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Jia X, Li X, Shen T, Zhou L, Yang G, Wang F, Zhu X, Wan M, Li S, Zhang S. Monitoring of thermal lesions in ultrasound using fully convolutional neural networks: A preclinical study. ULTRASONICS 2023; 130:106929. [PMID: 36669371 DOI: 10.1016/j.ultras.2023.106929] [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: 03/10/2022] [Revised: 11/15/2022] [Accepted: 01/12/2023] [Indexed: 06/17/2023]
Abstract
Accurate monitoring of thermal ablation regions is an important guarantee for successful ablation treatment, which mainly depends on the subjective judgment of radiologists in current clinical practice. This work innovatively applied fully convolutional neural networks (FCNs) for detection and monitoring of thermal ablation regions in ultrasound (US) and comprehensively compared the performance of VGG16-FCN, U-Net, UNet++, Attention U-Net, MultiResUNet, and ResUNet, which have shown outstanding performance in medical image segmentation. The input of the models was US echo envelope data backscattered from the ablated regions. Excised porcine liver ablation dataset and clinical liver tumors ablation dataset were respectively used to evaluate the prediction ability of the models. With 1000 excised porcine liver ablation samples for training and 200 samples for testing, the UNet++ achieves both the highest Dice score (DSC) of 0.7824 ± 0.1098 and the best Hausdorff distance (HD) of 2.70 ± 1.38 mm. Additionally, considering potential clinical usage, we also tested the model generalizability by training on the excised dataset and testing on the clinical data, in which we obtained the performance with the highest DSC obtained by the ResUNet and the best HD by the UNet++. Our comparative study suggests that both UNet++ and ResUNet have relatively outstanding segmentation performance among all compared models, which are potential candidates for automatic segmentation of thermal ablation regions in US during clinical ablation treatment.
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Affiliation(s)
- Xin Jia
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xiejing Li
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Ting Shen
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Ling Zhou
- Department of Ultrasound, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Zhejiang 310016, China.
| | - Guang Yang
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Fan Wang
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xingguang Zhu
- Department of Medical Engineering, Beijing Huilongguan Hospital, Beijing 100096, China.
| | - Mingxi Wan
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Shiyan Li
- Department of Ultrasound, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Zhejiang 310016, China.
| | - Siyuan Zhang
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China; State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China; Sichuan Digital Economy Industry Development Research Institute, Sichuan 610000, China.
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Wong DCP, Ding JL. The mechanobiology of NK cells- 'Forcing NK to Sense' target cells. Biochim Biophys Acta Rev Cancer 2023; 1878:188860. [PMID: 36791921 DOI: 10.1016/j.bbcan.2023.188860] [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: 11/23/2022] [Revised: 01/06/2023] [Accepted: 01/16/2023] [Indexed: 02/16/2023]
Abstract
Natural killer (NK) cells are innate immune lymphocytes that recognize and kill cancer and infected cells, which makes them unique 'off-the-shelf' candidates for a new generation of immunotherapies. Biomechanical forces in homeostasis and pathophysiology accrue additional immune regulation for NK immune responses. Indeed, cellular and tissue biomechanics impact NK receptor clustering, cytoskeleton remodeling, NK transmigration through endothelial cells, nuclear mechanics, and even NK-dendritic cell interaction, offering a plethora of unexplored yet important dynamic regulation for NK immunotherapy. Such events are made more complex by the heterogeneity of human NK cells. A significant question remains on whether and how biochemical and biomechanical cues collaborate for NK cell mechanotransduction, a process whereby mechanical force is sensed, transduced, and translated to downstream mechanical and biochemical signalling. Herein, we review recent advances in understanding how NK cells perceive and mechanotransduce biophysical cues. We focus on how the cellular cytoskeleton crosstalk regulates NK cell function while bearing in mind the heterogeneity of NK cells, the direct and indirect mechanical cues for NK anti-tumor activity, and finally, engineering advances that are of translational relevance to NK cell biology at the systems level.
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Affiliation(s)
- Darren Chen Pei Wong
- Department of Biological Sciences, National University of Singapore, 117543, Singapore.
| | - Jeak Ling Ding
- Department of Biological Sciences, National University of Singapore, 117543, Singapore; Integrative Sciences and Engineering Programme, National University of Singapore, 119077, Singapore.
