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Fortier V, Mohamed A, McNabb E, Dana J, Zakarian R, Levesque IR, Reinhold C. R 2* Impact on Hepatic Fat Quantification With a Commercial Single Voxel Technique at 1.5 and 3.0 T. Can Assoc Radiol J 2024:8465371241255896. [PMID: 38832642 DOI: 10.1177/08465371241255896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024] Open
Abstract
Rationale and Objectives: Fat quantification accuracy using a commercial single-voxel high speed T2-corrected multi-echo (HISTO) technique and its robustness to R2* variations at 3.0 T, such as those introduced by iron in liver, has not been fully established. This study evaluated HISTO at 3.0 T and sought to reproduce results at 1.5 T. Methods: Phantoms were prepared with a range of fat content and R2*. Data were acquired at 1.5 T and 3.0 T, using HISTO and a Dixon technique. Fat quantification accuracy was evaluated as a function of R2*. The patient study included 239 consecutive patients. Data were acquired at 1.5 T or 3.0 T, using HISTO and Dixon techniques. The techniques were compared using Bland-Altman plots. Bias significance was evaluated using a one-sample t-test. Results: In phantoms, HISTO was accurate within 10% up to a R2* of 100 s-1 at both field strengths, while Dixon was accurate within 10% where R2* was accurately quantified (up to 350 s-1 at 1.5 T, and 550 s-1 at 3.0 T). In patients, where R2* was <100 s-1, fat quantification from both techniques agreed at 1.5 T (P = .71), but not at 3.0 T (P = .007), with a bias <1%. Conclusion: Results suggest that HISTO is reliable when R2* is <100 s-1, corresponding to patients with at most mild liver iron overload, and that it should be used with caution when R2* is >100 s-1. Dixon should be preferred for hepatic fat quantification due to its robustness to R2* variations.
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Affiliation(s)
- Véronique Fortier
- Department of Medical Imaging, McGill University Health Centre, Montreal, QC, Canada
- Diagnostic Radiology, McGill University, Montreal, QC, Canada
- Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
- Medical Physics Unit, McGill University, Montreal, QC, Canada
| | - Ahmed Mohamed
- Radiology Department, National Cancer Institute, Cairo University, Cairo, Egypt
| | - Evan McNabb
- Department of Medical Imaging, McGill University Health Centre, Montreal, QC, Canada
| | - Jérémy Dana
- Department of Medical Imaging, McGill University Health Centre, Montreal, QC, Canada
| | - Rita Zakarian
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Ives R Levesque
- Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
- Medical Physics Unit, McGill University, Montreal, QC, Canada
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Caroline Reinhold
- Department of Medical Imaging, McGill University Health Centre, Montreal, QC, Canada
- Diagnostic Radiology, McGill University, Montreal, QC, Canada
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Montreal Imaging Experts Inc., Montreal, QC, Canada
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Gustavo Cuña E, Schulz H, Tuzzi E, Biagi L, Bosco P, García-Fontes M, Mattos J, Tosetti M, Engelmann J, Scheffler K, Hagberg GE. Simulated and experimental phantom data for multi-center quality assurance of quantitative susceptibility maps at 3 T, 7 T and 9.4 T. Phys Med 2023; 110:102590. [PMID: 37116389 DOI: 10.1016/j.ejmp.2023.102590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 04/30/2023] Open
Abstract
PURPOSE To develop methods for quality assurance of quantitative susceptibility mapping (QSM) using MRI at different magnetic field strengths, and scanners, using different MR-sequence protocols, and post-processing pipelines. METHODS We built a custom phantom based on iron in two forms: homogeneous susceptibility ('free iron') and with fine-scaled variations in susceptibility ('clustered iron') at different iron concentrations. The phantom was measured at 3.0 T (two scanners), 7.0 T and 9.4 T using multi-echo, gradient echo acquisition sequences. A digital phantom analogue to the iron-phantom, tailored to obtain similar results as in experimentation was developed, with similar geometry and susceptibility values. Morphology enabled dipole inversion was applied to the phase images to obtain QSM for experimental and simulated data using the MEDI + 0 approach for background regularization. RESULTS Across all scanners, QSM-values showed a linear increase with iron concentrations. The QSM-relaxivity was 0.231 ± 0.047 ppm/mM for free and 0.054 ± 0.013 ppm/mM for clustered iron, with adjusted determination coefficients (DoC) ≥ 0.87. Similarly, the simulations yielded linear increases (DoC ≥ 0.99). In both the experimental and digital phantoms, the estimated molar susceptibility was lower with clustered iron, because clustering led to highly localized field effects. CONCLUSION Our iron phantom can be used to evaluate the capability of QSM to detect local variations in susceptibility across different field strengths, when using different MR-sequence protocols. The devised simulation method captures the effect of iron clustering in QSM as seen experimentally and could be used in the future to optimize QSM processing pipelines and achieve higher accuracy for local field effects, as also seen in Alzheimer's beta-amyloid plaques.
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Affiliation(s)
- Enrique Gustavo Cuña
- Medical Physics, Centro Uruguayo de Imagenología Molecular, Montevideo, Uruguay.
| | - Hildegard Schulz
- High Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Elisa Tuzzi
- High Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | | | | | | | - Javier Mattos
- Centro Uruguayo de Imagenología Molecular, Montevideo, Uruguay
| | | | - Jörn Engelmann
- High Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Klaus Scheffler
- High Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Department for Biomedical Magnetic Resonance, University Hospital, Tübingen, Germany
| | - Gisela E Hagberg
- High Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Department for Biomedical Magnetic Resonance, University Hospital, Tübingen, Germany
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Grant ES, Hall LT, Hollenberg LCL, McColl G, Simpson DA. Nonmonotonic Superparamagnetic Behavior of the Ferritin Iron Core Revealed via Quantum Spin Relaxometry. ACS NANO 2023; 17:372-381. [PMID: 36534782 DOI: 10.1021/acsnano.2c08698] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Ferritin is the primary storage protein in our body and is of significant interest in biochemistry, nanotechnology, and condensed matter physics. More specifically within this sphere of interest are the magnetic properties of the iron core of ferritin, which have been utilized as a contrast agent in applications such as magnetic resonance imaging. This magnetism depends on both the number of iron atoms present, L, and the nature of the magnetic ordering of their electron spins. In this work, we create a series of ferritin samples containing homogeneous iron loads and apply diamond-based quantum spin relaxometry to systematically study their room temperature magnetic properties. We observe anomalous magnetic behavior that can be explained using a theoretical model detailing a morphological change to the iron core occurring at relatively low iron loads. This model provides an L0.35±0.06 scaling of the uncompensated Fe spins, in agreement with previous theoretical predictions. The necessary inclusion of this morphological change within the model is also supported by electron microscopy studies of ferritin with low iron content. This provides evidence for a magnetic consequence of this morphological change and positions diamond-based quantum spin relaxometry as an effective, noninvasive tool for probing the magnetic properties of metalloproteins. The low detection limit (ferritin 2% loaded at a concentration of 7.5 ± 0.4 μg/mL) also makes this a promising method for precision applications where low analyte concentrations are unavoidable, such as in biological research or even clinical analysis.
