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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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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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Doost A, Rangel A, Nguyen Q, Morahan G, Arnolda L. Micro-CT scan with virtual dissection of left ventricle is a non-destructive, reproducible alternative to dissection and weighing for left ventricular size. Sci Rep 2020; 10:13853. [PMID: 32807896 PMCID: PMC7431593 DOI: 10.1038/s41598-020-70734-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/13/2020] [Indexed: 11/20/2022] Open
Abstract
Micro-CT scan images enhanced by iodine staining provide high-resolution visualisation of soft tissues in laboratory mice. We have compared Micro-CT scan-derived left ventricular (LV) mass with dissection and weighing. Ex-vivo micro-CT scan images of the mouse hearts were obtained following staining by iodine. The LV was segmented and its volume was assessed using a semi-automated method by Drishti software. The left ventricle was then dissected in the laboratory and its actual weight was measured and compared against the estimated results. LV mass was calculated multiplying its estimated volume and myocardial specific gravity. Thirty-five iodine-stained post-natal mouse hearts were studied. Mice were of either sex and 68 to 352 days old (median age 202 days with interquartile range 103 to 245 days) at the time of sacrifice. Samples were from 20 genetically diverse strains. Median mouse body weight was 29 g with interquartile range 24 to 34 g. Left Ventricular weights ranged from 40.0 to 116.7 mg. The segmented LV mass estimated from micro-CT scan and directly measured dissected LV mass were strongly correlated (R2 = 0. 97). Segmented LV mass derived from Micro-CT images was very similar to the physically dissected LV mass (mean difference = 0.09 mg; 95% confidence interval − 3.29 mg to 3.1 mg). Micro-CT scanning provides a non-destructive, efficient and accurate visualisation tool for anatomical analysis of animal heart models of human cardiovascular conditions. Iodine-stained soft tissue imaging empowers researchers to perform qualitative and quantitative assessment of the cardiac structures with preservation of the samples for future histological analysis.
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Affiliation(s)
- Ata Doost
- Australian National University Medical School, Canberra, ACT, Australia
| | - Alejandra Rangel
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Building 32, Wollongong, NSW, 2522, Australia
| | - Quang Nguyen
- Centre for Diabetes Research, Harry Perkins Institute of Medical Research, University of Western Australia, Perth, Australia
| | - Grant Morahan
- Centre for Diabetes Research, Harry Perkins Institute of Medical Research, University of Western Australia, Perth, Australia
| | - Leonard Arnolda
- Australian National University Medical School, Canberra, ACT, Australia. .,Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Building 32, Wollongong, NSW, 2522, Australia.
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Mayer S, Peukert N, Gnatzy R, Gosemann JH, Lacher M, Suttkus A. Physiologic Changes in a Small Animal Model for Neonatal Minimally Invasive Surgery. J Laparoendosc Adv Surg Tech A 2018; 28:912-917. [PMID: 29782214 DOI: 10.1089/lap.2018.0075] [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] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Minimally invasive surgery (MIS) has gained increasing importance in neonatal surgery but the effects on neonatal physiology remain unclear. We aimed to characterize the impact of capnoperitoneum on physiologic parameters in a small animal model for neonatal MIS. MATERIAL AND METHODS Twenty-four 10-day-old Sprague Dawley rats underwent inhalative anesthesia (1% isoflurane in 100% O2 250 mL/minutes) and were allowed to breathe spontaneously. CO2 was insufflated into the abdominal cavity for 1 hour via a 24G cannula. Anesthetized litter mates without insufflation served as sham controls, those without any treatment as external controls. Continuous monitoring included O2-saturation, heart and respiration rate, pulse and breath distension. After euthanasia, blood gas analysis was performed. RESULTS All animals survived the experiment. Capnoperitoneum was best tolerated at a pressure of 2 mmHg and a flow of 0.5 L/minutes. A significant decrease in heart rate was observed within the first 30 minutes of insufflation comparing the CO2 and sham group (P < .05). In both, the CO2 and sham group, postmortem pH-levels were lower and pCO2 levels were higher compared to external controls (P < .05). Additionally, levels of pCO2 were higher but pH levels remained unchanged in the CO2 compared to sham group (P < .05). CONCLUSION We established a small animal model for neonatal laparoscopy. A pressure of 2 mmHg and flow of 0.5 L/minutes induced physiologic alterations but was well tolerated by the animals. These settings can be used in future studies on the impact of the capnoperitoneum in neonatal MIS.
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Affiliation(s)
- Steffi Mayer
- Department of Pediatric Surgery, University of Leipzig , Leipzig, Germany
| | - Nicole Peukert
- Department of Pediatric Surgery, University of Leipzig , Leipzig, Germany
| | - Richard Gnatzy
- Department of Pediatric Surgery, University of Leipzig , Leipzig, Germany
| | | | - Martin Lacher
- Department of Pediatric Surgery, University of Leipzig , Leipzig, Germany
| | - Anne Suttkus
- Department of Pediatric Surgery, University of Leipzig , Leipzig, Germany
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Maronpot RR, Nyska A, Troth SP, Gabrielson K, Sysa-Shah P, Kalchenko V, Kuznetsov Y, Harmelin A, Schiffenbauer YS, Bonnel D, Stauber J, Ramot Y. Regulatory Forum Opinion Piece*: Imaging Applications in Toxicologic Pathology-Recommendations for Use in Regulated Nonclinical Toxicity Studies. Toxicol Pathol 2018. [PMID: 28641506 DOI: 10.1177/0192623317710014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Available imaging systems for use in preclinical toxicology studies increasingly show utility as important tools in the toxicologic pathologist's armamentarium, permit longitudinal evaluation of functional and morphological changes in tissues, and provide important information such as organ and lesion volume not obtained by conventional toxicology study parameters. Representative examples of practical imaging applications in toxicology research and preclinical studies are presented for ultrasound, positron emission tomography/single-photon emission computed tomography, optical, magnetic resonance imaging, and matrix-assisted laser desorption ionization-imaging mass spectrometry imaging. Some of the challenges for making imaging systems good laboratory practice-compliant for regulatory submission are presented. Use of imaging data on a case-by-case basis as part of safety evaluation in regulatory submissions is encouraged.
