1
|
Ngo TKN, Yang SJ, Mao BH, Nguyen TKM, Ng QD, Kuo YL, Tsai JH, Saw SN, Tu TY. A deep learning-based pipeline for analyzing the influences of interfacial mechanochemical microenvironments on spheroid invasion using differential interference contrast microscopic images. Mater Today Bio 2023; 23:100820. [PMID: 37810748 PMCID: PMC10558776 DOI: 10.1016/j.mtbio.2023.100820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 07/16/2023] [Accepted: 09/24/2023] [Indexed: 10/10/2023] Open
Abstract
Metastasis is the leading cause of cancer-related deaths. During this process, cancer cells are likely to navigate discrete tissue-tissue interfaces, enabling them to infiltrate and spread throughout the body. Three-dimensional (3D) spheroid modeling is receiving more attention due to its strengths in studying the invasive behavior of metastatic cancer cells. While microscopy is a conventional approach for investigating 3D invasion, post-invasion image analysis, which is a time-consuming process, remains a significant challenge for researchers. In this study, we presented an image processing pipeline that utilized a deep learning (DL) solution, with an encoder-decoder architecture, to assess and characterize the invasion dynamics of tumor spheroids. The developed models, equipped with feature extraction and measurement capabilities, could be successfully utilized for the automated segmentation of the invasive protrusions as well as the core region of spheroids situated within interfacial microenvironments with distinct mechanochemical factors. Our findings suggest that a combination of the spheroid culture and DL-based image analysis enable identification of time-lapse migratory patterns for tumor spheroids above matrix-substrate interfaces, thus paving the foundation for delineating the mechanism of local invasion during cancer metastasis.
Collapse
Affiliation(s)
- Thi Kim Ngan Ngo
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Sze Jue Yang
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Bin-Hsu Mao
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Thi Kim Mai Nguyen
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Qi Ding Ng
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Yao-Lung Kuo
- Department of Surgery, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan
- Department of Surgery, National Cheng Kung University Hospital, Tainan, 70101, Taiwan
| | - Jui-Hung Tsai
- Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, 70101, Taiwan
| | - Shier Nee Saw
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Ting-Yuan Tu
- Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan, 70101, Taiwan
- Medical Device Innovation Center, National Cheng Kung University, Tainan, 70101, Taiwan
| |
Collapse
|
2
|
Huang J, Saw SN, He T, Yang R, Qin Y, Chen Y, Kiong LC. DCNNLFS: A Dilated Convolutional Neural Network with Late Fusion Strategy for Intelligent Classification of Gastric Histopathology Images. IEEE J Biomed Health Inform 2023; PP:1-10. [PMID: 37983160 DOI: 10.1109/jbhi.2023.3334709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Gastric cancer has a high incidence rate, significantly threatening patients' health. Gastric histopathology images can reliably diagnose related diseases. Still, the data volume of histopathology images is too large, making misdiagnosis or missed diagnosis easy. The classification model based on deep learning has made some progress on gastric histopathology images. However, traditional convolutional neural networks (CNN) generally use pooling operations, which will reduce the spatial resolution of the image, resulting in poor prediction results. The image feature in previous CNN has a poor perception of details. Therefore, we design a dilated CNN with a late fusion strategy (DCNNLFS) for gastric histopathology image classification. The DCNNLFS model utilizes dilated convolutions, enabling it to expand the receptive field. The dilated convolutions can learn the different contextual information by adjusting the dilation rate. The DCNNLFS model uses a late fusion strategy to enhance the classification ability of DCNNLFS. We run related experiments on a gastric histopathology image dataset to verify the excellence of the DCNNLFS model, where the three metrics Precision, Accuracy, and F1-Score are 0.938, 0.935, and 0.959.
