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Grolman E, Sirianni QEA, Dunmore-Buyze J, Cruje C, Drangova M, Gillies ER. Depolymerizing self-immolative polymeric lanthanide chelates for vascular imaging. Acta Biomater 2023; 169:530-541. [PMID: 37507034 DOI: 10.1016/j.actbio.2023.07.034] [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: 04/12/2023] [Revised: 07/03/2023] [Accepted: 07/22/2023] [Indexed: 07/30/2023]
Abstract
Medical imaging is widely used clinically and in research to understand disease progression and monitor responses to therapies. Vascular imaging enables the study of vascular disease and therapy, but exogenous contrast agents are generally needed to distinguish the vasculature from surrounding soft tissues. Lanthanide-based agents are commonly employed in MRI, but are also of growing interest for micro-CT, as the position of their k-edges allows them to provide enhanced contrast and also to be employed in dual-energy micro-CT, a technique that can distinguish contrast-enhanced blood vessels from tissues such as bone. Small molecule Gd3+ chelates are available, but are excreted too rapidly. At the same time, a lack of rapid clearance from the body for long-circulating agents presents toxicity concerns. To address these challenges, we describe here the use of self-immolative polymers for the development of new degradable chelates that depolymerize completely from end-to-end following the cleavage of a single end-cap from the polymer terminus. We demonstrate that tuning the end-cap allows the rate of depolymerization to be controlled, while tuning the polymer length enables the polymer to exhibit long circulation times in the blood of mice. After successfully providing one hour of blood contrast, depolymerization led to excretion of the resulting small molecule chelates into the bladder. Despite the high doses required for micro-CT, the agents were well tolerated in mice. Thus, these self-immolative polymeric chelates provide a new platform for the development of medical imaging contrast agents. STATEMENT OF SIGNIFICANCE: Vascular imaging is used clinically to diagnose and monitor vascular disease and in research to understand the progression of disease and study responses to new therapies. For techniques such as magnetic resonance imaging and x-ray computed tomography (CT), long circulating contrast agents are needed to differentiate the vasculature from surrounding tissues. However, if these agents are not rapidly excreted from the body, they can lead to toxicity. We present here a new polymeric system that can chelate hundreds of lanthanide ions for imaging contrast and can circulate for one hour in the blood, but then after end-cap cleavage breaks down completely into small molecules for excretion. The successful application of this system in micro-CT in mice is demonstrated.
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Affiliation(s)
- Eric Grolman
- School of Biomedical Engineering, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B9, Canada; Robarts Research Institute, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada
| | - Quinton E A Sirianni
- Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada
| | - Joy Dunmore-Buyze
- Robarts Research Institute, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada
| | - Charmainne Cruje
- Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5C1, Canada
| | - Maria Drangova
- School of Biomedical Engineering, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B9, Canada; Robarts Research Institute, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5C1, Canada.
| | - Elizabeth R Gillies
- School of Biomedical Engineering, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B9, Canada; Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada; Department of Chemical and Biochemical Engineering, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B9, Canada.
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Wang H, Rehmetulla A, Guo S, Kong X, Lü Z, Guan Y, Xu C, Sulaiman K, Wei G, Liu H. Machine learning based on structural and FTIR spectroscopic datasets for seed autoclassification. RSC Adv 2022; 12:11413-11419. [PMID: 35425064 PMCID: PMC9004588 DOI: 10.1039/d2ra00239f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 03/28/2022] [Indexed: 11/21/2022] Open
Abstract
A single feature set is often unable to effectively classify complex biological samples due to their similar morphology and sizes. This paper proposes a protocol for the fast identification of seed medicinal materials based on micro-structural and infrared spectroscopic characteristics. Three different feature datasets, namely micro-CT, FTIR, and mixed datasets, were established via principal component analysis (PCA) and competitive adaptive reweighted sampling (CARS) and then used to train a back-propagation neural network. The mixed dataset consists of 34-dimensional micro-CT eigenvalues and 13-dimensional FTIR eigenvalues, optimized by PCA and CARS processing and then used to train a BP neural network. The results showed that the classification accuracy reached 89.5% for the micro-CT dataset and 93.3% for the FTIR dataset, and the classification accuracy of the mixed dataset achieved 99.2%, much higher than those of the traditional single feature datasets. This study provides a new protocol for multi-dimensional characteristic architecture with excellent performance for the classification and identification of Chinese medicinal materials. In machine learning, traditional single datasets often cause confusion between species, mixing features to form a mixed dataset will solve this challenge.![]()
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Affiliation(s)
- Hanqiu Wang
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Aybek Rehmetulla
- Institute of Traditional Chinese Medicine and Ethnomedicine, Xinjiang Uyghur Autonomous Region, Urumqi 830002, China
| | - Shanshan Guo
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Xin Kong
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Zhiwei Lü
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Yu Guan
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Cong Xu
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Kaiser Sulaiman
- Institute of Traditional Chinese Medicine and Ethnomedicine, Xinjiang Uyghur Autonomous Region, Urumqi 830002, China
| | - Gongxiang Wei
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Huiqiang Liu
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
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3
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PEG-modified gadolinium nanoparticles as contrast agents for in vivo micro-CT. Sci Rep 2021; 11:16603. [PMID: 34400681 PMCID: PMC8367985 DOI: 10.1038/s41598-021-95716-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/09/2021] [Indexed: 12/30/2022] Open
Abstract
Vascular research is largely performed in rodents with the goal of developing treatments for human disease. Micro-computed tomography (micro-CT) provides non-destructive three-dimensional imaging that can be used to study the vasculature of rodents. However, to distinguish vasculature from other soft tissues, long-circulating contrast agents are required. In this study, we demonstrated that poly(ethylene glycol) (PEG)-coated gadolinium nanoparticles can be used as a vascular contrast agent in micro-CT. The coated particles could be lyophilized and then redispersed in an aqueous solution to achieve 100 mg/mL of gadolinium. After an intravenous injection of the contrast agent into mice, micro-CT scans showed blood pool contrast enhancements of at least 200 HU for 30 min. Imaging and quantitative analysis of gadolinium in tissues showed the presence of contrast agent in clearance organs including the liver and spleen and very low amounts in other organs. In vitro cell culture experiments, subcutaneous injections, and analysis of mouse body weight suggested that the agents exhibited low toxicity. Histological analysis of tissues 5 days after injection of the contrast agent showed cytotoxicity in the spleen, but no abnormalities were observed in the liver, lungs, kidneys, and bladder.
