Frontiers in acoustics最新文献

{"title":"Characterizing random complex biological media by quantifying ultrasound multiple scattering.","authors":"Omid Yousefian, Azadeh Dashti, Haley Geithner, Yasamin Karbalaeisadegh, Shanshan Yao, John Blackwell, Mir Ali, Stephanie Montgomery, Yong Zhu, Thomas Egan, Marie Muller","doi":"10.3389/facou.2025.1545057","DOIUrl":"10.3389/facou.2025.1545057","url":null,"abstract":"<p><strong>Introduction: </strong>In this <i>in silico</i>, <i>in vitro</i>, and <i>in vivo</i> study, we propose metrics for the characterization of highly scattering media using backscattered acoustic waves in the MHz range, for application to the characterization of biological media.</p><p><strong>Methods: </strong>Multi-element array transducers are used to record the ultrasonic Inter element Response Matrix (IRM) of scattering phantoms and of lung tissue in rodent models of pulmonary fibrosis. The distribution of singular values of the IRM in the frequency domain is then studied to quantify the multiple scattering contribution. Numerical models of scattering media, as well as gelatin-glass bead and polydimethylsiloxane phantoms with different scatterer densities, are used as a first step to demonstrate the proof of concept.</p><p><strong>Results: </strong>The results show that changes in microstructure of a complex random medium affect parameters associated with the distribution of singular values. Two metrics are proposed: <i>E</i>(<i>X</i>), which is the expected value of the singular value distribution, and <math> <msub><mrow><mi>λ</mi></mrow> <mrow><mi>max</mi></mrow> </msub> </math> , the maximum value of the probability density function of the singular value distribution, i.e., the most represented singular value. After validation of the methods <i>in silico</i> and in phantoms, we show that these metrics are relevant to evaluate pulmonary fibrosis in an <i>in vivo</i> rodent study on six control rats and eighteen rats with varying degrees of severity of pulmonary fibrosis. In rats, a moderate correlation was found between the severity of pulmonary fibrosis and metrics <i>E</i>(<i>X</i>) and <math> <msub><mrow><mi>λ</mi></mrow> <mrow><mi>max</mi></mrow> </msub> </math> .</p><p><strong>Discussion: </strong>These results suggest that such parameters could be used as metrics to estimate the amount of multiple scattering in highly heterogeneous media, and that these parameters could contribute to the evaluation of structural changes in lung microstructure.</p>","PeriodicalId":520258,"journal":{"name":"Frontiers in acoustics","volume":"3 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12068836/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144057353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A pilot study of cardiac guided wave elastography: An <i>ex vivo</i> testing in a rodent model with mechanical testing validation.","authors":"Jingfei Liu, Daniella Corporan, Don Vanderlaan, Muralidhar Padala, Stanislav Y Emelianov","doi":"10.3389/facou.2024.1485055","DOIUrl":"10.3389/facou.2024.1485055","url":null,"abstract":"<p><p>Many heart diseases can change the elasticity of myocardial tissues, making elastography a potential medical imaging strategy for heart disease diagnosis and cardiovascular risk assessment. Among the existing elastography methods, ultrasound elastography is an appealing choice because of ultrasound's inherent advantages of low cost, high safety, wide availability, and deep penetration. The existing investigations of cardiac ultrasound elastography were implemented based on a bulk model of heart tissue, treating the waves generated in the myocardial tissues as shear waves. In this pilot study, we considered the distinct geometric characteristics of heart tissue, i.e., being a layered structure and its dispersive nature as biological tissue. Based on these considerations, we modeled heart tissues as a layered-dispersive structure and developed a new ultrasound elastography method, ultrasonic guided wave elastography, to characterize the myocardial elasticity. The validity of this layered-dispersive model and the reliability of the developed guided wave elastography were first verified on tissue-mimicking phantoms. Then, the guided wave elastography was applied to an <i>ex vivo</i> imaging of a rat heart tissue specimen in real-time during the biaxial planar mechanical testing. The comparison of the real-time myocardial elasticity obtained from guided wave elastography and mechanical testing demonstrated strong matching, verifying the reliability of the developed cardiac guided wave elastography as a potential method for characterizing myocardial elasticity.</p>","PeriodicalId":520258,"journal":{"name":"Frontiers in acoustics","volume":"2 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11504380/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142516230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}