BACKGROUND:Previous studies provided contradictory evidence regarding the relationship between metal concentrations and ischemic stroke (IS). METHODS:A total of 100 adults with IS were included in this study, as well as an equal number of controls. Inductively coupled plasma-mass was used to measure metals' concentrations in whole blood and plasma. In order to identify metals that were associated with IS, we applied principal component analysis (PCA) and principal component (PC) regression. Finally, we included 3867 participants from the US National Health and Nutrition Examination Survey (NHANES) 2011-2020 to estimate the association between urine tin (Sn) and stroke with logistic regression and COX proportional hazard models. RESULTS:The fourth PC, characterized by copper (Cu) and Sn in whole blood, was associated with a higher risk of IS (OR=19.43, 95 %CI: 4.25, 88.89 for the highest quartile vs. the lowest quartile). A higher risk of IS was linked to the second PC, characterized by Sn, aluminum (Al), titanium (Ti), nickel (Ni) in plasma (OR= 12.85, 95 %CI: 3.91, 42.26 for the highest quartile vs. the lowest quartile). For NHANES, Sn was associated with a higher risk of stroke (OR= 1.69, 95 %CI: 1.07, 2.66 for the highest quartile vs. the lowest quartile). There was no significant relationship between urine Sn and all-cause deaths. CONCLUSION:In this research, the exposures of Sn, Cu, Al, Ti, and Ni were associated with IS. Specifically, the relationship between Sn and the risk of stroke has been established among both Chinese and US participants.

This study evaluates the performance of subharmonic-aided pressure estimation (SHAPE) with ultrasound contrast agents using data obtained from calibration procedures. A commercial scanner of ultrasonography (GE Healthcare Logiq E20, Wuxi, China) was used to perform SHAPE on a flowing contrast agent (Sonazoid) in a phantom setup under controlled microbubble stability and flow velocity conditions. Subharmonic time-intensity curves were collected during the SHAPE calibration procedure for analysis. Subharmonic amplitude of diluted contrast agents exhibited a time-dependent decline but was not affected by velocity. SHAPE sensitivity was measured through reciprocal pressurizing and depressurizing sequences to mitigate the effect of subharmonic decline over time. A wide range of mechanical index (MI) levels within the steady growth phase of the calibration curve showed higher SHAPE sensitivity compared to the traditionally recommended “optimal” MI at the maximum slope. The approximate maximum SHAPE sensitivity was −0.04 dB/mm Hg. Subharmonic amplitude was linearly correlated with pressure at a range of MI levels (R2 > 0.9, p < 0.05) but showed significant variations (approximately 2 dB standard deviation) in the time series. The lowered sensitivity compared to previous reports, combined with the substantial variation in subharmonic amplitude, raises concerns about the accuracy and consistency of SHAPE in clinical applications.

Background: Subharmonic aided pressure estimation (SHAPE) is an innovative non-invasive technique that leverages ultrasound subharmonic imaging to estimate pressure. This method exploits the "negative correlation between subharmonic amplitude and ambient pressure" observed in experimental settings. Despite extensive experimental validation and some promising results in clinical studies, the underlying mechanism of SHAPE remains incompletely understood. Although some studies have attempted to provide theoretical explanations, definitive conclusions have yet to be reached. In addition, theoretical investigations have mainly focused on the steady oscillation of bubbles under long pulse excitation, which contrasts with the short pulse excitation required for clinical SHAPE applications. An understanding of the SHAPE principle under short pulse excitation is needed. Methods: The exponential elasticity model (EEM) was used to simulate Sonazoid bubbles, and a probe-to-probe acoustic propagation model was introduced to mimic a practical SHAPE scenario. The simulated acoustic signals in response to three-cycle sinusoidal pulse excitations were analyzed for spectral composition. The relationship between microbubble oscillation patterns and subharmonic characteristics was identified through detailed investigation. Results: For the excitation pulse of 2.5 MHz frequency and 350 kPa magnitude, bubbles larger than the resonance radius (2.29 mu m) exhibited significant subharmonics in the magnitude spectrum, while bubbles smaller than the subharmonic resonance radius (3.85 mu m) showed the activity of scattering subharmonic energy and the sensitivity to ambient pressure. The emergence of subharmonics when increasing excitation power was related to the increasing amplification of the bubble self-oscillation and the period-doubling features in the acoustically forced oscillation. The negative correlation between subharmonic amplitude and ambient pressure was attributed to the reduced self-oscillation caused by increasing ambient pressure and hence bubble size reduction. Microbubbles falling between 2 and 3 mu m showed the desired subharmonic sensitivity to ambient pressure under the specified excitation conditions. Conclusion: The transient oscillatory behavior of microbubbles in response to short pulse excitation, characterized by a ringing down self-oscillation after the acoustic forcing effect has ceased, is crucial for understanding the subharmonic emergence and the observed negative correlation between subharmonic amplitude and ambient pressure. The proposed concepts of subharmonic resonance radius, subharmonic-significant bubbles, and subharmonic-active bubbles provide valuable insights into the diverse subharmonic behavior of microbubbles. The theoretical explanation of this negative correlation highlights the importance of using subharmonicsignificant-and-active bubbles for SHAPE applications.

