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Klos A, Bailly L, Rolland du Roscoat S, Orgéas L, Henrich Bernardoni N, Broche L, King A. Optimising 4D imaging of fast-oscillating structures using X-ray microtomography with retrospective gating. Sci Rep 2024; 14:20499. [PMID: 39227377 PMCID: PMC11372196 DOI: 10.1038/s41598-024-68684-1] [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: 06/04/2024] [Accepted: 07/26/2024] [Indexed: 09/05/2024] Open
Abstract
Imaging the internal architecture of fast-vibrating structures at micrometer scale and kilohertz frequencies poses great challenges for numerous applications, including the study of biological oscillators, mechanical testing of materials, and process engineering. Over the past decade, X-ray microtomography with retrospective gating has shown very promising advances in meeting these challenges. However, breakthroughs are still expected in acquisition and reconstruction procedures to keep improving the spatiotemporal resolution, and study the mechanics of fast-vibrating multiscale structures. Thereby, this works aims to improve this imaging technique by minimising streaking and motion blur artefacts through the optimisation of experimental parameters. For that purpose, we have coupled a numerical approach relying on tomography simulation with vibrating particles with known and ideal 3D geometry (micro-spheres or fibres) with experimental campaigns. These were carried out on soft composites, imaged in synchrotron X-ray beamlines while oscillating up to 400 Hz, thanks to a custom-developed vibromechanical device. This approach yields homogeneous angular sampling of projections and gives reliable predictions of image quality degradation due to motion blur. By overcoming several technical and scientific barriers limiting the feasibility and reproducibility of such investigations, we provide guidelines to enhance gated-CT 4D imaging for the analysis of heterogeneous, high-frequency oscillating materials.
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Affiliation(s)
- Antoine Klos
- Univ. Grenoble Alpes, CNRS, Grenoble INP, 3SR, 38000, Grenoble, France
- Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab, 38000, Grenoble, France
| | - Lucie Bailly
- Univ. Grenoble Alpes, CNRS, Grenoble INP, 3SR, 38000, Grenoble, France.
| | | | - Laurent Orgéas
- Univ. Grenoble Alpes, CNRS, Grenoble INP, 3SR, 38000, Grenoble, France
| | | | - Ludovic Broche
- ID19 beamline, ESRF - The European Synchrotron, CS 40220, 38043, Grenoble, France
| | - Andrew King
- PSICHE beamline, Synchrotron SOLEIL, F-91190, Saint-Aubin, France
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2
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Zhang Y, Jiang Z, Zhang Y, Ren L. A review on 4D cone-beam CT (4D-CBCT) in radiation therapy: Technical advances and clinical applications. Med Phys 2024; 51:5164-5180. [PMID: 38922912 PMCID: PMC11321939 DOI: 10.1002/mp.17269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/05/2024] [Accepted: 06/01/2024] [Indexed: 06/28/2024] Open
Abstract
Cone-beam CT (CBCT) is the most commonly used onboard imaging technique for target localization in radiation therapy. Conventional 3D CBCT acquires x-ray cone-beam projections at multiple angles around the patient to reconstruct 3D images of the patient in the treatment room. However, despite its wide usage, 3D CBCT is limited in imaging disease sites affected by respiratory motions or other dynamic changes within the body, as it lacks time-resolved information. To overcome this limitation, 4D-CBCT was developed to incorporate a time dimension in the imaging to account for the patient's motion during the acquisitions. For example, respiration-correlated 4D-CBCT divides the breathing cycles into different phase bins and reconstructs 3D images for each phase bin, ultimately generating a complete set of 4D images. 4D-CBCT is valuable for localizing tumors in the thoracic and abdominal regions where the localization accuracy is affected by respiratory motions. This is especially important for hypofractionated stereotactic body radiation therapy (SBRT), which delivers much higher fractional doses in fewer fractions than conventional fractionated treatments. Nonetheless, 4D-CBCT does face certain limitations, including long scanning times, high imaging doses, and compromised image quality due to the necessity of acquiring sufficient x-ray projections for each respiratory phase. In order to address these challenges, numerous methods have been developed to achieve fast, low-dose, and high-quality 4D-CBCT. This paper aims to review the technical developments surrounding 4D-CBCT comprehensively. It will explore conventional algorithms and recent deep learning-based approaches, delving into their capabilities and limitations. Additionally, the paper will discuss the potential clinical applications of 4D-CBCT and outline a future roadmap, highlighting areas for further research and development. Through this exploration, the readers will better understand 4D-CBCT's capabilities and potential to enhance radiation therapy.
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Affiliation(s)
- Yawei Zhang
- University of Florida Proton Therapy Institute, Jacksonville, FL 32206, USA
- Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL 32608, USA
| | - Zhuoran Jiang
- Medical Physics Graduate Program, Duke University, Durham, NC 27710, USA
| | - You Zhang
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lei Ren
- Department of Radiation Oncology, University of Maryland, Baltimore, MD 21201, USA
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van Thiel BS, de Boer M, Ridwan Y, de Kleijnen MGJ, van Vliet N, van der Linden J, de Beer I, van Heijningen PM, Vermeij WP, Hoeijmakers JHJ, Danser AHJ, Kanaar R, Duncker DJ, van der Pluijm I, Essers J. Hybrid Molecular and Functional Micro-CT Imaging Reveals Increased Myocardial Apoptosis Preceding Cardiac Failure in Progeroid Ercc1 Mice. Mol Imaging Biol 2024; 26:628-637. [PMID: 38498063 PMCID: PMC11281969 DOI: 10.1007/s11307-024-01902-4] [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: 11/20/2023] [Revised: 02/15/2024] [Accepted: 02/19/2024] [Indexed: 03/19/2024]
Abstract
PURPOSE In this study, we explored the role of apoptosis as a potential biomarker for cardiac failure using functional micro-CT and fluorescence molecular tomography (FMT) imaging techniques in Ercc1 mutant mice. Ercc1 is involved in multiple DNA repair pathways, and its mutations contribute to accelerated aging phenotypes in both humans and mice, due to the accumulation of DNA lesions that impair vital DNA functions. We previously found that systemic mutations and cardiomyocyte-restricted deletion of Ercc1 in mice results in left ventricular (LV) dysfunction at older age. PROCEDURES AND RESULTS Here we report that combined functional micro-CT and FMT imaging allowed us to detect apoptosis in systemic Ercc1 mutant mice prior to the development of overt LV dysfunction, suggesting its potential as an early indicator and contributing factor of cardiac impairment. The detection of apoptosis in vivo was feasible as early as 12 weeks of age, even when global LV function appeared normal, underscoring the potential of apoptosis as an early predictor of LV dysfunction, which subsequently manifested at 24 weeks. CONCLUSIONS This study highlights the utility of combined functional micro-CT and FMT imaging in assessing cardiac function and detecting apoptosis, providing valuable insights into the potential of apoptosis as an early biomarker for cardiac failure.
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Affiliation(s)
- Bibi S van Thiel
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Department of Vascular Surgery, Erasmus MC Cardiovascular Institute, Erasmus University Medical Center, Room 702A, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Martine de Boer
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC Cardiovascular Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Yanto Ridwan
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Department of Radiotherapy, Erasmus University Medical Center, Room 702A, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands
| | - Marion G J de Kleijnen
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC Cardiovascular Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Nicole van Vliet
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Janette van der Linden
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC Cardiovascular Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Isa de Beer
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Paula M van Heijningen
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Wilbert P Vermeij
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
| | - Jan H J Hoeijmakers
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
- Institute for Genome Stability in Aging and Disease, Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - A H Jan Danser
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Roland Kanaar
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
| | - Dirk J Duncker
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC Cardiovascular Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ingrid van der Pluijm
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands.
- Department of Vascular Surgery, Erasmus MC Cardiovascular Institute, Erasmus University Medical Center, Room 702A, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
| | - Jeroen Essers
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands.
- Department of Vascular Surgery, Erasmus MC Cardiovascular Institute, Erasmus University Medical Center, Room 702A, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
- Department of Radiotherapy, Erasmus University Medical Center, Room 702A, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
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Deep 3D reconstruction of synchrotron X-ray computed tomography for intact lungs. Sci Rep 2023; 13:1738. [PMID: 36720962 PMCID: PMC9889716 DOI: 10.1038/s41598-023-27627-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 01/04/2023] [Indexed: 02/02/2023] Open
Abstract
Synchrotron X-rays can be used to obtain highly detailed images of parts of the lung. However, micro-motion artifacts induced by such as cardiac motion impede quantitative visualization of the alveoli in the lungs. This paper proposes a method that applies a neural network for synchrotron X-ray Computed Tomography (CT) data to reconstruct the high-quality 3D structure of alveoli in intact mouse lungs at expiration, without needing ground-truth data. Our approach reconstructs the spatial sequence of CT images by using a deep-image prior with interpolated input latent variables, and in this way significantly enhances the images of alveolar structure compared with the prior art. The approach successfully visualizes 3D alveolar units of intact mouse lungs at expiration and enables us to measure the diameter of the alveoli. We believe that our approach helps to accurately visualize other living organs hampered by micro-motion.
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Shi Y, Li J, Li K, Zhang X, Chang P, Huang Z, Liu Y, Wang Y, Zhan Y, Cao X, Zhu S. Detector-trigger-based cardiac multiphase micro-CT imaging for small animals. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2023; 31:1047-1066. [PMID: 37483057 DOI: 10.3233/xst-230034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
BACKGROUND Micro-computed tomography is important in cardiac imaging for preclinical small animal models, but motion artifacts may appear due to the rapid heart rates. To avoid influence of motion artifacts, the prospective ECG gating schemes based on an X-ray source trigger have been investigated. However, due to the lack of pulsed X-ray exposure modes, high-resolution micro-focus X-ray sources do not support source triggering in most cases. OBJECTIVE To develop a fast-cardiac multiphase acquisition strategy using prospective ECG gating for micro-focus X-ray tubes with a continuous emission mode. METHODS The proposed detector-trigger-based prospective ECG gating acquisition scheme (DTB-PG) triggers the X-ray detector at the R peak of ECG, and then collects multiple phase projections of the heart in one ECG cycle by sequence acquisition. Cardiac multiphase images are reconstructed after performing the same acquisition in all views. The feasibility of this strategy was verified in multiphase imaging experiments of a phantom with 150 ms motion period and a mouse heart on a micro-focus micro-CT system with continuous emission mode. RESULTS Using a high frame-rate CMOS detector, DTB-PG discriminates the positions of the motion phantom well in 10 different phases and enables to distinguish the changes in the cardiac volume of the mouse in different phases. The acquisition rate of DTB-PG is much faster than other prospective gating schemes as demonstrated by theoretical analysis. CONCLUSIONS DTB-PG combines the advantages of prospective ECG gating strategies and X-ray detector-trigger mode to suppress motion artifacts, achieve ultra-fast acquisition rates, and relax hardware limitations.