Collapse
|
3
|
Saw SN, Lim MC, Liew CN, Ahmad Kamar A, Sulaiman S, Saaid R, Loo CK. The accuracy of international and national fetal growth charts in detecting small-for-gestational-age infants using the Lambda-Mu-Sigma method. Front Surg 2023; 10:1123948. [PMID: 37114151 PMCID: PMC10126230 DOI: 10.3389/fsurg.2023.1123948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/28/2023] [Indexed: 04/29/2023] Open
Abstract
Objective To construct a national fetal growth chart using retrospective data and compared its diagnostic accuracy in predicting SGA at birth with existing international growth charts. Method This is a retrospective study where datasets from May 2011 to Apr 2020 were extracted to construct the fetal growth chart using the Lambda-Mu-Sigma method. SGA is defined as birth weight <10th centile. The local growth chart's diagnostic accuracy in detecting SGA at birth was evaluated using datasets from May 2020 to Apr 2021 and was compared with the WHO, Hadlock, and INTERGROWTH-21st charts. Balanced accuracy, sensitivity, and specificity were reported. Results A total of 68,897 scans were collected and five biometric growth charts were constructed. Our national growth chart achieved an accuracy of 69% and a sensitivity of 42% in identifying SGA at birth. The WHO chart showed similar diagnostic performance as our national growth chart, followed by the Hadlock (67% accuracy and 38% sensitivity) and INTERGROWTH-21st (57% accuracy and 19% sensitivity). The specificities for all charts were 95-96%. All growth charts showed higher accuracy in the third trimester, with an improvement of 8-16%, as compared to that in the second trimester. Conclusion Using the Hadlock and INTERGROWTH-21st chart in the Malaysian population may results in misdiagnose of SGA. Our population local chart has slightly higher accuracy in predicting preterm SGA in the second trimester which can enable earlier intervention for babies who are detected as SGA. All growth charts' diagnostic accuracies were poor in the second trimester, suggesting the need of improvising alternative techniques for early detection of SGA to improve fetus outcomes.
Collapse
Affiliation(s)
- Shier Nee Saw
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Mei Cee Lim
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Chuan Nyen Liew
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Azanna Ahmad Kamar
- Department of Paediatrics, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Sofiah Sulaiman
- Department of Obstetrics and Gynaecology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Rahmah Saaid
- Department of Obstetrics and Gynaecology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Chu Kiong Loo
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Universiti Malaya, Kuala Lumpur, Malaysia
| |
Collapse
|
4
|
Liao S, Li X, Deng M, Liu B, Wang Y, Saw SN, Li Z. A Miniaturized Ultrasonic Micro-hole Perforator for Minimally Invasive Craniotomy. IEEE Trans Biomed Eng 2023; PP. [PMID: 37018608 DOI: 10.1109/tbme.2023.3234965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Micro-hole perforation on skull is urgently desired for minimally invasive insertion of micro-tools in brain for diagnostic or treatment purpose. However, a micro drill bit would easily fracture, making it difficult to safely generate a micro-hole on the hard skull. METHODS In this study, we present a method for ultrasonic vibration assisted micro-hole perforation on skull in a manner similar to subcutaneous injection on soft tissue. For this purpose, a high amplitude miniaturized ultrasonic tool with a 500 μm tip diameter micro-hole perforator was developed with simulation and experimental characterization. In-depth investigation of micro-hole generation mechanism was performed with systematic experiments on animal skull with a bespoke test rig; effects of vibration amplitude and feed rate on hole forming characteristics were systematically studied. It was observed that by exploiting skull bone's unique structural and material properties, the ultrasonic micro-perforator could locally damage bone tissue with micro-porosities, induce sufficient plastic deformation to bone tissue around the micro-hole and refrain elastic recovery after tool withdraw, generating a micro-hole on skull without material. RESULTS Under optimized conditions, high quality micro-holes could be formed on the hard skull with a force (< 1N) even smaller than that for subcutaneous injection on soft skin. CONCLUSION This study would provide a safe and effective method and a miniaturized device for micro-hole perforation on skull for minimally invasive neural interventions.
