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Kumada T, Toyoda H, Ogawa S, Gotoh T, Suzuki Y, Imajo K, Sugimoto K, Kakegawa T, Kuroda H, Yasui Y, Tamaki N, Kurosaki M, Izumi N, Akita T, Tanaka J, Nakajima A. Advanced fibrosis leads to overestimation of steatosis with quantitative ultrasound in individuals without hepatic steatosis. Ultrasonography 2024; 43:121-131. [PMID: 38316132 PMCID: PMC10915114 DOI: 10.14366/usg.23194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 02/07/2024] Open
Abstract
PURPOSE The effect of hepatic fibrosis stage on quantitative ultrasound based on the attenuation coefficient (AC) for liver lipid quantification is controversial. The objective of this study was to determine how the degree of fibrosis assessed by magnetic resonance (MR) elastography affects AC based on the ultrasound-guided attenuation parameter according to the grade of hepatic steatosis, using magnetic resonance imaging (MRI)-derived proton density fat fraction (MRIderived PDFF) as the reference standard. METHODS Between February 2020 and April 2021, 982 patients with chronic liver disease who underwent AC and MRI-derived PDFF measurement as well as MR elastography were enrolled. Multiple regression was used to investigate whether AC was affected by the degree of liver stiffness. RESULTS AC increased as liver stiffness progressed in 344 patients without hepatic steatosis (P=0.009). In multivariable analysis, AC was positively correlated with skin-capsule distance (P<0.001), MR elastography value (P=0.037), and MRI-derived PDFF (P<0.001) in patients without hepatic steatosis. In 52 of 982 patients (5%), the correlation between AC and MRIderived PDFF fell outside the 95% confidence interval for the regression line slope. Patients with MRI-derived PDFF lower than their AC (n=36) had higher fibrosis-4 scores, albumin-bilirubin scores, and MR elastography values than patients with MRI-derived PDFF greater than their AC (n=16; P=0.018, P=0.001, and P=0.011, respectively). CONCLUSION AC is affected by liver fibrosis (MR elastography value ≥6.7 kPa) only in patients without hepatic steatosis (MRI-derived PDFF <5.2%). These values should be interpreted with caution in patients with advanced liver fibrosis.
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Affiliation(s)
- Takashi Kumada
- Department of Nursing, Faculty of Nursing, Gifu Kyoritsu University, Ogaki, Japan
| | - Hidenori Toyoda
- Department of Gastroenterology and Hepatology, Ogaki Municipal Hospital, Ogaki, Japan
| | - Sadanobu Ogawa
- Department of Imaging Diagnosis, Ogaki Municipal Hospital, Ogaki, Japan
| | - Tatsuya Gotoh
- Department of Imaging Diagnosis, Ogaki Municipal Hospital, Ogaki, Japan
| | - Yasuaki Suzuki
- Department of Gastroenterology, Nayoro City General Hospital, Nayoro, Japan
| | - Kento Imajo
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
- Department of Gastroenterology, Shin-yurigaoka General Hospital, Kawasaki, Japan
| | - Katsutoshi Sugimoto
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Tatsuya Kakegawa
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Hidekatsu Kuroda
- Division of Hepatology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan
| | - Yutaka Yasui
- Department of Gastroenterology and Hepatology, Musashino Red Cross Hospital, Musashino-shi, Japan
| | - Nobuharu Tamaki
- Department of Gastroenterology and Hepatology, Musashino Red Cross Hospital, Musashino-shi, Japan
| | - Masayuki Kurosaki
- Department of Gastroenterology and Hepatology, Musashino Red Cross Hospital, Musashino-shi, Japan
| | - Namiki Izumi
- Department of Gastroenterology and Hepatology, Musashino Red Cross Hospital, Musashino-shi, Japan
| | - Tomoyuki Akita
- Department of Epidemiology, Infectious Disease Control, and Prevention, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan
| | - Junko Tanaka
- Department of Epidemiology, Infectious Disease Control, and Prevention, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan
| | - Atsushi Nakajima
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
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Bisht SR, Paul A, Patel P, Thareja P, Mercado-Shekhar KP. Systematic quantification of differences in shear wave elastography estimates between linear-elastic and viscoelastic material assumptionsa). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:2025-2036. [PMID: 38470185 DOI: 10.1121/10.0025291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 02/27/2024] [Indexed: 03/13/2024]
Abstract