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Affiliation(s)
- Yu Shi
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
| | - Juntao Li
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
| | - Ke Li
- Xi'an Key Laboratory for Prevention and Treatment of Common Aging Diseases, Translational and Research Centre for Prevention and Therapy of Chronic Disease, Institute of Basic and Translational Medicine, Xi'an Medical University, Xi'an, China
| | - Xuexue Zhang
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
| | - Peng Chang
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
| | - Zujian Huang
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
| | - Yanyun Liu
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
| | - Yihan Wang
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
| | - Yonghua Zhan
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
| | - Xu Cao
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
| | - Shouping Zhu
- School of Life Science and Technology, Xidian University & Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, Xi'an, Shaanxi, China
- Xi'an Key Laboratory of Intelligent Sensing and Regulation of trans-Scale Life Information & International Joint Research Center for Advanced Medical Imaging and Intelligent Diagnosis and Treatment, School of Life Science and Technology, Xidian University, Xi'an, Shaanxi, China
- Innovation Center for Advanced Medical Imaging and Intelligent Medicine, Guangzhou Institute of Technology, Xidian University, Guangzhou, Guangdong, China
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Badea CT. Principles of Micro X-ray Computed Tomography. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00006-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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El Ketara S, Ford NL. Time-course study of a gold nanoparticle contrast agent for cardiac-gated micro-CT imaging in mice. Biomed Phys Eng Express 2020; 6:035025. [PMID: 33438670 DOI: 10.1088/2057-1976/ab8741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Although micro-computed tomography (micro-CT) images have high contrast for bone or air, between soft tissues the contrast is typically low. To overcome this inherent issue, attenuating exogenous contrast agents are used to provide contrast enhancement in the vasculature and abdominal organs. The aim of this study is to measure the contrast enhancement time course for a gold nanoparticle blood-pool contrast agent and use it to perform cardiac-gated 4D micro-CT scans of the heart. Six healthy female C57BL/6 mice were anesthetized and imaged after receiving an injected dose of MVivo gold nanoparticle blood-pool contrast agent. Following the injection, we performed micro-CT scans at 0, 0.25, 0.5, 0.75, 1, 2, 4, 8, 24, 48 and 72 h. The mean CT number was measured for 7 different organs. No contrast enhancement was noticed in the bladder, kidneys or muscle during the time-course study. However, it clearly appears that the contrast enhancement is high in both right ventricle and vena cava. To perform cardiac-gated imaging, either the gold nanoparticle agent (n = 3) or an iodine-based (n = 3) contrast agent was introduced and images representing 9 phases of the cardiac cycle were obtained in 6 additional mice. A few typical cardiac parameters were measured or calculated, with similar accuracy between the gold and iodinated agents, but better visualization of structures with the gold agent. The MVivo Au contrast agent can be used for investigations of cardiac or vascular disease with a single bolus injection, with an optimal cardiac imaging window identified during the first hour after injection, demonstrating similar image quality to iodinated contrast agents and excellent measurement accuracy. Furthermore, the long-lasting contrast enhancement of up to 8 h can be very useful for scanning protocols that require longer acquisition times.
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Affiliation(s)
- Samir El Ketara
- Oral Biological and Medical Sciences, The University of British Columbia, Vancouver, Canada. Université Grenobles Alpes, Grenoble, France
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Gitsioudis G, Nunninger M, Missiou A, Wolf P, Katus HA, Korosoglou G. Multimodality cardiac computed tomography angiography and magnetic resonance with clinical-grade scanners provide robust assessment of cardiac morphology and function in rabbits. J Thorac Dis 2019; 11:4762-4771. [PMID: 31903266 DOI: 10.21037/jtd.2019.10.46] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Background Non-invasive computer tomography (CT)- and magnetic resonance (MR)-based cardiac imaging still remains challenging in rodents. To investigate the robustness of non-invasive multimodality cardiac imaging in rabbits using clinical-grade CT and MR scanners. Methods A total of 16 rabbits (2.7-4.0 kg) serially underwent cardiac-gated imaging using a clinical-grade 256-row CT and a 1.5 Tesla MR-scanner at baseline and at 4-month follow-up (16±1 weeks). Image analysis included image quality (5-grade scale), left ventricular (LV) volumes, LV stroke volume, LV diameters, LV wall thickness and ejection fraction (LVEF). Results Cardiac MR (CMR) and CT angiography (CTA) provide images with an overall good image quality (excellent or good quality: CMR 82% vs. CTA 78%, P=0.68). Linear regression analysis demonstrated a good correlation of all diameters (diam.) and volumes (vol.) as assessed by CTA and CMR (diam.: r=0.9, 95% CI: 0.8-0.9; vol.: r=0.8, 95% CI: 0.6-0.9; P<0.0001 for both). CTA-based volumetric analysis revealed slightly higher LVEF values as compared to CMR (CTA: 64%±1%, CMR: 59%±1%, P=0.002). Analysis of inter-/intra-observer agreement demonstrated excellent agreements for diameters (CMR: 98.5%/98.7%; CTA: 98.2%/97.4%) and volumes (CMR: 99.9%/98.8%; CTA 98.7%/98.7%). Finally, serial CMR- and CTA-based assessment of cardiac diameters and volumes delivered excellent intersession agreements of baseline versus follow-up data (diam.: CMR: r=0.89; CTA: r=0.92; vol.: CMR: r=0.87; CTA: r=0.96, P<0.0001 for all). Conclusions Multimodality non-invasive assessment of cardiac function and aortic hemodynamics is feasible and robust in rabbits using clinical-grade and MR and CT scanners. These imaging modalities could improve serial cardiac assessment for disease monitoring in preclinical settings.
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Affiliation(s)
- Gitsios Gitsioudis
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany.,Department of Cardiology, University of Heidelberg, Heidelberg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg, Heidelberg, Germany.,Department of Internal Medicine, Cardiology, Hospital of Bietigheim-Vaihingen, Academic Hospital of the University of Heidelberg, Bietigheim, Germany
| | - Maximilian Nunninger
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany.,Department of Cardiology, University of Heidelberg, Heidelberg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg, Heidelberg, Germany
| | - Anna Missiou
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany.,Department of Cardiology, University of Heidelberg, Heidelberg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg, Heidelberg, Germany.,Department of Cardiology, Clinic of Ludwigsburg, Academic Hospital of the University of Heidelberg, Ludwigsburg, Germany
| | - Peter Wolf
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany.,Department of Cardiology, University of Heidelberg, Heidelberg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg, Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany.,Department of Cardiology, University of Heidelberg, Heidelberg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg, Heidelberg, Germany
| | - Grigorios Korosoglou
- Department of Cardiology, University of Heidelberg, Heidelberg, Germany.,Department of Cardiology, University of Heidelberg, Heidelberg, Germany DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg, Heidelberg, Germany
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Kojonazarov B, Belenkov A, Shinomiya S, Wilchelm J, Kampschulte M, Mizuno S, Ghofrani HA, Grimminger F, Weissmann N, Seeger W, Schermuly RT. Evaluating Systolic and Diastolic Cardiac Function in Rodents Using Microscopic Computed Tomography. Circ Cardiovasc Imaging 2019; 11:e007653. [PMID: 30525986 DOI: 10.1161/circimaging.118.007653] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND The use of microscopic computed tomography to assess the key functional parameters of systolic emptying or diastolic filling in small animals has not been previously reported. The aim of the study was to test whether microscopic computed tomography can assess the dynamics of both left ventricle and right ventricle (RV) diastolic filling and systolic emptying in an experimental model of pulmonary arterial hypertension Methods and Results: The Wistar-Kyoto rats were injected subcutaneously with the VEGF (vascular endothelial growth factor)-receptor inhibitor SU5416 (20 mg/kg body weight) and were then exposed to chronic hypoxia (10% oxygen) for 21 days (SU5416-hypoxia) followed by normoxia for an additional 2 weeks. Thereafter, multiphase cine cardiac images were acquired using a microscopic computed tomography scanner in conjunction with a blood-pool iodinated contrast agent. Examination of the 3-dimensional images of SU5416-hypoxia rats confirmed the presence of severe pulmonary arterial hypertension. Functional parameters that describe the dynamics of ventricular systolic ejection and diastolic filling were calculated. RV peak ejection rate was significantly decreased ( P<0.03) in SU5416-hypoxia rats compared with controls. RV peak filling rate had a significant decrease compared with controls ( P<0.03), particularly in the early phase of diastole ( P<0.03). This was accompanied by increased time to peak filling rate ( P<0.03) and total filling time ( P<0.06). Spearman analysis between microscopic computed tomography RV diastolic indices and invasively derived RV end-diastolic pressure indicated excellent correlation. CONCLUSIONS We developed a method that allows rapid and accurate assessment of cardiac functional indices and that paves the way for more extensive preclinical cardiovascular research.
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Affiliation(s)
- Baktybek Kojonazarov
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.)
| | | | | | - Jochen Wilchelm
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.)
| | - Marian Kampschulte
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.)
| | - Shiro Mizuno
- Kanazawa Medical University, Ishikawa, Japan (S.S., S.M.)
| | - Hossein Ardeschir Ghofrani
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.)
| | - Friedrich Grimminger
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.)
| | - Norbert Weissmann
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.)
| | - Werner Seeger
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.).,Max-Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (W.S.)
| | - Ralph Theo Schermuly
- German Center for Lung Research (DZL), Justus-Liebig University of Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany (B.K., J.W., M.K., H.A.G., F.G., N.W., W.S., R.T.S.)
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10
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Numerical simulation of novel concept 4D cardiac microtomography for small rodents based on all-optical Thomson scattering X-ray sources. Sci Rep 2019; 9:8439. [PMID: 31186451 PMCID: PMC6560041 DOI: 10.1038/s41598-019-44779-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 05/20/2019] [Indexed: 12/17/2022] Open
Abstract
Accurate dynamic three-dimensional (4D) imaging of the heart of small rodents is required for the preclinical study of cardiac biomechanics and their modification under pathological conditions, but technological challenges are met in laboratory practice due to the very small size and high pulse rate of the heart of mice and rats as compared to humans. In 4D X-ray microtomography (4D μCT), the achievable spatio-temporal resolution is hampered by limitations in conventional X-ray sources and detectors. Here, we propose a proof-of-principle 4D μCT platform, exploiting the unique spatial and temporal features of novel concept, all-optical X-ray sources based on Thomson scattering (TS). The main spatial and spectral properties of the photon source are investigated using a TS simulation code. The entire data acquisition workflow has been also simulated, using a novel 4D numerical phantom of a mouse chest with realistic intra- and inter-cycle motion. The image quality of a typical single 3D time frame has been studied using Monte Carlo simulations, taking into account the effects of the typical structure of the TS X-ray beam. Finally, we discuss the perspectives and shortcomings of the proposed platform.
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11
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Guo X, Liu Y, Kim JL, Kim EY, Kim EQ, Jansen A, Li K, Chan M, Keenan BT, Conejo-Garcia J, Lim DC. Effect of cyclical intermittent hypoxia on Ad5CMVCre induced solitary lung cancer progression and spontaneous metastases in the KrasG12D+; p53fl/fl; myristolated p110fl/fl ROSA-gfp mouse. PLoS One 2019; 14:e0212930. [PMID: 30811514 PMCID: PMC6392281 DOI: 10.1371/journal.pone.0212930] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 02/12/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Epidemiological data suggests that obstructive sleep apnea (OSA) is associated with increased cancer incidence and mortality. We investigate the effects of cyclical intermittent hypoxia (CIH), akin to the underlying pathophysiology of OSA, on lung cancer progression and metastatic profile in a mouse model. METHODS Intrathoracic injection of Ad5CMVCre virus into a genetically engineered mouse (GEM) KrasG12D+/-; p53fl/fl; myristolated-p110αfl/fl-ROSA-gfp was utilized to induce a solitary lung cancer. Male mice were then exposed to either CIH or Sham for 40-41 days until harvest. To monitor malignant progression, serial micro CT scans with respiratory gating (no contrast) was performed. To detect spontaneous metastases in distant organs, H&E and immunohistochemistry were performed. RESULTS Eighty-eight percent of injected Ad5CMVCre virus was recovered from left lung tissue, indicating reliable and accurate injections. Serial micro CT demonstrated that CIH increases primary lung tumor volume progression compared to Sham on days 33 (p = 0.004) and 40 (p<0.001) post-injection. In addition, CIH increases variability in tumor volume on day 19 (p<0.0001), day 26 (p<0.0001), day 33 (p = 0.025) and day 40 (p = 0.004). Finally, metastases are frequently detected in heart, mediastinal lymph nodes, and right lung using H&E and immunohistochemistry. CONCLUSIONS Using a GEM mouse model of metastatic lung cancer, we report that male mice with solitary lung cancer have accelerated malignant progression and increased variability in tumor growth when exposed to cyclical intermittent hypoxia. Our results indicate that cyclical intermittent hypoxia is a pathogenic factor in non-small cell lung cancer that promotes the more rapid growth of developing tumors.
