1
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Mohammadkhah M, Klinge S. Review paper: The importance of consideration of collagen cross-links in computational models of collagen-based tissues. J Mech Behav Biomed Mater 2023; 148:106203. [PMID: 37879165 DOI: 10.1016/j.jmbbm.2023.106203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/25/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023]
Abstract
Collagen as the main protein in Extra Cellular Matrix (ECM) is the main load-bearing component of fibrous tissues. Nanostructure and architecture of collagen fibrils play an important role in mechanical behavior of these tissues. Extensive experimental and theoretical studies have so far been performed to capture these properties, but none of the current models realistically represent the complexity of network mechanics because still less is known about the collagen's inner structure and its effect on the mechanical properties of tissues. The goal of this review article is to emphasize the significance of cross-links in computational modeling of different collagen-based tissues, and to reveal the need for continuum models to consider cross-links properties to better reflect the mechanical behavior observed in experiments. In addition, this study outlines the limitations of current investigations and provides potential suggestions for the future work.
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Affiliation(s)
- Melika Mohammadkhah
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany.
| | - Sandra Klinge
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
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2
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Yang X, Ding Y, Mei J, Xiong W, Wang J, Huang Z, Li R. Second-Trimester Cervical Shear Wave Elastography Combined With Cervical Length for the Prediction of Spontaneous Preterm Birth. ULTRASOUND IN MEDICINE & BIOLOGY 2022; 48:820-829. [PMID: 35272890 DOI: 10.1016/j.ultrasmedbio.2022.01.003] [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: 07/28/2021] [Revised: 12/06/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
The goal of this study was to explore the value of shear wave elastography (SWE) combined with cervical length (CL) in the prediction of spontaneous preterm birth (sPTB) between 18 and 24 weeks of gestation. In this study, SWE was used to evaluate four regions of the cervix: the external and anterior lip (region A1), the external and posterior lip (region A2), the internal and anterior lip (region A3) and the internal and posterior lip (region A4). The cervical Young's modulus (YM) was compared between women who spontaneously delivered prematurely (<37 wk) and those who delivered full term. Finally, the predictive power of SWE was evaluated using receiver operating characteristic analysis. Overall, 773 patients were included in this study, of whom 60 (7.8%) had a sPTB. In the univariate analysis, prior sPTB, history of spontaneous abortion, history of cervical surgery, CL and YM at the anterior portion of both the internal and external os and the posterior portion of the internal os were associated with sPTB (p < 0.05). Multiple regression analyses were performed to develop the prediction probability for sPTB. YM and CL were independent predictors of sPTB in asymptomatic women, and the combination of YM and CL improved the ability to predict sPTB (area under the receiver operating characteristic curve = 0.98, 95% confidence interval: 0.97-0.99, p < 0.001). The interventions had relatively little impact on the outcome indicators measured. Cervical YM added to the CL may improve the predictive performance of second-trimester transvaginal ultrasound for sPTB.
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Affiliation(s)
- Xiaofeng Yang
- First Affiliate Hospital of Jinan University, Guangzhou, China
| | - Yuzhen Ding
- First Affiliate Hospital of Jinan University, Guangzhou, China
| | - Jie Mei
- Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China
| | - Wen Xiong
- Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China
| | - Jingyun Wang
- First Affiliate Hospital of Jinan University, Guangzhou, China
| | - Zhengrui Huang
- First Affiliate Hospital of Jinan University, Guangzhou, China
| | - Ruiman Li
- First Affiliate Hospital of Jinan University, Guangzhou, China.
