The aim of this study is to describe a comprehensive contrast-enhanced ultrasound (CEUS) imaging protocol and analysis method to implement CEUS LI-RADS (Liver Imaging Reporting and Data System) in a ...quantifiable manner. The methods that are validated with a prospective single-center study aim to simplify CEUS LI-RADS evaluation, remove observer bias, and potentially improve the sensitivity of CEUS LI-RADS.
This prospective single-center study enrolled patients with hepatocellular carcinoma (April 2021-June 2022; N = 31; mean age ± SD, 67 ± 6 years; 24 men/7 women). For each patient, at least 2 CEUS loops spanning over 5 minutes were collected for different lesion scan planes using an articulated arm to hold the transducer. Automatic respiratory gating and motion compensation algorithms removed errors due to breathing motion. The long axis of the lesion was measured in the contrast and fundamental images to capture nodule size. Parametric processing of time-intensity curve analysis on linearized data provided quantifiable information of the wash-in and washout dynamics via rise time ( RT ) and degree of washout ( DW ) parameters extracted from the time-intensity curve, respectively. A Welch t test was performed between lesion and parenchyma RT for each lesion to confirm statistically significant differences. P values for bootstrapped 95% confidence intervals of the relative degree of washout ( rDW ), ratio of DW between the lesion and surrounding parenchyma, were computed to quantify lesion washout. Coefficient of variation (COV) of RT , DW , and rDW was calculated for each patient between injections for both the lesion and surrounding parenchyma to gauge reproducibility of these metrics. Spearman rank correlation tests were performed among size, RT , DW , and rDW values to evaluate statistical dependence between the variables.
The mean ± SD lesion diameter was 23 ± 8 mm. The RT for all lesions, capturing arterial phase hyperenhancement, was shorter than that of surrounding liver parenchyma ( P < 0.05). All lesions also demonstrated significant ( P < 0.05) but variable levels of washout at both 2-minute and 5-minute time points, quantified in rDW . The COV of RT for the lesion and surrounding parenchyma were both 11%, and the COV of DW and rDW at 2 and 5 minutes ranged from 22% to 31%. Statistically significant relationships between lesion and parenchyma RT and between lesion RT and lesion DW at the 2- and 5-minute time points were found ( P < 0.05).
The imaging protocol and analysis method presented provide robust, quantitative metrics that describe the dynamic vascular patterns of LI-RADS 5 lesions classified as hepatocellular carcinomas. The RT of the bolus transit quantifies the arterial phase hyperenhancement, and the DW and rDW parameters quantify the washout from linearized CEUS intensity data. This unique methodology is able to implement the CEUS-LIRADS scheme in a quantifiable manner for the first time and remove its existing issues of currently being qualitative and suffering from subjective evaluations.
A problem of employee transfers exists within the Federal Aviation Administration, specifically at the Detroit TRACON, in Romulus, MI. This problem leads to additional costs due to constantly ...training new personnel. The purpose of this qualitative case study was to explore the relationship between employee development, employee morale, and employee retention. These factors can work together to effectively attract new talent as well as retain experienced workers within an organization. The theoretical framework supporting the problem was Maslow’s Hierarchy of Needs regarding employee retention and Herzberg’s Two-Factor Theory to attract new talent for an organization and how leaders of all organizations can use satisfiers to outweigh dissatisfiers to positively influence retention. Research questions addressed how employee morale is related to retention at the Detroit TRACON facility, how managers can create an environment where employees feel valued, what engages employees while in the workplace, and how development opportunities can increase retention at the Detroit TRACON facility. The research population consisted of participants who had left or transferred from air traffic facilities over the past 5 years and who either transferred to Detroit TRACON or left Detroit TRACON within the last 5 years. From this research population, a sample of 10 was randomly chosen. The analysis of the data was organized by the research question and related Interview Questions. Themes were developed from the analysis of this data for each research question.The results of the study indicated that improved morale can have a positive influence on employee retention. An employee’s level of engagement within the workplace is influenced by leadership within the organization as well as by the overall workplace environment.
We introduce a method to improve three-dimensional particle tracking velocimetry (3D-PTV) algorithms. 3D-PTV is an experimental method used to measure the Lagrangian trajectories of individual ...particles over time. The trajectories are constructed by linking the particle positions from a sequence of images. Different 3D-PTV algorithms have been proposed in the literature, ranging from simply taking the nearest neighbor in the next frame to using multiframe schemes. This work focuses on the initialization of the four-frame best estimate (4BE) method introduced by Ouellette et al (2006 Exp. Fluids 40 301-13). Previously, tracking algorithms have been initialized by using the particle's nearest neighbor(s) in the next frame or by using a velocity guess to predict the particle's location in the next frame. We propose a more robust initialization, coupled with 4BE, that performs better than existing methods in the literature, in the sense of yielding a higher number of correct tracks. The performance of the proposed initialization method is compared to the 4BE method that uses nearest neighbor initialization by applying both methods on direct numerical simulation data from the Johns Hopkins turbulence databases. We show that the modified initialization greatly improves tracking in two canonical cases, homogeneous isotropic turbulence and turbulent channel flow (inhomogenous and anisotropic), greatly increasing the percentage of correct tracks found even under challenging seeding/particle displacement conditions.