Quantitative, accurate, and standardized metrics are important for reliable shear wave elastography (SWE)-based biomarkers. For over two decades, the linear-elastic material assumption has been employed in SWE modes. In recent years, viscoelasticity estimation methods have been adopted in a few clinical systems. The current study aims to systematically quantify differences in SWE estimates obtained using linear-elastic and viscoelastic material assumptions. An acousto-mechanical simulation framework of acoustic radiation force impulse-based SWE was created to elucidate the effect of material viscosity and shear modulus on SWE estimates. Shear modulus estimates exhibited errors up to 72% when a numerical viscoelastic phantom was assessed as linearly elastic. Shear modulus estimates of polyvinyl alcohol phantoms between rheometry and SWE following the Kelvin-Voigt viscoelastic model assumptions were not significantly different. However, the percentage difference in shear modulus estimates between rheometry and SWE using the linear-elastic assumption was 50.1%-62.1%. In ex vivo liver, the percentage difference in shear modulus estimates between linear-elastic and viscoelastic methods was 76.1%. These findings provide a direct and systematic quantification of the potential error introduced when viscoelastic tissues are imaged with SWE following the linear-elastic assumption. This work emphasizes the need to utilize viscoelasticity estimation methods for developing robust quantitative imaging biomarkers.
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Affiliation(s)
- Sapna R Bisht
- Department of Biological Sciences and Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Abhijit Paul
- Department of Biological Sciences and Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Panchami Patel
- Department of Chemical Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Prachi Thareja
- Department of Chemical Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Karla P Mercado-Shekhar
- Department of Biological Sciences and Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
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Bisht S, Marri BP, Karmakar J, Mercado Shekhar KP. Viscoelastic Characterization of Phantoms for Ultrasound Elastography Created Using Low- and High-Viscosity Poly(vinyl alcohol) with Ethylene Glycol as the Cryoprotectant. ACS OMEGA 2024; 9:8352-8361. [PMID: 38405437 PMCID: PMC10882697 DOI: 10.1021/acsomega.3c09224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/15/2024] [Accepted: 01/31/2024] [Indexed: 02/27/2024]
Abstract
Ultrasound elastography enables noninvasive characterization of the tissue mechanical properties. Phantoms are widely used in ultrasound elastography for developing, testing, and validating imaging techniques. Creating phantoms with a range of viscoelastic properties relevant to human organs and pathological conditions remains an active area of research. Poly(vinyl alcohol) (PVA) cryogel phantoms offer a long shelf life, robustness, and convenient handling and storage. The goal of this study was to develop tunable phantoms using PVA with a clinically relevant range of viscoelastic properties. We combined low- and high-viscosity PVA to tune the viscoelastic properties of the phantom. Further, phantoms were created with an ethylene glycol-based cryoprotectant to determine whether it reduces the variability in the viscoelastic properties. Scanning electron microscopy (SEM) was performed to evaluate the differences in microstructure between phantoms. The density, longitudinal sound speed, and acoustic attenuation spectra (5-20 MHz) of the phantoms were measured. The phantoms were characterized using a shear wave viscoelastography approach assuming the Kelvin-Voigt model. Microstructural differences were revealed by SEM between phantoms with and without a cryoprotectant and with different PVA mixtures. The longitudinal sound speed and attenuation power-law fit exponent of the phantoms were within the clinical range (1510-1571 m/s and 1.23-1.38, respectively). The measured shear modulus (G) ranged from 3.3 to 17.7 kPa, and the viscosity (η) ranged from 2.6 to 7.3 Pa·s. The phantoms with the cryoprotectant were more homogeneous and had lower shear modulus and viscosity (G = 2.17 ± 0.2 kPa; η = 2.0 ± 0.05 Pa·s) than those without a cryoprotectant (G = 3.93 ± 0.7 kPa; η = 2.6 ± 0.14 Pa·s). Notably, phantoms with relatively constant viscosities and varying shear moduli were achieved by this method. These findings advance the development of well-characterized viscoelastic phantoms for use in elastography.