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Affiliation(s)
- Erin S Grant
- School of Physics, The University of Melbourne, Parkville, Victoria3010, Australia
| | - Liam T Hall
- School of Physics, The University of Melbourne, Parkville, Victoria3010, Australia
- School of Chemistry, The University of Melbourne, Parkville, Victoria3010, Australia
| | - Lloyd C L Hollenberg
- School of Physics, The University of Melbourne, Parkville, Victoria3010, Australia
| | - Gawain McColl
- Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria3010, Australia
| | - David A Simpson
- School of Physics, The University of Melbourne, Parkville, Victoria3010, Australia
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4
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Ouyang B, Yang Q, Wang X, He H, Ma L, Yang Q, Zhou Z, Cai S, Chen Z, Wu Z, Zhong J, Cai C. Single-shot T 2 mapping via multi-echo-train multiple overlapping-echo detachment planar imaging and multitask deep learning. Med Phys 2022; 49:7095-7107. [PMID: 35765150 DOI: 10.1002/mp.15820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 05/02/2022] [Accepted: 06/13/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Quantitative magnetic resonance imaging provides robust biomarkers in clinics. Nevertheless, the lengthy scan time reduces imaging throughput and increases the susceptibility of imaging results to motion. In this context, a single-shot T2 mapping method based on multiple overlapping-echo detachment (MOLED) planar imaging was presented, but the relatively small echo time range limits its accuracy, especially in tissues with large T2 . PURPOSE In this work we proposed a novel single-shot method, Multi-Echo-Train Multiple OverLapping-Echo Detachment (METMOLED) planar imaging, to accommodate a large range of T2 quantification without additional measurements to rectify signal degeneration arisen from refocusing pulse imperfection. METHODS Multiple echo-train techniques were integrated into the MOLED sequence to capture larger TE information. Maps of T2 , B1 , and spin density were reconstructed synchronously from acquired METMOLED data via multitask deep learning. A typical U-Net was trained with 3000/600 synthetic data with geometric/brain patterns to learn the mapping relationship between METMOLED signals and quantitative maps. The refocusing pulse imperfection was settled through the inherent information of METMOLED data and auxiliary tasks. RESULTS Experimental results on the digital brain (structural similarity (SSIM) index = 0.975/0.991/0.988 for MOLED/METMOLED-2/METMOLED-3, hyphenated number denotes the number of echo-trains), physical phantom (the slope of linear fitting with reference T2 map = 1.047/1.017/1.006 for MOLED/METMOLED-2/METMOLED-3), and human brain (Pearson's correlation coefficient (PCC) = 0.9581/0.9760/0.9900 for MOLED/METMOLED-2/METMOLED-3) demonstrated that the METMOLED improved the quantitative accuracy and the tissue details in contrast to the MOLED. These improvements were more pronounced in tissues with large T2 and in application scenarios with high temporal resolution (PCC = 0.8692/0.9465/0.9743 for MOLED/METMOLED-2/METMOLED-3). Moreover, the METMOLED could rectify the signal deviations induced by the non-ideal slice profiles of refocusing pulses without additional measurements. A preliminary measurement also demonstrated that the METMOLED is highly repeatable (mean coefficient of variation (CV) = 1.65%). CONCLUSIONS METMOLED breaks the restriction of echo-train length to TE and implements unbiased T2 estimates in an extensive range. Furthermore, it corrects the effect of refocusing pulse inaccuracy without additional measurements or signal post-processing, thus retaining its single-shot characteristic. This technique would be beneficial for accurate T2 quantification.
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Affiliation(s)
- Binyu Ouyang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, 361005, China
| | - Qizhi Yang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, 361005, China
| | - Xiaoyin Wang
- Center for Brain Imaging Science and Technology, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Hongjian He
- Center for Brain Imaging Science and Technology, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Lingceng Ma
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, 361005, China
| | - Qinqin Yang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, 361005, China
| | - Zihan Zhou
- Center for Brain Imaging Science and Technology, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Shuhui Cai
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, 361005, China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, 361005, China
| | - Zhigang Wu
- MSC Clinical and Technical Solutions, Philips Healthcare, Shenzhen, Guangdong, 518005, China
| | - Jianhui Zhong
- Center for Brain Imaging Science and Technology, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China.,Department of Imaging Sciences, University of Rochester, Rochester, New York, 14642, USA
| | - Congbo Cai
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, 361005, China
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5
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Bulte JWM, Shakeri-Zadeh A. In Vivo MRI Tracking of Tumor Vaccination and Antigen Presentation by Dendritic Cells. Mol Imaging Biol 2022; 24:198-207. [PMID: 34581954 PMCID: PMC8477715 DOI: 10.1007/s11307-021-01647-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/21/2021] [Accepted: 08/26/2021] [Indexed: 01/24/2023]
Abstract
Cancer vaccination using tumor antigen-primed dendritic cells (DCs) was introduced in the clinic some 25 years ago, but the overall outcome has not lived up to initial expectations. In addition to the complexity of the immune response, there are many factors that determine the efficacy of DC therapy. These include accurate administration of DCs in the target tissue site without unwanted cell dispersion/backflow, sufficient numbers of tumor antigen-primed DCs homing to lymph nodes (LNs), and proper timing of immunoadjuvant administration. To address these uncertainties, proton (1H) and fluorine (19F) magnetic resonance imaging (MRI) tracking of ex vivo pre-labeled DCs can now be used to non-invasively determine the accuracy of therapeutic DC injection, initial DC dispersion, systemic DC distribution, and DC migration to and within LNs. Magnetovaccination is an alternative approach that tracks in vivo labeled DCs that simultaneously capture tumor antigen and MR contrast agent in situ, enabling an accurate quantification of antigen presentation to T cells in LNs. The ultimate clinical premise of MRI DC tracking would be to use changes in LN MRI signal as an early imaging biomarker to predict the efficacy of tumor vaccination and anti-tumor response long before treatment outcome becomes apparent, which may aid clinicians with interim treatment management.
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Affiliation(s)
- Jeff W M Bulte
- Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, MRB 659, 733 N. Broadway, MD, 21205, Baltimore, USA.
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, MRB 659, 733 N. Broadway, MD, 21205, Baltimore, USA.
- Department of Chemical & Biomolecular Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Ali Shakeri-Zadeh
- Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, MRB 659, 733 N. Broadway, MD, 21205, Baltimore, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, MRB 659, 733 N. Broadway, MD, 21205, Baltimore, USA
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6
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Aslan TN. Relaxivity properties of magnetoferritin: The iron loading effect. J Biosci Bioeng 2022; 133:474-480. [DOI: 10.1016/j.jbiosc.2022.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/11/2022] [Accepted: 01/11/2022] [Indexed: 12/16/2022]
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7
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Alrayashi R, Braun RD, Muca A, Kühl A, Hali M, Holt AG. Postmortem neuroimaging: Temporal and spatial sensitivity of manganese-enhanced magnetic resonance imaging (MEMRI) and impact of Mn 2+ uptake. Hear Res 2021; 407:108276. [PMID: 34107410 DOI: 10.1016/j.heares.2021.108276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 04/20/2021] [Accepted: 05/08/2021] [Indexed: 11/29/2022]
Abstract
Magnetic resonance imaging data collection and analysis have been challenges in the field of auditory neuroscience. Recent studies have addressed these concerns by using manganese-enhanced magnetic resonance imaging (MEMRI). Basic challenges for in vivo application of MEMRI in rodents includes how to set inclusion criteria for adequate Mn2+ uptake and whether valid data can be collected from brains postmortem. Since brain Mn2+ uptake is complete within 2-4 h and clearance can take 2-4 weeks, one assumption has been that Mn2+-enhanced R1 values continue to reliably reflect the degree of Mn2+-uptake for some indeterminate time after death. To address these issues, the impact of death on R1 values was determined in rats administered Mn2+ and rats that were not. Images of auditory nuclei were collected at fixed intervals from rats before and after death for up to 10 h postmortem. By taking a ratio of pituitary and muscle T1-W intensities (P/M), a reliable quantitative method for assessing adequate brain Mn2+ uptake was created and suggest that P/M ratios should be adopted to objectively measure the quality of the Mn2+ injection. Postmortem R1 values decreased in all brain regions in both the After Mn2+ and No Mn2+ groups. However, the time-course of postmortem changes in R1 was dependent on brain region and degree of Mn2+ uptake. Thus, postmortem R1 values not only differ after death, but vary with time and across brain regions. Postmortem R1 values in unfixed brain tissue, including the auditory nuclei, should be interpreted with caution.
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Affiliation(s)
- Rasheed Alrayashi
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Rod D Braun
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Antonela Muca
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - André Kühl
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Mirabela Hali
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Avril Genene Holt
- Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA; John D. Dingell VAMC, Detroit, MI, USA.