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Affiliation(s)
- Xiaofeng Guo
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Yan Liu
- Department of Otolaryngology Head and Neck Surgery, the Second Hospital, Jilin University, Changchun, Jilin Province, China
| | - Jessica L. Kim
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Emily Y. Kim
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Edison Q. Kim
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alexandria Jansen
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Katherine Li
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - May Chan
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Brendan T. Keenan
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jose Conejo-Garcia
- Division of Sleep Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Diane C. Lim
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Immunology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, Florida, United States of America
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12
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Affiliation(s)
- Guohua Cao
- Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061, USA
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13
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D'Eurydice MN, Arns CH, Arns JY, Armstrong RT. Dynamic imaging of multiphase flow through porous media using 4D cumulative reconstruction. J Microsc 2018; 272:12-24. [PMID: 29971773 DOI: 10.1111/jmi.12728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/06/2018] [Indexed: 11/30/2022]
Abstract
This paper introduces an original application on reconstruction strategies for X-ray computed microtomography, enabling the observation of time-dependent changes that occur during multiphase flow. In general, by sparsely collecting radiographs, the reconstruction of the object is compromised. Optimizations can be achieved by combining specific characteristics of the dynamics with the acquisition. Herein, the proposed method relies on short random intervals in which no drastic changes occur in the sample to acquire as many radiographs as possible that constitute a reconstructible data set. As these intervals are unpredictable, the method tries to guarantee that the collected radiograph data during these specific intervals are enough to recover useful information about the dynamics. Simulations of a percolating fluid in a digital rock are used to replicate an X-ray computed microtomography experiment to test the proposed method. The results demonstrate the potential of the proposed strategy for imaging multiphase flow in porous media and how data collected during distinct events can be combined to enhance the reconstruction of frames of the percolation process.
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Affiliation(s)
- M N D'Eurydice
- School of Minerals and Energy Resources Engineering, University of New South Wales, Kensington, NSW, Australia.,Source Crafting Limited, Wellington, New Zealand
| | - C H Arns
- School of Minerals and Energy Resources Engineering, University of New South Wales, Kensington, NSW, Australia
| | - J-Y Arns
- School of Minerals and Energy Resources Engineering, University of New South Wales, Kensington, NSW, Australia
| | - R T Armstrong
- School of Minerals and Energy Resources Engineering, University of New South Wales, Kensington, NSW, Australia
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14
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Holbrook M, Clark DP, Badea CT. Low-dose 4D cardiac imaging in small animals using dual source micro-CT. Phys Med Biol 2018; 63:025009. [PMID: 29148430 DOI: 10.1088/1361-6560/aa9b45] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Micro-CT is widely used in preclinical studies, generating substantial interest in extending its capabilities in functional imaging applications such as blood perfusion and cardiac function. However, imaging cardiac structure and function in mice is challenging due to their small size and rapid heart rate. To overcome these challenges, we propose and compare improvements on two strategies for cardiac gating in dual-source, preclinical micro-CT: fast prospective gating (PG) and uncorrelated retrospective gating (RG). These sampling strategies combined with a sophisticated iterative image reconstruction algorithm provide faster acquisitions and high image quality in low-dose 4D (i.e. 3D + Time) cardiac micro-CT. Fast PG is performed under continuous subject rotation which results in interleaved projection angles between cardiac phases. Thus, fast PG provides a well-sampled temporal average image for use as a prior in iterative reconstruction. Uncorrelated RG incorporates random delays during sampling to prevent correlations between heart rate and sampling rate. We have performed both simulations and animal studies to validate these new sampling protocols. Sampling times for 1000 projections using fast PG and RG were 2 and 3 min, respectively, and the total dose was 170 mGy each. Reconstructions were performed using a 4D iterative reconstruction technique based on the split Bregman method. To examine undersampling robustness, subsets of 500 and 250 projections were also used for reconstruction. Both sampling strategies in conjunction with our iterative reconstruction method are capable of resolving cardiac phases and provide high image quality. In general, for equal numbers of projections, fast PG shows fewer errors than RG and is more robust to undersampling. Our results indicate that only 1000-projection based reconstruction with fast PG satisfies a 5% error criterion in left ventricular volume estimation. These methods promise low-dose imaging with a wide range of preclinical applications in cardiac imaging.
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Affiliation(s)
- M Holbrook
- Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC 27710, United States of America
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15
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Puett C, Inscoe C, Hartman A, Calliste J, Franceschi DK, Lu J, Zhou O, Lee YZ. An update on carbon nanotube-enabled X-ray sources for biomedical imaging. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2018; 10. [PMID: 28398001 DOI: 10.1002/wnan.1475] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 02/04/2017] [Accepted: 03/11/2017] [Indexed: 11/10/2022]
Abstract
A new imaging technology has emerged that uses carbon nanotubes (CNT) as the electron emitter (cathode) for the X-ray tube. Since the performance of the CNT cathode is controlled by simple voltage manipulation, CNT-enabled X-ray sources are ideal for the repetitive imaging steps needed to capture three-dimensional information. As such, they have allowed the development of a gated micro-computed tomography (CT) scanner for small animal research as well as stationary tomosynthesis, an experimental technology for large field-of-view human imaging. The small animal CT can acquire images at specific points in the respiratory and cardiac cycles. Longitudinal imaging therefore becomes possible and has been applied to many research questions, ranging from tumor response to the noninvasive assessment of cardiac output. Digital tomosynthesis (DT) is a low-dose and low-cost human imaging tool that captures some depth information. Known as three-dimensional mammography, DT is now used clinically for breast imaging. However, the resolution of currently-approved DT is limited by the need to swing the X-ray source through space to collect a series of projection views. An array of fixed and distributed CNT-enabled sources provides the solution and has been used to construct stationary DT devices for breast, lung, and dental imaging. To date, over 100 patients have been imaged on Institutional Review Board-approved study protocols. Early experience is promising, showing an excellent conspicuity of soft-tissue features, while also highlighting technical and post-acquisition processing limitations that are guiding continued research and development. Additionally, CNT-enabled sources are being tested in miniature X-ray tubes that are capable of generating adequate photon energies and tube currents for clinical imaging. Although there are many potential applications for these small field-of-view devices, initial experience has been with an X-ray source that can be inserted into the mouth for dental imaging. Conceived less than 20 years ago, CNT-enabled X-ray sources are now being manufactured on a commercial scale and are powering both research tools and experimental human imaging devices. WIREs Nanomed Nanobiotechnol 2018, 10:e1475. doi: 10.1002/wnan.1475 This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.
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Affiliation(s)
- Connor Puett
- Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA
| | - Christina Inscoe
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
- Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Allison Hartman
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
| | - Jabari Calliste
- Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Dora K Franceschi
- Department of Radiology, University of North Carolina, Chapel Hill, NC, USA
| | - Jianping Lu
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
- Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Otto Zhou
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
- Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Yueh Z Lee
- Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
- Department of Radiology, University of North Carolina, Chapel Hill, NC, USA
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16
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Jang SY, Kim HK, Youn H, Cho S, Cunningham IA. Fourier Analysis of Noise Characteristics in Cone-Beam Microtomography Laboratory Scanners. IEEE Trans Biomed Eng 2016; 64:173-183. [PMID: 27093307 DOI: 10.1109/tbme.2016.2552496] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
GOAL We investigate the signal and noise performance of an x-ray microtomography system that incorporates a complementary metal-oxide-semiconductor flat-panel detector as a projection image receptor. METHODS Signal and noise performance is analyzed in the Fourier domain using modulation-transfer function (MTF), noise-power spectrum (NPS), and noise-equivalent number of quanta (NEQ) with respect to magnification and different convolution kernels for image reconstruction. RESULTS Higher magnification provides lower NPS, and thus, higher NEQ performance in the transaxial planes from microtomography. A window function capable of smoothing the ramp filter edge to below one-half of the Nyquist limit results in better performance in terms of NPS and NEQ. The characteristics of convolution kernels do not affect signal and noise performance in longitudinal planes; hence, MTF performance mainly dominates the NEQ performance. The signal and noise performances investigated in this study are demonstrated with images obtained from the contrast phantom and postmortem mouse. CONCLUSION The results of our study could be helpful in developing x-ray microtomography systems based on flat-panel detectors.
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17
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Hendrikx G, Bauwens M, Wierts R, Mottaghy FM, Post MJ. Left ventricular function measurements in a mouse myocardial infarction model. Comparison between 3D-echocardiography and ECG-gated SPECT. Nuklearmedizin 2016; 55:115-22. [PMID: 27046440 DOI: 10.3413/nukmed-0776-15-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 02/22/2016] [Indexed: 12/20/2022]
Abstract
AIM To assess the accuracy of ECG-gated micro (µ)-SPECT in a mouse myocardial infarction (MI) model in comparison to 3D-echocardiography. ANIMALS, METHODS In a mouse (Swiss mice) MI model we compared the accuracy of technetium-99m sestamibi (99mTc-sestamibi) myocardial perfusion, electrocardiogram (ECG) gated µSPECT to 3D-echocardiography in determining left ventricular function. 3D-echocardiography and myocardial perfusion ECG-gated µSPECT data were acquired in the same animal at baseline (n = 11) and 7 (n = 8) and 35 (n = 9) days post ligation of the left anterior descending coronary artery (LAD). Sham operated mice were used as a control (8, 6 and 7 mice respectively). Additionally, after day 35 µSPECT scans, hearts were harvested and 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) staining and autoradiography was performed to determine infarct size. RESULTS In both infarcted and sham-operated mice we consistently found comparable values for the end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) obtained by 3D-echocardiography and ECG-gated µSPECT. Excellent correlations between measurements from 3D-echocardiography and ECG-gated µSPECT were found for EDV, ESV and EF (r = 0.9532, r = 0.9693 respectively and r = 0.9581) in infarcted mice. Furthermore, comparable infarct size values were found at day 35 post MI by TTC staining and autoradiography (27.71 ± 1.80% and 29.20 ± 1.18% with p = 0.43). CONCLUSION We have demonstrated that ECG-gated µSPECT imaging provides reliable left ventricular function measurements in a mouse MI model. Obtained results were comparable to the highly accurate 3D-echocardiography. This, in addition to the opportunity to simultaneously image multiple biological processes during a single acquisition makes µSPECT imaging a serious option for studying cardiovascular disease in small animals.
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Affiliation(s)
| | | | | | - Felix M Mottaghy
- Prof. Dr. Felix M. Mottaghy, Department of Nuclear Medicine, Maastricht University Medical Centre (MUMC+), Postbox 5800, 6202 AZ Maastricht, The Netherlands, Tel. +31/433 87 49 11,
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18
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van Deel E, Ridwan Y, van Vliet JN, Belenkov S, Essers J. In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography. J Vis Exp 2016:53603. [PMID: 26967592 PMCID: PMC4828165 DOI: 10.3791/53603] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that MicroCT provides quantitative high-resolution three-dimensional (3D) anatomical data non-destructively and longitudinally. Most importantly, with the development of a novel preclinical iodinated contrast agent called eXIA160, functional and metabolic assessment of the heart became possible. However, prior to the advent of commercial MicroCT scanners equipped with X-ray flat-panel detector technology and easy-to-use cardio-respiratory gating, preclinical studies of cardiovascular disease (CVD) in small animals required a MicroCT technologist with advanced skills, and thus were impractical for widespread implementation. The goal of this work is to provide a practical guide to the use of the high-speed Quantum FX MicroCT system for comprehensive determination of myocardial global and regional function along with assessment of myocardial perfusion, metabolism and viability in healthy mice and in a cardiac ischemia mouse model induced by permanent occlusion of the left anterior descending coronary artery (LAD).