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Affiliation(s)
- Sapna
R. Bisht
- Department of Biological
Sciences and Engineering, Indian Institute
of Technology Gandhinagar, Gandhinagar, Gujarat 382055, India
| | - Bhanu Prasad Marri
- Department of Biological
Sciences and Engineering, Indian Institute
of Technology Gandhinagar, Gandhinagar, Gujarat 382055, India
| | - Jayashree Karmakar
- Department of Biological
Sciences and Engineering, Indian Institute
of Technology Gandhinagar, Gandhinagar, Gujarat 382055, India
| | - Karla P. Mercado Shekhar
- Department of Biological
Sciences and Engineering, Indian Institute
of Technology Gandhinagar, Gandhinagar, Gujarat 382055, India
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Gülcü Taşkın D, Kayadibi Y, Baş A, Ayyıldız Civan H, Faruk Beşer Ö, Adaletli İ, Çokuğraş FÇ, Erkan T, Kutlu T. Accuracy Rate of Shear Wave Elastography in Detecting the Liver Fibrosis in Overweight and Obese Children with Hepatosteatosis. Turk Arch Pediatr 2023; 58:436-441. [PMID: 37357459 PMCID: PMC10441156 DOI: 10.5152/turkarchpediatr.2023.22255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 03/17/2023] [Indexed: 06/27/2023]
Abstract
OBJECTIVE The aim of this study was to compare the accuracy rate of liver stiffness calculated by shear wave elastography with liver biopsy results in obese and overweight children. MATERIALS AND METHODS Obese and overweight children between 3 and 18 years of age, who had hepatic steatosis and a healthy control group were included in this study. A blood sample was obtained for laboratory tests and shear wave elastography was performed for all subjects. Liver biopsies were performed only in patients with hepatosteatosis, providing permission for biopsy, and for whom the biopsy procedure was not contraindicated. RESULTS A cohort of 142 children (78 overweight/obese and 64 healthy) was included in this study. Shear wave elastography values were significantly higher in the patient group as com- pared to the control group (34.0 vs. 8.2 kPa; P < .001). Obese children had higher elastog- raphy values compared to non-obese children (50.2 vs. 23.7 kPa, P < .001). No correlation was detected between fibrosis score and elastography values. Elastography increased with increasing weight (correlation coefficient: 0.334, P = .003) and body mass index (correlation coefficient: 0.364, P = .001). CONCLUSION In obese and overweight patients, elastography values are higher than in healthy subjects as well as patients with liver fibrosis. Disease-specific cut-off, mean, and normal ref- erence range values should be defined with large-scale studies to improve interpretation of elastography values. Our results are contradictory in the determination of liver fibrosis with shear wave elastography in obese and overweight patients, thus further research with a larger patient population is recommended.
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Affiliation(s)
- Didem Gülcü Taşkın
- Department of Pediatric Gastroenterology, Adana City Training and Research Hospital, Adana, Turkey
| | - Yasemin Kayadibi
- Department of Radiology, İstanbul University Cerrahpaşa Faculty of Medicine istanbul, Turkey
| | - Ahmet Baş
- Department of Interventional Radiology, İstanbul University Cerrahpaşa Faculty of Medicine,İstanbul, Turkey
| | - Hasret Ayyıldız Civan
- Department of Pediatric Gastroenterology, Bakırköy Dr. Sadi Konuk Training and Research Hospital, İstanbul, Turkey
| | - Ömer Faruk Beşer
- Department of Pediatric Gastroenterology, #x0130;stanbul University Cerrahpaşa Faculty of Medicine, İstanbul, Turkey
| | - İbrahim Adaletli
- Department of Radiology, İstanbul University Cerrahpaşa Faculty of Medicine istanbul, Turkey
| | - Fügen Çullu Çokuğraş
- Department of Pediatric Gastroenterology, #x0130;stanbul University Cerrahpaşa Faculty of Medicine, İstanbul, Turkey
| | - Tülay Erkan
- Department of Pediatric Gastroenterology, #x0130;stanbul University Cerrahpaşa Faculty of Medicine, İstanbul, Turkey
| | - Tufan Kutlu
- Department of Pediatric Gastroenterology, #x0130;stanbul University Cerrahpaşa Faculty of Medicine, İstanbul, Turkey
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Seppecher L, Bretin E, Millien P, Petrusca L, Brusseau E. Reconstructing the Spatial Distribution of the Relative Shear Modulus in Quasi-static Ultrasound Elastography: Plane Stress Analysis. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:710-722. [PMID: 36639283 DOI: 10.1016/j.ultrasmedbio.2022.09.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 09/28/2022] [Accepted: 09/30/2022] [Indexed: 06/17/2023]
Abstract