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8
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Szulc DA, Lee XA, Cheng HYM, Cheng HLM. Bright Ferritin-a Reporter Gene Platform for On-Demand, Longitudinal Cell Tracking on MRI. iScience 2020; 23:101350. [PMID: 32707432 PMCID: PMC7381694 DOI: 10.1016/j.isci.2020.101350] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/14/2020] [Accepted: 07/03/2020] [Indexed: 02/02/2023] Open
Abstract
A major unresolved challenge in cell-based regenerative medicine is the absence of non-invasive technologies for tracking cell fate in deep tissue and with high spatial resolution over an extended interval. MRI is highly suited for this task, but current methods fail to provide longitudinal monitoring or high sensitivity, or both. In this study, we fill this technological gap with the first discovery and demonstration of in vivo cellular production of endogenous bright contrast via an MRI genetic reporter system that forms manganese-ferritin nanoparticles. We demonstrate this technology in human embryonic kidney cells genetically modified to stably overexpress ferritin and show that, in the presence of manganese, these cells produce far greater contrast than conventional ferritin overexpression with iron or manganese-permeable cells. In living mice, diffusely implanted bright-ferritin cells produce the highest and most sustained contrast in skeletal muscle. The bright-ferritin platform has potential for on-demand, longitudinal, and sensitive cell tracking in vivo.
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Affiliation(s)
- Daniel A Szulc
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, RS407, Toronto, ON M5S 3G9, Canada; Ted Rogers Centre for Heart Research, Translational Biology & Engineering Program, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Xavier A Lee
- Ted Rogers Centre for Heart Research, Translational Biology & Engineering Program, University of Toronto, Toronto, ON M5G 1M1, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Hai-Ying Mary Cheng
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Hai-Ling Margaret Cheng
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, RS407, Toronto, ON M5S 3G9, Canada; Ted Rogers Centre for Heart Research, Translational Biology & Engineering Program, University of Toronto, Toronto, ON M5G 1M1, Canada; The Edward S. Rogers Sr. Department of Electrical & Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada.
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Dezortova M, Lescinskij A, Dusek P, Herynek V, Acosta‐Cabronero J, Bruha R, Jiru F, Robinson SD, Hajek M. Multiparametric Quantitative Brain MRI in Neurological and Hepatic Forms of Wilson's Disease. J Magn Reson Imaging 2019; 51:1829-1835. [DOI: 10.1002/jmri.26984] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 12/23/2022] Open
Affiliation(s)
- Monika Dezortova
- MR Unit, Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental Medicine Prague Czech Republic
| | - Artem Lescinskij
- MR Unit, Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental Medicine Prague Czech Republic
- Department of Radiology, First Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
| | - Petr Dusek
- Department of Radiology, First Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
- Department of Neurology and Centre of Clinical Neuroscience, First Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
| | - Vit Herynek
- MR Unit, Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental Medicine Prague Czech Republic
- Center for Advanced Preclinical Imaging, First Faculty of MedicineCharles University Prague Czech Republic
| | | | - Radan Bruha
- Fourth Department of Internal Medicine, First Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
| | - Filip Jiru
- MR Unit, Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental Medicine Prague Czech Republic
| | - Simon D. Robinson
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of Vienna Vienna Austria
| | - Milan Hajek
- MR Unit, Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental Medicine Prague Czech Republic
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Zhang J, Wu J, Chen S, Zhang Z, Cai S, Cai C, Chen Z. Robust Single-Shot T 2 Mapping via Multiple Overlapping-Echo Acquisition and Deep Neural Network. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:1801-1811. [PMID: 30714913 DOI: 10.1109/tmi.2019.2896085] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Quantitative magnetic resonance imaging (MRI) is of great value to both clinical diagnosis and scientific research. However, most MRI experiments remain qualitative, especially dynamic MRI, because repeated sampling with variable weighting parameter makes quantitative imaging time-consuming and sensitive to motion artifacts. A single-shot quantitative T2 mapping method based on multiple overlapping-echo acquisition (dubbed MOLED-4) was proposed to obtain reliable T2 mapping in milliseconds. Different from traditional MRI acceleration methods, such as compressed sensing and parallel imaging, MOLED-4 accelerates quantitative T2 mapping via synchronized multisampling and then deep learning to map the complex nonlinear relationship that is difficult to solve by traditional optimization-based methods. The results of simulation, phantom, and in vivo human brain experiments show the great performance of the proposed method. The principle of MOLED-4 may be extended to other ultrafast quantitative parameter mappings and potentially lead to new dynamic MRI with high efficiency to catch quantitative variation of tissue properties.
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11
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Quantitative comparison of different iron forms in the temporal cortex of Alzheimer patients and control subjects. Sci Rep 2018; 8:6898. [PMID: 29720594 PMCID: PMC5932027 DOI: 10.1038/s41598-018-25021-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/10/2018] [Indexed: 12/25/2022] Open
Abstract
We present a quantitative study of different molecular iron forms found in the temporal cortex of Alzheimer (AD) patients. Applying the methodology we developed in our previous work, we quantify the concentrations of non-heme Fe(III) by Electron Paramagnetic Resonance (EPR), magnetite/maghemite and ferrihydrite by SQUID magnetometry, together with the MRI transverse relaxation rate [Formula: see text], to obtain a systematic view of molecular iron in the temporal cortex. Significantly higher values of [Formula: see text], a larger concentration of ferrihydrite, and a larger magnetic moment of magnetite/maghemite particles are found in the brain of AD patients. Moreover, we found correlations between the concentration of the iron detected by EPR, the concentration of the ferrihydrite mineral and the average iron loading of ferritin. We discuss these findings in the framework of iron dis-homeostasis, which has been proposed to occur in the brain of AD patients.
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12
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Cai C, Zeng Y, Zhuang Y, Cai S, Chen L, Ding X, Bao L, Zhong J, Chen Z. Single-Shot ${\text{T}}_{{2}}$ Mapping Through OverLapping-Echo Detachment (OLED) Planar Imaging. IEEE Trans Biomed Eng 2017; 64:2450-2461. [DOI: 10.1109/tbme.2017.2661840] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Patrick PS, Rodrigues TB, Kettunen MI, Lyons SK, Neves AA, Brindle KM. Development of Timd2 as a reporter gene for MRI. Magn Reson Med 2016; 75:1697-707. [PMID: 25981669 PMCID: PMC4832381 DOI: 10.1002/mrm.25750] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/27/2015] [Accepted: 03/27/2015] [Indexed: 12/20/2022]
Abstract
PURPOSE To assess the potential of an MRI gene reporter based on the ferritin receptor Timd2 (T-cell immunoglobulin and mucin domain containing protein 2), using T1- and T2-weighted imaging. METHODS Pellets of cells that had been modified to express the Timd2 transgene, and incubated with either iron-loaded or manganese-loaded ferritin, were imaged using T1- and T2-weighted MRI. Mice were also implanted subcutaneously with Timd2-expressing cells and the resulting xenograft tissue imaged following intravenous injection of ferritin using T2-weighted imaging. RESULTS Timd2-expressing cells, but not control cells, showed a large increase in both R2 and R1 in vitro following incubation with iron-loaded and manganese-loaded ferritin, respectively. Expression of Timd2 had no effect on cell viability or proliferation; however, manganese-loaded ferritin, but not iron-loaded ferritin, was toxic to Timd2-expressing cells. Timd2-expressing xenografts in vivo showed much smaller changes in R2 following injection of iron-loaded ferritin than the same cells incubated in vitro with iron-loaded ferritin. CONCLUSION Timd2 has demonstrated potential as an MRI reporter gene, producing large increases in R2 and R1 with ferritin and manganese-loaded ferritin respectively in vitro, although more modest changes in R2 in vivo. Manganese-loaded apoferritin was not used in vivo due to the toxicity observed in vitro. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance.