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Affiliation(s)
- Elza van Deel
- Department of Genetics, Erasmus MC, Rotterdam; Department of Experimental Cardiology, Erasmus MC, Rotterdam
| | | | | | | | - Jeroen Essers
- Department of Genetics, Erasmus MC, Rotterdam; Department of Vascular Surgery, Erasmus MC, Rotterdam; Department of Radiation Oncology, Erasmus MC, Rotterdam;
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19
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Brehm M, Sawall S, Maier J, Sauppe S, Kachelrieß M. Cardiorespiratory motion-compensated micro-CT image reconstruction using an artifact model-based motion estimation. Med Phys 2015; 42:1948-58. [PMID: 25832085 DOI: 10.1118/1.4916083] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Cardiac in vivo micro-CT imaging of small animals typically requires double gating due to long scan times and high respiratory rates. The simultaneous respiratory and cardiac gating can either be done prospectively or retrospectively. In any case, for true 5D imaging, i.e., three spatial dimensions plus one respiratory-temporal dimension plus one cardiac temporal dimension, the amount of information corresponding to a given respiratory and cardiac phase is orders of magnitude lower than the total amount of information acquired. Achieving similar image quality for 5D than for usual 3D investigations would require increasing the amount of data and thus the applied dose to the animal. Therefore, the goal is phase-correlated imaging with high image quality but without increasing the dose level. METHODS To achieve this, the authors propose a new image reconstruction algorithm that makes use of all available projection data, also of that corresponding to other motion windows. In particular, the authors apply a motion-compensated image reconstruction approach that sequentially compensates for respiratory and cardiac motion to decrease the impact of sparsification. In that process, all projection data are used no matter which motion phase they were acquired in. Respiratory and cardiac motion are compensated for by using motion vector fields. These motion vector fields are estimated from initial phase-correlated reconstructions based on a deformable registration approach. To decrease the sensitivity of the registration to sparse-view artifacts, an artifact model-based approach is used including a cyclic consistent nonrigid registration algorithm. RESULTS The preliminary results indicate that the authors' approach removes the sparse-view artifacts of conventional phase-correlated reconstructions while maintaining temporal resolution. In addition, it achieves noise levels and spatial resolution comparable to that of nongated reconstructions due to the improved dose usage. By using the proposed motion estimation, no sensitivity to streaking artifacts has been observed. CONCLUSIONS Using sequential double gating combined with artifact model-based motion estimation allows to accurately estimate respiratory and cardiac motion from highly undersampled data. No sensitivity to streaking artifacts introduced by sparse angular sampling has been observed for the investigated dose levels. The motion-compensated image reconstruction was able to correct for both, respiratory and cardiac motion, by applying the estimated motion vector fields. The administered dose per animal can thus be reduced for 5D imaging allowing for longitudinal studies at the highest image quality.
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Affiliation(s)
- Marcus Brehm
- Varian Medical System Imaging Laboratory, Täfernstrasse 7, Baden-Dättwil 5405, Switzerland and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany
| | - Stefan Sawall
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany
| | - Joscha Maier
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany
| | - Sebastian Sauppe
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany
| | - Marc Kachelrieß
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany
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20
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Mokso R, Schwyn DA, Walker SM, Doube M, Wicklein M, Müller T, Stampanoni M, Taylor GK, Krapp HG. Four-dimensional in vivo X-ray microscopy with projection-guided gating. Sci Rep 2015; 5:8727. [PMID: 25762080 PMCID: PMC4356984 DOI: 10.1038/srep08727] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 01/21/2015] [Indexed: 11/19/2022] Open
Abstract
Visualizing fast micrometer scale internal movements of small animals is a key challenge for functional anatomy, physiology and biomechanics. We combine phase contrast tomographic microscopy (down to 3.3 μm voxel size) with retrospective, projection-based gating (in the order of hundreds of microseconds) to improve the spatiotemporal resolution by an order of magnitude over previous studies. We demonstrate our method by visualizing 20 three-dimensional snapshots through the 150 Hz oscillations of the blowfly flight motor.
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Affiliation(s)
- Rajmund Mokso
- Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - Daniel A Schwyn
- 1] Department of Bioengineering, Imperial College London, UK [2] Department of Zoology, University of Oxford, UK
| | | | - Michael Doube
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, UK
| | | | | | - Marco Stampanoni
- 1] Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland [2] Institute for Biomedical Engineering, ETH and University of Zurich, Switzerland
| | | | - Holger G Krapp
- Department of Bioengineering, Imperial College London, UK
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21
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Bondoc AB, Detombe S, Dunmore-Buyze J, Gutpell KM, Liu L, Kaszuba A, Han S, McGirr R, Hadway J, Drangova M, Hoffman LM. Application of 3-d echocardiography and gated micro-computed tomography to assess cardiomyopathy in a mouse model of duchenne muscular dystrophy. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:2857-2867. [PMID: 25308942 DOI: 10.1016/j.ultrasmedbio.2014.07.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 04/15/2014] [Accepted: 07/27/2014] [Indexed: 06/04/2023]
Abstract
The purpose of this study was to measure changes in cardiac function as cardiomyopathy progresses in a mouse model of Duchenne muscular dystrophy using 3-D ECG-gated echocardiography. This study is the first to correlate cardiac volumes acquired using 3-D echocardiography with those acquired using retrospectively gated micro-computed tomography (CT). Both were further compared with standard M-mode echocardiography and histologic analyses. We found that although each modality measures a decrease in cardiac function as disease progresses in mdx/utrn(-/-) mice (n = 5) compared with healthy C57BL/6 mice (n = 8), 3-D echocardiography has higher agreement with gold-standard measurements acquired by gated micro-CT, with little standard deviation between measurements. M-Mode echocardiography measurements, in comparison, exhibit considerably greater variability and user bias. Given the radiation dose associated with micro-CT and the geometric assumptions made in M-mode echocardiography to calculate ventricular volume, we suggest that use of 3-D echocardiography has important advantages that may allow for the measurement of early disease changes that occur before overt cardiomyopathy.
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Affiliation(s)
- Andrew B Bondoc
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Sarah Detombe
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada
| | - Joy Dunmore-Buyze
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada
| | - Kelly M Gutpell
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada; Department of Anatomy & Cell Biology, Western University, London, Ontario, Canada
| | - Linshan Liu
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Amanda Kaszuba
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
| | - Seongryoung Han
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
| | - Rebecca McGirr
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
| | - Jennifer Hadway
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada; Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada
| | - Maria Drangova
- Department of Medical Biophysics, Western University, London, Ontario, Canada; Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada
| | - Lisa M Hoffman
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada; Department of Anatomy & Cell Biology, Western University, London, Ontario, Canada.
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22
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Abstract
PURPOSE The objective of this study was to compare a new generation of four-dimensional micro-single photon emission computed tomography (microSPECT) with microCT for the quantitative in vivo assessment of murine cardiac function. PROCEDURES Four-dimensional isotropic cardiac images were acquired from anesthetized normal C57BL/6 mice with either microSPECT (n = 6) or microCT (n = 6). One additional mouse with myocardial infarction (MI) was scanned with both modalities. Prior to imaging, mice were injected with either technetium tetrofosmin for microSPECT or a liposomal blood pool contrast agent for microCT. Segmentation of the left ventricle (LV) was performed using Vitrea (Vital Images) software, to derive global and regional function. RESULTS Measures of global LV function between microSPECT and microCT groups were comparable (e.g., ejection fraction = 71 ± 6 % microSPECT and 68 ± 4 % microCT). Regional functional indices (wall motion, wall thickening, regional ejection fraction) were also similar for the two modalities. In the mouse with MI, microSPECT identified a large perfusion defect that was not evident with microCT. CONCLUSIONS Despite lower spatial resolution, microSPECT was comparable to microCT in the quantitative evaluation of cardiac function. MicroSPECT offers an advantage over microCT in the ability to evaluate simultaneously myocardial radiotracer distribution and function, simultaneously. MicroSPECT should be considered as an alternative to microCT and magnetic resonance for preclinical cardiac imaging in the mouse.
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Ashton JR, Befera N, Clark D, Qi Y, Mao L, Rockman HA, Johnson GA, Badea CT. Anatomical and functional imaging of myocardial infarction in mice using micro-CT and eXIA 160 contrast agent. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 9:161-8. [PMID: 24523061 DOI: 10.1002/cmmi.1557] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 05/10/2013] [Accepted: 06/17/2013] [Indexed: 11/09/2022]
Abstract
Noninvasive small animal imaging techniques are essential for evaluation of cardiac disease and potential therapeutics. A novel preclinical iodinated contrast agent called eXIA 160 has recently been developed, which has been evaluated for micro-CT cardiac imaging. eXIA 160 creates strong contrast between blood and tissue immediately after its injection and is subsequently taken up by the myocardium and other metabolically active tissues over time. We focus on these properties of eXIA and show its use in imaging myocardial infarction in mice. Five C57BL/6 mice were imaged ~2 weeks after left anterior descending coronary artery ligation. Six C57BL/6 mice were used as controls. Immediately after injection of eXIA 160, an enhancement difference between blood and myocardium of ~340 HU enabled cardiac function estimation via 4D micro-CT scanning with retrospective gating. Four hours post-injection, the healthy perfused myocardium had a contrast difference of ~140 HU relative to blood while the infarcted myocardium showed no enhancement. These differences allowed quantification of infarct size via dual-energy micro-CT. In vivo micro-SPECT imaging and ex vivo triphenyl tetrazolium chloride (TTC) staining provided validation for the micro-CT findings. Root mean squared error of infarct measurements was 2.7% between micro-CT and SPECT, and 4.7% between micro-CT and TTC. Thus, micro-CT with eXIA 160 can be used to provide both morphological and functional data for preclinical studies evaluating myocardial infarction and potential therapies. Further studies are warranted to study the potential use of eXIA 160 as a CT molecular imaging tool for other metabolically active tissues in the mouse.
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Affiliation(s)
- Jeffrey R Ashton
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, 27710, USA
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24
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Clark DP, Badea CT. Micro-CT of rodents: state-of-the-art and future perspectives. Phys Med 2014; 30:619-34. [PMID: 24974176 PMCID: PMC4138257 DOI: 10.1016/j.ejmp.2014.05.011] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 05/15/2014] [Accepted: 05/28/2014] [Indexed: 02/06/2023] Open
Abstract
Micron-scale computed tomography (micro-CT) is an essential tool for phenotyping and for elucidating diseases and their therapies. This work is focused on preclinical micro-CT imaging, reviewing relevant principles, technologies, and applications. Commonly, micro-CT provides high-resolution anatomic information, either on its own or in conjunction with lower-resolution functional imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). More recently, however, advanced applications of micro-CT produce functional information by translating clinical applications to model systems (e.g., measuring cardiac functional metrics) and by pioneering new ones (e.g. measuring tumor vascular permeability with nanoparticle contrast agents). The primary limitations of micro-CT imaging are the associated radiation dose and relatively poor soft tissue contrast. We review several image reconstruction strategies based on iterative, statistical, and gradient sparsity regularization, demonstrating that high image quality is achievable with low radiation dose given ever more powerful computational resources. We also review two contrast mechanisms under intense development. The first is spectral contrast for quantitative material discrimination in combination with passive or actively targeted nanoparticle contrast agents. The second is phase contrast which measures refraction in biological tissues for improved contrast and potentially reduced radiation dose relative to standard absorption imaging. These technological advancements promise to develop micro-CT into a commonplace, functional and even molecular imaging modality.
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Affiliation(s)
- D P Clark
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Box 3302, Durham, NC 27710, USA
| | - C T Badea
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Box 3302, Durham, NC 27710, USA.