Collapse
Affiliation(s)
- Shufu Liao
- Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument, School of Biomedical Engineering, Sun Yat-Sen University, Guangzhou, China
| | - Xuan Li
- Centre for Medical and Industrial Ultrasonics, James Watt School of Engineering, University of Glasgow, Glasgow, U.K
| | - Maosen Deng
- Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument, School of Biomedical Engineering, Sun Yat-Sen University, Guangzhou, China
| | - Bin Liu
- International School of Information Science & Engineering, Dalian University of Technology, Dalian, P.R. China
| | - Yatong Wang
- Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument, School of Biomedical Engineering, Sun Yat-Sen University, Guangzhou, China
| | - Shier Nee Saw
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Zhe Li
- Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument, School of Biomedical Engineering, Sun Yat-Sen University, Guangzhou, China
| |
Collapse
|
5
|
Saw SN, Ng KH. Current challenges of implementing artificial intelligence in medical imaging. Phys Med 2022; 100:12-17. [PMID: 35714523 DOI: 10.1016/j.ejmp.2022.06.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 04/26/2022] [Accepted: 06/11/2022] [Indexed: 12/31/2022] Open
Abstract
The idea of using artificial intelligence (AI) in medical practice has gained vast interest due to its potential to revolutionise healthcare systems. However, only some AI algorithms are utilised due to systems' uncertainties, besides the never-ending list of ethical and legal concerns. This paper intends to provide an overview of current AI challenges in medical imaging with an ultimate aim to foster better and effective communication among various stakeholders to encourage AI technology development. We identify four main challenges in implementing AI in medical imaging, supported with consequences and past events when these problems fail to mitigate. Among them is the creation of a robust AI algorithm that is fair, trustable and transparent. Another issue is on data governance, in which best practices in data sharing must be established to promote trust and protect the patients' privacy. Next, stakeholders, such as the government, technology companies and hospital management, should come to a consensus in creating trustworthy AI policies and regulatory frameworks, which is the fourth challenge, to support, encourage and spur innovation in digital AI healthcare technology. Lastly, we discussed the efforts of various organizations such as the World Health Organisation (WHO), American College of Radiology (ACR), European Society of Radiology (ESR) and Radiological Society of North America (RSNA), who are already actively pursuing ethical developments in AI. The efforts by various stakeholders will eventually overcome hurdles and the deployment of AI-driven healthcare applications in clinical practice will become a reality and hence lead to better healthcare services and outcomes.
Collapse
Affiliation(s)
- Shier Nee Saw
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Universiti Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Kwan Hoong Ng
- Department of Biomedical Imaging, Universiti Malaya, 50603 Kuala Lumpur, Malaysia; Department of Medical Imaging and Radiological Sciences, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
| |
Collapse
|
6
|
Teng LY, Mattar CNZ, Biswas A, Hoo WL, Saw SN. Interpreting the role of nuchal fold for fetal growth restriction prediction using machine learning. Sci Rep 2022; 12:3907. [PMID: 35273269 PMCID: PMC8913636 DOI: 10.1038/s41598-022-07883-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/25/2022] [Indexed: 11/28/2022] Open
Abstract
The objective of the study is to investigate the effect of Nuchal Fold (NF) in predicting Fetal Growth Restriction (FGR) using machine learning (ML), to explain the model's results using model-agnostic interpretable techniques, and to compare the results with clinical guidelines. This study used second-trimester ultrasound biometry and Doppler velocimetry were used to construct six FGR (birthweight < 3rd centile) ML models. Interpretability analysis was conducted using Accumulated Local Effects (ALE) and Shapley Additive Explanations (SHAP). The results were compared with clinical guidelines based on the most optimal model. Support Vector Machine (SVM) exhibited the most consistent performance in FGR prediction. SHAP showed that the top contributors to identify FGR were Abdominal Circumference (AC), NF, Uterine RI (Ut RI), and Uterine PI (Ut PI). ALE showed that the cutoff values of Ut RI, Ut PI, and AC in differentiating FGR from normal were comparable with clinical guidelines (Errors between model and clinical; Ut RI: 15%, Ut PI: 8%, and AC: 11%). The cutoff value for NF to differentiate between healthy and FGR is 5.4 mm, where low NF may indicate FGR. The SVM model is the most stable in FGR prediction. ALE can be a potential tool to identify a cutoff value for novel parameters to differentiate between healthy and FGR.