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Jin X, Li Y, Liu W, Mu Y, Wang J, Qian Z, Li W, Zhou J. Study on the relationship between reduced scattering coefficient and Young's modulus of tumors in microwave ablation. MINIM INVASIV THER 2020; 30:347-355. [PMID: 32459544 DOI: 10.1080/13645706.2020.1742742] [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] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND OBJECTIVE In the clinical treatment of tumors using microwave ablation (MWA), although temperature can be used as an important reference index for evaluating the curative effect of ablation, it cannot fully reflect the biological activity status of tumor tissue during thermal ablation. Finding multi-parameter comprehensive evaluation factors to achieve real-time evaluation of therapeutic effects has become the key for precise ablation. More and more scholars use the reduced scattering coefficient (μs') and Young's modulus (E) to evaluate the treatment outcomes of MWA. However, the intrinsic relationship between these parameters is unclear. This paper aims to investigate the specific relationship between μs' and E during MWA. MATERIAL AND METHODS The MWA experiment was conducted on porcine liver in vitro, the two-parameter simultaneous acquisition system was designed to obtain the reduced scattering coefficient and Young's modulus of the liver tissue during MWA. The relationship between reduced scattering coefficient and Young's modulus was investigated. RESULTS It is found that the trend of change of μs' is very similar to E in the process of MWA, i.e. first increasing and then reaching a steady state, and in some experiments there are synchronous changes. Based on this, the quantitative relationship between E-μs' is established, enabling the quantitative estimation of Young's modulus of liver tissue based on reduced scattering coefficient. The maximum absolute error is 29.37 kPa and the minimum absolute error is 0.88 kPa. CONCLUSION This study contributes to the further establishment of a multi-parameter MWA effectiveness evaluation model. It is also valuable for clinically evaluating the ablation outcomes of tumor in real time.
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Affiliation(s)
- Xiaofei Jin
- Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Yiran Li
- Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Wenwen Liu
- Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Yongjie Mu
- Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Juan Wang
- Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Zhiyu Qian
- Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Weitao Li
- Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
| | - Juan Zhou
- Lauterberg Imaging Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
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Zhang S, Wu S, Shang S, Qin X, Jia X, Li D, Cui Z, Xu T, Niu G, Bouakaz A, Wan M. Detection and Monitoring of Thermal Lesions Induced by Microwave Ablation Using Ultrasound Imaging and Convolutional Neural Networks. IEEE J Biomed Health Inform 2020; 24:965-973. [DOI: 10.1109/jbhi.2019.2939810] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Motooka Y, Fujino K, Gregor A, Bernards N, Chan H, Inage T, Ujiie H, Kato T, Kinoshita T, Ishiwata T, Suzuki M, Yasufuku K. Endobronchial Ultrasound-Guided Radiofrequency Ablation of Lung Tumors and Mediastinal Lymph Nodes: A Preclinical Study in Animal Lung Tumor and Mediastinal Adenopathy Models. Semin Thorac Cardiovasc Surg 2020; 32:570-578. [PMID: 32057971 DOI: 10.1053/j.semtcvs.2020.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 02/04/2020] [Indexed: 12/19/2022]
Abstract
Radiofrequency ablation (RFA) can be a therapeutic option in medically inoperable lung cancer patients. In this study, we evaluated a prototype bipolar RFA device applicator that can be deployed from a standard endobronchial ultrasound (EBUS) bronchoscope to determine feasibility and histopathological analysis in animal models. Rabbit lung cancers were created by transbronchial injection of VX2 rabbit cancer cells. Once the tumors were developed, they were ablated transpleurally, under EBUS guidance using the prototype RFA device. The animals were then sacrificed for specimen resection. Pig inflammatory lung pseudo-tumors and lymphadenopathy were created by transbronchial injection of a talc paste and ablated transbronchially under EBUS guidance. Pigs were evaluated at 5 days, 2 weeks, and 4 weeks following ablation by bronchoscopy and cone beam computed tomography before necropsy. Nicotinamide adenine dinucleotide hydrogen diaphorase staining was employed to measure the ablation area. Twenty-four VX2 rabbit tumors were ablated. The total ablated area ranged from 0.6 to 3.0 cm2 (mean: 1.8 cm2), corresponding to a total energy range of 1 to 6 kJ. Six pig lung pseudo-tumors and 5 mediastinal lymph nodes were ablated. Adjacent airway ulceration was observed in 3 ablations of lymph nodes. These airway complications resolved within 4 weeks of RFA without any treatment. There was no hemoptysis, air embolism, respiratory distress, or other serious complication noted. In these 2 animal models, we provide evidence that EBUS-guided bipolar RFA is feasible and histopathology shows that can ablate lung tumors and mediastinal lymph nodes under real-time ultrasound guidance.