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25
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Armitage SEJ, Pollmann SI, Detombe SA, Drangova M. Least-error projection sorting to optimize retrospectively gated cardiac micro-CT of free-breathing mice. Med Phys 2013; 39:1452-61. [PMID: 22380378 DOI: 10.1118/1.3681949] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop and characterize a technique for optimizing image quality by eliminating streaking artifacts in retrospectively gated microcomputed tomography (micro-CT) images of mice caused by insufficient and irregular angular sampling. METHODS A least-error sorting technique was developed to minimize streak artifacts in retrospectively gated cardiac micro-CT images. To ensure complete filling of projection space, for each angular position, the projection acquired closest to the desired cardiac phase is used to reconstruct a volumetric image. An acrylic slanted-edge phantom undergoing cyclic motion was used to characterize the system's resolution. The phantom was scanned using a volumetric micro-CT scanner equipped with a flat-panel detector mounted on a slip-ring gantry. Projection images of the moving phantom were collected over a period of 60 s using a variety of acquisition protocols with the rotation period of the gantry ranging from 1 to 5 s. The modulation transfer function (MTF) of the reconstructed images was measured for many combinations of acquisition and reconstruction parameters. The use of the least-error technique was also demonstrated in vivo. RESULTS The motion blurring introduced into the images at physiologically significant velocities of 6 cm∕s agreed well with predicted values; limiting resolution (frequency at 10% MTF) degraded from 2.5 to 1.0 mm(-1) for a velocity of 6 cm∕s and 5 s∕rotation gantry speed. Faster gantry rotation speeds led to improved temporal resolution but the scanner's data storage and transfer rates and field of view limitations made scanning at gantry speeds faster than 2 s∕rotation impractical. CONCLUSIONS The least-error technique effectively eliminates streaking artifact caused by missing views and allows for optimization of image quality in retrospectively gated micro-CT.
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26
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Detombe SA, Dunmore-Buyze J, Petrov IE, Drangova M. X-ray dose delivered during a longitudinal micro-CT study has no adverse effect on cardiac and pulmonary tissue in C57BL/6 mice. Acta Radiol 2013; 54:435-41. [PMID: 23436828 DOI: 10.1177/0284185113475608] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Micro-computed tomography (micro-CT) offers numerous advantages for small animal imaging, including the ability to monitor the same animals throughout a longitudinal study. However, concerns are often raised regarding the effects of X-ray dose accumulated over the course of the experiment. PURPOSE To scan C57BL/6 mice multiple times per week for 6 weeks, in order to determine the effect of the cumulative dose on pulmonary and cardiac tissue at the end of the study. MATERIAL AND METHODS C57BL/6 male mice were split into two groups (irradiated group = 10, control group = 10). The irradiated group was scanned (80 kVp/50 mA) three times weekly for 6 weeks, resulting in a weekly dose of 0.84 Gy, and a total study dose of 5.04 Gy. The control group was scanned on the final week. Scans from week 6 were reconstructed and the lungs and heart were analyzed. RESULTS Overall, there was no significant difference in lung volume or lung density or in left ventricular volume or ejection fraction between the control group and the irradiated group. Histological samples taken from excised lung and myocardial tissue also showed no evidence of inflammation or fibrosis in the irradiated group. CONCLUSION This study demonstrated that a 5 Gy X-ray dose accumulated over 6 weeks during a longitudinal micro-CT study had no significant effects on the pulmonary and myocardial tissue of C57BL/6 mice. As a result, the many advantages of micro-CT imaging, including rapid acquisition of high-resolution, isotropic images in free-breathing mice, can be taken advantage of in longitudinal studies without concern for negative dose-related effects.
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Affiliation(s)
- Sarah A Detombe
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON
- Department of Medical Biophysics, Western University, London, ON, Canada
| | - Joy Dunmore-Buyze
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON
| | - Ivailo E Petrov
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON
| | - Maria Drangova
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON
- Department of Medical Biophysics, Western University, London, ON, Canada
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27
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Clark D, Badea A, Liu Y, Johnson GA, Badea CT. Registration-based segmentation of murine 4D cardiac micro-CT data using symmetric normalization. Phys Med Biol 2012; 57:6125-45. [PMID: 22971564 DOI: 10.1088/0031-9155/57/19/6125] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Micro-CT can play an important role in preclinical studies of cardiovascular disease because of its high spatial and temporal resolution. Quantitative analysis of 4D cardiac images requires segmentation of the cardiac chambers at each time point, an extremely time consuming process if done manually. To improve throughput this study proposes a pipeline for registration-based segmentation and functional analysis of 4D cardiac micro-CT data in the mouse. Following optimization and validation using simulations, the pipeline was applied to in vivo cardiac micro-CT data corresponding to ten cardiac phases acquired in C57BL/6 mice (n = 5). After edge-preserving smoothing with a novel adaptation of 4D bilateral filtration, one phase within each cardiac sequence was manually segmented. Deformable registration was used to propagate these labels to all other cardiac phases for segmentation. The volumes of each cardiac chamber were calculated and used to derive stroke volume, ejection fraction, cardiac output, and cardiac index. Dice coefficients and volume accuracies were used to compare manual segmentations of two additional phases with their corresponding propagated labels. Both measures were, on average, >0.90 for the left ventricle and >0.80 for the myocardium, the right ventricle, and the right atrium, consistent with trends in inter- and intra-segmenter variability. Segmentation of the left atrium was less reliable. On average, the functional metrics of interest were underestimated by 6.76% or more due to systematic label propagation errors around atrioventricular valves; however, execution of the pipeline was 80% faster than performing analogous manual segmentation of each phase.
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Affiliation(s)
- Darin Clark
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC 27710, USA
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28
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Burk LM, Lee YZ, Wait JM, Lu J, Zhou OZ. Non-contact respiration monitoring for in-vivo murine micro computed tomography: characterization and imaging applications. Phys Med Biol 2012; 57:5749-63. [PMID: 22948192 DOI: 10.1088/0031-9155/57/18/5749] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A cone beam micro-CT has previously been utilized along with a pressure-tracking respiration sensor to acquire prospectively gated images of both wild-type mice and various adult murine disease models. While the pressure applied to the abdomen of the subject by this sensor is small and is generally without physiological effect, certain disease models of interest, as well as very young animals, are prone to atelectasis with added pressure, or they generate too weak a respiration signal with this method to achieve optimal prospective gating. In this work we present a new fibre-optic displacement sensor which monitors respiratory motion of a subject without requiring physical contact. The sensor outputs an analogue signal which can be used for prospective respiration gating in micro-CT imaging. The device was characterized and compared against a pneumatic air chamber pressure sensor for the imaging of adult wild-type mice. The resulting images were found to be of similar quality with respect to physiological motion blur; the quality of the respiration signal trace obtained using the non-contact sensor was comparable to that of the pressure sensor and was superior for gating purposes due to its better signal-to-noise ratio. The non-contact sensor was then used to acquire in-vivo micro-CT images of a murine model for congenital diaphragmatic hernia and of 11-day-old mouse pups. In both cases, quality CT images were successfully acquired using this new respiration sensor. Despite the presence of beam hardening artefacts arising from the presence of a fibre-optic cable in the imaging field, we believe this new technique for respiration monitoring and gating presents an opportunity for in-vivo imaging of disease models which were previously considered too delicate for established animal handling methods.
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Affiliation(s)
- Laurel M Burk
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, USA.
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29
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Johnston SM, Johnson GA, Badea CT. Temporal and spectral imaging with micro-CT. Med Phys 2012; 39:4943-58. [PMID: 22894420 PMCID: PMC3416878 DOI: 10.1118/1.4736809] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 06/20/2012] [Accepted: 06/27/2012] [Indexed: 12/18/2022] Open
Abstract
PURPOSE Micro-CT is widely used for small animal imaging in preclinical studies of cardiopulmonary disease, but further development is needed to improve spatial resolution, temporal resolution, and material contrast. We present a technique for visualizing the changing distribution of iodine in the cardiac cycle with dual source micro-CT. METHODS The approach entails a retrospectively gated dual energy scan with optimized filters and voltages, and a series of computational operations to reconstruct the data. Projection interpolation and five-dimensional bilateral filtration (three spatial dimensions + time + energy) are used to reduce noise and artifacts associated with retrospective gating. We reconstruct separate volumes corresponding to different cardiac phases and apply a linear transformation to decompose these volumes into components representing concentrations of water and iodine. Since the resulting material images are still compromised by noise, we improve their quality in an iterative process that minimizes the discrepancy between the original acquired projections and the projections predicted by the reconstructed volumes. The values in the voxels of each of the reconstructed volumes represent the coefficients of linear combinations of basis functions over time and energy. We have implemented the reconstruction algorithm on a graphics processing unit (GPU) with CUDA. We tested the utility of the technique in simulations and applied the technique in an in vivo scan of a C57BL∕6 mouse injected with blood pool contrast agent at a dose of 0.01 ml∕g body weight. Postreconstruction, at each cardiac phase in the iodine images, we segmented the left ventricle and computed its volume. Using the maximum and minimum volumes in the left ventricle, we calculated the stroke volume, the ejection fraction, and the cardiac output. RESULTS Our proposed method produces five-dimensional volumetric images that distinguish different materials at different points in time, and can be used to segment regions containing iodinated blood and compute measures of cardiac function. CONCLUSIONS We believe this combined spectral and temporal imaging technique will be useful for future studies of cardiopulmonary disease in small animals.
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Affiliation(s)
- Samuel M Johnston
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina 27710, USA
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30
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Detombe SA, Dunmore-Buyze J, Drangova M. Evaluation of eXIA 160 cardiac-related enhancement in C57BL/6 and BALB/c mice using micro-CT. CONTRAST MEDIA & MOLECULAR IMAGING 2012; 7:240-6. [PMID: 22434637 DOI: 10.1002/cmmi.488] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Evaluation of cardiovascular function in mice using micro-CT requires that a contrast agent be administered to differentiate the blood from the myocardium. eXIA 160, an aqueous colloidal poly-disperse contrast agent with a high iodine concentration (160 mg I ml(-1)), creates strong contrast between blood and tissue with a low injection volume. In this study, the blood-pool enhancement time-course of eXIA 160 is monitored over a 48 h period to determine its optimal use during cardiac function studies in C57BL/6 and BALB/c mice. Eight-second scans were performed (80 kV(p), 110 mA) using the GE Locus Ultra micro-CT scanner. Six C57BL/6 and six BALB/c male mice (22-24 g) were injected via tail vein with 5 µl g(-1) body weight eXIA 160. A precontrast scan was performed; following injection, mice were scanned at 5, 15, 30, 45 and 60 min, and 2, 4, 8, 12, 24 and 48 h. Images were reconstructed, and enhancement-time curves were generated for each of the following tissues: left ventricle (LV), myocardium, liver, spleen, renal cortex, bladder and brown adipose tissue. The highest contrast in the LV occurred at 5 min in both strains (~670 HU above precontrast value). Uptake of the contrast agent by the myocardium was also observed: myocardial tissue showed increasing enhancement over a 4 h period in both strains, remaining even once the contrast was eliminated from the vasculature. In both C57BL/6 and BALB/c strains, eXIA 160 provided high contrast between blood and myocardial tissue for a period of 30 min following injection. Notably, this contrast agent was also taken up by the myocardium and provided continued enhancement when it was eliminated from the blood, making LV wall motion studies possible. In conclusion, eXIA 160, with its high iodine concentration and targeted tissue uptake characteristics, is an ideal agent to use when evaluating cardiovascular function in mice.