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Clark D, Badea C. Advances in micro-CT imaging of small animals. Phys Med 2021; 88:175-192. [PMID: 34284331 PMCID: PMC8447222 DOI: 10.1016/j.ejmp.2021.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/23/2021] [Accepted: 07/05/2021] [Indexed: 12/22/2022] Open
Abstract
PURPOSE Micron-scale computed tomography (micro-CT) imaging is a ubiquitous, cost-effective, and non-invasive three-dimensional imaging modality. We review recent developments and applications of micro-CT for preclinical research. METHODS Based on a comprehensive review of recent micro-CT literature, we summarize features of state-of-the-art hardware and ongoing challenges and promising research directions in the field. RESULTS Representative features of commercially available micro-CT scanners and some new applications for both in vivo and ex vivo imaging are described. New advancements include spectral scanning using dual-energy micro-CT based on energy-integrating detectors or a new generation of photon-counting x-ray detectors (PCDs). Beyond two-material discrimination, PCDs enable quantitative differentiation of intrinsic tissues from one or more extrinsic contrast agents. When these extrinsic contrast agents are incorporated into a nanoparticle platform (e.g. liposomes), novel micro-CT imaging applications are possible such as combined therapy and diagnostic imaging in the field of cancer theranostics. Another major area of research in micro-CT is in x-ray phase contrast (XPC) imaging. XPC imaging opens CT to many new imaging applications because phase changes are more sensitive to density variations in soft tissues than standard absorption imaging. We further review the impact of deep learning on micro-CT. We feature several recent works which have successfully applied deep learning to micro-CT data, and we outline several challenges specific to micro-CT. CONCLUSIONS All of these advancements establish micro-CT imaging at the forefront of preclinical research, able to provide anatomical, functional, and even molecular information while serving as a testbench for translational research.
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Affiliation(s)
- D.P. Clark
- Quantitative Imaging and Analysis Lab, Department of Radiology, Duke University Medical Center, Durham, NC 27710
| | - C.T. Badea
- Quantitative Imaging and Analysis Lab, Department of Radiology, Duke University Medical Center, Durham, NC 27710
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Sawall S, Amato C, Klein L, Wehrse E, Maier J, Kachelrieß M. Toward molecular imaging using spectral photon-counting computed tomography? Curr Opin Chem Biol 2021; 63:163-170. [PMID: 34051510 DOI: 10.1016/j.cbpa.2021.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 04/07/2021] [Indexed: 12/22/2022]
Abstract
Molecular imaging is a valuable tool in drug discovery and development, early screening and diagnosis of diseases, and therapy assessment among others. Although many different imaging modalities are in use today, molecular imaging with computed tomography (CT) is still challenging owing to its low sensitivity and soft tissue contrast compared with other modalities. Recent technical advances, particularly the introduction of spectral photon-counting detectors, might allow overcoming these challenges. Herein, the fundamentals and recent advances in CT relevant to molecular imaging are reviewed and potential future preclinical and clinical applications are highlighted. The review concludes with a discussion of potential future advancements of CT for molecular imaging.
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Affiliation(s)
- Stefan Sawall
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, 69120, Baden-Württemberg, Germany; Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, Heidelberg, 69120, Baden-Württemberg, Germany.
| | - Carlo Amato
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, 69120, Baden-Württemberg, Germany; Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, Heidelberg, 69120, Baden-Württemberg, Germany
| | - Laura Klein
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, 69120, Baden-Württemberg, Germany; Physical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 226, Heidelberg, 69120, Baden-Württemberg, Germany
| | - Eckhard Wehrse
- Division of Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, 69120, Baden-Württemberg, Germany; Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, Heidelberg, 69120, Baden-Württemberg, Germany
| | - Joscha Maier
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, 69120, Baden-Württemberg, Germany
| | - Marc Kachelrieß
- Division of X-Ray Imaging and CT, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, 69120, Baden-Württemberg, Germany; Medical Faculty, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 672, Heidelberg, 69120, Baden-Württemberg, Germany
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Willemink MJ, Varga-Szemes A, Schoepf UJ, Codari M, Nieman K, Fleischmann D, Mastrodicasa D. Emerging methods for the characterization of ischemic heart disease: ultrafast Doppler angiography, micro-CT, photon-counting CT, novel MRI and PET techniques, and artificial intelligence. Eur Radiol Exp 2021; 5:12. [PMID: 33763754 PMCID: PMC7991013 DOI: 10.1186/s41747-021-00207-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/22/2021] [Indexed: 12/24/2022] Open
Abstract
After an ischemic event, disruptive changes in the healthy myocardium may gradually develop and may ultimately turn into fibrotic scar. While these structural changes have been described by conventional imaging modalities mostly on a macroscopic scale-i.e., late gadolinium enhancement at magnetic resonance imaging (MRI)-in recent years, novel imaging methods have shown the potential to unveil an even more detailed picture of the postischemic myocardial phenomena. These new methods may bring advances in the understanding of ischemic heart disease with potential major changes in the current clinical practice. In this review article, we provide an overview of the emerging methods for the non-invasive characterization of ischemic heart disease, including coronary ultrafast Doppler angiography, photon-counting computed tomography (CT), micro-CT (for preclinical studies), low-field and ultrahigh-field MRI, and 11C-methionine positron emission tomography. In addition, we discuss new opportunities brought by artificial intelligence, while addressing promising future scenarios and the challenges for the application of artificial intelligence in the field of cardiac imaging.
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Affiliation(s)
- Martin J. Willemink
- grid.168010.e0000000419368956Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94035 USA
| | - Akos Varga-Szemes
- grid.259828.c0000 0001 2189 3475Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC USA
| | - U. Joseph Schoepf
- grid.259828.c0000 0001 2189 3475Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC USA
| | - Marina Codari
- grid.168010.e0000000419368956Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94035 USA
| | - Koen Nieman
- grid.168010.e0000000419368956Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA USA ,Stanford Cardiovascular Institute, Stanford, CA 94305 USA
| | - Dominik Fleischmann
- grid.168010.e0000000419368956Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94035 USA ,Stanford Cardiovascular Institute, Stanford, CA 94305 USA
| | - Domenico Mastrodicasa
- Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA, 94035, USA. .,Stanford Cardiovascular Institute, Stanford, CA, 94305, USA.