Quasi-static ultrasound elastography (QSUE) is an imaging technique that mainly provides axial strain maps of tissues when the latter are subjected to compression. In this article, a method for reconstructing the relative shear modulus distribution within a linear elastic and isotropic medium, in QSUE, is introduced. More specifically, the plane stress inverse problem is considered. The proposed method is based on the variational formulation of the equilibrium equations and on the choice of adapted discretization spaces, and only requires displacement fields in the analyzed media to be determined. Results from plane stress and 3-D numerical simulations, as well as from phantom experiments, showed that the method is able to reconstruct the different regions within a medium, with shear modulus contrasts that unambiguously reveal whether inclusions are stiffer or softer than the surrounding material. More specifically, for the plane stress simulations, inclusion-to-background modulus ratios were found to be very accurately estimated, with an error lower than 3%. For the 3-D simulations, for which the plane stress conditions are no longer satisfied, these ratios were, as expected, less accurate, with an error that remained lower than 10% for two of the three cases analyzed but was around 34% for the last case. Concerning the phantom experiments, a comparison with a shear wave elastography technique from a clinical ultrasound scanner was also made. Overall, the inclusion-to-background shear modulus ratios obtained with our approach were found to be closer to those given by the phantom manufacturer than the ratios provided by the clinical system.
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Affiliation(s)
- Laurent Seppecher
- Institut Camille Jordan, Ecole Centrale de Lyon & UCBL, Lyon, France
| | - Elie Bretin
- Institut Camille Jordan, INSA de Lyon & UCBL, Lyon, France
| | - Pierre Millien
- Institut Langevin, CNRS UMR 7587, ESPCI Paris, PSL Research University, Paris, France
| | - Lorena Petrusca
- Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM Saint-Etienne, CNRS, Inserm, CREATIS UMR 5220, U1294, Lyon, France
| | - Elisabeth Brusseau
- Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM Saint-Etienne, CNRS, Inserm, CREATIS UMR 5220, U1294, Lyon, France.
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Poul SS, Ormachea J, Ge GR, Parker KJ. Comprehensive experimental assessments of rheological models' performance in elastography of soft tissues. Acta Biomater 2022; 146:259-273. [PMID: 35525481 DOI: 10.1016/j.actbio.2022.04.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/26/2022] [Accepted: 04/28/2022] [Indexed: 02/08/2023]
Abstract
Elastography researchers have utilized several rheological models to characterize soft tissue viscoelasticity over the past thirty years. Due to the frequency-dependent behavior of viscoelastic parameters as well as the different techniques and frequencies employed in various studies of soft tissues, rheological models have value in standardizing disparate techniques via explicit mathematical representations. However, the important question remains: which of the several available models should be considered for widespread adoption within a theoretical framework? We address this by evaluating the performance of three well established rheological models to characterize ex vivo bovine liver tissues: the Kelvin-Voigt (KV) model as a 2-parameter model, and the standard linear solid (SLS) and Kelvin-Voigt fractional derivative (KVFD) models as 3-parameter models. The assessments were based on the analysis of time domain behavior (using stress relaxation tests) and frequency domain behavior (by measuring shear wave speed (SWS) dispersion). SWS was measured over a wide range of frequency from 1 Hz to 1 kHz using three different tests: (i) harmonic shear tests using a rheometer, (ii) reverberant shear wave (RSW) ultrasound elastography scans, and (iii) RSW optical coherence elastography scans, with each test targeting a distinct frequency range. Our results demonstrated that the KVFD model produces the only mutually consistent rendering of time and frequency domain data for liver. Furthermore, it reduces to a 2-parameter model for liver (correspondingly to a 2-parameter "spring-pot" or power-law model for SWS dispersion) and provides the most accurate predictions of the material viscoelastic behavior in time (>98% accuracy) and frequency (>96% accuracy) domains. STATEMENT OF SIGNIFICANCE: Rheological models are applied in quantifying tissues viscoelastic properties. This study is unique in presenting comprehensive assessments of rheological models.