Transient perivascular inflammation of the carotid artery (TIPIC) syndrome is a relatively rare disease, and ultrasound is the first screening method for initial diagnosis of the disease. Contrast-enhanced ultrasound (CEUS) has unique advantages in the follow-up of patients with TIPIC syndrome. This paper reports a patient with TIPIC syndrome who was treated with acute left neck pain. The inflammation was significantly relieved and subsided after treatment with non-steroidal anti-inflammatory drugs. The ultrasound changes of carotid artery lesions in this patient during follow-up were analyzed, and the application value of CEUS in the follow-up diagnosis of this disease was summarized, in the hope of providing clinical reference.

This study examines the reliability of subharmonic-aided pressure estimation (SHAPE) using polydisperse microbubbles. SHAPE utilizes the subharmonic response of ultrasound contrast agent microbubbles to estimate pressure non-invasively. Despite its potential, gaps in theoretical understanding and experimental inconsistencies with polydisperse microbubbles necessitate further investigation. This research explores the impact of microbubble distribution, excitation parameters, and contrast-enhanced ultrasound imaging modes on SHAPE's signal consistency, measurement linearity, and sensitivity. A one-dimensional microbubble population model was developed to simulate microbubble behavior and the Hilbert transform demodulation technique was applied for subharmonic analyses. Variability in SHAPE was further assessed through flow phantom experiments using Sonazoid agents and a commercial SHAPE scanner. Findings indicate that bubble distribution in both size and location, microbubble interactions, and CEUS imaging modes significantly influence subharmonic responses. An excitation frequency of 3.5 MHz is recommended for robust SHAPE. Monte Carlo simulations confirmed the inherent variability of subharmonic amplitude signals due to dynamic bubble distributions. Using monodisperse microbubbles enhanced SHAPE sensitivity and consistency, without markedly reducing signal variability. These results underscore the necessity of further research to optimize SHAPE for clinical applications, focusing on microbubble characteristics and excitation conditions to enhance consistency and reliability.

Objective: This study aimed to investigate the impact of microbubble degradation and flow velocity on Sub-Harmonic Aided Pressure Estimation (SHAPE), and to explore the correlation between subharmonic amplitude and pressure as a single factor. Methods: We develop an open-loop vascular phantom platform system and utilize a commercial ultrasound machine and microbubbles for subharmonic imaging. Subharmonic amplitude was measured continuously at constant pressure and flow velocity to assess the impact of microbubble degradation. Flow velocity was varied within a range of 4-14 cm/s at constant pressure to investigate its relationship to subharmonic amplitude. Furthermore, pressure was varied within a range of 10-110 mm Hg at constant flow velocity to assess its isolated effect on subharmonic amplitude. Results: Under constant pressure and flow velocity, subharmonic amplitude exhibited a continuous decrease at an average rate of 0.221 dB/min, signifying ongoing microbubble degradation during the experimental procedures. Subharmonic amplitude demonstrated a positive correlation with flow velocity, with a variation ratio of 0.423 dB/(cm/s). Under controlled conditions of microbubble degradation and flow velocity, a strong negative linear correlation was observed between pressure and subharmonic amplitude across different Mechanical Index (MI) settings (all R-2 > 0.90). The sensitivity of SHAPE was determined to be 0.025 dB/mmHg at an MI of 0.04. Conclusion: The assessment of SHAPE sensitivity is affected by microbubble degradation and flow velocity. Excluding the aforementioned influencing factors, a strong linear negative correlation between pressure and subharmonic amplitude was still evident, albeit with a sensitivity coefficient lower than previously reported values.

Background Evidence of the association between serum lipid profiles and intraplaque neovascularization (IPN) is still limited. We aimed to study the value of a novel Doppler method, superb microvascular imaging, in correlating serum lipid profiles and evidence of IPN in a population with a high risk of stroke. Methods and Results A community‐based cross‐sectional study was conducted in Beijing, China. Residents (aged ≥40 years) underwent questionnaire interviews, physical examinations, and laboratory testing in 2018 and 2019. Subjects with a high risk of stroke were then selected. Standard carotid ultrasound and carotid plaque superb microvascular imaging examinations were then performed on the high–stroke‐risk participants. Logistic regression was used to evaluate the relationship between serum lipid profiles and carotid plaque IPN. Overall, a total of 250 individuals (mean age, 67.20±8.12 years; 66.4% men) met the study inclusion criteria. Superb microvascular imaging revealed carotid plaque IPN in 96 subjects (38.4%). Subjects with IPN were more likely to be current smokers (34.0% versus 46.9%, P=0.046), and their identified carotid plaques were much thicker (2.35±0.63 mm versus 2.75±0.80 mm, P=0.001). Serum lipids, including total cholesterol, non–high‐density lipoprotein cholesterol, and low‐density lipoprotein cholesterol were positively associated with the presence of IPN (4.33±1.00 mmol/L versus 4.79±1.12 mmol/L, P=0.001; 2.96±0.92 mmol/L versus 3.40±1.01 mmol/L, P=0.001; 2.18±0.76 mmol/L versus 2.46±0.80 mmol/L, P=0.005, respectively), and after adjustment for other confounders, the positive relationship remained significant. Furthermore, non–high‐density lipoprotein cholesterol (odds ratio, 2.62 [95% CI, 1.35–5.06]) was significantly associated with the presence of carotid plaque IPN even after adjusting for low‐density lipoprotein cholesterol. Conclusions Total cholesterol, non–high‐density lipoprotein cholesterol, and low‐density lipoprotein cholesterol were positively associated with the presence of carotid IPN in a Chinese high–stroke‐risk population. Further prospective studies should be conducted to better understand how much finding IPN adds to current stroke prediction tools.