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Affiliation(s)
- P. Stephen Patrick
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
- Cancer Research UK Cambridge Institute, University of CambridgeCambridgeUnited Kingdom
| | - Tiago B. Rodrigues
- Cancer Research UK Cambridge Institute, University of CambridgeCambridgeUnited Kingdom
| | - Mikko I. Kettunen
- Cancer Research UK Cambridge Institute, University of CambridgeCambridgeUnited Kingdom
| | - Scott K. Lyons
- Cancer Research UK Cambridge Institute, University of CambridgeCambridgeUnited Kingdom
| | - André A. Neves
- Cancer Research UK Cambridge Institute, University of CambridgeCambridgeUnited Kingdom
| | - Kevin M. Brindle
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
- Cancer Research UK Cambridge Institute, University of CambridgeCambridgeUnited Kingdom
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Uddin MN, Lebel RM, Wilman AH. Value of transverse relaxometry difference methods for iron in human brain. Magn Reson Imaging 2016; 34:51-9. [DOI: 10.1016/j.mri.2015.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 05/06/2015] [Accepted: 09/11/2015] [Indexed: 01/14/2023]
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15
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Engineering intracellular biomineralization and biosensing by a magnetic protein. Nat Commun 2015; 6:8721. [PMID: 26522873 PMCID: PMC4667635 DOI: 10.1038/ncomms9721] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 09/24/2015] [Indexed: 11/08/2022] Open
Abstract
Remote measurement and manipulation of biological systems can be achieved using magnetic techniques, but a missing link is the availability of highly magnetic handles on cellular or molecular function. Here we address this need by using high-throughput genetic screening in yeast to select variants of the iron storage ferritin (Ft) that display enhanced iron accumulation under physiological conditions. Expression of Ft mutants selected from a library of 10(7) variants induces threefold greater cellular iron loading than mammalian heavy chain Ft, over fivefold higher contrast in magnetic resonance imaging, and robust retention on magnetic separation columns. Mechanistic studies of mutant Ft proteins indicate that improved magnetism arises in part from increased iron oxide nucleation efficiency. Molecular-level iron loading in engineered Ft enables detection of individual particles inside cells and facilitates creation of Ft-based intracellular magnetic devices. We demonstrate construction of a magnetic sensor actuated by gene expression in yeast.
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Watanabe T, Frahm J, Michaelis T. In Vivo Brain MR Imaging at Subnanoliter Resolution: Contrast and Histology. Magn Reson Med Sci 2015; 15:11-25. [PMID: 26346405 DOI: 10.2463/mrms.2015-0048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
This article provides an overview of in vivo magnetic resonance (MR) imaging contrasts obtained for mammalian brain in relation to histological knowledge. Emphasis is paid to the (1) significance of high spatial resolution for the optimization of T1, T2, and magnetization transfer contrast, (2) use of exogenous extra- and intracellular contrast agents for validating endogenous contrast sources, and (3) histological structures and biochemical compounds underlying these contrasts and (4) their relevance to neuroradiology. Comparisons between MR imaging at subnanoliter resolution and histological data indicate that (a) myelin sheaths, (b) nerve cells, and (c) the neuropil are most responsible for observed MR imaging contrasts, while (a) diamagnetic macromolecules, (b) intracellular paramagnetic ions, and (c) extracellular free water, respectively, emerge as the dominant factors. Enhanced relaxation rates due to paramagnetic ions, such as iron and manganese, have been observed for oligodendrocytes, astrocytes, microglia, and blood cells in the brain as well as for nerve cells. Taken together, a plethora of observations suggests that the delineation of specific structures in high-resolution MR imaging of mammalian brain and the absence of corresponding contrasts in MR imaging of the human brain do not necessarily indicate differences between species but may be explained by partial volume effects. Second, paramagnetic ions are required in active cells in vivo which may reduce the magnetization transfer ratio in the brain through accelerated T1 recovery. Third, reductions of the magnetization transfer ratio may be more sensitive to a particular pathological condition, such as astrocytosis, microglial activation, inflammation, and demyelination, than changes in relaxation. This is because the simultaneous occurrence of increased paramagnetic ions (i.e., shorter relaxation times) and increased free water (i.e., longer relaxation times) may cancel T1 or T2 effects, whereas both processes reduce the magnetization transfer ratio.
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Affiliation(s)
- Takashi Watanabe
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie
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17
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Song J, Cai Z, White AG, Jin T, Wang X, Kadayakkara D, Anderson CJ, Ambrose Z, Young WB. Visualization and quantification of simian immunodeficiency virus-infected cells using non-invasive molecular imaging. J Gen Virol 2015; 96:3131-3142. [PMID: 26297664 DOI: 10.1099/jgv.0.000245] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In vivo imaging can provide real-time information and three-dimensional (3D) non-invasive images of deep tissues and organs, including the brain, whilst allowing longitudinal observation of the same animals, thus eliminating potential variation between subjects. Current in vivo imaging technologies, such as magnetic resonance imaging (MRI), positron emission tomography-computed tomography (PET-CT) and bioluminescence imaging (BLI), can be used to pinpoint the spatial location of target cells, which is urgently needed for revealing human immunodeficiency virus (HIV) dissemination in real-time and HIV-1 reservoirs during suppressive antiretroviral therapy (ART). To demonstrate that in vivo imaging can be used to visualize and quantify simian immunodeficiency virus (SIV)-transduced cells, we genetically engineered SIV to carry different imaging reporters. Based on the expression of the reporter genes, we could visualize and quantify the SIV-transduced cells via vesicular stomatitis virus glycoprotein pseudotyping in a mouse model using BLI, PET-CT or MRI. We also engineered a chimeric EcoSIV for in vivo infection study. Our results demonstrated that BLI is sensitive enough to detect as few as five single cells transduced with virus, whilst PET-CT can provide 3D images of the spatial location of as few as 10 000 SIV-infected cells. We also demonstrated that MRI can provide images with high spatial resolution in a 3D anatomical context to distinguish a small population of SIV-transduced cells. The in vivo imaging platform described here can potentially serve as a powerful tool to visualize lentiviral infection, including when and where viraemia rebounds, and how reservoirs are formed and maintained during latency or suppressive ART.
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Affiliation(s)
- Jiasheng Song
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Zhengxin Cai
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Alexander G White
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Tao Jin
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Xiaolei Wang
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Deepak Kadayakkara
- Department of Oncology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Carolyn J Anderson
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Zandrea Ambrose
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Won-Bin Young
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Abbas Z, Gras V, Möllenhoff K, Keil F, Oros-Peusquens AM, Shah NJ. Analysis of proton-density bias corrections based on T1 measurement for robust quantification of water content in the brain at 3 Tesla. Magn Reson Med 2014; 72:1735-45. [PMID: 24436248 DOI: 10.1002/mrm.25086] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 11/25/2013] [Accepted: 11/25/2013] [Indexed: 11/07/2022]
Abstract
PURPOSE Estimating tissue water content using high field MRI, such as 3 Tesla (T), is challenging due to the difficulty in dissociating the radio frequency inhomogeneity pattern from the signal arising from tissue intrinsic proton density (PD) variations. To overcome this problem the longitudinal relaxation time T1 can be combined with an initial guess of the PD to yield the desired PD bias correction. However, it is necessary to know whether T1 effects, i.e., any effect contributing to T1 while being independent of tissue hydration, influence the estimated correction. METHODS Twenty-five healthy subjects underwent a quantitative 3T MRI protocol enabling acquisition of 64 slices with 1 mm in-plane resolution and 2 mm slice thickness in 14 min. Influence of T1 effects on the estimated water content map is evaluated using a dedicated method including T1 and T2 * information and region of interest-based water content values are compared with the literature. RESULTS Our analysis indicates that the PD bias correction based on T1 is largely insensitive to T1 effects. Besides, water content results are in good agreement with literature values obtained at 1.5T. CONCLUSION This study demonstrates the applicability of a PD bias correction based on T1 to yield tissue water content at 3T.