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7
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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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8
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Panetta D, Gabelloni M, Faggioni L, Pelosi G, Aringhieri G, Caramella D, Salvadori PA. Cardiac Computed Tomography Perfusion: Contrast Agents, Challenges and Emerging Methodologies from Preclinical Research to the Clinics. Acad Radiol 2021; 28:e1-e13. [PMID: 32220550 DOI: 10.1016/j.acra.2019.12.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/20/2019] [Accepted: 12/24/2019] [Indexed: 12/19/2022]
Abstract
Computed Tomography (CT) has long been regarded as a purely anatomical imaging modality. Recent advances on CT technology and Contrast Agents (CA) in both clinical and preclinical cardiac imaging offer opportunities for the use of CT in functional imaging. Combined with modern ECG-gating techniques, functional CT has now become a reality allowing a comprehensive evaluation of myocardial global and regional function, perfusion and coronary angiography. This article aims at reviewing the current status of cardiac CT perfusion and micro-CT perfusion with established and experimental scanners and contrast agents, from clinical practice to the experimental domain of investigations based on animal models of heart diseases.
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9
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Sawall S, Beckendorf J, Amato C, Maier J, Backs J, Vande Velde G, Kachelrieß M, Kuntz J. Coronary micro-computed tomography angiography in mice. Sci Rep 2020; 10:16866. [PMID: 33033290 PMCID: PMC7546728 DOI: 10.1038/s41598-020-73735-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 09/17/2020] [Indexed: 11/09/2022] Open
Abstract
Coronary computed tomography angiography is an established technique in clinical practice and a valuable tool in the diagnosis of coronary artery disease in humans. Imaging of coronaries in preclinical research, i.e. in small animals, is very difficult due to the high demands on spatial and temporal resolution. Mice exhibit heart rates of up to 600 beats per minute motivating the need for highest detector framerates while the coronaries show diameters below 100 μm indicating the requirement for highest spatial resolution. We herein use a custom built micro-CT equipped with dedicated reconstruction algorithms to illustrate that coronary imaging in mice is possible. The scanner provides a spatial and temporal resolution sufficient for imaging of smallest, moving anatomical structures and the dedicated reconstruction algorithms reduced radiation dose to less than 1 Gy but do not yet allow for longitudinal studies. Imaging studies were performed in ten mice administered with a blood-pool contrast agent. Results show that the course of the left coronary artery can be visualized in all mice and all major branches can be identified for the first time using micro-CT. This reduces the gap in cardiac imaging between clinical practice and preclinical research.
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Affiliation(s)
- Stefan Sawall
- German Cancer Research Center (DKFZ), X-Ray Imaging and CT, Heidelberg, 69120, Germany. .,Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, 69120, Germany.
| | - Jan Beckendorf
- University Hospital Heidelberg, Molecular Cardiology and Epigenetics (Internal Medicine VIII), Heidelberg, 69120, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Heidelberg, Germany
| | - Carlo Amato
- German Cancer Research Center (DKFZ), X-Ray Imaging and CT, Heidelberg, 69120, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, 69120, Germany
| | - Joscha Maier
- German Cancer Research Center (DKFZ), X-Ray Imaging and CT, Heidelberg, 69120, Germany.,Department of Physics and Astronomy, Ruprecht-Karls-University Heidelberg, Heidelberg, 69120, Germany
| | - Johannes Backs
- University Hospital Heidelberg, Molecular Cardiology and Epigenetics (Internal Medicine VIII), Heidelberg, 69120, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Heidelberg, Germany
| | - Greetje Vande Velde
- Department of Imaging & Pathology/ MoSAIC, Faculty of Medicine, KU Leuven, Leuven, Belgium
| | - Marc Kachelrieß
- German Cancer Research Center (DKFZ), X-Ray Imaging and CT, Heidelberg, 69120, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, 69120, Germany
| | - Jan Kuntz
- German Cancer Research Center (DKFZ), X-Ray Imaging and CT, Heidelberg, 69120, Germany.,Medical Faculty, Ruprecht-Karls-University Heidelberg, Heidelberg, 69120, Germany
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10
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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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11
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Badea CT, Clark DP, Holbrook M, Srivastava M, Mowery Y, Ghaghada KB. Functional imaging of tumor vasculature using iodine and gadolinium-based nanoparticle contrast agents: a comparison of spectral micro-CT using energy integrating and photon counting detectors. Phys Med Biol 2019; 64:065007. [PMID: 30708357 PMCID: PMC6607440 DOI: 10.1088/1361-6560/ab03e2] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Advances in computed tomography (CT) hardware have propelled the development of novel CT contrast agents. In particular, the spectral capabilities of x-ray CT can facilitate simultaneous imaging of multiple contrast agents. This approach is particularly useful for functional imaging of solid tumors by simultaneous visualization of multiple targets or architectural features that govern cancer development and progression. Nanoparticles are a promising platform for contrast agent development. While several novel imaging moieties based on high atomic number elements are being explored, iodine (I) and gadolinium (Gd) are particularly attractive because of their existing approval for clinical use. In this work, we investigate the in vivo discrimination of I and Gd nanoparticle contrast agents using both dual energy micro-CT with energy integrating detectors (DE-EID) and photon counting detector (PCD)-based spectral micro-CT. Simulations and phantom experiments were performed using varying concentrations of I and Gd to determine the imaging performance with optimized acquisition parameters. Quantitative spectral micro-CT imaging using liposomal-iodine (Lip-I) and liposomal-Gd (Lip-Gd) nanoparticle contrast agents was performed in sarcoma bearing mice for anatomical and functional imaging of tumor vasculature. Iterative reconstruction provided high sensitivity to detect and discriminate relatively low I and Gd concentrations. According to the Rose criterion applied to the experimental results, the detectability limits for I and Gd were approximately 2.5 mg ml-1 for both DE-EID CT and PCD micro-CT, even if the radiation dose was approximately 3.8 times lower with PCD micro-CT. The material concentration maps confirmed expected biodistributions of contrast agents in the blood, liver, spleen and kidneys. The PCD provided lower background signal and better simultaneous visualization of tumor vasculature and intratumoral distribution patterns of nanoparticle contrast agent compared to DE-EID decompositions. Preclinical spectral CT systems such as this could be useful for functional characterization of solid tumors, simultaneous quantitative imaging of multiple targets and for identifying clinically-relevant applications that benefit from the use of spectral imaging. Additionally, it could aid in the development nanoparticles that show promise in the developing field of cancer theranostics (therapy and diagnostics) by measuring vascular tumor biomarkers such as fractional blood volume and the delivery of liposomal chemotherapeutics.