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Affiliation(s)
- Sarah A Detombe
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, ON, Canada
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31
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Detombe SA, Xiang FL, Dunmore-Buyze J, White JA, Feng Q, Drangova M. Rapid microcomputed tomography suggests cardiac enlargement occurs during conductance catheter measurements in mice. J Appl Physiol (1985) 2012; 113:142-8. [PMID: 22518829 DOI: 10.1152/japplphysiol.00831.2011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Conductance catheters (CC) represent an established method of determining cardiac function in mice; however, the potentially detrimental effects a catheter may have on the mouse heart have never been evaluated. The present study takes advantage of rapid three-dimensional (3D) microcomputed tomography (CT) to compare simultaneously acquired micro-CT and CC measurements of left ventricular (LV) volumes in healthy and infarcted mice and to determine changes in LV volume and function associated with CC insertion. LV volumes were measured in C57BL/6 mice (10 healthy, 10 infarcted, 2% isoflurane anesthesia) using a 1.4-Fr Millar CC. 3D micro-CT images of each mouse were acquired before CC insertion as well as during catheterization. Each CT scan produced high-resolution images throughout the entire cardiac cycle in <1 min, enabling accurate volume measurements as well as direct visualization of the CC within the LV. Bland-Altman analysis demonstrated that CC measurements underestimate volume compared with CT measurements in both healthy [bias of -18.4 and -28.9 μl for end-systolic (ESV) and end-diastolic volume (EDV), respectively] and infarcted mice (ESV = -51.6 μl and EDV = -71.7 μl); underestimation was attributed to the off-center placement of the catheter. Individual evaluation of each heart revealed LV dilation following CC insertion in 40% of mice in each group. No change in ejection fraction was observed, suggesting the enlargement was caused by volume overload associated with disruption of the papillary muscles or chords. The enlargement witnessed was not significant; however, the results suggest the potential for CC insertion to detrimentally affect mouse myocardium, necessitating further investigation.
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Affiliation(s)
- Sarah A Detombe
- Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada
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32
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Guo X, Johnston SM, Qi Y, Johnson GA, Badea CT. 4D micro-CT using fast prospective gating. Phys Med Biol 2012; 57:257-71. [PMID: 22156062 DOI: 10.1088/0031-9155/57/1/257] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Micro-CT is currently used in preclinical studies to provide anatomical information. But, there is also significant interest in using this technology to obtain functional information. We report here a new sampling strategy for 4D micro-CT for functional cardiac and pulmonary imaging. Rapid scanning of free-breathing mice is achieved with fast prospective gating (FPG) implemented on a field programmable gate array. The method entails on-the-fly computation of delays from the R peaks of the ECG signals or the peaks of the respiratory signals for the triggering pulses. Projection images are acquired for all cardiac or respiratory phases at each angle before rotating to the next angle. FPG can deliver the faster scan time of retrospective gating (RG) with the regular angular distribution of conventional prospective gating for cardiac or respiratory gating. Simultaneous cardio-respiratory gating is also possible with FPG in a hybrid retrospective/prospective approach. We have performed phantom experiments to validate the new sampling protocol and compared the results from FPG and RG in cardiac imaging of a mouse. Additionally, we have evaluated the utility of incorporating respiratory information in 4D cardiac micro-CT studies with FPG. A dual-source micro-CT system was used for image acquisition with pulsed x-ray exposures (80 kVp, 100 mA, 10 ms). The cardiac micro-CT protocol involves the use of a liposomal blood pool contrast agent containing 123 mg I ml(-1) delivered via a tail vein catheter in a dose of 0.01 ml g(-1) body weight. The phantom experiment demonstrates that FPG can distinguish the successive phases of phantom motion with minimal motion blur, and the animal study demonstrates that respiratory FPG can distinguish inspiration and expiration. 4D cardiac micro-CT imaging with FPG provides image quality superior to RG at an isotropic voxel size of 88 μm and 10 ms temporal resolution. The acquisition time for either sampling approach is less than 5 min. The radiation dose associated with the proposed method is in the range of a typical micro-CT dose (256 mGy for the cardiac study). Ignoring respiration does not significantly affect anatomic information in cardiac studies. FPG can deliver short scan times with low-dose 4D micro-CT imaging without sacrificing image quality. FPG can be applied in high-throughput longitudinal studies in a wide range of applications, including drug safety and cardiopulmonary phenotyping.
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Affiliation(s)
- Xiaolian Guo
- Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, People's Republic of China
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33
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Affiliation(s)
- Erik L. Ritman
- Department of Physiology and Biomedical Engineering, Mayo Clinic, College of Medicine; Rochester, Minnesota 55905;
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34
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Sawall S, Bergner F, Lapp R, Mronz M, Karolczak M, Hess A, Kachelriess M. Low-dose cardio-respiratory phase-correlated cone-beam micro-CT of small animals. Med Phys 2011; 38:1416-24. [PMID: 21520853 DOI: 10.1118/1.3551993] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Micro-CT imaging of animal hearts typically requires a double gating procedure because scans during a breath-hold are not possible due to the long scan times and the high respiratory rates, Simultaneous respiratory and cardiac gating can either be done prospectively or retrospectively. True five-dimensional information can be either retrieved with retrospective gating or with prospective gating if several prospective gates are acquired. In any case, the amount of information available to reconstruct one volume for a given respiratory and cardiac phase is orders of magnitud lower than the total amount of information acquired. For example, the reconstruction of a volume from a 10% wide respiratory and a 20% wide cardiac window uses only 2% of the data acquired. Achieving a similar image quality as a nongated scan would therefore require to increase the amount of data and thereby the dose to the animal by up to a factor of 50. METHODS To achieve the goal of low-dose phase-correlated (LDPC) imaging, the authors propose to use a highly efficient combination of slightly modified existing algorithms. In particular, the authors developed a variant of the McKinnon-Bates image reconstruction algorithm and combined it with bilateral filtering in up to five dimensions to significantly reduce image noise without impairing spatial or temporal resolution. RESULTS The preliminary results indicate that the proposed LDPC reconstruction method typically reduces image noise by a factor of up to 6 (e.g., from 170 to 30 HU), while the dose values lie in a range from 60 to 500 mGy. Compared to other publications that apply 250-1800 mGy for the same task [C. T. Badea et al., "4D micro-CT of the mouse heart," Mol. Imaging 4(2), 110-116 (2005); M. Drangova et al., "Fast retrospectively gated quantitative four-dimensional (4D) cardiac micro computed tomography imaging of free-breathing mice," Invest. Radiol. 42(2), 85-94 (2007); S. H. Bartling et al., "Retrospective motion gating in small animal CT of mice and rats," Invest. Radiol. 42(10), 704-714 (2007)], the authors' LDPC approach therefore achieves a more than tenfold dose usage improvement. CONCLUSIONS The LDPC reconstruction method improves phase-correlated imaging from highly undersampled data. Artifacts caused by sparse angular sampling are removed and the image noise is decreased, while spatial and temporal resolution are preserved. Thus, the administered dose per animal can be decreased allowing for long-term studies with reduced metabolic inference.
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Affiliation(s)
- Stefan Sawall
- Institute of Medical Physics, University of Erlangen-Nürnberg, 91052 Erlangen, Germany.
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35
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Badea CT, Johnston SM, Qi Y, Johnson GA. 4D micro-CT for cardiac and perfusion applications with view under sampling. Phys Med Biol 2011; 56:3351-69. [PMID: 21558587 DOI: 10.1088/0031-9155/56/11/011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Micro-CT is commonly used in preclinical studies to provide anatomical information. There is growing interest in obtaining functional measurements from 4D micro-CT. We report here strategies for 4D micro-CT with a focus on two applications: (i) cardiac imaging based on retrospective gating and (ii) pulmonary perfusion using multiple contrast injections/rotations paradigm. A dual source micro-CT system is used for image acquisition with a sampling rate of 20 projections per second. The cardiac micro-CT protocol involves the use of a liposomal blood pool contrast agent. Fast scanning of free breathing mice is achieved using retrospective gating. The ECG and respiratory signals are used to sort projections into ten cardiac phases. The pulmonary perfusion protocol uses a conventional contrast agent (Isovue 370) delivered by a micro-injector in four injections separated by 2 min intervals to allow for clearance. Each injection is synchronized with the rotation of the animal, and each of the four rotations is started with an angular offset of 22.5 from the starting angle of the previous rotation. Both cardiac and perfusion protocols result in an irregular angular distribution of projections that causes significant streaking artifacts in reconstructions when using traditional filtered backprojection (FBP) algorithms. The reconstruction involves the use of the point spread function of the micro-CT system for each time point, and the analysis of the distribution of the reconstructed data in the Fourier domain. This enables us to correct for angular inconsistencies via deconvolution and identify regions where data is missing. The missing regions are filled with data from a high quality but temporally averaged prior image reconstructed with all available projections. Simulations indicate that deconvolution successfully removes the streaking artifacts while preserving temporal information. 4D cardiac micro-CT in a mouse was performed with adequate image quality at isotropic voxel size of 88 µm and 10 ms temporal resolution. 4D pulmonary perfusion images were obtained in a mouse at 176 µm and 687 ms temporal resolution. Compared with FBP reconstruction, the streak reduction ratio is 70% and the contrast to noise ratio is 2.5 times greater in the deconvolved images. The radiation dose associated with the proposed methods is in the range of a typical micro-CT dose (0.17 Gy for the cardiac study and 0.21 Gy for the perfusion study). The low dose 4D micro-CT imaging presented here can be applied in high-throughput longitudinal studies in a wide range of applications, including drug safety and cardiopulmonary phenotyping.
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Affiliation(s)
- Cristian T Badea
- Center for In Vivo Microscopy, Box 3302, Duke University Medical Center, Durham, NC 27710,USA.
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36
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Badea CT, Hedlund LW, Cook J, Berridge BR, Johnson GA. Micro-CT imaging assessment of dobutamine-induced cardiac stress in rats. J Pharmacol Toxicol Methods 2011; 63:24-9. [PMID: 20399875 PMCID: PMC2916074 DOI: 10.1016/j.vascn.2010.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/06/2010] [Accepted: 04/08/2010] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Dobutamine (DOB) stress in animal models of heart disease has been imaged so far using echocardiography and magnetic resonance imaging. The purpose of this study was to assess normal response to DOB stress in rats using anatomical and functional data using micro-computed tomography (CT). METHODS Ten normal adult male rats were first injected with a liposomal-based blood pool contrast agent and next infused with DOB via a tail vein catheter. Using prospective gating, 5 pairs of systole/diastole micro-CT images were acquired (a) pre-infusion baseline; (b) at heart rate plateau during infusion of 10 μg/kg/min DOB; (c) at post-DOB infusion baseline; (d) at heart rate plateau during infusion of 30 μg/kg/min DOB; and (e) after post-infusion return to baseline. Heart rate, peripheral and breathing distensions were monitored by oximetry. Micro-CT images with 88-μm isotropic voxels were segmented to obtain cardiac function based on volumetric measurements of the left ventricle. RESULTS DOB stress increased heart rate and cardiac output with both doses. Ejection fraction increased above baseline by an average of 35.9% with the first DOB dose and 18.4% with the second dose. No change was observed in the relative peripheral arterial pressures associated with the significant increases in cardiac output. DISCUSSION Micro-CT proved to be a robust imaging method able to provide isotropic data on cardiac morphology and function. Micro-CT has the advantage of being faster and more cost-effective than MR and is able to provide higher accuracy than echocardiography. The impact of such an enabling technology can be enormous in evaluating cardiotoxic effects of various test drugs.