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Affiliation(s)
- Zaheer Abbas
- Institute of Neuroscience and Medicine-4, Medical Imaging Physics (INM-4), Research Centre Jülich, Jülich, Germany
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Dezortova M, Herynek V, Krssak M, Kronerwetter C, Trattnig S, Hajek M. Two forms of iron as an intrinsic contrast agent in the basal ganglia of PKAN patients. CONTRAST MEDIA & MOLECULAR IMAGING 2013; 7:509-15. [PMID: 22991317 DOI: 10.1002/cmmi.1482] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Iron deposits in the human brain can be considered as intrinsic contrast agents for magnetic resonance imaging and are used as markers of neurodegeneration accompanied by brain-iron accumulation. We studied one of them - panthotenate-kinase associated neurodegeneration (PKAN) - by using relaxometry at 1.5, 3.0 and 7 T in a group of six patients; we also measured a group of five volunteers for comparison. Based on the magnetic field dependency of antiferromagnetic ferritin and maghemite iron oxide nanoparticle relaxivities, we derived a two-component model for the description of iron deposits in the globus pallidus of PKAN patients. According to this model, we estimated the iron content in PKAN patients as 391 µg/ml of antiferromagnetic iron (ferritin) and 1.1 µg/ml of ferrimagnetic iron, compared with 178 µg/ml of iron in ferritin found in controls. This two-component model explains the nonlinear shape of the relaxometric curves in in vivo measurements of the relaxation rates of PKAN patients and is supported by histological findings in the original reports on PKAN patients.
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Affiliation(s)
- Monika Dezortova
- MR Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
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20
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Zhang J, Tao R, Liu C, Wu W, Zhang Y, Cui J, Wang J. Possible effects of iron deposition on the measurement of DTI metrics in deep gray matter nuclei: an in vitro and in vivo study. Neurosci Lett 2013; 551:47-52. [PMID: 23872093 DOI: 10.1016/j.neulet.2013.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Revised: 06/28/2013] [Accepted: 07/02/2013] [Indexed: 11/28/2022]
Abstract
The aim of this study was to explore the possible effects of iron deposition on the measurement of diffusion tensor imaging (DTI) metrics in deep gray matter nuclei in the normal human brain. Susceptibility-weighted imaging (SWI) and DTI were performed on nine MnCl2 phantoms and 85 healthy adults. The SWI phase value (PV) and DTI metrics including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were measured in phantoms and the frontal white matter (FWM), caudate (CA), putamen (PU), and globus pallidus (GP) of both hemispheres in healthy adults. The FA correlated linearly with PV and MnCl2 concentrations in phantoms. The PV in the PU was positively correlated with age. The FA was negatively correlated with age in the FWM and positively correlated with age in the PU. AD positively correlated with PV in CA, PU, and GP. FA increased with elevated PV in the PU when controlling for the impact of age. The age-related increasing of PV, which predominantly caused by iron deposition, probably influences the measurement of DTI metrics in the PU in the normal human brain and should be considered when diagnosing various neurodegenerative diseases using DTI metrics.
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Affiliation(s)
- Jiuquan Zhang
- Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
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21
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Tang H, Jensen JH, Sammet CL, Sheth S, Swaminathan SV, Hultman K, Kim D, Wu EX, Brown TR, Brittenham GM. MR characterization of hepatic storage iron in transfusional iron overload. J Magn Reson Imaging 2013; 39:307-16. [PMID: 23720394 DOI: 10.1002/jmri.24171] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 03/15/2013] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To quantify the two principal forms of hepatic storage iron, diffuse, soluble iron (primarily ferritin), and aggregated, insoluble iron (primarily hemosiderin) using a new MRI method in patients with transfusional iron overload. MATERIALS AND METHODS Six healthy volunteers and 20 patients with transfusion-dependent thalassemia syndromes and iron overload were examined. Ferritin- and hemosiderin-like iron were determined based on the measurement of two distinct relaxation parameters: the "reduced" transverse relaxation rate, RR2 , and the "aggregation index," A, using three sets of Carr-Purcell-Meiboom-Gill (CPMG) datasets with different interecho spacings. Agarose phantoms, simulating the relaxation and susceptibility properties of tissue with different concentrations of dispersed (ferritin-like) and aggregated (hemosiderin-like) iron, were used for validation. RESULTS Both phantom and in vivo human data confirmed that transverse relaxation components associated with the dispersed and aggregated iron could be separated using the two-parameter (RR2 , A) method. The MRI-determined total hepatic storage iron was highly correlated (r = 0.95) with measurements derived from biopsy or biosusceptometry. As total hepatic storage iron increased, the proportion stored as aggregated iron became greater. CONCLUSION This method provides a new means for noninvasive MRI determination of the partition of hepatic storage iron between ferritin and hemosiderin in iron overload disorders.
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Affiliation(s)
- Haiying Tang
- Imaging, Discovery Medicine & Clinical Pharmacology, Bristol Myers Squibb, Princeton, New Jersey, USA
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22
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Matsumoto Y, Jasanoff A. Metalloprotein-based MRI probes. FEBS Lett 2013; 587:1021-9. [PMID: 23376346 DOI: 10.1016/j.febslet.2013.01.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/21/2013] [Accepted: 01/23/2013] [Indexed: 02/02/2023]
Abstract
Metalloproteins have long been recognized as key determinants of endogenous contrast in magnetic resonance imaging (MRI) of biological subjects. More recently, both natural and engineered metalloproteins have been harnessed as biotechnological tools to probe gene expression, enzyme activity, and analyte concentrations by MRI. Metalloprotein MRI probes are paramagnetic and function by analogous mechanisms to conventional gadolinium or iron oxide-based MRI contrast agents. Compared with synthetic agents, metalloproteins typically offer worse sensitivity, but the possibilities of using protein engineering and targeted gene expression approaches in conjunction with metalloprotein contrast agents are powerful and sometimes definitive strengths. This review summarizes theoretical and practical aspects of metalloprotein-based contrast agents, and discusses progress in the exploitation of these proteins for molecular imaging applications.
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Affiliation(s)
- Yuri Matsumoto
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Rm. 16-561, Cambridge, MA 02139, USA
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Abstract
Magnetic resonance imaging (MRI) enables a noninvasive in vivo quantification of iron in various organs. Several techniques have been developed that detect signal alterations derived mainly from the magnetic properties of ferritin and hemosiderin, the major iron storage compounds. High magnetic susceptibility of ferritin shortens the transversal relaxation time of nearby water protons and thus induces a focal signal extinction of iron-rich areas in T2-weighted (T2w) MRI. T2w tissue contrast is additionally influenced by other factors such as water content, myelin density, and the presence of other metals. Therefore, more specific methods are needed with higher specificity to iron. These in vivo techniques can be divided into three groups: relaxometry, magnetic field correlation imaging and phase-based contrast covering susceptibility-weighted imaging, and quantitative susceptibility mapping. The differential diagnosis of various neurological disorders is aided by characteristic patterns of iron depositions. Reliable estimates of cerebral tissue iron concentration are equally important in studying physiological age-related as well as pathological conditions in neurodegenerative, neuroinflammatory, and vascular diseases. In the future, monitoring changes in iron storage and content may serve as sensitive biomarker for diagnosis as well as treatment monitoring.
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Affiliation(s)
- Petr Dusek
- Department of Neurology and Center of Clinical Neuroscience, Charles University in Prague, 1st Faculty of Medicine and General University Hospital, Prague, Czech Republic; Institut für interventionelle und diagnostische Neuroradiologie, Universitätsmedizin Göttingen, Göttingen, Germany.
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Sammet CL, Swaminathan SV, Tang H, Sheth S, Jensen JH, Nunez A, Hultman K, Kim D, Wu EX, Brittenham GM, Brown TR. Measurement and correction of stimulated echo contamination in T2-based iron quantification. Magn Reson Imaging 2012; 31:664-8. [PMID: 23260394 DOI: 10.1016/j.mri.2012.10.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 10/11/2012] [Accepted: 10/30/2012] [Indexed: 11/17/2022]
Abstract
The purpose of this study was to characterize the effects of stimulated echo contamination on MR-based iron measurement derived from quantitative T2 images and develop a method for retrospective correction. Two multiple spin-echo (MSE) pulse sequences were implemented with different amounts of stimulated echo contamination. Agarose-based phantoms were constructed that simulate the relaxation and susceptibility properties of tissue with different concentrations of dispersed (ferritin-like) and aggregated (hemosiderin-like) iron. Additionally, myocardial iron was assessed in nine human subjects with transfusion iron overload. These data were used to determine the influence of stimulated echoes on iron measurements made by an MR-based iron quantification model that can separately measure dispersed and aggregated iron. The study found that stimulated echo contamination caused an underestimation of dispersed (ferritin-like) iron and an overestimation of aggregated (hemosiderin-like) iron when applying this model. The relationship between the measurements made with and without stimulated echo appears to be linear. The findings suggest that while it is important to use MSE sequences with minimal stimulated echo in T2-based iron quantification, it appears that data acquired with sub-optimal sequences can be retrospectively corrected using the methodology described here.