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Affiliation(s)
- C T Badea
- Department of Radiology, Center for In Vivo Microscopy, Duke University, Durham, NC 27710, United States of America.,http://civm.duhs.duke.edu/.,Author to whom any correspondence should be addressed
| | - D P Clark
- Department of Radiology, Center for In Vivo Microscopy, Duke University, Durham, NC 27710, United States of America
| | - M Holbrook
- Department of Radiology, Center for In Vivo Microscopy, Duke University, Durham, NC 27710, United States of America
| | - M Srivastava
- Singleton Department of Pediatric Radiology, Texas Children's Hospital, Houston, TX 77030, United States of America
| | - Y Mowery
- Department of Radiation Oncology, Duke University, Durham, NC 27710, United States of America
| | - K B Ghaghada
- Singleton Department of Pediatric Radiology, Texas Children's Hospital, Houston, TX 77030, United States of America
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12
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In Vivo Detection and Measurement of Aortic Aneurysm and Dissection in Mouse Models Using Microcomputed Tomography with Contrast Agent. CONTRAST MEDIA & MOLECULAR IMAGING 2019; 2019:5940301. [PMID: 30956627 PMCID: PMC6431409 DOI: 10.1155/2019/5940301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/11/2019] [Indexed: 02/03/2023]
Abstract
Objectives The aim of this study was to evaluate the potential of microcomputed tomography (micro-CT) using the intravascular contrast agent ExiTron nano 12000 for aorta imaging and monitoring the dynamic changing process of the aorta in mouse models with aortic aneurysm and dissection. Materials and Methods Experiments were performed on healthy mice and mice with aortic dissection. Mice that were developing aortic dissection and healthy mice underwent micro-CT imaging after injection of ExiTron nano 12000. Time-dependent signal enhancement (at 1, 2, 3, 6, and 12 hours after intravenous injection of the contrast agent, respectively) in the aorta of healthy mice was measured to confirm the optimal imaging time of aorta. Various contrast agent doses (70, 100, and 150 μl per 25 g mouse, respectively) were investigated to determine the optimal required dose for imaging of the aorta. The mice were scanned with micro-CT at 1, 14, and 28 days after onset of aneurysm and dissection to monitor the dynamic changing process of the aorta. Mouse aortas were stained with hematoxylin and eosin staining, and the diameter of the aorta was measured and compared with those obtained by micro-CT. Results Time-dependent signal enhancement in the aorta shows that the contrast agent has a long blood half-life of 6 hours, with a peak enhancement at 2 hours after injection. Injection of 100 μl ExiTron nano 12000 per 25 g mouse allows for effective visualization of the aorta. Micro-CT combined with contrast agent can monitor the changing process of the aorta in the mouse model of aortic aneurysm and dissection dynamically. The values of the diameter of the aortas obtained from the in vivo micro-CT imaging were compared with those obtained from histology and showed a significant correlation (R2 = 0.96). Conclusions These data demonstrate that in vivo micro-CT is an accurate and feasible technique to detect aortic aneurysm or dissection in a mouse model, and the micro-CT technique using the innovative contrast agent ExiTron nano 12000 allows for monitoring various processes dynamically such as aortic remodeling in longitudinal studies.
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13
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Ford NL, Tan S, Deman P. An investigation of radiation damage in rat lungs following dual-energy micro-CT imaging. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/aaf240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Holbrook M, Clark DP, Badea CT. Overcoming detector limitations of x-ray photon counting for preclinical microcomputed tomography. J Med Imaging (Bellingham) 2018; 6:011004. [PMID: 30840718 DOI: 10.1117/1.jmi.6.1.011004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/30/2018] [Indexed: 12/21/2022] Open
Abstract
Spectral computed tomography (CT) using photon counting detectors (PCDs) can provide accurate tissue composition measurements by utilizing the energy dependence of x-ray attenuation in different materials. PCDs are especially suited for K-edge imaging, revealing the spatial distribution of select imaging probes through quantitative material decomposition. We report on a prototype spectral micro-CT system with a CZT-based PCD (DxRay, Inc.) that has 16 × 16 pixels of 0.5 × 0.5 mm 2 , a thickness of 3 mm, and four energy thresholds. Due to the PCD's limited size ( 8 × 8 mm 2 ), our system uses a translate-rotate projection acquisition strategy to cover a field of view relevant for preclinical imaging ( ∼ 4.5 cm ). Projection corrections were implemented to minimize artifacts associated with dead pixels and projection stitching. A sophisticated iterative algorithm was used to reconstruct both phantom and ex vivo mouse data. To achieve preclinically relevant spatial resolution, we trained a convolutional neural network to perform pan-sharpening between low-resolution PCD data ( 247 - μ m voxels) and high-resolution energy-integrating detector data ( 82 - μ m voxels), recovering a high-resolution estimate of the spectral contrast suitable for material decomposition. Long-term, preclinical spectral CT systems such as ours could serve in the developing field of theranostics (therapy and diagnostics) for cancer research.
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Affiliation(s)
- Matthew Holbrook
- Duke University, Center for In Vivo Microscopy, Department of Radiology, Durham, North Carolina, United States
| | - Darin P Clark
- Duke University, Center for In Vivo Microscopy, Department of Radiology, Durham, North Carolina, United States
| | - Cristian T Badea
- Duke University, Center for In Vivo Microscopy, Department of Radiology, Durham, North Carolina, United States
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15
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Faight E, Verdelis K, Ahearn JM, Shields KJ. 3D MicroCT spatial and temporal characterization of thoracic aorta perivascular adipose tissue and plaque volumes in the ApoE-/- mouse model. Adipocyte 2018; 7:156-165. [PMID: 29956579 DOI: 10.1080/21623945.2018.1493900] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Perivascular adipose tissue (PVAT) influences vascular function and pathology. We present a protocol using micro-computed tomography (microCT), a novel imaging technique typically used for hard biological tissue, to characterize the temporal and spatial development of aorta PVAT and luminal plaque soft tissue. Apolipoprotein E deficient (ApoE) and C57Bl/6J (control) mice were fed a high fat western diet up to 30 weeks. 3D microCT reconstructions were used to quantify: 1) vascular wall volume, a surrogate measure of remodeling, was greater in ApoE, 2) aorta PVAT volume was reduced in ApoE, 3) plaque volumes increased over time in ApoE, 4) plaque development co-localized with luminal ostia, origins of branching arteries, which traveled through areas of greatest PVAT volume, 5) qualitatively, the same arteries showed evidence of increased tortuosity in ApoE. This study reflects the potential of microCT analyses to assess vascular wall, PVAT and arterial trajectory modifications in relevant animal models. Abbreviations: PVAT: perivascular adipose tissue; ApoE: apolipoprotein E deficient mouse strain; Control: C57Bl/6J mouse strain; PTA: 0.3% phosphotungstic acid; microCT: micro-computed tomography; CV: cardiovascular; CVD: cardiovascular disease; IQR: interquartile range; PPARγ: peroxisome proliferator activated receptor - gamma; VV: vasa vasorum; 3D: three dimensional.