Collapse
Affiliation(s)
- Lung Yun Teng
- Department of Information Technology, Faculty of Computer Science and Information Technology, Universiti Malaya, 50603, Kuala Lumpur, Malaysia
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Department of Obstetrics and Gynaecology, National University Health System, Singapore, Singapore
| | - Arijit Biswas
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Department of Obstetrics and Gynaecology, National University Health System, Singapore, Singapore
| | - Wai Lam Hoo
- Department of Information Technology, Faculty of Computer Science and Information Technology, Universiti Malaya, 50603, Kuala Lumpur, Malaysia
| | - Shier Nee Saw
- Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
| |
Collapse
|
7
|
Saw SN, Dai Y, Yap CH. A Review of Biomechanics Analysis of the Umbilical-Placenta System With Regards to Diseases. Front Physiol 2021; 12:587635. [PMID: 34475826 PMCID: PMC8406807 DOI: 10.3389/fphys.2021.587635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
Placenta is an important organ that is crucial for both fetal and maternal health. Abnormalities of the placenta, such as during intrauterine growth restriction (IUGR) and pre-eclampsia (PE) are common, and an improved understanding of these diseases is needed to improve medical care. Biomechanics analysis of the placenta is an under-explored area of investigation, which has demonstrated usefulness in contributing to our understanding of the placenta physiology. In this review, we introduce fundamental biomechanics concepts and discuss the findings of biomechanical analysis of the placenta and umbilical cord, including both tissue biomechanics and biofluid mechanics. The biomechanics of placenta ultrasound elastography and its potential in improving clinical detection of placenta diseases are also discussed. Finally, potential future work is listed.
Collapse
Affiliation(s)
- Shier Nee Saw
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Yichen Dai
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, London, United Kingdom
| |
Collapse
|
8
|
Park S, Saw SN, Li X, Paknezhad M, Coppola D, Dinish US, Ebrahim Attia AB, Yew YW, Guan Thng ST, Lee HK, Olivo M. Model learning analysis of 3D optoacoustic mesoscopy images for the classification of atopic dermatitis. Biomed Opt Express 2021; 12:3671-3683. [PMID: 34221687 PMCID: PMC8221944 DOI: 10.1364/boe.415105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/15/2021] [Accepted: 03/09/2021] [Indexed: 05/07/2023]
Abstract
Atopic dermatitis (AD) is a skin inflammatory disease affecting 10% of the population worldwide. Raster-scanning optoacoustic mesoscopy (RSOM) has recently shown promise in dermatological imaging. We conducted a comprehensive analysis using three machine-learning models, random forest (RF), support vector machine (SVM), and convolutional neural network (CNN) for classifying healthy versus AD conditions, and sub-classifying different AD severities using RSOM images and clinical information. CNN model successfully differentiates healthy from AD patients with 97% accuracy. With limited data, RF achieved 65% accuracy in sub-classifying AD patients into mild versus moderate-severe cases. Identification of disease severities is vital in managing AD treatment.
Collapse
Affiliation(s)
- Sojeong Park
- Bioinformatics Institute, Agency of Science, Technology and Research, ASTAR, 30 Biopolis Street, #07-01 Matrix, 138671, Singapore
- Co-first authors
| | - Shier Nee Saw
- Bioinformatics Institute, Agency of Science, Technology and Research, ASTAR, 30 Biopolis Street, #07-01 Matrix, 138671, Singapore
- Current address: Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, University of Malaya, Malaysia
- Co-first authors
| | - Xiuting Li
- Laboratory of Bio-Optical Imaging, Singapore Bioimaging Consortium, ASTAR, 11 Biopolis Way, 138667, Singapore
- Co-first authors
| | - Mahsa Paknezhad
- Bioinformatics Institute, Agency of Science, Technology and Research, ASTAR, 30 Biopolis Street, #07-01 Matrix, 138671, Singapore
| | - Davide Coppola
- Bioinformatics Institute, Agency of Science, Technology and Research, ASTAR, 30 Biopolis Street, #07-01 Matrix, 138671, Singapore
| | - U S Dinish
- Laboratory of Bio-Optical Imaging, Singapore Bioimaging Consortium, ASTAR, 11 Biopolis Way, 138667, Singapore
| | | | - Yik Weng Yew
- National Skin Centre, 1 Mandalay, 308205, Singapore
| | | | - Hwee Kuan Lee
- Bioinformatics Institute, Agency of Science, Technology and Research, ASTAR, 30 Biopolis Street, #07-01 Matrix, 138671, Singapore
- School of Computing, National University of Singapore, 13 Computing Drive, Singapore, 117417, Singapore