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An in vitro and in vivo analysis of the correlation between susceptibility-weighted imaging phase values and R2* in cirrhotic livers. PLoS One 2012; 7:e45477. [PMID: 23029037 PMCID: PMC3445544 DOI: 10.1371/journal.pone.0045477] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 08/21/2012] [Indexed: 01/28/2023] Open
Abstract
Objective To establish a baseline of susceptibility-weighted imaging (SWI) phase value as a means of detecting iron abnormalities in cirrhotic liver and to analyze its relationship with R2*. Materials and Methods Sixteen MnCl2 phantoms, thirty-seven healthy individuals and 87 cirrhotic patients were performed SWI and multi-echo T2*-weighted imaging, and the signal processing in NMR (SPIN) software was used to measure the radian on SWI phase images and the R2* on T2* maps. The mean minus two times standard deviation (SD) of Siemens Phase Unit (SPU) in healthy individuals was designated as a threshold to separate the regions of interest (ROIs) into high- and low-iron areas in healthy participants and cirrhotic patients. The SWI phase values of high-iron areas were calculated. The R2* values was measured in the same ROI in both healthy participants and patients. Results SWI phase values correlated linearly with R2* values in cases of MnCl2 concentrations lower than 2.3 mM in vitro (r = −0.996, P<0.001). The mean value and SD of 37 healthy participants were 2003 and 15 (SPU), respectively. A threshold of 1973 SPU (−0.115 radians) was determined. The SWI phase value and R2* values had a negative correlation in the cirrhotic patients (r = −0.742, P<0.001). However, no similar relationship was found in the healthy individuals (r = 0.096, P = 0.576). Both SWI phase values and R2* values were found to have significant correlations with serum ferritin concentrations in 42 patients with blood samples (r = −0.512, P = 0.001 and r = 0.641, P<0.001, respectively). Conclusion SWI phase values had significant correlations with R2* after the establishment of a baseline on the phase image. SWI phase images may be used for non-invasive quantitative measurement of mild and moderate iron deposition in hepatic cirrhosis in vivo.
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Antharam V, Collingwood JF, Bullivant JP, Davidson MR, Chandra S, Mikhaylova A, Finnegan ME, Batich C, Forder JR, Dobson J. High field magnetic resonance microscopy of the human hippocampus in Alzheimer's disease: quantitative imaging and correlation with iron. Neuroimage 2012; 59:1249-60. [PMID: 21867761 PMCID: PMC3690369 DOI: 10.1016/j.neuroimage.2011.08.019] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 08/01/2011] [Accepted: 08/06/2011] [Indexed: 11/21/2022] Open
Abstract
We report R(2) and R(2) in human hippocampus from five unfixed post-mortem Alzheimer's disease (AD) and three age-matched control cases. Formalin-fixed tissues from opposing hemispheres in a matched AD and control were included for comparison. Imaging was performed in a 600MHz (14T) vertical bore magnet at MR microscopy resolution to obtain R(2) and R(2) (62 μm×62 μm in-plane, 80 μm slice thickness), and R(1) at 250 μm isotropic resolution. R(1), R(2) and R(2) maps were computed for individual slices in each case, and used to compare subfields between AD and controls. The magnitudes of R(2) and R(2) changed very little between AD and control, but their variances in the Cornu Ammonis and dentate gyrus were significantly higher in AD compared for controls (p<0.001). To investigate the relationship between tissue iron and MRI parameters, each tissue block was cryosectioned at 30 μm in the imaging plane, and iron distribution was mapped using synchrotron microfocus X-ray fluorescence spectroscopy. A positive correlation of R(2) and R(2)* with iron was demonstrated. While studies with fixed tissues are more straightforward to conduct, fixation can alter iron status in tissues, making measurement of unfixed tissue relevant. To our knowledge, these data represent an advance in quantitative imaging of hippocampal subfields in unfixed tissue, and the methods facilitate direct analysis of the relationship between MRI parameters and iron. The significantly increased variance in AD compared for controls warrants investigation at lower fields and in-vivo, to determine if this parameter is clinically relevant.
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Affiliation(s)
- Vijay Antharam
- Department of Medicine, University of Florida, Gainesville, FL, USA
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Lotfipour AK, Wharton S, Schwarz ST, Gontu V, Schäfer A, Peters AM, Bowtell RW, Auer DP, Gowland PA, Bajaj NP. High resolution magnetic susceptibility mapping of the substantia nigra in Parkinson's disease. J Magn Reson Imaging 2011; 35:48-55. [DOI: 10.1002/jmri.22752] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 07/21/2011] [Indexed: 01/06/2023] Open
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Magnetic resonance imaging of tumors colonized with bacterial ferritin-expressing Escherichia coli. PLoS One 2011; 6:e25409. [PMID: 21984917 PMCID: PMC3184983 DOI: 10.1371/journal.pone.0025409] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 09/02/2011] [Indexed: 12/31/2022] Open
Abstract
Background Recent studies have shown that human ferritin can be used as a reporter of gene expression for magnetic resonance imaging (MRI). Bacteria also encode three classes of ferritin-type molecules with iron accumulation properties. Methods and Findings Here, we investigated whether these bacterial ferritins can also be used as MRI reporter genes and which of the bacterial ferritins is the most suitable reporter. Bacterial ferritins were overexpressed in probiotic E. coli Nissle 1917. Cultures of these bacteria were analyzed and those generating highest MRI contrast were further investigated in tumor bearing mice. Among members of three classes of bacterial ferritin tested, bacterioferritin showed the most promise as a reporter gene. Although all three proteins accumulated similar amounts of iron when overexpressed individually, bacterioferritin showed the highest contrast change. By site-directed mutagenesis we also show that the heme iron, a unique part of the bacterioferritin molecule, is not critical for MRI contrast change. Tumor-specific induction of bacterioferritin-expression in colonized tumors resulted in contrast changes within the bacteria-colonized tumors. Conclusions Our data suggest that colonization and gene expression by live vectors expressing bacterioferritin can be monitored by MRI due to contrast changes.
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Premenopausal hysterectomy is associated with increased brain ferritin iron. Neurobiol Aging 2011; 33:1950-8. [PMID: 21925770 DOI: 10.1016/j.neurobiolaging.2011.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Revised: 07/19/2011] [Accepted: 08/05/2011] [Indexed: 01/19/2023]
Abstract
Iron is essential for triggering oligodendrocytes to myelinate, however, in gray matter (GM) iron increases with age and is associated with age-related degenerative brain diseases. Women have lower iron levels than men, both in the periphery and in the brain, particularly in white matter (WM), possibly due to iron loss through menstruation. We tested the hypothesis that hysterectomy could increase WM iron levels. We assessed 3 WM and 5 gray matter regions in 39 postmenopausal women, of whom 15 had premenopausal hysterectomy, utilizing a validated magnetic resonance imaging technique called field-dependent R2 increase (FDRI) that quantifies ferritin iron. A group of 54 matched male subjects was included for comparison. Amongst women, hysterectomy was associated with significantly higher frontal lobe WM iron. Men had higher iron levels than women without hysterectomy in 3 brain regions but did not differ from women with hysterectomy in any region. The results suggest that menstruation-associated blood loss is a source of gender differences in brain iron. It is possible that brain iron can be influenced by peripheral iron levels and may thus be a modifiable risk factor for age-related degenerative diseases.
