Ultrasound simulation of blood with different red blood cell aggregations and concentrations

BACKGROUND: Considerable progress of ultrasound simulation on blood has enhanced the characterizing of red blood cell (RBC) aggregation. OBJECTIVE: A novel simulation method aims at modeling the blood with different RBC aggregations and concentrations is proposed. METHODS: The modeling process is as follows: (i) A three-dimensional scatterer model is first built by a mapping with a Hilbert space-filling curve from the one-dimensional scatterer distribution. (ii) To illustrate the relationship between the model parameters and the RBC aggregation level, a variety of blood samples are prepared and scanned to acquire their radiofrequency signals in-vitro. (iii) The model parameters are determined by matching the Nakagami-distribution characteristics of envelope signals simulated from the model with those measured from the blood samples. RESULTS: Nakagami metrics m estimated from 15 kinds of blood samples (hematocrits of 20%, 40%, 60% and plasma concentrations of 15%, 30%, 45%, 60%, 75%) are compared with metrics estimated by their corresponding models (each with different eligible parameters). Results show that for the three hematocrit levels, the mean and standard deviation of the root-mean-squared deviations of m are 0.27 ± 0.0026, 0.16 ± 0.0021, 0.12 ± 0.0018 respectively. CONCLUSION: The proposed simulation model provides a viable data source to evaluate the performance of the ultrasound-based methods for quantifying RBC aggregation.

Ultrasound simulation technique as state-of-health estimation method of lithium-ion batteries

Ultrasound is a non-destructive technique recently proposed to estimate Lithium-ion batteries degradation. However, recent research has been devoted towards understanding the physical phenomena behind the ultrasonic wave propagation through a Lithium-ion battery. To achieve this, the second-order-scalar elastic and acoustic wave equations are solved with explicit and implicit finite difference method, considering the interfaces between materials with different physical properties. Results showed that implicit method presents less noise than the explicit scheme. In addition, changes in the physical properties of battery materials that occur in charge and discharge processes, highly affect the ultrasonic wave propagation inside the battery. Finally, this study demonstrates the feasibility of using numerical methods as a precursor of battery degradation estimator.

Novel and flexible ultrasound simulation with smartphones and tablets in fetal echocardiography

Purpose Evaluation of a novel ultrasound-simulation-app for training fetal echocardiography as a possible useful addition for students, residents and specialist doctors. Furthermore, comparison to a conventional learning-method with special attention on orientation and recognition of physiological structures. Methods Prospective two-arm study with the participation of 226 clinical students. 108 students were given an extract from a textbook on fetal echocardiography (PDF-group, n = 108) for 30 min to study. 118 students were able to use the new ultrasound-simulator-app (Simulator-group, n = 118) to learn for 30 min. The knowledge of the students was examined both before and after the learning-period by having them identify sonographic structures in videos using single-choice selection. Results There were no significant differences between the two groups regarding age (p = 0.87), gender (p = 0.28), and the number of previously performed ultrasound-examinations (p = 0.45). In the Simulator-group, there was a significantly higher learning effect regarding the proportion of students with an increase of correct answers in the video test examination (p = 0.005). At the end of learning, the students in the Simulator-group needed significantly less time to display the structures in the app’s simulation (median initially 10.9 s vs. 6.8 s at the end; p < 0.001). Conclusions The novel ultrasound-simulation-app seems to be a useful addition and improvement to ultrasound training. Previous difficulties such as simultaneously having patients, ultrasound-machines, and professors at disposal can thus be avoided. This means that another important step towards remote learning can be taken, which has been proven increasingly essential lately, due to the COVID-19 pandemic.

TUSX: an accessible toolbox for transcranial ultrasound simulation

Normally, the complicated nature of acoustic simulation makes it infeasible for most research groups doing individual transcranial ultrasound studies, hindering interpretation of results and complicating the determination of safety limits. We present here an open-source MATLAB toolbox to perform acoustic simulations using subject-specific medical images for transcranial ultrasound experiments. This toolbox, Transcranial Ultrasound Simulation Toolbox (TUSX), consists of an integrated processing pipeline that takes in structural MR or CT images, processes them for accurate simulation, and runs the simulations using k-Wave, an existing open-source acoustics package. We describe here the processing TUSX performs, along with its reasoning. We also validate its output using real-world pressure measurements in a water tank.

Validation of a Novel Ultrasound Simulation Model for Teaching Foundation-Level Ultrasonography Skills to Veterinary Students

Veterinary ultrasonography is a complex, advanced skill requiring repetitive exposure and supervision to gain competence. Consequently, newly graduated veterinarians are underprepared and lack the resources to achieve basic ultrasound proficiency upon graduation. Ultrasound simulation has been proposed as an adjunct educational tool for teaching entry-level ultrasound skills to student veterinarians. The objectives of this multicentric prospective observational cohort study were to describe the development of a novel ultrasound training model, establish model construct and face validity, and seek participant feedback. The model was constructed using three-dimensional silicone shapes embedded in ballistics gel within a glass container. A novice cohort of 15 veterinary students and 14 expert participants were prospectively enrolled in the study. Each cohort underwent training and assessment phases using a simulation model. Participants were asked to (a) determine shape location, (b) identify shape type using a shape bank, and (c) measure shape axes using the caliper tool. Time for each phase was recorded. Anonymous post-participation survey feedback was obtained. For most shapes (4/6), experts performed significantly better than novices in identifying shape type and location. Generally, no significant difference was found in mean axis shape measurements between cohorts or compared to the true mean axis measurements. No significant difference was found in scan time for either phase. This study’s results support the validation of this ultrasound simulation model and may demonstrate early evidence for its use as a training tool in the veterinary curriculum to teach entry-level ultrasound skills.

Estimation of Tissue Attenuation from Ultrasonic B-Mode Images—Spectral-Log-Difference and Method-of-Moments Algorithms Compared

We report on results from the comparison of two algorithms designed to estimate the attenuation coefficient from ultrasonic B-mode scans obtained from a numerical phantom simulating an ultrasound breast scan. It is well documented that this parameter significantly diverges between normal tissue and malignant lesions. To improve the diagnostic accuracy it is of great importance to devise and test algorithms that facilitate the accurate, low variance and spatially resolved estimation of the tissue’s attenuation properties. A numerical phantom is realized using k-Wave, which is an open source Matlab toolbox for the time-domain simulation of acoustic wave fields that facilitates both linear and nonlinear wave propagation in homogeneous and heterogeneous tissue, as compared to strictly linear ultrasound simulation tools like Field II. k-Wave allows to simulate arbitrary distributions, resolved down to single voxel sizes, of parameters including the speed of sound, mass density, scattering strength and to include power law acoustic absorption necessary for simulation tasks in medical diagnostic ultrasound. We analyze the properties and the attainable accuracy of both the spectral-log-difference technique, and a statistical moments based approach and compare the results to known reference values from the sound field simulation.