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Affiliation(s)
- Cristian T. Badea
- Center for In Vivo Microscopy, Department of Radiology, Box 3302 Duke University Medical Center, Durham, NC U.S.A. 27710
| | - Laurence W. Hedlund
- Center for In Vivo Microscopy, Department of Radiology, Box 3302 Duke University Medical Center, Durham, NC U.S.A. 27710
| | - James Cook
- Center for In Vivo Microscopy, Department of Radiology, Box 3302 Duke University Medical Center, Durham, NC U.S.A. 27710
| | - Brian R. Berridge
- GlaxoSmithKline Safety Assessment, 5 Moore Drive, Research Triangle Park, NC U.S.A. 27709
| | - G. Allan Johnson
- Center for In Vivo Microscopy, Department of Radiology, Box 3302 Duke University Medical Center, Durham, NC U.S.A. 27710
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Sandhu GS, Solorio L, Broome AM, Salem N, Kolthammer J, Shah T, Flask C, Duerk JL. Whole animal imaging. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2010; 2:398-421. [PMID: 20836038 DOI: 10.1002/wsbm.71] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Translational research plays a vital role in understanding the underlying pathophysiology of human diseases, and hence development of new diagnostic and therapeutic options for their management. After creating an animal disease model, pathophysiologic changes and effects of a therapeutic intervention on them are often evaluated on the animals using immunohistologic or imaging techniques. In contrast to the immunohistologic techniques, the imaging techniques are noninvasive and hence can be used to investigate the whole animal, oftentimes in a single exam which provides opportunities to perform longitudinal studies and dynamic imaging of the same subject, and hence minimizes the experimental variability, requirement for the number of animals, and the time to perform a given experiment. Whole animal imaging can be performed by a number of techniques including x-ray computed tomography, magnetic resonance imaging, ultrasound imaging, positron emission tomography, single photon emission computed tomography, fluorescence imaging, and bioluminescence imaging, among others. Individual imaging techniques provide different kinds of information regarding the structure, metabolism, and physiology of the animal. Each technique has its own strengths and weaknesses, and none serves every purpose of image acquisition from all regions of an animal. In this review, a broad overview of basic principles, available contrast mechanisms, applications, challenges, and future prospects of many imaging techniques employed for whole animal imaging is provided. Our main goal is to briefly describe the current state of art to researchers and advanced students with a strong background in the field of animal research.
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Affiliation(s)
- Gurpreet Singh Sandhu
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Luis Solorio
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ann-Marie Broome
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Nicolas Salem
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Jeff Kolthammer
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Tejas Shah
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Chris Flask
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Jeffrey L Duerk
- Department of Biomedical Engineering, Case Center of Imaging Research, Case Western Reserve University, Cleveland, OH 44106, USA
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Foster WK, Ford NL. Investigating the effect of longitudinal micro-CT imaging on tumour growth in mice. Phys Med Biol 2010; 56:315-26. [PMID: 21160110 DOI: 10.1088/0031-9155/56/2/002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The aim of this study is to determine the impact of longitudinal micro-CT imaging on the growth of B16F1 tumours in C57BL/6 mice. Sixty mice received 2 × 10(5) B16F1 cells subcutaneously in the hind flank and were divided into control (no scan), 'low-dose' (80 kVp, 70 mA, 8 s, 0.07 Gy), 'medium-dose' (80 kVp, 50 mA, 30 s, 0.18 Gy) and 'high-dose' (80 kVp, 50 mA, 50 s, 0.30 Gy) groups. All imaging was performed on a fast volumetric micro-CT scanner (GE Locus Ultra, London, Canada). Each mouse was imaged on days 4, 8, 12 and 16. After the final imaging session, each tumour was excised, weighed on an electronic balance, imaged to obtain the final tumour volume and processed for histology. Final tumour volume was used to evaluate the impact of longitudinal micro-CT imaging on the tumour growth. An ANOVA indicated no statistically significant difference in tumour volume (p = 0.331, α = β = 0.1) when discriminating against a treatment-sized effect. Histological samples revealed no observable differences in apoptosis or cell proliferation. We conclude that four imaging sessions, using standard protocols, over the course of 16 days did not cause significant changes in final tumour volume for B16F1 tumours in female C57BL/6 mice (ANOVA, α = β = 0.1, p = 0.331).
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Affiliation(s)
- W Kyle Foster
- Department of Physics, Ryerson University, Toronto, Ontario M5B 2K3, Canada
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Cao G, Burk LM, Lee YZ, Calderon-Colon X, Sultana S, Lu J, Zhou O. Prospective-gated cardiac micro-CT imaging of free-breathing mice using carbon nanotube field emission x-ray. Med Phys 2010; 37:5306-12. [PMID: 21089765 DOI: 10.1118/1.3491806] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Carbon nanotube (CNT) based field emission x-ray source technology has recently been investigated for diagnostic imaging applications because of its attractive characteristics including electronic programmability, fast switching, distributed source, and multiplexing. The purpose of this article is to demonstrate the potential of this technology for high-resolution prospective-gated cardiac micro-CT imaging. METHODS A dynamic cone-beam micro-CT scanner was constructed using a rotating gantry, a stationary mouse bed, a flat-panel detector, and a sealed CNT based microfocus x-ray source. The compact single-beam CNT x-ray source was operated at 50 KVp and 2 mA anode current with 100 microm x 100 microm effective focal spot size. Using an intravenously administered iodinated blood-pool contrast agent, prospective cardiac and respiratory-gated micro-CT images of beating mouse hearts were obtained from ten anesthetized free-breathing mice in their natural position. Four-dimensional cardiac images were also obtained by gating the image acquisition to different phases in the cardiac cycle. RESULTS High-resolution CT images of beating mouse hearts were obtained at 15 ms temporal resolution and 6.2 lp/mm spatial resolution at 10% of system MTF. The images were reconstructed at 76 microm isotropic voxel size. The data acquisition time for two cardiac phases was 44 +/- 9 min. The CT values observed within the ventricles and the ventricle wall were 455 +/- 49 and 120 +/- 48 HU, respectively. The entrance dose for the acquisition of a single phase of the cardiac cycle was 0.10 Gy. CONCLUSIONS A high-resolution dynamic micro-CT scanner was developed from a compact CNT microfocus x-ray source and its feasibility for prospective-gated cardiac micro-CT imaging of free-breathing mice under their natural position was demonstrated.
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Affiliation(s)
- Guohua Cao
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Namati E, Thiesse J, Sieren JC, Ross A, Hoffman EA, McLennan G. Longitudinal assessment of lung cancer progression in the mouse using in vivo micro-CT imaging. Med Phys 2010; 37:4793-805. [PMID: 20964199 DOI: 10.1118/1.3476454] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Small animal micro-CT imaging is being used increasingly in preclinical biomedical research to provide phenotypic descriptions of genomic models. Most of this imaging is coincident with animal death and is used to show the extent of disease as an end point. Longitudinal imaging overcomes the limitation of single time-point imaging because it enables tracking of the natural history of disease and provides qualitative and, where possible, quantitative assessments of the effects of an intervention. The pulmonary system is affected by many disease conditions, such as lung cancer, chronic obstructive pulmonary disease, asthma, and granulomatous disorders. Noninvasive imaging can accurately assess the lung phenotype within the living animal, evaluating not only global lung measures, but also regional pathology. However, imaging the lung in the living animal is complicated by rapid respiratory motion, which leads to image based artifacts. Furthermore, no standard mouse lung imaging protocols exist for longitudinal assessment, with each group needing to develop their own systematic approach. METHODS In this article, the authors present an outline for performing longitudinal breath-hold gated micro-CT imaging for the assessment of lung nodules in a mouse model of lung cancer. The authors describe modifications to the previously published intermittent isopressure breath-hold technique including a new animal preparation and anesthesia protocol, implementation of a ring artifact reduction, variable scanner geometry, and polynomial beam hardening correction. In addition, the authors describe a multitime-point data set registration and tumor labeling and tracking strategy. RESULTS In vivo micro-CT data sets were acquired at months 2, 3, and 4 posturethane administration in cancer mice (n = 5) and simultaneously in control mice (n = 3). 137 unique lung nodules were identified from the cancer mice while no nodules were detected in the control mice. A total of 411 nodules were segmented and labeled over the three time-points. Lung nodule metrics including RECIST, Ortho, WHO, and 3D volume were determined and extracted. A tumor incidence rate of 30.44 +/- 1.93 SEM for n = 5 was found with identification of nodules as small as 0.11 mm (RECIST) and as large as 1.66 mm (RECIST). In addition, the tumor growth and doubling rate between months 2-3 and 3-4 were calculated. Here, the growth rate was slightly higher in the second period based on the 3D volume data (0.12 +/- 0.13 to 0.13 +/- 0.17 microl) but significantly less based on the linear diameter metrics [RECIST (0.33 +/- 0.19 to 0.17 +/- 0.18 mm); Ortho (0.24 +/- 0.15 to 0.16 +/- 0.15 mm)], indicating the need to understand how each metric is obtained and how to correctly interpret change in tumor size. CONCLUSIONS In conclusion, micro-CT imaging provides a unique platform for in vivo longitudinal assessment of pulmonary lung cancer progression and potentially tracking of therapies at very high resolutions. The ability to evaluate the same subject over time provides for a sensitive assay that can be carried out on a smaller sample size. When integrated with image processing and analysis routines as detailed in this study, the data acquired from micro-CT imaging can now provide a very powerful assessment of pulmonary disease outcomes.
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Affiliation(s)
- Eman Namati
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA; School of Computer Science, Engineering and Mathematics, Flinders University, Adelaide 5042, Australia.
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Bucholz E, Ghaghada K, Qi Y, Mukundan S, Rockman HA, Johnson GA. Cardiovascular phenotyping of the mouse heart using a 4D radial acquisition and liposomal Gd-DTPA-BMA. Magn Reson Med 2010; 63:979-87. [PMID: 20373399 DOI: 10.1002/mrm.22259] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
MR microscopy has enormous potential for small-animal cardiac imaging because it is capable of producing volumetric images at multiple time points to accurately measure cardiac function. MR has not been used as frequently as ultrasound to measure cardiac function in the small animal because the MR methods required relatively long scan times, limiting throughput. Here, we demonstrate four-dimensional radial acquisition in conjunction with a liposomal blood pool agent to explore functional differences in three populations of mice: six C57BL/6J mice, six DBA/2J mice, and six DBA/2J CSQ+ mice, all with the same gestational age and approximately the same weight. Cardiovascular function was determined by measuring both left ventricular and right ventricular end diastolic volume, end systolic volume, stroke volume, and ejection fraction. Statistical significance was observed in end diastolic volume, end systolic volume, and ejection fraction for left ventricular measurements between all three populations of mice. No statistically significant difference was observed in stroke volume in either the left or right ventricle for any of the three populations of mice. This study shows that MRI is capable of efficient, high-throughput, four-dimensional cardiovascular phenotyping of the mouse.
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Affiliation(s)
- Elizabeth Bucholz
- Center for In Vivo Microscopy, Duke University, Durham, North Carolina, USA
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Nikolov HN, Pelz DM, Lownie SP, Norley CJ, Khan V, Drangova M, Holdsworth DW. Micro-CT–compatible Technique for Measuring Self-expanding Stent Forces. J Vasc Interv Radiol 2010; 21:562-70. [DOI: 10.1016/j.jvir.2010.01.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 09/03/2009] [Accepted: 01/30/2010] [Indexed: 11/28/2022] Open
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Kuntz J, Dinkel J, Zwick S, Bäuerle T, Grasruck M, Kiessling F, Gupta R, Semmler W, Bartling SH. Fully automated intrinsic respiratory and cardiac gating for small animal CT. Phys Med Biol 2010; 55:2069-85. [PMID: 20299735 DOI: 10.1088/0031-9155/55/7/018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used for both cardiac and respiratory gating. The proposed algorithm makes it possible to reconstruct motion-corrected still images as well as to generate four-dimensional (4D) datasets representing the cardiac and pulmonary anatomy of free-breathing animals without the use of electrocardiogram (ECG) or respiratory sensors. Variation analysis of projections from several rotations is used to place a region of interest (ROI) on the diaphragm. The ROI is cranially extended to include the heart. The centre of mass (COM) variation within this ROI, the filtered frequency response and the local maxima are used to derive a binary motion-gating parameter for phase-sensitive gated reconstruction. This algorithm was implemented on a flat-panel-based cone-beam CT scanner and evaluated using a moving phantom and animal scans (seven rats and eight mice). Volumes were determined using a semiautomatic segmentation. In all cases robust gating signals could be obtained. The maximum volume error in phantom studies was less than 6%. By utilizing extrinsic gating via externally placed cardiac and respiratory sensors, the functional parameters (e.g. cardiac ejection fraction) and image quality were equivalent to this current gold standard. This algorithm obviates the necessity of both gating hardware and user interaction. The simplicity of the proposed algorithm enables adoption in a wide range of small animal cone-beam CT scanners.