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Gao J, Lee R, Trujillo M. Reliability of Performing Multiparametric Ultrasound in Adult Livers. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2022; 41:699-711. [PMID: 33982805 DOI: 10.1002/jum.15751] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
PURPOSE The aim of the study was to test inter-observer and intra-observer reliability of measuring multiparametric ultrasound in adult livers. METHODS We prospectively measured shear wave velocity (SWV, m/s), shear wave dispersion slope (SWD, m/s/kHz), attenuation coefficient (ATI, dB/cm/MHz), normalized local variance (NLV), and echo intensity ratio of liver to kidney (L/K ratio) in 21 adults who underwent liver magnetic resonance imaging-proton density fat fraction (MRI-PDFF). Intraclass correlation coefficient and 95% Bland-Altman limits of agreement (95% LOA) were used to analyze intra- and inter-observer reproducibility. RESULTS Based on liver MRI-PDFF, 21 participants (8 men and 13 women, mean age 55 years) were divided into group 1 (11 normal livers, MRI-PDFF <5%) and group 2 (10 steatotic livers, MRI-PDFF ≥5%). ICCs for intra-observer repeatability and inter-observer reproducibility in measuring multiple ultrasound parameters in both normal and steatotic livers were above 0.75. However, 95% confidence interval for measuring SWD in all livers and L/K ratio in normal livers was 0.38-0.90 and 0.47-0.91, respectively. Differences in SWV, SWD, ATI, NLV, L/K ratio, and MRI-PDFF between participants with and without hepatic steatosis were significant (p < .05), whereas serum biomarkers and body mass index were not (p > .05), based on a two-tailed t-test. CONCLUSIONS The results suggest that the repeatability and reproducibility for measuring liver SWV, ATI, and NLV are moderate to excellent, while those for SWD and L/K ratio are poor. Standardized machine settings, scanning protocols, and operator training are suggested in performing multiparametric ultrasound of the liver.
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Affiliation(s)
- Jing Gao
- Rocky Vista University, Ivins, Utah, USA
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Poul SS, Ormachea J, Hollenbach SJ, Parker KJ. Validations of the microchannel flow model for characterizing vascularized tissues. FLUIDS 2021; 5. [PMID: 34707336 PMCID: PMC8547714 DOI: 10.3390/fluids5040228] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The microchannel flow model postulates that stress-strain behavior in soft tissues is influenced by the time constants of fluid-filled vessels related to Poiseuille’s law. A consequence of this framework is that changes in fluid viscosity and changes in vessel diameter (through vasoconstriction) have a measurable effect on tissue stiffness. These influences are examined through the theory of the microchannel flow model. Then, the effects of viscosity and vasoconstriction are demonstrated in gelatin phantoms and in perfused tissues, respectively. We find good agreement between theory and experiments using both a simple model made from gelatin and from living, perfused, placental tissue ex vivo.