- Singapore Eye Research Institute (SERI), 11 Third Hospital Ave, Singapore, 168751, Singapore
- Image and Pervasive Access Laboratory (IPAL), 1 Fusionopolis Way, #21-01 Connexis (South Tower), 138632, Singapore
- Rehabilitation Research Institute of Singapore, 11 Mandalay Road #14-03, Clinical Sciences Building, 308232, Singapore
| | - Malini Olivo
- Laboratory of Bio-Optical Imaging, Singapore Bioimaging Consortium, ASTAR, 11 Biopolis Way, 138667, Singapore
| |
Collapse
|
9
|
Saw SN, Biswas A, Mattar CNZ, Lee HK, Yap CH. Machine learning improves early prediction of small-for-gestational-age births and reveals nuchal fold thickness as unexpected predictor. Prenat Diagn 2021; 41:505-516. [PMID: 33462877 DOI: 10.1002/pd.5903] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 01/05/2021] [Accepted: 01/10/2021] [Indexed: 12/18/2022]
Abstract
OBJECTIVE To investigate the performance of the machine learning (ML) model in predicting small-for-gestational-age (SGA) at birth, using second-trimester data. METHODS Retrospective data of 347 patients, consisting of maternal demographics and ultrasound parameters collected between the 20th and 25th gestational weeks, were studied. ML models were applied to different combinations of the parameters to predict SGA and severe SGA at birth (defined as 10th and third centile birth weight). RESULTS Using second-trimester measurements, ML models achieved an accuracy of 70% and 73% in predicting SGA and severe SGA whereas clinical guidelines had accuracies of 64% and 48%. Uterine PI (Ut PI) was found to be an important predictor, corroborating with existing literature, but surprisingly, so was nuchal fold thickness (NF). Logistic regression showed that Ut PI and NF were significant predictors and statistical comparisons showed that these parameters were significantly different in disease. Further, including NF was found to improve ML model performance, and vice versa. CONCLUSION ML could potentially improve the prediction of SGA at birth from second-trimester measurements, and demonstrated reduced NF to be an important predictor. Early prediction of SGA allows closer clinical monitoring, which provides an opportunity to discover any underlying diseases associated with SGA.
Collapse
Affiliation(s)
- Shier Nee Saw
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore.,Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, University of Malaya, Malaysia
| | - Arijit Biswas
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore
| | - Hwee Kuan Lee
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), Singapore.,Rehabilitation Research Institute of Singapore, Singapore.,School of Computing, National University of Singapore, Singapore.,Image and Pervasive Access Lab (IPAL), CNRS UMI, Singapore.,Singapore Eye Research Institute, Singapore
| | - Choon Hwai Yap
- Department of Bioengineering, Imperial College London, London, UK
| |
Collapse
|
10
|
Tun WM, Yap CH, Saw SN, James JL, Clark AR. Differences in placental capillary shear stress in fetal growth restriction may affect endothelial cell function and vascular network formation. Sci Rep 2019; 9:9876. [PMID: 31285454 PMCID: PMC6614400 DOI: 10.1038/s41598-019-46151-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 06/19/2019] [Indexed: 11/09/2022] Open
Abstract
Fetal growth restriction (FGR) affects 5-10% of pregnancies, leading to clinically significant fetal morbidity and mortality. FGR placentae frequently exhibit poor vascular branching, but the mechanisms driving this are poorly understood. We hypothesize that vascular structural malformation at the organ level alters microvascular shear stress, impairing angiogenesis. A computational model of placental vasculature predicted elevated placental micro-vascular shear stress in FGR placentae (0.2 Pa in severe FGR vs 0.05 Pa in normal placentae). Endothelial cells cultured under predicted FGR shear stresses migrated significantly slower and with greater persistence than in shear stresses predicted in normal placentae. These cell behaviors suggest a dominance of vessel elongation over branching. Taken together, these results suggest (1) poor vascular development increases vessel shear stress, (2) increased shear stress induces cell behaviors that impair capillary branching angiogenesis, and (3) impaired branching angiogenesis continues to drive elevated shear stress, jeopardizing further vascular formation. Inadequate vascular branching early in gestation could kick off this cyclic loop and continue to negatively impact placental angiogenesis throughout gestation.