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3
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Moghaddam AO, Lin Z, Sivaguru M, Phillips H, McFarlin BL, Toussaint KC, Johnson AJW. Heterogeneous microstructural changes of the cervix influence cervical funneling. Acta Biomater 2022; 140:434-445. [PMID: 34958969 PMCID: PMC8828692 DOI: 10.1016/j.actbio.2021.12.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/03/2021] [Accepted: 12/21/2021] [Indexed: 12/31/2022]
Abstract
The cervix acts as a dynamic barrier between the uterus and vagina, retaining the fetus during pregnancy and allowing birth at term. Critical to this function, the physical properties of the cervix change, or remodel, but abnormal remodeling can lead to preterm birth (PTB). Although cervical remodeling has been studied, the complex 3D cervical microstructure has not been well-characterized. In this complex, dynamic, and heterogeneous tissue microenvironment, the microstructural changes are likely also heterogeneous. Using quantitative, 3D, second-harmonic generation microscopy, we demonstrate that rat cervical remodeling during pregnancy is not uniform across the cervix; the collagen fibers orient progressively more perpendicular to the cervical canals in the inner cervical zone, but do not reorient in other regions. Furthermore, regions that are microstructurally distinct early in pregnancy become more similar as pregnancy progresses. We use a finite element simulation to show that heterogeneous regional changes influence cervical funneling, an important marker of increased risk for PTB; the internal cervical os shows ∼6.5x larger radial displacement when fibers in the inner cervical zone are parallel to the cervical canals compared to when fibers are perpendicular to the canals. Our results provide new insights into the microstructural and tissue-level cervical changes that have been correlated with PTB and motivate further clinical studies exploring the origins of cervical funneling. STATEMENT OF SIGNIFICANCE: Cervical funneling, or dilation of the internal cervical os, is highly associated with increased risk of preterm birth. This study explores the 3D microstructural changes of the rat cervix during pregnancy and illustrates how these changes influence cervical funneling, assuming similar evolution in rats and humans. Quantitative imaging showed that microstructural remodeling during pregnancy is nonuniform across cervical regions and that initially distinct regions become more similar. We report, for the first time, that remodeling of the inner cervical zone can influence the dilation of the internal cervical os and allow the cervix to stay closed despite increased intrauterine pressure. Our results suggest a possible relationship between the microstructural changes of this zone and cervical funneling, motivating further clinical investigations.
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Affiliation(s)
- A. Ostadi Moghaddam
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
| | - Z. Lin
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - M. Sivaguru
- Flow Cytometry and Microscopy to Omics, Roy J. Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
| | - H. Phillips
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - B. L. McFarlin
- Department of Women, Children and Family Health Science, University of Illinois College of Nursing, Chicago, IL 60612, USA
| | - K. C. Toussaint
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - A. J. Wagoner Johnson
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA,Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA,Corresponding author at: 2101A Mechanical Engineering Laboratory MC-244, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801, United States.
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Rus G, Faris IH, Torres J, Callejas A, Melchor J. Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis? SENSORS (BASEL, SWITZERLAND) 2020; 20:E2379. [PMID: 32331295 PMCID: PMC7219338 DOI: 10.3390/s20082379] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 12/24/2022]
Abstract
The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues' mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.
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Affiliation(s)
- Guillermo Rus
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit “ModelingNature” MNat UCE.PP2017.03, University of Granada, 18071 Granada, Spain
| | - Inas H. Faris
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Jorge Torres
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Antonio Callejas
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Juan Melchor
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit “ModelingNature” MNat UCE.PP2017.03, University of Granada, 18071 Granada, Spain
- Department of Statistics and Operations Research, University of Granada, 18071 Granada, Spain
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5
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Yoshida K, Jayyosi C, Lee N, Mahendroo M, Myers KM. Mechanics of cervical remodelling: insights from rodent models of pregnancy. Interface Focus 2019; 9:20190026. [PMID: 31485313 PMCID: PMC6710664 DOI: 10.1098/rsfs.2019.0026] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2019] [Indexed: 01/01/2023] Open
Abstract
The uterine cervix undergoes a complex remodelling process during pregnancy, characterized by dramatic changes in both extracellular matrix (ECM) structure and mechanical properties. Understanding the cervical remodelling process in a term or preterm birth will aid efforts for the prevention of preterm births (PTBs), which currently affect 14.8 million babies annually worldwide. Animal models of pregnancy, particularly rodents, continue to provide valuable insights into the cervical remodelling process, through the study of changes in ECM structure and mechanical properties at defined gestation time points. Currently, there is a lack of a collective, quantitative framework to relate the complex, nonlinear mechanical behaviour of the rodent cervix to changes in ECM structure. This review aims to fill this gap in knowledge by outlining the current understanding of cervical remodelling during pregnancy in rodent models in the context of solid biomechanics. Here we highlight the collective contribution of multiple mechanical studies which give evidence that cervical softening coincides with known ECM changes throughout pregnancy. Taken together, mechanical tests on tissue from pregnant rodents reveal the cervix's remarkable ability to soften dramatically during gestation to allow for a compliant tissue that can withstand damage and can dissipate mechanical loads.