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Affiliation(s)
- Sedigheh S. Poul
- Department of Mechanical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Juvenal Ormachea
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Stefanie J. Hollenbach
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY 14623, USA
| | - Kevin J. Parker
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627, USA
- Correspondence:
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Cabrelli LC, Uliana JH, da Cruz Junior LB, Bachmann L, Carneiro AAO, Pavan TZ. Glycerol-in-SEBS gel as a material to manufacture stable wall-less vascular phantom for ultrasound and photoacoustic imaging. Biomed Phys Eng Express 2021; 7. [PMID: 34496358 DOI: 10.1088/2057-1976/ac24d6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 09/08/2021] [Indexed: 11/12/2022]
Abstract
Styrene-ethylene/butylene-styrene (SEBS) copolymer-in-mineral oil gel is an appropriate tissue-mimicking material to manufacture stable phantoms for ultrasound and photoacoustic imaging. Glycerol dispersion has been proposed to further tune the acoustic properties and to incorporate hydrophilic additives into SEBS gel. However, this type of material has not been investigated to produce wall-less vascular flow phantom for these imaging modalities. In this paper, the development of a wall-less vascular phantom for ultrasound and photoacoustic imaging is reported. Mixtures of glycerol/TiO2-in-SEBS gel samples were manufactured at different proportions of glycerol (10%, 15%, and 20%) and TiO2(0% to 0.5%) to characterize their optical and acoustic properties. Optical absorption in the 500-950 nm range was independent of the amount of glycerol and TiO2, while optical scattering increased linearly with the concentration of TiO2. Acoustic attenuation and speed of sound were not influenced by the presence of TiO2. The sample manufactured using weight percentages of 10% SEBS, 15% glycerol, and 0.2% TiO2was selected to make the vascular phantom. The phantom proved to be stable during the pulsatile blood-mimicking fluid (BMF) flow, without any observed damage to its structure or leaks. Ultrasound color Doppler images showed a typical laminar flow, while the B-mode images showed a homogeneous speckled pattern due to the presence of the glycerol droplets in the gel. The photoacoustic images of the phantom showed a well-defined signal coming from the surface of the phantom and from the vessels where BMF was flowing. The Spearman's correlations between the photoacoustic and tabulated spectra calculated from the regions containing BMF, in this case a mixture of salt solutions (NiCl2and CuSO4), were higher than 0.95. Our results demonstrated that glycerol-in-SEBS gel was an adequate material to make a stable vascular flow phantom for ultrasound photoacoustic imaging.
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Affiliation(s)
- Luciana C Cabrelli
- Departamento de Física, FFCLRP, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Joao H Uliana
- Departamento de Física, FFCLRP, Universidade de São Paulo, Ribeirão Preto, Brazil
| | | | - Luciano Bachmann
- Departamento de Física, FFCLRP, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Antonio A O Carneiro
- Departamento de Física, FFCLRP, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Theo Z Pavan
- Departamento de Física, FFCLRP, Universidade de São Paulo, Ribeirão Preto, Brazil
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Zhao L, Lin H, Hu Y, Chen X, Chen S, Zhang X. Corneal Lamb wave imaging for quantitative assessment of collagen cross-linking treatment based on comb-push ultrasound shear elastography. ULTRASONICS 2021; 116:106478. [PMID: 34174743 DOI: 10.1016/j.ultras.2021.106478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 05/03/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
Keratoconus, a serious corneal disorder, often causes highly irregular astigmatism and different degrees of visual impairment. Riboflavin/UVA corneal collagen cross-linking(CXL) is currently approved for effective treatment of keratoconus by enhancing the mechanical strength of collagen fibers in the cornea. However, few methods are capable of quantitatively and non-destructively assessing the mechanical properties of the cornea before and after CXL treatments. This study developed a corneal viscoelasticity imaging method based on comb-push ultrasound shear elastography (CUSE) and implemented this method on a Verasonics™ Vantage 256 ultrasound open system with a high-frequency linear array ultrasound transducer. Push beams were generated by three teeth each consisting of 10 elements (working frequency = 10.41 MHz) for inducing Lamb wave propagation in the cornea, and then the system immediately switched to the plane wave imaging mode using 60 elements in the middle (working frequency = 18 MHz). This method can provide a high-resolution 2D Lamb wave velocity image overlapping with a B-mode image as well as quantitative viscoelasticity estimation according to experimentally obtained phase velocity dispersion of Lamb waves. The validation experiments were performed on ex vivo porcine corneas, and the accuracy of elasticity estimation was verified by a tensile test. The results showed that the shear elasticity increased and the viscosity decreased after CXL treatment. The shear elasticity results (reported as mean ± standard deviation) of one control group with no CXL treatment and three CXL-treated groups named as 10 min, 30 min, and 60 min groups according to UV irradiation time were 14.62 ± 3.38 kPa, 49.47 ± 3.63 kPa, 116.54 ± 23.99 kPa, and 197.89 ± 39.64 kPa, respectively, which was in agreement with the results of tensile tests. The ultrasound safety measurement indicated that this method could have acceptable safety, but further to ocular tissue and vision function. The study demonstrated the possibility of using a commercial ultrasound system to obtain high-resolution images of corneal mechanical properties as well as the ability to quantify changes induced by CXL treatment. Therefore, the proposed method could serve as a helpful tool in the studies related in corneal biomechanics.