Collapse
Affiliation(s)
- Win M Tun
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Shier Nee Saw
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Joanna L James
- Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
| |
Collapse
|
11
|
Saw SN, Tay JJH, Poh YW, Yang L, Tan WC, Tan LK, Clark A, Biswas A, Mattar CNZ, Yap CH. Altered Placental Chorionic Arterial Biomechanical Properties During Intrauterine Growth Restriction. Sci Rep 2018; 8:16526. [PMID: 30409992 PMCID: PMC6224524 DOI: 10.1038/s41598-018-34834-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/24/2018] [Indexed: 12/16/2022] Open
Abstract
Intrauterine growth restriction (IUGR) is a pregnancy complication due to placental dysfunction that prevents the fetus from obtaining enough oxygen and nutrients, leading to serious mortality and morbidity risks. There is no treatment for IUGR despite having a prevalence of 3% in developed countries, giving rise to an urgency to improve our understanding of the disease. Applying biomechanics investigation on IUGR placental tissues can give important new insights. We performed pressure-diameter mechanical testing of placental chorionic arteries and found that in severe IUGR cases (RI > 90th centile) but not in IUGR cases (RI < 90th centile), vascular distensibility was significantly increased from normal. Constitutive modeling demonstrated that a simplified Fung-type hyperelastic model was able to describe the mechanical properties well, and histology showed that severe IUGR had the lowest collagen to elastin ratio. To demonstrate that the increased distensibility in the severe IUGR group was related to their elevated umbilical resistance and pulsatility indices, we modelled the placental circulation using a Windkessel model, and demonstrated that vascular compliance (and not just vascular resistance) directly affected blood flow pulsatility, suggesting that it is an important parameter for the disease. Our study showed that biomechanics study on placenta could extend our understanding on placenta physiology.
Collapse
Affiliation(s)
- Shier Nee Saw
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Jess Jia Hwee Tay
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Yu Wei Poh
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Liying Yang
- Department of Obstetrics & Gynecology, Singapore General Hospital, Singapore, Singapore
| | - Wei Ching Tan
- Department of Obstetrics & Gynecology, Singapore General Hospital, Singapore, Singapore
| | - Lay Kok Tan
- Department of Obstetrics & Gynecology, Singapore General Hospital, Singapore, Singapore
| | - Alys Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Arijit Biswas
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore, Singapore
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore, Singapore
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
| |
Collapse
|
12
|
Saw SN, Poh YW, Chia D, Biswas A, Mattar CNZ, Yap CH. Characterization of the hemodynamic wall shear stresses in human umbilical vessels from normal and intrauterine growth restricted pregnancies. Biomech Model Mechanobiol 2018; 17:1107-1117. [PMID: 29691766 DOI: 10.1007/s10237-018-1017-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/13/2018] [Indexed: 12/13/2022]
Abstract
Significant reductions in blood flow and umbilical diameters were reported in pregnancies affected by intrauterine growth restriction (IUGR) from placental insufficiency. However, it is not known if IUGR umbilical blood vessels experience different hemodynamic wall shear stresses (WSS) compared to normal umbilical vessels. As WSS is known to influence vasoactivity and vascular growth and remodeling, which can regulate flow rates, it is important to study this parameter. In this study, we aim to characterize umbilical vascular WSS environment in normal and IUGR pregnancies, and evaluate correlation between WSS and vascular diameter, and gestational age. Twenty-two normal and 21 IUGR pregnancies were assessed via ultrasound between the 27th and 39th gestational week. IUGR was defined as estimated fetal weight and/or abdominal circumference below the 10th centile, with no improvement during the remainder of the pregnancy. Vascular diameter was determined by 3D ultrasound scans and image segmentation. Umbilical artery (UA) WSS was computed via computational flow simulations, while umbilical vein (UV) WSS was computed via the Poiseuille equation. Univariate multiple regression analysis was used to test for the differences between normal and IUGR cohort. UV volumetric flow rate, UA and UV diameters were significantly lower in IUGR fetuses, but flow velocities and WSS trends in UA and UV were very similar between normal and IUGR groups. In both groups, UV WSS showed a significant negative correlation with diameter, but UA WSS had no correlation with diameter, suggesting a constancy of WSS environment and the existence of WSS homeostasis in UA, but not in UV. Despite having reduced flow rate and vascular sizes, IUGR UAs had hemodynamic mechanical stress environments and trends that were similar to those in normal pregnancies. This suggested that endothelial dysfunction or abnormal mechanosensing was unlikely to be the cause of small vessels in IUGR umbilical cords.