The purpose of the present study was to examine the relationship between battering severity and alcohol use among battered women. The study used multiple regression analyses to examine predictive ...relationships between three forms of trauma exposure—childhood physical and sexual abuse and domestic violence—and alcohol use. This study is among the first to investigate these relationships, using a sample of 78 battered women drawn from both shelter and nonresidential community agencies. Both battering severity and childhood sexual abuse were positively correlated with alcohol use. Multiple regression analysis showed that childhood sexual abuse was the stronger predictor when collinearity was controlled.
Measurement of mixed venous oxygen saturation helps determine whether cardiac output and oxygen delivery are sufficient for metabolic needs. As recommended by the American Association of ...Critical-Care Nurses guideline, blood samples for determining mixed venous oxygen saturation are obtained by slowly, in 1 to 2 minutes, withdrawing 1.5 mL of blood from the distal port of the pulmonary artery catheter. In theory, the negative force of rapid withdrawal could pull oxygenated blood from the pulmonary capillary bed, causing falsely elevated saturation values.
To determine if the speed of withdrawal affects oxygen content in blood samples used to measure mixed venous oxygen saturation.
The sample consisted of heart failure patients with pulmonary artery catheters admitted to a cardiac intensive care unit. A prospective, randomized, 2 × 2 crossover design was used to compare mixed venous oxygen saturation in blood samples obtained quickly or slowly. A total of 50 sets of saturation values were analyzed. Each set included 1 blood sample obtained slowly, in 1 to 2 minutes, and 1 obtained rapidly, in 5 seconds.
The mean difference in saturation values between the fast and the slow groups was -0.3 (CI, -1.5 to 0.8; P = .55), indicating that no meaningful systematic bias is attributable to fast withdrawal of blood.
Rapid blood sampling does not falsely elevate measurements of mixed venous oxygen saturation.
Ultrasound contrast agents are micron-sized bubbles that are used for ultrasound imaging enhancement and that can potentially be used for targeted drug delivery applications. One strategy to ...manipulate them inside the cardiovascular system is to use the Bjerknes force, caused by the phase difference between a transmitted ultrasound pressure wave and the microbubble volume oscillations induced by the pressure wave. Although the mechanism causing this force is well established, the balance between ultrasound-induced forces and hydrodynamic forces is poorly understood when the microbubbles are immersed in physiologically-realistic Reynolds and Womersley number flows. In this thesis, experiments were conducted in a cylindrical tube under steady and pulsatile flows over a range of Reynolds and Womersley numbers relevant to drug delivery in the systemic circulation. Two experimental setups were developed: one in which the microbubbles were imaged using a clinical ultrasound imaging system, and a second in which they were imaged by high-speed video using a long distance microscope. In the ultrasound experimental setup, a commercial L15-7io transducer was used to image microbubbles in quiescent, steady, and pulsatile flows. These experiments were extended in the optical experimental setup to explore higher Reynolds numbers. In the optical experiments, individual microbubble trajectories were captured at high magnification and high temporal resolution to determine the relationship between acoustic and hydrodynamic forces. The relative scaling of these forces was computed for different acoustic pressure amplitudes and pulse repetition frequencies. The Bjerknes force scaled linearly with pulse repetition frequency and quadratically with acoustic amplitude. The displacement of the microbubbles due to the ultrasound decreased with increasing Reynolds number suggesting a threshold for clinical applications due to the residence time of microbubbles in the ultrasound beam.
•Aneurysmal hemodynamics are helpful in treatment planning and prediction.•In vitro models can validate patient-specific computational simulations of aneurysms.•Dimensionally-accurate, ...optically-transparent phantoms can be done by 3D printing.•Such models may inform optimal patient-specific neurointerventional strategies.
Perianeurysmal hemodynamics play a vital role in the initiation, growth and rupture of intracranial aneurysms. In vitro investigations of aneurysmal hemodynamics are helpful to visualize and measure blood flow, and aiding surgical planning approaches. Improving in vitro model creation can improve the feasibility and accuracy of hemodynamic investigations and surgical planning, improving clinical value. In this study, in vitro models were created from three-dimensional rotational angiography (3DRA) of six patients harboring intracranial aneurysms using a multi-step process involving 3D printing, index of refraction matching and silicone casting that renders the models transparent for flow visualization. Each model was treated with the same commercially-available, patient-specific, endovascular devices (coils and/or stents). All models were scanned by synchrotron X-ray microtomography to obtain high-resolution imaging of the vessel lumen, aneurysmal sac and endovascular devices. Dimensional accuracy was compared by quantifying the differences between the microtomographic reconstructions of the fabricated phantoms and the original 3DRA obtained during patient treatment. True-scale in vitro flow phantoms were successfully created for all six patients. Optical transparency was verified by using an index of refraction matched working fluid that replicated the mechanical behavior of blood. Synchrotron imaging of vessel lumen, aneurysmal sac and endovascular devices was successfully obtained, and dimensional errors were found to be O(100 μm). The creation of dimensionally-accurate, optically-transparent flow phantoms of patient-specific intracranial aneurysms is feasible using 3D printing technology. Such models may enable in vitro investigations of aneurysmal hemodynamics to aid in treatment planning and outcome prediction to devise optimal patient-specific neurointerventional strategies.
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