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Affiliation(s)
- Linfeng Zhao
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Haoming Lin
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Yaxin Hu
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Xin Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Siping Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Xinyu Zhang
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China.
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Parker KJ, Ormachea J. The quantification of liver fat from wave speed and attenuation. Phys Med Biol 2021; 66. [PMID: 34192672 DOI: 10.1088/1361-6560/ac1023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/30/2021] [Indexed: 12/19/2022]
Abstract
A framework is developed for estimating the volume fraction of fat in steatotic livers from viscoelastic measures of shear wave speed and attenuation. These measures are emerging on clinical ultrasound systems' elastography options so this approach can become widely available for assessing and monitoring steatosis. The framework assumes a distribution of fat vesicles as spherical inhomogeneities within the liver and uses a composite rheological model (Christensen 1969J. Mech. Phys. Solids1723-41) to determine the shear modulus as a function of increasing volume of fat within the liver. We show that accurate measurements of shear wave speed and attenuation provide the necessary and sufficient information to solve for the unknown fat volume and the underlying liver stiffness. Extension of the framework to compression wave measurements is also possible. Data from viscoelastic phantoms, human liver studies, and steatotic animal livers are shown to provide reasonable estimates of the volume fraction of fat.
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Affiliation(s)
- K J Parker
- Department of Electrical and Computer Engineering, University of Rochester, 724 Computer Studies Building, Box 270231, Rochester, NY 14627, United States of America
| | - J Ormachea
- Department of Electrical and Computer Engineering, University of Rochester, 724 Computer Studies Building, Box 270231, Rochester, NY 14627, United States of America
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Dharma IA, Kawashima D, Baidillah MR, Darma PN, Takei M. In-vivoviscoelastic properties estimation in subcutaneous adipose tissue by integration of poroviscoelastic-mass transport model (pve-MTM) into wearable electrical impedance tomography (w-EIT). Biomed Phys Eng Express 2021; 7. [PMID: 33887715 DOI: 10.1088/2057-1976/abfaea] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 04/22/2021] [Indexed: 11/11/2022]
Abstract
In-vivoviscoelastic properties have been estimated in human subcutaneous adipose tissue (SAT) by integration of poroviscoelastic-mass transport model (pve-MTM) into wearable electrical impedance tomography (w-EIT) under the influence of external compressive pressure-P.Thepve-MTM predicts the ion concentration distributioncmod(t)by coupling the poroviscoelastic and mass transport model to describe the hydrodynamics, rheology, and transport phenomena inside SAT. Thew-EIT measures the time-difference conductivity distribution∆γ(t)in SAT resulted from the ion transport. Based on the integration, the two viscoelastic properties which are viscoelastic shear modulus of SATGvand relaxation time of SATτvare estimated by applying an iterative curve-fitting between the normalized average ion concentration distributioncˆmod(t)predicted frompve-MTM and the experimental normalized average ion concentration distributioncˆexp(t)derived fromw-EIT. Thein-vivoexperiments were conducted by applying external compressive pressure-Pon human calf boundary to induce interstitial fluid flow and ion movement in SAT. As a result, the value ofGvwas range from 4.9-6.3 kPa and the value ofτvwas range from 27.50-38.5 s with the value of average goodness-of-fit curve fittingR2 > 0.76. These values ofGvandτvwere compared to the human and animal tissue from the literature in order to verify this method. The results frompve-MTM provide evidence thatGvandτvplay a role in the predicted value ofcˆmod.
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Affiliation(s)
- Irfan Aditya Dharma
- Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan.,Department of Mechanical Engineering, Faculty of Industrial Technology, Universitas Islam Indonesia, Jalan Kaliurang KM. 14,5, Sleman, D.I.Yogyakarta 55584, Indonesia
| | - Daisuke Kawashima
- Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan
| | - Marlin Ramadhan Baidillah
- Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan
| | - Panji Nursetia Darma
- Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan
| | - Masahiro Takei
- Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan
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