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Affiliation(s)
- Yamato Motooka
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada; Department of Thoracic Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
| | - Kosuke Fujino
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada; Department of Thoracic Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Alexander Gregor
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Nicholas Bernards
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Harley Chan
- TECHNA Institute for the Advancement of Technology for Health, University Health Network, Toronto, Ontario, Canada
| | - Terunaga Inage
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Hideki Ujiie
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Tatsuya Kato
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Tomonari Kinoshita
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Tsukasa Ishiwata
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Makoto Suzuki
- Department of Thoracic Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kazuhiro Yasufuku
- Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada; TECHNA Institute for the Advancement of Technology for Health, University Health Network, Toronto, Ontario, Canada
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Lee D, Park S, Ang MJC, Park JG, Yoon S, Kim C, Lee SK, Cho KO, Choi J. Evaluation of liver lesions by use of shear wave elastography and computed tomography perfusion imaging after radiofrequency ablation in clinically normal dogs. Am J Vet Res 2019; 79:1140-1149. [PMID: 30372151 DOI: 10.2460/ajvr.79.11.1140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate acute changes of the liver by use of shear wave elastography (SWE) and CT perfusion after radiofrequency ablation (RFA). ANIMALS 7 healthy Beagles. PROCEDURES RFA was performed on the liver (day 0). Stiffness of the ablation lesion, transitional zone, and normal parenchyma were evaluated by use of SWE, and blood flow, blood volume, and arterial liver perfusion of those regions were evaluated by use of CT perfusion on days 0 and 4. All RFA lesions were histologically examined on day 4. RESULTS Examination of the SWE color-coded map distinctly revealed stiffness of the liver tissue, which increased from the normal parenchyma to the transitional zone and then to the ablation zone. For CT perfusion, blood flow, blood volume, and arterial liver perfusion decreased from the transitional zone to the normal parenchyma and then to the ablation zone. Tissue stiffness and CT perfusion variables did not differ significantly between days 0 and 4. Histologic examination revealed central diffuse necrosis and peripheral hyperemia with infiltration of lymphoid cells and macrophages. CONCLUSIONS AND CLINICAL RELEVANCE Coagulation necrosis induced a loss of blood perfusion and caused tissue hardening (stiffness) in the ablation zone. Hyperemic and inflammatory changes of the transitional zone resulted in increased blood perfusion. Acute changes in stiffness and perfusion of liver tissue after RFA could be determined by use of SWE and CT perfusion. These results can be used to predict the clinical efficacy of RFA and to support further studies, including those involving hepatic neoplasia.