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Bartzokis G, Lu PH, Tingus K, Peters DG, Amar CP, Tishler TA, Finn JP, Villablanca P, Altshuler LL, Mintz J, Neely E, Connor JR. Gender and iron genes may modify associations between brain iron and memory in healthy aging. Neuropsychopharmacology 2011; 36:1375-84. [PMID: 21389980 PMCID: PMC3096807 DOI: 10.1038/npp.2011.22] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Brain iron increases with age and is abnormally elevated early in the disease process in several neurodegenerative disorders that impact memory including Alzheimer's disease (AD). Higher brain iron levels are associated with male gender and presence of highly prevalent allelic variants in genes encoding for iron metabolism proteins (hemochromatosis H63D (HFE H63D) and transferrin C2 (TfC2)). In this study, we examined whether in healthy older individuals memory performance is associated with increased brain iron, and whether gender and gene variant carrier (IRON+) vs noncarrier (IRON-) status (for HFE H63D/TfC2) modify the associations. Tissue iron deposited in ferritin molecules can be measured in vivo with magnetic resonance imaging utilizing the field-dependent relaxation rate increase (FDRI) method. FDRI was assessed in hippocampus, basal ganglia, and white matter, and IRON+ vs IRON- status was determined in a cohort of 63 healthy older individuals. Three cognitive domains were assessed: verbal memory (delayed recall), working memory/attention, and processing speed. Independent of gene status, worse verbal-memory performance was associated with higher hippocampal iron in men (r=-0.50, p=0.003) but not in women. Independent of gender, worse verbal working memory performance was associated with higher basal ganglia iron in IRON- group (r=-0.49, p=0.005) but not in the IRON+ group. Between-group interactions (p=0.006) were noted for both of these associations. No significant associations with white matter or processing speed were observed. The results suggest that in specific subgroups of healthy older individuals, higher accumulations of iron in vulnerable gray matter regions may adversely impact memory functions and could represent a risk factor for accelerated cognitive decline. Combining genetic and MRI biomarkers may provide opportunities to design primary prevention clinical trials that target high-risk groups.
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Affiliation(s)
- George Bartzokis
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-6968, USA.
| | - Po H Lu
- Department of Neurology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Kathleen Tingus
- Department of Neurology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Douglas G Peters
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA,Department of Psychiatry, Greater Los Angeles VA Healthcare System, Los Angeles, CA, USA
| | - Chetan P Amar
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA,Department of Psychiatry, Greater Los Angeles VA Healthcare System, Los Angeles, CA, USA
| | - Todd A Tishler
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA,Department of Psychiatry, Greater Los Angeles VA Healthcare System, Los Angeles, CA, USA
| | - J Paul Finn
- Department of Radiology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Pablo Villablanca
- Department of Radiology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Lori L Altshuler
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Jim Mintz
- Department of Epidemiology and Biostatistics, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Elizabeth Neely
- Department of Neurosurgery, Penn State Hershey Medical Center, Hershey, PA, USA
| | - James R Connor
- Department of Neurosurgery, Penn State Hershey Medical Center, Hershey, PA, USA
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31
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Lelyveld VS, Brustad E, Arnold FH, Jasanoff A. Metal-substituted protein MRI contrast agents engineered for enhanced relaxivity and ligand sensitivity. J Am Chem Soc 2011; 133:649-51. [PMID: 21171606 DOI: 10.1021/ja107936d] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Engineered metalloproteins constitute a flexible new class of analyte-sensitive molecular imaging agents detectable by magnetic resonance imaging (MRI), but their contrast effects are generally weaker than synthetic agents. To augment the proton relaxivity of agents derived from the heme domain of cytochrome P450 BM3 (BM3h), we formed manganese(III)-containing proteins that have higher electron spin than their native ferric iron counterparts. Metal substitution was achieved by coexpressing BM3h variants with the bacterial heme transporter ChuA in Escherichia coli and supplementing the growth medium with Mn3+-protoporphyrin IX. Manganic BM3h variants exhibited up to 2.6-fold higher T1 relaxivities relative to native BM3h at 4.7 T. Application of ChuA-mediated porphyrin substitution to a collection of thermostable chimeric P450 domains resulted in a stable, high-relaxivity BM3h derivative displaying a 63% relaxivity change upon binding of arachidonic acid, a natural ligand for the P450 enzyme and an important component of biological signaling pathways. This work demonstrates that protein-based MRI sensors with robust ligand sensitivity may be created with ease by including metal substitution among the toolkit of methods available to the protein engineer.
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Affiliation(s)
- Victor S Lelyveld
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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32
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Wu EX, Kim D, Tosti CL, Tang H, Jensen JH, Cheung JS, Feng L, Au WY, Ha SY, Sheth SS, Brown TR, Brittenham GM. Magnetic resonance assessment of iron overload by separate measurement of tissue ferritin and hemosiderin iron. Ann N Y Acad Sci 2010; 1202:115-22. [PMID: 20712781 DOI: 10.1111/j.1749-6632.2010.05587.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With transfusional iron overload, almost all the excess iron is sequestered intracellularly as rapidly mobilizable, dispersed, soluble ferritin iron, and as aggregated, insoluble hemosiderin iron for long-term storage. Established magnetic resonance imaging (MRI) indicators of tissue iron (R(2), R(2)*) are principally influenced by hemosiderin iron and change slowly, even with intensive iron chelation. Intracellular ferritin iron is evidently in equilibrium with the low-molecular-weight cytosolic iron pool that can change rapidly with iron chelation. We have developed a new MRI method to separately measure ferritin and hemosiderin iron, based on the non-monoexponential signal decay induced by aggregated iron in multiple-spin-echo sequences. We have initially validated the method in agarose phantoms and in human liver explants and shown the feasibility of its application in patients with thalassemia major. Measurement of tissue ferritin iron is a promising new means to rapidly evaluate the effectiveness of iron-chelating regimens.
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Affiliation(s)
- Ed X Wu
- Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam, Hong Kong, China
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33
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Jensen JH, Tang H, Tosti CL, Swaminathan SV, Nunez A, Hultman K, Szulc KU, Wu EX, Kim D, Sheth S, Brown TR, Brittenham GM. Separate MRI quantification of dispersed (ferritin-like) and aggregated (hemosiderin-like) storage iron. Magn Reson Med 2010; 63:1201-9. [PMID: 20432291 DOI: 10.1002/mrm.22273] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A new MRI method is proposed for separately quantifying the two principal forms of tissue storage (nonheme) iron: ferritin iron, a dispersed, soluble fraction that can be rapidly mobilized, and hemosiderin iron, an aggregated, insoluble fraction that serves as a long-term reserve. The method utilizes multiple spin echo sequences, exploiting the fact that aggregated iron can induce nonmonoexponential signal decay for multiple spin echo sequences. The method is validated in vitro for agarose phantoms, simulating dispersed iron with manganese chloride, and aggregated iron with iron oxide microspheres. To demonstrate feasibility for human studies, preliminary in vivo data from two healthy controls and six patients with transfusional iron overload are presented. For both phantoms and human subjects, conventional R(2) and R(2)* relaxation rates are also measured in order to contrast the proposed method with established MRI iron quantification techniques. Quantification of dispersed (ferritin-like) iron may provide a new means of monitoring the risk of iron-induced toxicity in patients with iron overload and, together with quantification of aggregated (hemosiderin-like) iron, improve the accuracy of estimates for total storage iron.
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Affiliation(s)
- Jens H Jensen
- Department of Radiology, New York University School of Medicine, Center for Biomedical Imaging, New York, New York 10016-3295, USA.