Collapse
Affiliation(s)
- Shier Nee Saw
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, #02-04, Singapore, 117575, Singapore
| | - Yu Wei Poh
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, #02-04, Singapore, 117575, Singapore
| | - Dawn Chia
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore, Singapore
| | - Arijit Biswas
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore, Singapore
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health Systems, Singapore, Singapore
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, #02-04, Singapore, 117575, Singapore.
| |
Collapse
|
13
|
Saw SN, Low JYR, Mattar CNZ, Biswas A, Chen L, Yap CH. Motorizing and Optimizing Ultrasound Strain Elastography for Detection of Intrauterine Growth Restriction Pregnancies. Ultrasound Med Biol 2018; 44:532-543. [PMID: 29329688 DOI: 10.1016/j.ultrasmedbio.2017.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/29/2017] [Accepted: 12/03/2017] [Indexed: 06/07/2023]
Abstract
Intrauterine growth restriction is a prevalent disease in pregnancy in which placental insufficiency leads to 5 to 10 times higher mortality and lifelong morbidities. The current detection rate is poor, and recently, ultrasound strain elastography (USEL) was proposed as a new diagnostic technique. Currently, placental USEL uses maternal subcutaneous fat as the reference layer, but this is not ideal as fat tissue stiffness can vary widely between subjects. Current USEL also uses manual palpation, and under different compression depths and rates, viscoelastic tissues such as placenta can yield different stiffness results. In the study described here, we strove to improve placental USEL by (i) using an external polymeric pad of known stiffness as the reference layer and (ii) adopting motorized control of the transducer during USEL to standardize palpation motion. Results indicated that motorized USEL reduced measurement variability by 67% compared with freehand USEL. Satisfactory and statistically significant correlations between USEL measurements and mechanical testing validation results were obtained for our new USEL protocol. Placental tissues were found to be non-linear and viscoelastic in nature and, thus, differed in stiffness at different compression rates and depths. Our study also revealed that there was a specific compression depth and rate during USEL that provided better correlation to mechanical testing, and should be considered in clinical placental USEL.
Collapse
Affiliation(s)
- Shier Nee Saw
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Jess Yi Ru Low
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Citra Nurfarah Zaini Mattar
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University Health Systems, National University of Singapore, Singapore
| | - Arijit Biswas
- Department of Obstetrics and Gynecology, Yong Loo Lin School of Medicine, National University Health Systems, National University of Singapore, Singapore
| | - Lujie Chen
- Engineering Product Development, Singapore University of Technology and Design, Singapore
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, Singapore.
| |
Collapse
|
14
|
Saw SN, Dawn C, Biswas A, Mattar CNZ, Yap CH. Characterization of the in vivo wall shear stress environment of human fetus umbilical arteries and veins. Biomech Model Mechanobiol 2016; 16:197-211. [DOI: 10.1007/s10237-016-0810-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/20/2016] [Indexed: 10/21/2022]
|
15
|
Affiliation(s)
- Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore..
| | - Shier Nee Saw
- Department of Biomedical Engineering, National University of Singapore
| |
Collapse
|
16
|
Lau JS, Saw SN, Buist ML, Biswas A, Zaini Mattar CN, Yap CH. Mechanical testing and non-linear viscoelastic modelling of the human placenta in normal and growth restricted pregnancies. J Biomech 2016; 49:173-84. [DOI: 10.1016/j.jbiomech.2015.11.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Revised: 10/20/2015] [Accepted: 11/25/2015] [Indexed: 02/07/2023]
|