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Affiliation(s)
- Kyoko Yoshida
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Charles Jayyosi
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Nicole Lee
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Mala Mahendroo
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kristin M. Myers
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
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Yan Y, Gomez-Lopez N, Basij M, Shahvari AV, Vadillo-Ortega F, Hernandez-Andrade E, Hassan SS, Romero R, MehrMohammadi M. Photoacoustic imaging of the uterine cervix to assess collagen and water content changes in murine pregnancy. BIOMEDICAL OPTICS EXPRESS 2019; 10:4643-4655. [PMID: 31565515 PMCID: PMC6757472 DOI: 10.1364/boe.10.004643] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/03/2019] [Accepted: 08/03/2019] [Indexed: 05/11/2023]
Abstract
The uterine cervix plays a central role in the maintenance of pregnancy and in the process of parturition. Cervical remodeling involves dramatic changes in extracellular matrix composition and, in particular, of collagen and water content during cervical ripening (a term that describes the anatomical, biochemical, and physiologic changes in preparation for labor). Untimely cervical ripening in early gestation predisposes to preterm labor and delivery, the leading cause of infant death worldwide. Inadequate ripening of the cervix is associated with failure of induction or prolonged labor. The current approach to evaluate the state of the cervix relies on digital examination and sonographic examination. Herein, we present a novel imaging method that combines ultrasound (US) and photoacoustic (PA) techniques to evaluate cervical remodeling by assessing the relative collagen and water content of this organ. The method was tested in vitro in extracted collagen phantoms and ex vivo in murine cervical tissues that were collected in mid-pregnancy and at term. We report, for the first time, that our imaging approach provides information about the molecular changes in the cervix at different gestational ages. There was a strong correlation between the results of PA imaging and the histological assessment of the uterine cervix over the course of gestation. These findings suggest that PA imaging is a powerful method to assess the biochemical composition of the cervix and open avenues to non-invasively investigate the composition of this organ, which is essential for reproductive success.
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Affiliation(s)
- Yan Yan
- Department of Biomedical Engineering, Wayne State University, Detroit, MI 48202, USA
| | - Nardhy Gomez-Lopez
- Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland and Detroit, MI 48201, USA
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Department of Biochemistry, Immunology, and, Microbiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- C.S. Mott Center for Human Growth and Development, Wayne State University, Detroit, MI 48201, USA
| | - Maryam Basij
- Department of Biomedical Engineering, Wayne State University, Detroit, MI 48202, USA
| | | | - Felipe Vadillo-Ortega
- Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland and Detroit, MI 48201, USA
- Unidad de Vinculación de la Facultad de Medicina,UNAM y Dirección de Investigación, Instituto Nacional de Medicina Genómica, CDMX, Mexico
| | - Edgar Hernandez-Andrade
- Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland and Detroit, MI 48201, USA
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Sonia S. Hassan
- Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland and Detroit, MI 48201, USA
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Roberto Romero
- Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland and Detroit, MI 48201, USA
- Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Epidemiology and Biostatistics, Michigan State University, East Lansing, MI 48824, USA
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48201, USA
- Detroit Medical Center, Detroit, MI 48201, USA
- Department of Obstetrics and Gynecology, Florida International University, Miami, FL 33199, USA
| | - Mohammad MehrMohammadi
- Department of Biomedical Engineering, Wayne State University, Detroit, MI 48202, USA
- Department of Electrical and Computer Engineering, Wayne State University, Detroit, MI 48202, USA
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Massó P, Callejas A, Melchor J, Molina FS, Rus G. In Vivo Measurement of Cervical Elasticity on Pregnant Women by Torsional Wave Technique: A Preliminary Study. SENSORS 2019; 19:s19153249. [PMID: 31344796 PMCID: PMC6696138 DOI: 10.3390/s19153249] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/18/2019] [Accepted: 07/22/2019] [Indexed: 12/12/2022]