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Monitoring of Thermal-Induced Changes in Liver Stiffness During Controlled Hyperthermia and Microwave Ablation in an Ex Vivo Bovine Model Using Point Shear Wave Elastography. Cardiovasc Intervent Radiol 2019; 42:744-750. [DOI: 10.1007/s00270-018-02152-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 12/20/2018] [Indexed: 12/17/2022]
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Zhang L, Li Q, Wang CY, Tsui PH. Ultrasound single-phase CBE imaging for monitoring radiofrequency ablation. Int J Hyperthermia 2018; 35:548-558. [PMID: 30354749 DOI: 10.1080/02656736.2018.1512160] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Radiofrequency (RF) ablation (RFA) is the most commonly used minimally invasive procedure for thermal ablation of liver tumors. Ultrasound not only provides real-time feedback of the electrode location for RFA guidance but also enables visualization of the tissue temperature. Changes in backscattered energy (CBE) have been widely applied to ultrasound temperature imaging for assessing thermal ablation. Pilot studies have revealed that significant shadowing features appear in CBE imaging and are caused by the electrode and RFA-induced gas bubbles. To resolve this problem, the current study proposed ultrasound single-phase CBE imaging based on positive CBE values. An in vitro model with tissue samples derived from the porcine tenderloin was used to validate the proposed method. During RFA with various electrode lengths, ultrasound scans of tissue samples were obtained using a clinical ultrasound scanner equipped with a convex array transducer of 3 MHz. Raw image data comprising 256 scan lines of backscattered RF signals were acquired for B-mode, conventional CBE, and single-phase CBE imaging by using the proposed algorithmic scheme. The ablation sizes estimated using CBE imaging and gross examinations were compared to calculate the correlation coefficient. The experimental results indicated that single-phase CBE imaging largely suppressed artificial CBE information in the shadowed region. Moreover, compared with conventional CBE imaging, single-phase CBE imaging provided a more accurate estimation of ablation sizes (the correlation coefficient was higher than 0.8).
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Affiliation(s)
- Lin Zhang
- a School of Microelectronics , Tianjin University , Tianjin , China
| | - Qiang Li
- a School of Microelectronics , Tianjin University , Tianjin , China
| | - Chiao-Yin Wang
- b Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University , Taoyuan , Taiwan.,c Department of Medical Imaging and Radiological Sciences , College of Medicine, Chang Gung University , Taoyuan , Taiwan
| | - Po-Hsiang Tsui
- c Department of Medical Imaging and Radiological Sciences , College of Medicine, Chang Gung University , Taoyuan , Taiwan.,d Medical Imaging Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital at Linkou , Taoyuan , Taiwan.,e Department of Medical Imaging and Intervention , Chang Gung Memorial Hospital at Linkou , Taoyuan , Taiwan
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Zhou Z, Wu S, Lin MY, Fang J, Liu HL, Tsui PH. Three-dimensional Visualization of Ultrasound Backscatter Statistics by Window-modulated Compounding Nakagami Imaging. ULTRASONIC IMAGING 2018; 40:171-189. [PMID: 29506441 DOI: 10.1177/0161734618756101] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this study, the window-modulated compounding (WMC) technique was integrated into three-dimensional (3D) ultrasound Nakagami imaging for improving the spatial visualization of backscatter statistics. A 3D WMC Nakagami image was produced by summing and averaging a number of 3D Nakagami images (number of frames denoted as N) formed using sliding cubes with varying side lengths ranging from 1 to N times the transducer pulse. To evaluate the performance of the proposed 3D WMC Nakagami imaging method, agar phantoms with scatterer concentrations ranging from 2 to 64 scatterers/mm3 were made, and six stages of fatty liver (zero, one, two, four, six, and eight weeks) were induced in rats by methionine-choline-deficient diets (three rats for each stage, total n = 18). A mechanical scanning system with a 5-MHz focused single-element transducer was used for ultrasound radiofrequency data acquisition. The experimental results showed that 3D WMC Nakagami imaging was able to characterize different scatterer concentrations. Backscatter statistics were visualized with various numbers of frames; N = 5 reduced the estimation error of 3D WMC Nakagami imaging in visualizing the backscatter statistics. Compared with conventional 3D Nakagami imaging, 3D WMC Nakagami imaging improved the image smoothness without significant image resolution degradation, and it can thus be used for describing different stages of fatty liver in rats.