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Affiliation(s)
- Erin Faight
- Lupus Center of Excellence, Autoimmunity Institute, Department of Medicine, Allegheny Health Network, Pittsburgh, PA, USA
| | - Kostas Verdelis
- Division of Endodontics at the Department of Restorative Dentistry and Comprehensive Care and the Department of Oral Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joseph M. Ahearn
- Lupus Center of Excellence, Autoimmunity Institute, Department of Medicine, Allegheny Health Network, Pittsburgh, PA, USA
| | - Kelly J. Shields
- Lupus Center of Excellence, Autoimmunity Institute, Department of Medicine, Allegheny Health Network, Pittsburgh, PA, USA
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16
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Wang Z, Herremans E, Janssen S, Cantre D, Verboven P, Nicolaï B. Visualizing 3D Food Microstructure Using Tomographic Methods: Advantages and Disadvantages. Annu Rev Food Sci Technol 2018; 9:323-343. [DOI: 10.1146/annurev-food-030117-012639] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Zi Wang
- Postharvest Group, Division MeBioS, KU Leuven, 3001 Leuven, Belgium
| | - Els Herremans
- Postharvest Group, Division MeBioS, KU Leuven, 3001 Leuven, Belgium
| | - Siem Janssen
- Postharvest Group, Division MeBioS, KU Leuven, 3001 Leuven, Belgium
| | - Dennis Cantre
- Postharvest Group, Division MeBioS, KU Leuven, 3001 Leuven, Belgium
| | - Pieter Verboven
- Postharvest Group, Division MeBioS, KU Leuven, 3001 Leuven, Belgium
| | - Bart Nicolaï
- Postharvest Group, Division MeBioS, KU Leuven, 3001 Leuven, Belgium
- Flanders Centre of Postharvest Technology, VCBT, 3001 Leuven, Belgium
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17
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In Vivo Quantification of Myocardial Infarction in Mice Using Micro-CT and a Novel Blood Pool Agent. CONTRAST MEDIA & MOLECULAR IMAGING 2017; 2017:2617047. [PMID: 29114173 PMCID: PMC5662822 DOI: 10.1155/2017/2617047] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 09/12/2017] [Indexed: 11/25/2022]
Abstract
We herein developed a micro-CT method using the innovative contrast agent ExiTron™ MyoC 8000 to longitudinally monitor cardiac processes in vivo in small animals. Experiments were performed on healthy mice and mice with myocardial infarction inflicted by ligation of the left anterior descending artery. Time-dependent signal enhancement in different tissues of healthy mice was measured and various contrast agent doses were investigated so as to determine the minimum required dose for imaging of the myocardium. Due to its ability to be taken up by healthy myocardium but not by infarct tissue, ExiTron MyoC 8000 enables detection of myocardial infarction even at a very low dose. The signal enhancement in the myocardium of infarcted mice after contrast agent injection was exploited for quantification of infarct size. The values of infarct size obtained from the imaging method were compared with those obtained from histology and showed a significant correlation (R2 = 0.98). Thus, the developed micro-CT method allows for monitoring of a variety of processes such as cardiac remodeling in longitudinal studies.
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18
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Abstract
Current photon counting x-ray detector (PCD) technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID). In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM). Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with a spectral separation on the order of the energy resolution of the PCD hardware.
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Affiliation(s)
- Darin P. Clark
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, United States of America
| | - Cristian T. Badea
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, United States of America
- * E-mail:
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19
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Yeh BM, FitzGerald PF, Edic PM, Lambert JW, Colborn RE, Marino ME, Evans PM, Roberts JC, Wang ZJ, Wong MJ, Bonitatibus PJ. Opportunities for new CT contrast agents to maximize the diagnostic potential of emerging spectral CT technologies. Adv Drug Deliv Rev 2017; 113:201-222. [PMID: 27620496 PMCID: PMC5344792 DOI: 10.1016/j.addr.2016.09.001] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 12/15/2022]
Abstract
The introduction of spectral CT imaging in the form of fast clinical dual-energy CT enabled contrast material to be differentiated from other radiodense materials, improved lesion detection in contrast-enhanced scans, and changed the way that existing iodine and barium contrast materials are used in clinical practice. More profoundly, spectral CT can differentiate between individual contrast materials that have different reporter elements such that high-resolution CT imaging of multiple contrast agents can be obtained in a single pass of the CT scanner. These spectral CT capabilities would be even more impactful with the development of contrast materials designed to complement the existing clinical iodine- and barium-based agents. New biocompatible high-atomic number contrast materials with different biodistribution and X-ray attenuation properties than existing agents will expand the diagnostic power of spectral CT imaging without penalties in radiation dose or scan time.
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Affiliation(s)
- Benjamin M Yeh
- Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143-0628, United States.