Abstract
A torsional wave (TW) sensor prototype was employed to quantify stiffness of the cervix in pregnant women. A cross-sectional study in a total of 18 women between 16 weeks and 35 weeks + 5 days of gestation was performed. The potential of TW technique to assess cervical ripening was evaluated by the measurement of stiffness related to gestational age and cervical length. Statistically significant correlations were found between cervical stiffness and gestational age (R2=0.370, p=0.0074, using 1 kHz waves and R2=0.445, p=0.0250, using 1.5 kHz waves). A uniform decrease in stiffness of the cervical tissue was confirmed to happen during the complete gestation. There was no significant correlation between stiffness and cervical length. A stronger association between gestational age and cervical stiffness was found compared to gestational age and cervical length correlation. As a conclusion, TW technique is a feasible approach to objectively quantify the decrease of cervical stiffness related to gestational age. Further research is required to evaluate the application of TW technique in obstetric evaluations, such as prediction of preterm delivery and labor induction failure.
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Affiliation(s)
- Paloma Massó
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain
- San Cecilio University Hospital, 18016 Granada, Spain
| | - Antonio Callejas
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain
- Department of Structural Mechanics, University of Granada, 18071 Granada, Spain
| | - Juan Melchor
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain.
- Department of Structural Mechanics, University of Granada, 18071 Granada, Spain.
- Excellence Research Unit, "Modelling Nature" (MNat), University of Granada, 18071 Granada, Spain.
| | - Francisca S Molina
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain
- San Cecilio University Hospital, 18016 Granada, Spain
| | - Guillermo Rus
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain
- Department of Structural Mechanics, University of Granada, 18071 Granada, Spain
- Excellence Research Unit, "Modelling Nature" (MNat), University of Granada, 18071 Granada, Spain
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8
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Rosado-Mendez IM, Carlson LC, Woo KM, Santoso AP, Guerrero QW, Palmeri ML, Feltovich H, Hall TJ. Quantitative assessment of cervical softening during pregnancy in the Rhesus macaque with shear wave elasticity imaging. Phys Med Biol 2018. [PMID: 29517492 DOI: 10.1088/1361-6560/aab532] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Abnormal parturition, e.g. pre- or post-term birth, is associated with maternal and neonatal morbidity and increased economic burden. This could potentially be prevented by accurate detection of abnormal softening of the uterine cervix. Shear wave elasticity imaging (SWEI) techniques that quantify tissue softness, such as shear wave speed (SWS) measurement, are promising for evaluation of the cervix. Still, interpretation of results can be complicated by biological variability (i.e. spatial variations of cervix stiffness, parity), as well as by experimental factors (i.e. type of transducer, posture during scanning). Here we investigated the ability of SWEI to detect cervical softening, as well as sources of SWS variability that can affect this task, in the pregnant and nonpregnant Rhesus macaque. Specifically, we evaluated SWS differences when imaging the cervix transabdominally with a typical linear array abdominal transducer, and transrectally with a prototype intracavitary linear array transducer. Linear mixed effects (LME) models were used to model SWS as a function of menstrual cycle day (in nonpregnant animals) and gestational age (in pregnant animals). Other variables included parity, shear wave direction, and cervix side (anterior versus posterior). In the nonpregnant cervix, the LME model indicated that SWS increased by 2% (95% confidence interval 0-3%) per day, starting eight days before menstruation. During pregnancy, SWS significantly decreased at a rate of 6% (95% CI 5-7%) per week (intracavitary approach) and 3% (95% CI 2-4%) per week (transabdominal approach), and interactions between the scanning approach and other fixed effects were also significant. These results suggest that, while absolute SWS values are influenced by factors such as scanning approach and SWEI implementation, these sources of variability do not compromise the sensitivity of SWEI to cervical softening. Our results also highlight the importance of standardizing SWEI approaches to improve their accuracy for cervical assessment.