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Affiliation(s)
| | - Abraham Nyska
- 2 Toxicologic Pathology, Sackler School of Medicine, Tel Aviv University, Timrat, Israel
| | - Sean P Troth
- 3 Merck & Co., Inc., West Point, Pennsylvania, USA
| | - Kathleen Gabrielson
- 4 Department of Molecular and Comparative Pathobiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Polina Sysa-Shah
- 4 Department of Molecular and Comparative Pathobiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Vyacheslav Kalchenko
- 5 Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | - Yuri Kuznetsov
- 5 Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | - Alon Harmelin
- 5 Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | | | | | | | - Yuval Ramot
- 8 Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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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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Challenging cardiac function post-spinal cord injury with dobutamine. Auton Neurosci 2016; 209:19-24. [PMID: 28065654 DOI: 10.1016/j.autneu.2016.12.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 09/28/2016] [Accepted: 12/13/2016] [Indexed: 12/29/2022]
Abstract
There is general consensus that spinal cord injuries (SCI) above T6 result in altered sympathetic control of the heart, which negatively influences cardiac structure and function. To by-pass disrupted circuitry and investigate cardiac responses under enhanced sympathetic activity we utilized dobutamine (DOB) stress echocardiography. Animals were divided into a T2, 25g-cm contusive SCI (SCI) or an uninjured control (CON) group. Echocardiography was performed pre-SCI and at 1, 2 and 6weeks post-SCI. Increasing doses of DOB (5, 10 & 20μg/min/kg) were infused intravenously pre-SCI and at 1 and 6weeks post-SCI. Parasternal-short axis images were used to compare group differences in systolic function and track changes in response to SCI and DOB over time. One week post-SCI, stroke volume (SV), end diastolic volume (EDV), cardiac output (CO) and ejection fraction (EF) were all reduced compared to CON and these deficits persisted to 6weeks. We also found an increase in collagen deposition at 6weeks post SCI. Pre-SCI, DOB elicited a decrease in EDV and increases in CO, EF and HR but not SV. At 6weeks following SCI, in addition to increases in CO, EF and HR, DOB also induced increases in SV. This is the first report, to our knowledge, of DOB responses in a contusive SCI model with persistent cardiac impairments. The return of CO to pre-SCI levels and the substantial increase in SV at low DOB dosages shows that impaired descending control of the heart is directly contributing to reduced resting SV after SCI.
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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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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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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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Badea CT, Hedlund LW, Qi Y, Berridge B, Johnson GA. In vivo imaging of rat coronary arteries using bi-plane digital subtraction angiography. J Pharmacol Toxicol Methods 2011; 64:151-7. [PMID: 21683146 DOI: 10.1016/j.vascn.2011.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 04/19/2011] [Accepted: 05/31/2011] [Indexed: 12/14/2022]
Abstract
INTRODUCTION X-ray based digital subtraction angiography (DSA) is a common clinical imaging method for vascular morphology and function. Coronary artery characterization is one of its most important applications. We show that bi-plane DSA of rat coronary arteries can provide a powerful imaging tool for translational safety assessment in drug discovery. METHODS A novel, dual tube/detector system, constructed explicitly for preclinical imaging, supports image acquisition at 10 frames/s with 88-micron spatial resolution. Ventilation, x-ray exposure, and contrast injection are all precisely synchronized using a biological sequence controller implemented as a LabVIEW application. A set of experiments were performed to test and optimize the sampling and image quality. We applied the DSA imaging protocol to record changes in the visualization of coronaries and myocardial perfusion induced by a vasodilator drug, nitroprusside. The drug was infused into a tail vein catheter using a peristaltic infusion pump at a rate of 0.07 mL/h for 3 min (dose: 0.0875 mg). Multiple DSA sequences were acquired before, during, and up to 25 min after drug infusion. Perfusion maps of the heart were generated in MATLAB to compare the drug effects over time. RESULTS The best trade-off between the injection time, pressure, and image quality was achieved at 60 PSI, with the injection of 150 ms occurring early in diastole (60 ms delay) and resulting in the delivery of 113 μL of contrast agent. DSA images clearly show the main branches of the coronary arteries in an intact, beating heart. The drug test demonstrated that DSA can detect relative changes in coronary circulation via perfusion maps. CONCLUSIONS The methodology for DSA imaging of rat coronary arteries can serve as a template for future translational studies to assist in safety evaluation of new pharmaceuticals. Although x-ray imaging involves radiation, the associated dose (0.4 Gy) is not a major limitation.
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Affiliation(s)
- Cristian T Badea
- Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC 27710, USA.
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