| | - Paul F FitzGerald
- General Electric Global Research, One Research Circle, Niskayuna, NY 12309, United States
| | - Peter M Edic
- General Electric Global Research, One Research Circle, Niskayuna, NY 12309, United States
| | - Jack W Lambert
- Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143-0628, United States
| | - Robert E Colborn
- General Electric Global Research, One Research Circle, Niskayuna, NY 12309, United States
| | - Michael E Marino
- General Electric Global Research, One Research Circle, Niskayuna, NY 12309, United States
| | - Paul M Evans
- GE Healthcare Life Sciences, The Grove Centre, White Lion Road, Amersham, Buckinghamshire HP7 9LL, United Kingdom
| | - Jeannette C Roberts
- General Electric Global Research, One Research Circle, Niskayuna, NY 12309, United States
| | - Zhen J Wang
- Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143-0628, United States
| | - Margaret J Wong
- Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143-0628, United States
| | - Peter J Bonitatibus
- General Electric Global Research, One Research Circle, Niskayuna, NY 12309, United States
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20
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Clark DP, Lee CL, Kirsch DG, Badea CT. Spectrotemporal CT data acquisition and reconstruction at low dose. Med Phys 2016; 42:6317-36. [PMID: 26520724 DOI: 10.1118/1.4931407] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
PURPOSE X-ray computed tomography (CT) is widely used, both clinically and preclinically, for fast, high-resolution anatomic imaging; however, compelling opportunities exist to expand its use in functional imaging applications. For instance, spectral information combined with nanoparticle contrast agents enables quantification of tissue perfusion levels, while temporal information details cardiac and respiratory dynamics. The authors propose and demonstrate a projection acquisition and reconstruction strategy for 5D CT (3D+dual energy+time) which recovers spectral and temporal information without substantially increasing radiation dose or sampling time relative to anatomic imaging protocols. METHODS The authors approach the 5D reconstruction problem within the framework of low-rank and sparse matrix decomposition. Unlike previous work on rank-sparsity constrained CT reconstruction, the authors establish an explicit rank-sparse signal model to describe the spectral and temporal dimensions. The spectral dimension is represented as a well-sampled time and energy averaged image plus regularly undersampled principal components describing the spectral contrast. The temporal dimension is represented as the same time and energy averaged reconstruction plus contiguous, spatially sparse, and irregularly sampled temporal contrast images. Using a nonlinear, image domain filtration approach, the authors refer to as rank-sparse kernel regression, the authors transfer image structure from the well-sampled time and energy averaged reconstruction to the spectral and temporal contrast images. This regularization strategy strictly constrains the reconstruction problem while approximately separating the temporal and spectral dimensions. Separability results in a highly compressed representation for the 5D data in which projections are shared between the temporal and spectral reconstruction subproblems, enabling substantial undersampling. The authors solved the 5D reconstruction problem using the split Bregman method and GPU-based implementations of backprojection, reprojection, and kernel regression. Using a preclinical mouse model, the authors apply the proposed algorithm to study myocardial injury following radiation treatment of breast cancer. RESULTS Quantitative 5D simulations are performed using the MOBY mouse phantom. Twenty data sets (ten cardiac phases, two energies) are reconstructed with 88 μm, isotropic voxels from 450 total projections acquired over a single 360° rotation. In vivo 5D myocardial injury data sets acquired in two mice injected with gold and iodine nanoparticles are also reconstructed with 20 data sets per mouse using the same acquisition parameters (dose: ∼60 mGy). For both the simulations and the in vivo data, the reconstruction quality is sufficient to perform material decomposition into gold and iodine maps to localize the extent of myocardial injury (gold accumulation) and to measure cardiac functional metrics (vascular iodine). Their 5D CT imaging protocol represents a 95% reduction in radiation dose per cardiac phase and energy and a 40-fold decrease in projection sampling time relative to their standard imaging protocol. CONCLUSIONS Their 5D CT data acquisition and reconstruction protocol efficiently exploits the rank-sparse nature of spectral and temporal CT data to provide high-fidelity reconstruction results without increased radiation dose or sampling time.
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Affiliation(s)
- Darin P Clark
- Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina 27710
| | - Chang-Lung Lee
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710
| | - David G Kirsch
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710
| | - Cristian T Badea
- Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina 27710
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21
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Touch M, Clark DP, Barber W, Badea CT. A neural network-based method for spectral distortion correction in photon counting x-ray CT. Phys Med Biol 2016; 61:6132-53. [PMID: 27469292 DOI: 10.1088/0031-9155/61/16/6132] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Spectral CT using a photon counting x-ray detector (PCXD) shows great potential for measuring material composition based on energy dependent x-ray attenuation. Spectral CT is especially suited for imaging with K-edge contrast agents to address the otherwise limited contrast in soft tissues. We have developed a micro-CT system based on a PCXD. This system enables both 4 energy bins acquisition, as well as full-spectrum mode in which the energy thresholds of the PCXD are swept to sample the full energy spectrum for each detector element and projection angle. Measurements provided by the PCXD, however, are distorted due to undesirable physical effects in the detector and can be very noisy due to photon starvation in narrow energy bins. To address spectral distortions, we propose and demonstrate a novel artificial neural network (ANN)-based spectral distortion correction mechanism, which learns to undo the distortion in spectral CT, resulting in improved material decomposition accuracy. To address noise, post-reconstruction denoising based on bilateral filtration, which jointly enforces intensity gradient sparsity between spectral samples, is used to further improve the robustness of ANN training and material decomposition accuracy. Our ANN-based distortion correction method is calibrated using 3D-printed phantoms and a model of our spectral CT system. To enable realistic simulations and validation of our method, we first modeled the spectral distortions using experimental data acquired from (109)Cd and (133)Ba radioactive sources measured with our PCXD. Next, we trained an ANN to learn the relationship between the distorted spectral CT projections and the ideal, distortion-free projections in a calibration step. This required knowledge of the ground truth, distortion-free spectral CT projections, which were obtained by simulating a spectral CT scan of the digital version of a 3D-printed phantom. Once the training was completed, the trained ANN was used to perform distortion correction on any subsequent scans of the same system with the same parameters. We used joint bilateral filtration to perform noise reduction by jointly enforcing intensity gradient sparsity between the reconstructed images for each energy bin. Following reconstruction and denoising, the CT data was spectrally decomposed using the photoelectric effect, Compton scattering, and a K-edge material (i.e. iodine). The ANN-based distortion correction approach was tested using both simulations and experimental data acquired in phantoms and a mouse with our PCXD-based micro-CT system for 4 bins and full-spectrum acquisition modes. The iodine detectability and decomposition accuracy were assessed using the contrast-to-noise ratio and relative error in iodine concentration estimation metrics in images with and without distortion correction. In simulation, the material decomposition accuracy in the reconstructed data was vastly improved following distortion correction and denoising, with 50% and 20% reductions in material concentration measurement error in full-spectrum and 4 energy bins cases, respectively. Overall, experimental data confirms that full-spectrum mode provides superior results to 4-energy mode when the distortion corrections are applied. The material decomposition accuracy in the reconstructed data was vastly improved following distortion correction and denoising, with as much as a 41% reduction in material concentration measurement error for full-spectrum mode, while also bringing the iodine detectability to 4-6 mg ml(-1). Distortion correction also improved the 4 bins mode data, but to a lesser extent. The results demonstrate the experimental feasibility and potential advantages of ANN-based distortion correction and joint bilateral filtration-based denoising for accurate K-edge imaging with a PCXD. Given the computational efficiency with which the ANN can be applied to projection data, the proposed scheme can be readily integrated into existing CT reconstruction pipelines.