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Affiliation(s)
- Ivan M Rosado-Mendez
- Medical Physics Department, University of Wisconsin, Madison, WI, United States of America. Present address: Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico
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9
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Abstract
The process of parturition is poorly understood, but the cervix clearly plays a key role. Because of this, recent research efforts have been directed at objective quantification of cervical remodeling. Investigation has focused on two basic areas: (1) quantification of tissue deformability and (2) presence, orientation, and/or concentration of microstructural components (e.g. collagen). Methods to quantify tissue deformability include strain elastography and shear wave elasticity imaging (SWEI). Methods to describe tissue microstructure include attenuation and backscatter. A single parameter is unlikely to describe the complexities of cervical remodeling, but combining related parameters should improve accuracy of cervical evaluation. This chapter reviews options for cervical tissue characterization.
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Affiliation(s)
- Helen Feltovich
- Maternal Fetal Medicine, Intermountain Healthcare, Utah Valley Hospital, 1034 N 500 W, Provo, UT 84604.
| | - Lindsey Drehfal
- Medical Physics, University of Wisconsin-Madison, Madison WI
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10
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Rosado-Mendez IM, Palmeri ML, Drehfal LC, Guerrero QW, Simmons H, Feltovich H, Hall TJ. Assessment of Structural Heterogeneity and Viscosity in the Cervix Using Shear Wave Elasticity Imaging: Initial Results from a Rhesus Macaque Model. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:790-803. [PMID: 28189282 PMCID: PMC5348278 DOI: 10.1016/j.ultrasmedbio.2016.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 11/02/2016] [Accepted: 12/14/2016] [Indexed: 05/13/2023]
Abstract
Shear wave elasticity imaging has shown promise in evaluation of the pregnant cervix. Changes in shear wave group velocity have been attributed exclusively to changes in stiffness. This assumes homogeneity within the region of interest and purely elastic tissue behavior. However, the cervix is structurally/microstructurally heterogeneous and viscoelastic. We therefore developed strategies to investigate these complex tissue properties. Shear wave elasticity imaging was performed ex vivo on 14 unripened and 13 misoprostol-ripened cervix specimens from rhesus macaques. After tests of significant and uniform shear wave displacement, as well as reliability of estimates, group velocity decreased significantly from the distal (vaginal) to proximal (uterine) end of unripened, but not ripened, specimens. Viscosity was quantified by the slope of the phase velocity versus frequency. Dispersion was observed in both groups (median: 5.5 m/s/kHz, interquartile range: 1.5-12.0 m/s/kHz), also decreasing toward the proximal cervix. This work suggests that comprehensive assessment of complex tissues such as cervix requires consideration of structural heterogeneity and viscosity.
