 (2.3) levels, respectively; difference (90% confidence interval): –0.1 (–1.4 to 1.6), P=0.904. Dye extended uniformly, cranially and caudally, from the point of injection. A 3D prosection created from a Thiel cadaver confirmed that the dorsal ramus emerges from the costotransverse foramen deep to the intertransverse ligament within the retro-superior costotransverse ligament space. Combined ESP and RL block in six patients before mastectomy achieved extensive anterior, lateral, and posterior chest wall paraesthesia over four to six dermatomes. ConclusionsCombined ESP and RL injections showed equivalent and consistent spread at T3 and T6 injection sites. A pilot study confirmed translation to patients.

Sonographic evaluation of the commonest sites of placental localization in pregnant women in Umuahia, Abia State

Background: The Placenta is an organ of pregnancy that provides nutrition, excretory functions and oxygen to the fetus.&#x0D; Aim: The purpose of the study is to determine and provide information on the commonest sites of placental localization in pregnant women in their second and third trimesters in Umuahia, Abia state because there are few documented reports on the sonographic assessment of placental localization in Umuahia.&#x0D; Methodology: Prospective study of pregnant women in their second and third trimesters was carried out trans- abdominally using an ultrasound scan machine with a 3.5 MHz transducer. Placental localization was classified into anterior, posterior, fundal and low-lying, Ultrasonography was used because it is non-ionizing, cheap and readily available. Exclusion criteria; pregnant women with a history of Caesarian section, uterine fibroids and multiple gestation.&#x0D; Results: One hundred women between the ages of 20yrs and 42yrs with a mean age of 28.60±4.95 on their routine antenatal visit were used for the study. The women were in their second and third trimesters, and fetal gender distribution was 55 males and 45 females. Placental localization was classified into Anterior 44%, fundal 20%, posterior 30% and previa 3%.&#x0D; Conclusion: Anterior placentation was the commonest, followed by posterior, then fundal with placenta previa being the least site of placental localization. There was no statistical significance between placental localization and maternal age, gestational age, fetal weight, gender, fetal presentation and heart rate. Evaluation for placental localization in the second and third trimesters is important to rule out placenta previa.