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Affiliation(s)
- Mengheng Touch
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA. Medical Physics Graduate Program, Duke University, Durham, NC 27710, USA
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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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Mannheim JG, Schlichthaerle T, Kuebler L, Quintanilla-Martinez L, Kohlhofer U, Kneilling M, Pichler BJ. Comparison of small animal CT contrast agents. CONTRAST MEDIA & MOLECULAR IMAGING 2016; 11:272-84. [PMID: 26991457 DOI: 10.1002/cmmi.1689] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/21/2015] [Accepted: 01/16/2016] [Indexed: 11/09/2022]
Abstract
Non-invasive in vivo small animal computed tomography (CT) imaging provides high resolution bone scans but cannot differentiate between soft tissues. For most applications injections of contrast agents (CAs) are necessary. Aim of this study was to uncover the advantages and disadvantages of commercially available CT CAs (ExiTron nano 12 000 and 6000, eXIA 160 and 160XL, Fenestra VC and LC) regarding their pharmacokinetics, toxicological side-effects and the influence of anesthesia on the biodistribution, based on an injection volume of 100 μL/25 g body weight. The pharmacokinetics of the CAs were determined for up to five days. The CA-induced toxicological/physiological side-effects were evaluated by determining blood counts, liver enzymes, thyroxine and total protein values, pro-inflammatory mediators (messenger ribonucleic acid (mRNA)), histology and immunohistochemistry. ExiTron nano 12 000 and 6000 yielded a long-term contrast enhancement (CE) in the liver and spleen for up to five days. Some of the evaluated CAs did not show any CE at all. Anesthesia did not impair the CAs' biodistribution. The CAs differentially affected the body weight, blood counts, liver enzymes, thyroxine and total protein values. ExiTron nano 12 000 and 6000 induced histiocytes in the liver and spleen. Moreover, ExiTron nano 12 000 and eXIA 160 enhanced tumor necrosis factor (TNF) mRNA expression levels in the kidneys. Thus, we recommend ExiTron nano 12 000 and 6000 when multiple injections should be avoided. We recommend careful selection of the employed CA in order to achieve an acceptable CE in the organs of interest and to avoid influences on the animal physiology. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Julia G Mannheim
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Thomas Schlichthaerle
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Tuebingen, Germany.,Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Laura Kuebler
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | | | - Ursula Kohlhofer
- Institute of Pathology, University Hospital Tuebingen, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Manfred Kneilling
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Tuebingen, Germany.,Department of Dermatology, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Bernd J Pichler
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Tuebingen, Germany
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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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Ashton JR, West JL, Badea CT. In vivo small animal micro-CT using nanoparticle contrast agents. Front Pharmacol 2015; 6:256. [PMID: 26581654 PMCID: PMC4631946 DOI: 10.3389/fphar.2015.00256] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 10/19/2015] [Indexed: 12/12/2022] Open
Abstract
Computed tomography (CT) is one of the most valuable modalities for in vivo imaging because it is fast, high-resolution, cost-effective, and non-invasive. Moreover, CT is heavily used not only in the clinic (for both diagnostics and treatment planning) but also in preclinical research as micro-CT. Although CT is inherently effective for lung and bone imaging, soft tissue imaging requires the use of contrast agents. For small animal micro-CT, nanoparticle contrast agents are used in order to avoid rapid renal clearance. A variety of nanoparticles have been used for micro-CT imaging, but the majority of research has focused on the use of iodine-containing nanoparticles and gold nanoparticles. Both nanoparticle types can act as highly effective blood pool contrast agents or can be targeted using a wide variety of targeting mechanisms. CT imaging can be further enhanced by adding spectral capabilities to separate multiple co-injected nanoparticles in vivo. Spectral CT, using both energy-integrating and energy-resolving detectors, has been used with multiple contrast agents to enable functional and molecular imaging. This review focuses on new developments for in vivo small animal micro-CT using novel nanoparticle probes applied in preclinical research.
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Affiliation(s)
- Jeffrey R Ashton
- Department of Biomedical Engineering, Duke University, Durham NC, USA ; Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Durham NC, USA
| | - Jennifer L West
- Department of Biomedical Engineering, Duke University, Durham NC, USA
| | - Cristian T Badea
- Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Durham NC, USA
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Rothe JH, Rudolph I, Rohwer N, Kupitz D, Gregor-Mamoudou B, Derlin T, Furth C, Amthauer H, Brenner W, Buchert R, Cramer T, Apostolova I. Time course of contrast enhancement by micro-CT with dedicated contrast agents in normal mice and mice with hepatocellular carcinoma: comparison of one iodinated and two nanoparticle-based agents. Acad Radiol 2015; 22:169-78. [PMID: 25282584 DOI: 10.1016/j.acra.2014.07.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 07/27/2014] [Accepted: 07/28/2014] [Indexed: 11/16/2022]
Abstract
RATIONALE AND OBJECTIVES The aim of the present study was to characterize the kinetics of two nanoparticle-based contrast agents for preclinical imaging, Exitron nano 6000 and Exitron nano 12000, and the iodinated agent eXIA 160 in both healthy mice and in a mouse model of hepatocellular carcinoma (HCC). Semiautomatic segmentation of liver lesions for estimation of total tumor load of the liver was evaluated in HCC mice. MATERIALS AND METHODS The normal time course of contrast enhancement was assessed in 15 healthy C57BL/6 mice. Imaging of tumor spread in the liver was evaluated in 15 mice harboring a transgenic HCC model (ASV-B mice). Automatic segmentation of liver lesions for determination of total tumor burden of the liver was tested in three additional ASV-B mice before and after an experimental therapy. RESULTS In healthy mice, clearance of the contrast agent from blood was completed within 3-4 hours for eXIA 160 and Exitron nano 6000, whereas complete blood clearance of Exitron nano 12000 required about 24 hours. eXIA 160 provided maximum liver contrast at 1 hour post injection (p.i.) followed by a continuous decline. Enhancement of liver contrast with Exitron nano 6000 and Exitron nano 12000 reached a plateau at about 4 hours p.i., which lasted until the end of the measurements at 96 hours p.i. Maximum contrast enhancement of the liver was not statistically different between Exitron nano 6000 and Exitron nano 12000, but was about three times lower for eXIA 160 (P < .05). Visually Exitron nano 12000 provided the best liver-to-tumor contrast. Semiautomatic liver and tumor segmentation was feasible after the administration of Exitron nano 12000 but did not work properly for the other two contrast agents. CONCLUSIONS Both nanoparticle-based contrast agents provided stronger and longer lasting contrast enhancement of healthy liver parenchyma. Exitron nano 12000 allowed automatic segmentation of tumor lesions for estimation of the total tumor load in the liver.