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Affiliation(s)
- Ivan M Rosado-Mendez
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
| | - Mark L Palmeri
- Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Lindsey C Drehfal
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Quinton W Guerrero
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Heather Simmons
- Wisconsin National Primate Research Center, Madison, Wisconsin, USA
| | - Helen Feltovich
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA; Maternal Fetal Medicine, Intermountain Healthcare, Provo, Utah, USA
| | - Timothy J Hall
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
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11
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Nott JP, Bonney EA, Pickering JD, Simpson NA. The structure and function of the cervix during pregnancy. TRANSLATIONAL RESEARCH IN ANATOMY 2016. [DOI: 10.1016/j.tria.2016.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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12
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Peralta L, Mourier E, Richard C, Charpigny G, Larcher T, Aït-Belkacem D, Balla NK, Brasselet S, Tanter M, Muller M, Chavatte-Palmer P. In Vivo Evaluation of Cervical Stiffness Evolution during Induced Ripening Using Shear Wave Elastography, Histology and 2 Photon Excitation Microscopy: Insight from an Animal Model. PLoS One 2015; 10:e0133377. [PMID: 26317774 PMCID: PMC4552804 DOI: 10.1371/journal.pone.0133377] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Accepted: 06/26/2015] [Indexed: 11/18/2022] Open
Abstract
Prematurity affects 11% of the births and is the main cause of infant mortality. On the opposite case, the failure of induction of parturition in the case of delayed spontaneous birth is associated with fetal suffering. Both conditions are associated with precocious and/or delayed cervical ripening. Quantitative and objective information about the temporal evolution of the cervical ripening may provide a complementary method to identify cases at risk of preterm delivery and to assess the likelihood of successful induction of labour. In this study, the cervical stiffness was measured in vivo in pregnant sheep by using Shear Wave Elastography (SWE). This technique assesses the stiffness of tissue through the measurement of shear waves speed (SWS). In the present study, 9 pregnant ewes were used. Cervical ripening was induced at 127 days of pregnancy (term: 145 days) by dexamethasone injection in 5 animals, while 4 animals were used as control. Elastographic images of the cervix were obtained by two independent operators every 4 hours during 24 hours after injection to monitor the cervical maturation induced by the dexamethasone. Based on the measurements of SWS during vaginal ultrasound examination, the stiffness in the second ring of the cervix was quantified over a circular region of interest of 5 mm diameter. SWS was found to decrease significantly in the first 4-8 hours after dexamethasone compared to controls, which was associated with cervical ripening induced by dexamethasone (from 1.779 m/s ± 0.548 m/s, p < 0.0005, to 1.291 m/s ± 0.516 m/s, p < 0.000). Consequently a drop in the cervical elasticity was quantified too (from 9.5 kPa ± 0.9 kPa, p < 0.0005, to 5.0 kPa ± 0.8 kPa, p < 0.000). Moreover, SWE measurements were highly reproducible between both operators at all times. Cervical ripening induced by dexamethasone was confirmed by the significant increase in maternal plasma Prostaglandin E2 (PGE2), as evidenced by the assay of its metabolite PGEM. Histological analyses and two-photon excitation microscopy, combining both Second Harmonic Generation (SHG) and Two-photon Fluorescence microscopy (2PF) contrasts, were used to investigate, at the microscopic scale, the structure of cervical tissue. Results show that both collagen and 2PF-active fibrillar structures could be closely related to the mechanical properties of cervical tissue that are perceptible in elastography. In conclusion, SWE may be a valuable method to objectively quantify the cervical stiffness and as a complementary diagnostic tool for preterm birth and for labour induction success.
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Affiliation(s)
- Laura Peralta
- Department of Structural Mechanics, University of Granada, Granada, Spain
| | - Eve Mourier
- INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy en Josas, France
- PremUp foundation, 75006 Paris, France
| | - Christophe Richard
- INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy en Josas, France
- PremUp foundation, 75006 Paris, France
| | - Gilles Charpigny
- INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy en Josas, France
| | | | - Dora Aït-Belkacem
- Aix-Marseille Université, CNRS, Centrale Marseille, Institut Fresnel UMR 7249, 13013 Marseille, France
| | - Naveen K. Balla
- Aix-Marseille Université, CNRS, Centrale Marseille, Institut Fresnel UMR 7249, 13013 Marseille, France
| | - Sophie Brasselet
- Aix-Marseille Université, CNRS, Centrale Marseille, Institut Fresnel UMR 7249, 13013 Marseille, France
| | - Mickael Tanter
- Institut Langevin, ESPCI ParisTech, CNRS, Université Paris Diderot - Paris 7, Paris, France
| | - Marie Muller
- Institut Langevin, ESPCI ParisTech, CNRS, Université Paris Diderot - Paris 7, Paris, France
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Pascale Chavatte-Palmer
- INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy en Josas, France
- PremUp foundation, 75006 Paris, France
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