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Affiliation(s)
- Zhuhuang Zhou
- 1 College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
- 2 Faculty of Information Technology, Beijing University of Technology, Beijing, China
| | - Shuicai Wu
- 1 College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Man-Yen Lin
- 3 Department of Electrical Engineering, Chang Gung University, Taoyuan, Taiwan
| | - Jui Fang
- 4 PhD Program in Biomedical Engineering, College of Engineering, Chang Gung University, Taoyuan, Taiwan
| | - Hao-Li Liu
- 3 Department of Electrical Engineering, Chang Gung University, Taoyuan, Taiwan
| | - Po-Hsiang Tsui
- 5 Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- 6 Medical Imaging Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- 7 Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
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Abstract
Radiofrequency ablation (RFA) has been widely used as an alternative treatment modality for liver tumors. Monitoring the temperature distribution in the tissue during RFA is required to assess the thermal dosage. Ultrasound temperature imaging based on the detection of echo time shifts has received the most attention in the past decade. The coefficient k, connecting the temperature change and the echo time shift, is a medium-dependent parameter used to describe the confounding effects of changes in the speed of sound and thermal expansion as temperature increases. The current algorithm of temperature estimate based on echo time shift detection typically uses a constant k, resulting in estimation errors when ablation temperatures are higher than 50°C. This study proposes an adaptive-k algorithm that enables the automatic adjustment of the coefficient k during ultrasound temperature monitoring of RFA. To verify the proposed algorithm, RFA experiments on in vitro porcine liver samples (total n = 15) were performed using ablation powers of 10, 15, and 20 W. During RFA, a clinical ultrasound system equipped with a 7.5-MHz linear transducer was used to collect backscattered signals for ultrasound temperature imaging using the constant- and adaptive-k algorithms. Concurrently, an infrared imaging system and thermocouples were used to measure surface temperature distribution of the sample and internal ablation temperatures for comparisons with ultrasound estimates. Experimental results demonstrated that the proposed adaptive-k method improved the performance in visualizing the temperature distribution. In particular, the estimation errors were also reduced even when the temperature of the tissue is higher than 50°C. The proposed adaptive-k ultrasound temperature imaging strategy has potential to serve as a thermal dosage evaluation tool for monitoring high-temperature RFA.
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Liu YD, Li Q, Zhou Z, Yeah YW, Chang CC, Lee CY, Tsui PH. Adaptive ultrasound temperature imaging for monitoring radiofrequency ablation. PLoS One 2017; 12:e0182457. [PMID: 28837584 PMCID: PMC5570358 DOI: 10.1371/journal.pone.0182457] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 07/18/2017] [Indexed: 12/31/2022] Open
Abstract
Radiofrequency ablation (RFA) has been widely used as an alternative treatment modality for liver tumors. Monitoring the temperature distribution in the tissue during RFA is required to assess the thermal dosage. Ultrasound temperature imaging based on the detection of echo time shifts has received the most attention in the past decade. The coefficient k, connecting the temperature change and the echo time shift, is a medium-dependent parameter used to describe the confounding effects of changes in the speed of sound and thermal expansion as temperature increases. The current algorithm of temperature estimate based on echo time shift detection typically uses a constant k, resulting in estimation errors when ablation temperatures are higher than 50°C. This study proposes an adaptive-k algorithm that enables the automatic adjustment of the coefficient k during ultrasound temperature monitoring of RFA. To verify the proposed algorithm, RFA experiments on in vitro porcine liver samples (total n = 15) were performed using ablation powers of 10, 15, and 20 W. During RFA, a clinical ultrasound system equipped with a 7.5-MHz linear transducer was used to collect backscattered signals for ultrasound temperature imaging using the constant- and adaptive-k algorithms. Concurrently, an infrared imaging system and thermocouples were used to measure surface temperature distribution of the sample and internal ablation temperatures for comparisons with ultrasound estimates. Experimental results demonstrated that the proposed adaptive-k method improved the performance in visualizing the temperature distribution. In particular, the estimation errors were also reduced even when the temperature of the tissue is higher than 50°C. The proposed adaptive-k ultrasound temperature imaging strategy has potential to serve as a thermal dosage evaluation tool for monitoring high-temperature RFA.
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Affiliation(s)
- Yi-Da Liu
- School of Electronic Information Engineering, Tianjin University, Tianjin, China
| | - Qiang Li
- School of Electronic Information Engineering, Tianjin University, Tianjin, China
| | - Zhuhuang Zhou
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
- Faculty of Information Technology, Beijing University of Technology, Beijing, China
| | - Yao-Wen Yeah
- Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan
| | - Chien-Cheng Chang
- Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan
- * E-mail: (PHT); (CCC)
| | - Chia-Yen Lee
- Department of Electrical Engineering, National United University, Miao-Li, Taiwan
| | - Po-Hsiang Tsui
- Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Medical Imaging Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
- * E-mail: (PHT); (CCC)
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