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Affiliation(s)
- J Kuntz
- Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany.
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Johnston SM, Perez BA, Kirsch DG, Badea CT. Phase-selective image reconstruction of the lungs in small animals using Micro-CT. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2010; 7622:76223G.1-76223G.9. [PMID: 21243034 DOI: 10.1117/12.844359] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Gating in small animal imaging can compensate for artifacts due to physiological motion. This paper presents a strategy for sampling and image reconstruction in the rodent lung using micro-CT. The approach involves rapid sampling of free-breathing mice without any additional hardware to detect respiratory motion. The projection images are analyzed post-acquisition to derive a respiratory signal, which is used to provide weighting factors for each projection that favor a selected phase of the respiration (e.g. end-inspiration or end-expiration) for the reconstruction. Since the sampling cycle and the respiratory cycle are uncorrelated, the sets of projections corresponding to any of the selected respiratory phases do not have a regular angular distribution. This drastically affects the image quality of reconstructions based on simple filtered backprojection. To address this problem, we use an iterative reconstruction algorithm that combines the Simultaneous Algebraic Reconstruction Technique with Total Variation minimization (SART-TV). At each SART-TV iteration, backprojection is performed with a set of weighting factors that favor the desired respiratory phase. To reduce reconstruction time, the algorithm is implemented on a graphics processing unit. The performance of the proposed approach was investigated in simulations and in vivo scans of mice with primary lung cancers imaged with our in-house developed dual tube/detector micro-CT system. We note that if the ECG signal is acquired during sampling, the same approach could be used for phase-selective cardiac imaging.
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Affiliation(s)
- S M Johnston
- Center for In Vivo Microscopy, Dept. of Radiology, Duke University Medical Center, Durham, NC 27710
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Dinkel J, Bartling SH, Kuntz J, Grasruck M, Kopp-Schneider A, Iwasaki M, Dimmeler S, Gupta R, Semmler W, Kauczor HU, Kiessling F. Intrinsic gating for small-animal computed tomography: a robust ECG-less paradigm for deriving cardiac phase information and functional imaging. Circ Cardiovasc Imaging 2009; 1:235-43. [PMID: 19808548 DOI: 10.1161/circimaging.108.784702] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND A projection-based method of intrinsic cardiac gating in small-animal computed tomography imaging is presented. METHODS AND RESULTS In this method, which operates without external ECG monitoring, the gating reference signal is derived from the raw data of the computed tomography projections. After filtering, the derived gating reference signal is used to rearrange the projection images retrospectively into data sets representing different time points in the cardiac cycle during expiration. These time-stamped projection images are then used for tomographic reconstruction of different phases of the cardiac cycle. Intrinsic gating was evaluated in mice and rats and compared with extrinsic retrospective gating. An excellent agreement was achieved between ECG-derived gating signal and self-gating signal (coverage probability for a difference between the 2 measurements to be less than 5 ms was 89.2% in mice and 85.9% in rats). Functional parameters (ventricular volumes and ejection fraction) obtained from the intrinsic and the extrinsic data sets were not significantly different. The ease of use and reliability of intrinsic gating were demonstrated via a chemical stress test on 2 mice, in which the system performed flawlessly despite an increased heart rate. Because of intrinsic gating, the image quality was improved to the extent that even the coronary arteries of mice could be visualized in vivo despite a heart rate approaching 430 bpm. Feasibility of intrinsic gating for functional imaging and assessment of cardiac wall motion abnormalities was successfully tested in a mouse model of myocardial infarction. CONCLUSIONS Our results demonstrate that self-gating using advanced software postprocessing of projection data promises to be a valuable tool for rodent computed tomography imaging and renders ECG gating with external electrodes superfluous.
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Affiliation(s)
- Julien Dinkel
- Department of Radiology, German Cancer Research Center, Heidelberg, Germany.
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Ketterling JA, Aristizábal O. Prospective ECG-gated mouse cardiac imaging with a 34-MHz annular array transducer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2009; 56:1394-404. [PMID: 19574150 PMCID: PMC2752351 DOI: 10.1109/tuffc.2009.1195] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Prospective imaging with electrocardiogram (ECG) and respiratory gating presents an imaging application that leverages the improved image quality of high-frequency (>20 MHz) annular arrays without the need for rapid mechanical motion. The limitation of prospective imaging is that the object being imaged must have a periodically stable motion. The present study investigated the implementation of prospective imaging with a 34 MHz annular-array scan system to image the mouse heart at high effective frame rates, >200 frames/s (fps). M-mode data for all transmit-to-receive pairs were acquired at a series of spatial locations using ECG and respiratory gating, and the data were then synthetically focused in postprocessing. The pulse-repetition frequency of the M-mode data determined the effective frame rate of the final B-mode image sequence. The hearts of adult mice were prospectively imaged and compared with retrospective data acquired with a commercial ultrasonic biomicroscope (UBM). The annular array data were acquired at an effective frame rate of 500 fps spanning 0.5 s, and the UBM data were acquired at 1000 fps spanning 0.15 s. The resulting images showed that multiple heart cycles could be clearly resolved using prospective imaging and that synthetic focusing improved image resolution and SNR of the right ventricle, interventricular septum, posterior edge of the left ventricle (LV), and papillary muscles of the LV versus fixed-focused imaging and the retrospective imaging of the UBM machine.
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Affiliation(s)
- Jeffrey A Ketterling
- Lizzi Center for Biomedical Engineering, Riverside Research Institute, New York, NY, USA.
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Ertel D, Kyriakou Y, Lapp RM, Kalender WA. Respiratory phase-correlated micro-CT imaging of free-breathing rodents. Phys Med Biol 2009; 54:3837-46. [PMID: 19491456 DOI: 10.1088/0031-9155/54/12/015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We provide a dedicated phase-correlated imaging procedure for respiratory gating in micro-CT imaging with automatic detection of the optimal data window providing the least amount of motion blurring. A rawdata-based motion function (kymogram) was used for synchronization purposes and for identification of the optimal data window used for phase-correlated image reconstruction. Measurements were performed on a dual-source micro-CT scanner. Projection data were acquired over ten rotations for multi-segment phase-correlated reconstruction. Visual assessment was performed on datasets of ten free-breathing subjects. The kymogram approach provided a reliable synchronization signal for phase-correlated image reconstruction. Also, it allowed for the identification of phase intervals of increased and decreased motion and the corresponding detection of the optimal reconstruction phase. Phase-correlated images showed a strong improvement with respect to motion blurring compared to standard image reconstruction. A reconstruction for the calculated optimal data window provided the least amount of motion blurring and even allowed for the assessment of small structures in the lung. The dedicated retrospective phase-correlated image reconstruction procedure for respiratory gating is a feasible approach for motion-free imaging. A subject-specific optimal reconstruction phase can minimize motion blurring and further improve image quality.
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Affiliation(s)
- Dirk Ertel
- Institute of Medical Physics, University of Erlangen-Nürnberg, Erlangen, Germany.
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Cao G, Lee YZ, Peng R, Liu Z, Rajaram R, Calderon-Colon X, An L, Wang P, Phan T, Sultana S, Lalush DS, Lu JP, Zhou O. A dynamic micro-CT scanner based on a carbon nanotube field emission x-ray source. Phys Med Biol 2009; 54:2323-40. [PMID: 19321922 DOI: 10.1088/0031-9155/54/8/005] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Current commercial micro-CT scanners have the capability of imaging objects ex vivo with high spatial resolution, but performing in vivo micro-CT on free-breathing small animals is still challenging because their physiological motions are non-periodic and much faster than those of humans. In this paper, we present a prototype physiologically gated micro-computed tomography (micro-CT) scanner based on a carbon nanotube field emission micro-focus x-ray source. The novel x-ray source allows x-ray pulses and imaging sequences to be readily synchronized and gated to non-periodic physiological signals from small animals. The system performance is evaluated using phantoms and sacrificed and anesthetized mice. Prospective respiratory-gated micro-CT images of anesthetized free-breathing mice were collected using this scanner at 50 ms temporal resolution and 6.2 lp mm(-1) at 10% system MTF. The high spatial and temporal resolutions of the micro-CT scanner make it well suited for high-resolution imaging of free-breathing small animals.
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Affiliation(s)
- G Cao
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, USA.
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Ford NL, Martin EL, Lewis JF, Veldhuizen RAW, Holdsworth DW, Drangova M. Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema. Phys Med Biol 2009; 54:2121-30. [DOI: 10.1088/0031-9155/54/7/018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Granton PV, Pollmann SI, Ford NL, Drangova M, Holdsworth DW. Implementation of dual- and triple-energy cone-beam micro-CT for postreconstruction material decomposition. Med Phys 2009; 35:5030-42. [PMID: 19070237 DOI: 10.1118/1.2987668] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Micro-CT has become a powerful tool for small animal research, having the ability to obtain high-resolution in vivo and ex vivo images for analyzing bone mineral content, organ vasculature, and bone microarchitecture extraction. The use of exogenous contrast agents further extends the use of micro-CT techniques, but despite advancements in contrast agents, single-energy micro-CT is still limited in cases where two different materials share similar grey-scale intensity values. This study specifically addresses the development of multiple-energy cone-beam micro-CT, for applications where bone must be separated from blood vessels filled with a Pb-based contrast material (Microfil) in ex vivo studies of rodents and tissue specimens. The authors report the implementation of dual- and triple-energy CT algorithms for material-specific imaging using postreconstruction decomposition of micro-CT data; the algorithms were implemented on a volumetric cone-beam micro-CT scanner (GE Locus Ultra). For the dual-energy approach, extrinsic filtration was applied to the x-ray beam to produce spectra with different proportions of x rays above the K edge of Pb. The optimum x-ray tube energies (140 kVp filtered with 1.45 mm Cu and 96 kVp filtered with 0.3 mm Pb) that maximize the contrast between bone and Microfil were determined through numerical simulation. For the triple-energy decomposition, an additional low-energy spectrum (70 kVp, no added filtration) was used. The accuracy of decomposition was evaluated through simulations and experimental verification of a phantom containing a cortical bone simulating material (SB3), Microfil, and acrylic. Using simulations and phantom experiments, an accuracy greater than 95% was achieved in decompositions of bone and Microfil (for noise levels lower than 11 HU), while soft tissue was separated with accuracy better than 99%. The triple-energy technique demonstrated a slightly higher, but not significantly different, decomposition accuracy than the dual-energy technique for the same achieved noise level in the micro-CT images acquired at the multiple energies. The dual-energy technique was applied to the decomposition of an ex vivo rat specimen perfused with Microfil; successful decomposition of the bone and Microfil was achieved, enabling the visualization and characterization of the vasculature both in areas where the vessels traverse soft tissue and when they are surrounded by bone. In comparison, in single energy micro-CT, vessels surrounded by bone could not be distinguished from the cortical bone, based on grey-scale intensity alone. This work represents the first postreconstruction application of material-specific decomposition that directly takes advantage of the K edge characteristics of a contrast material injected into an animal specimen; the application of the technique resulted in automatic, accurate segmentation of 3D micro-CT images into bone, vessel, and tissue components. The algorithm uses only reconstructed images, rather than projection data, and is calibrated by an operator with signal values in regions identified as being comprised entirely of either cortical bone, contrast-enhanced vessel, or soft tissue; these required calibration values are observed directly within reconstructed CT images acquired at the multiple energies. These features facilitate future implementation on existing research micro-CT systems.
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Affiliation(s)
- P V Granton
- Department of Physics and Astronomy, University of Western Ontario, London Ontario N6A 3K7, Canada
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