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Affiliation(s)
- Jan H Rothe
- Clinic of Nuclear Medicine, University Medicine Charité, Berlin, Germany
| | - Ines Rudolph
- Clinic of Hepatology and Gastroenterology, University Medicine Charité, Berlin, Germany; German Cancer Consortium, Deutsches Krebsforschungzentrum (DKFZ), Heidelberg, Germany
| | - Nadine Rohwer
- Clinic of Hepatology and Gastroenterology, University Medicine Charité, Berlin, Germany
| | - Dennis Kupitz
- Department of Radiology and Nuclear Medicine, Medical School, Otto-von-Guericke University, Magdeburg A.ö.R., Magdeburg, Germany
| | | | - Thorsten Derlin
- Clinic of Radiology, University Medical Center, Hamburg, Germany
| | - Christian Furth
- Department of Radiology and Nuclear Medicine, Medical School, Otto-von-Guericke University, Magdeburg A.ö.R., Magdeburg, Germany
| | - Holger Amthauer
- Department of Radiology and Nuclear Medicine, Medical School, Otto-von-Guericke University, Magdeburg A.ö.R., Magdeburg, Germany
| | - Winfried Brenner
- Clinic of Nuclear Medicine, University Medicine Charité, Berlin, Germany
| | - Ralph Buchert
- Clinic of Nuclear Medicine, University Medicine Charité, Berlin, Germany
| | - Thorsten Cramer
- Clinic of Hepatology and Gastroenterology, University Medicine Charité, Berlin, Germany
| | - Ivayla Apostolova
- Department of Radiology and Nuclear Medicine, Medical School, Otto-von-Guericke University, Magdeburg A.ö.R., Magdeburg, Germany.
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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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Clark DP, Badea CT. Spectral diffusion: an algorithm for robust material decomposition of spectral CT data. Phys Med Biol 2014; 59:6445-66. [PMID: 25296173 DOI: 10.1088/0031-9155/59/21/6445] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Clinical successes with dual energy CT, aggressive development of energy discriminating x-ray detectors, and novel, target-specific, nanoparticle contrast agents promise to establish spectral CT as a powerful functional imaging modality. Common to all of these applications is the need for a material decomposition algorithm which is robust in the presence of noise. Here, we develop such an algorithm which uses spectrally joint, piecewise constant kernel regression and the split Bregman method to iteratively solve for a material decomposition which is gradient sparse, quantitatively accurate, and minimally biased. We call this algorithm spectral diffusion because it integrates structural information from multiple spectral channels and their corresponding material decompositions within the framework of diffusion-like denoising algorithms (e.g. anisotropic diffusion, total variation, bilateral filtration). Using a 3D, digital bar phantom and a material sensitivity matrix calibrated for use with a polychromatic x-ray source, we quantify the limits of detectability (CNR = 5) afforded by spectral diffusion in the triple-energy material decomposition of iodine (3.1 mg mL(-1)), gold (0.9 mg mL(-1)), and gadolinium (2.9 mg mL(-1)) concentrations. We then apply spectral diffusion to the in vivo separation of these three materials in the mouse kidneys, liver, and spleen.
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Affiliation(s)
- Darin P Clark
- Center for In Vivo Microscopy, Box 3302, Duke University Medical Center, Durham, NC 27710, USA
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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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Ashton JR, Clark DP, Moding EJ, Ghaghada K, Kirsch DG, West JL, Badea CT. Dual-energy micro-CT functional imaging of primary lung cancer in mice using gold and iodine nanoparticle contrast agents: a validation study. PLoS One 2014; 9:e88129. [PMID: 24520351 PMCID: PMC3919743 DOI: 10.1371/journal.pone.0088129] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 01/06/2014] [Indexed: 11/19/2022] Open
Abstract
Purpose To provide additional functional information for tumor characterization, we investigated the use of dual-energy computed tomography for imaging murine lung tumors. Tumor blood volume and vascular permeability were quantified using gold and iodine nanoparticles. This approach was compared with a single contrast agent/single-energy CT method. Ex vivo validation studies were performed to demonstrate the accuracy of in vivo contrast agent quantification by CT. Methods Primary lung tumors were generated in LSL-KrasG12D; p53FL/FL mice. Gold nanoparticles were injected, followed by iodine nanoparticles two days later. The gold accumulated in tumors, while the iodine provided intravascular contrast. Three dual-energy CT scans were performed–two for the single contrast agent method and one for the dual contrast agent method. Gold and iodine concentrations in each scan were calculated using a dual-energy decomposition. For each method, the tumor fractional blood volume was calculated based on iodine concentration, and tumor vascular permeability was estimated based on accumulated gold concentration. For validation, the CT-derived measurements were compared with histology and inductively-coupled plasma optical emission spectroscopy measurements of gold concentrations in tissues. Results Dual-energy CT enabled in vivo separation of gold and iodine contrast agents and showed uptake of gold nanoparticles in the spleen, liver, and tumors. The tumor fractional blood volume measurements determined from the two imaging methods were in agreement, and a high correlation (R2 = 0.81) was found between measured fractional blood volume and histology-derived microvascular density. Vascular permeability measurements obtained from the two imaging methods agreed well with ex vivo measurements. Conclusions Dual-energy CT using two types of nanoparticles is equivalent to the single nanoparticle method, but allows for measurement of fractional blood volume and permeability with a single scan. As confirmed by ex vivo methods, CT-derived nanoparticle concentrations are accurate. This method could play an important role in lung tumor characterization by CT.
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Affiliation(s)
- Jeffrey R. Ashton
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
| | - Darin P. Clark
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
| | - Everett J. Moding
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Ketan Ghaghada
- The Edward B. Singleton Department of Pediatric Radiology, Texas Children’s Hospital, Houston, Texas, United States of America
| | - David G. Kirsch
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Jennifer L. West
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
| | - Cristian T. Badea
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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