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34
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Iordanova B, Robison CS, Ahrens ET. Design and characterization of a chimeric ferritin with enhanced iron loading and transverse NMR relaxation rate. J Biol Inorg Chem 2010; 15:957-65. [PMID: 20401622 PMCID: PMC2936821 DOI: 10.1007/s00775-010-0657-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 03/28/2010] [Indexed: 10/19/2022]
Abstract
This paper describes the design and characterization of a novel ferritin chimera. The iron storage protein ferritin forms a paramagnetic ferrihydrite core. This biomineral, when placed in a magnetic field, can decrease the transverse NMR relaxation times (T (2) and T (2)*) of nearby mobile water protons. Ferritin nucleic acid constructs have recently been studied as "probeless" magnetic resonance imaging (MRI) reporters. Following reporter expression, ferritin sequesters endogenous iron and imparts hypointensity to T (2)- and T (2)*-weighted images in an amount proportional to the ferritin iron load. Wild-type ferritin consists of various ratios of heavy H and light L subunits, and their ratio affects ferritin's stability and iron storage capacity. We report a novel chimeric ferritin with a fixed subunit stoichiometry obtained by fusion of the L and the H subunits (L*H and H*L) using a flexible linker. We characterize these supramolecular ferritins expressed in human cells, including their iron loading characteristics, hydrodynamic size, subcellular localization, and effect on solvent water T (2) relaxation rate. Interestingly, we found that the L*H chimera exhibits a significantly enhanced iron loading ability and T (2) relaxation compared to wild-type ferritin. We suggest that the L*H chimera may be useful as a sensitive MRI reporter molecule.
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Affiliation(s)
- Bistra Iordanova
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA; Pittsburgh NMR Center for Biomedical Research, Pittsburgh, PA, USA
| | - Clinton S. Robison
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA; Pittsburgh NMR Center for Biomedical Research, Pittsburgh, PA, USA
| | - Eric T. Ahrens
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA; Pittsburgh NMR Center for Biomedical Research, Pittsburgh, PA, USA
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35
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Bartzokis G, Lu PH, Tishler TA, Peters DG, Kosenko A, Barrall KA, Finn JP, Villablanca P, Laub G, Altshuler LL, Geschwind DH, Mintz J, Neely E, Connor JR. Prevalent iron metabolism gene variants associated with increased brain ferritin iron in healthy older men. J Alzheimers Dis 2010; 20:333-41. [PMID: 20164577 DOI: 10.3233/jad-2010-1368] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Prevalent gene variants involved in iron metabolism [hemochromatosis (HFE) H63D and transferrin C2 (TfC2)] have been associated with higher risk and earlier age at onset of Alzheimer's disease (AD), especially in men. Brain iron increases with age, is higher in men, and is abnormally elevated in several neurodegenerative diseases, including AD and Parkinson's disease, where it has been reported to contribute to younger age at onset in men. The effects of the common genetic variants (HFE H63D and/or TfC2) on brain iron were studied across eight brain regions (caudate, putamen, globus pallidus, thalamus, hippocampus, white matter of frontal lobe, genu, and splenium of corpus callosum) in 66 healthy adults (35 men, 31 women) aged 55 to 76. The iron content of ferritin molecules (ferritin iron) in the brain was measured with MRI utilizing the Field Dependent Relaxation Rate Increase (FDRI) method. 47% of the sample carried neither genetic variant (IRON-) and 53% carried one and/or the other (IRON+). IRON+ men had significantly higher FDRI compared to IRON- men (p=0.013). This genotype effect was not observed in women who, as expected, had lower FDRI than men. This is the first published evidence that these highly prevalent genetic variants in iron metabolism genes can influence brain iron levels in men. Clinical phenomena such as differential gender-associated risks of developing neurodegenerative diseases and age at onset may be associated with interactions between iron genes and brain iron accumulation. Clarifying mechanisms of brain iron accumulation may help identify novel interventions for age-related neurodegenerative diseases.
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Affiliation(s)
- George Bartzokis
- Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-6968, USA.
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36
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Cohen B, Ziv K, Plaks V, Harmelin A, Neeman M. Ferritin nanoparticles as magnetic resonance reporter gene. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2010; 1:181-8. [PMID: 20049789 DOI: 10.1002/wnan.11] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Dynamic imaging of gene expression in live animals is among the exciting challenges of molecular imaging. To achieve that, one of the approaches is to use reporter genes that encode for the synthesis of easily detectable products. Such reporter genes can be designed to be expressed under the control of the regulatory elements included in a promoter region of a gene of interest, thus allowing the use of the same reporter gene for the detection of multiple genes. The most commonly used reporter genes include the firefly light-generating enzyme luciferase and the green fluorescent protein detectable by bioluminescence and fluorescence optical imaging, respectively. Over the last years a number of studies demonstrated the ability to use the iron-binding protein ferritin as a reporter gene that allows the detection of gene expression by magnetic resonance imaging (MRI). MRI provides high spatial resolution and soft tissue contrast for deep tissues along with a large arsenal of functional and anatomical contrast mechanisms that can be correlated with gene expression, and can potentially be translated into clinical use.
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Affiliation(s)
- Batya Cohen
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
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37
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Li TQ, Yao B, van Gelderen P, Merkle H, Dodd S, Talagala L, Koretsky AP, Duyn J. Characterization of T(2)* heterogeneity in human brain white matter. Magn Reson Med 2009; 62:1652-7. [PMID: 19859939 PMCID: PMC3508464 DOI: 10.1002/mrm.22156] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 06/26/2009] [Indexed: 11/07/2022]
Abstract
Recent in vivo MRI studies at 7.0 T have demonstrated extensive heterogeneity of T(2)* relaxation in white matter of the human brain. In order to study the origin of this heterogeneity, we performed T(2)* measurements at 1.5, 3.0, and 7.0 T in normal volunteers. Formalin-fixed brain tissue specimens were also studied using T(2)*-weighted MRI, histologic staining, chemical analysis, and electron microscopy. We found that T(2)* relaxation rate (R(2)* = 1/T(2)*) in white matter in living human brain is linearly dependent on the main magnetic field strength, and the T(2)* heterogeneity in white matter observed at 7.0 T can also be detected, albeit more weakly, at 1.5 and 3.0 T. The T(2)* heterogeneity exists also in white matter of the formalin-fixed brain tissue specimens, with prominent differences between the major fiber bundles such as the cingulum (CG) and the superior corona radiata. The white matter specimen with substantial difference in T(2)* has no significant difference in the total iron content, as determined by chemical analysis. On the other hand, evidence from histologic staining and electron microscopy demonstrates these tissue specimens have apparent difference in myelin content and microstructure.
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Affiliation(s)
- Tie-Qiang Li
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
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38
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Kim D, Jensen JH, Wu EX, Sheth SS, Brittenham GM. Breathhold multiecho fast spin-echo pulse sequence for accurate R2 measurement in the heart and liver. Magn Reson Med 2009; 62:300-6. [PMID: 19526516 DOI: 10.1002/mrm.22047] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Measurement of proton transverse relaxation rates (R(2)) is a generally useful means for quantitative characterization of pathological changes in tissue with a variety of clinical applications. The most widely used R(2) measurement method is the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence but its relatively long scan time requires respiratory gating for chest or body MRI, rendering this approach impractical for comprehensive assessment within a clinically-acceptable examination time. The purpose of our study was to develop a breathhold multiecho fast spin-echo (FSE) sequence for accurate measurement of R(2) in the liver and heart. Phantom experiments and studies of subjects in vivo were performed to compare the FSE data with the corresponding even-echo CPMG data. For pooled data, the R(2) measurements were strongly correlated (Pearson correlation coefficient = 0.99) and in excellent agreement (mean difference [CPMG - FSE] = 0.10 s(-1); 95% limits of agreement were 1.98 and -1.78 s(-1)) between the two pulse sequences.
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Affiliation(s)
- Daniel Kim
- Department of Radiology, New York University School of Medicine, New York, NY 10016, USA.
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39
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Meadowcroft MD, Connor JR, Smith MB, Yang QX. MRI and histological analysis of beta-amyloid plaques in both human Alzheimer's disease and APP/PS1 transgenic mice. J Magn Reson Imaging 2009; 29:997-1007. [PMID: 19388095 DOI: 10.1002/jmri.21731] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To investigate the relationship between MR image contrast associated with beta-amyloid (Abeta) plaques and their histology and compare the histopathological basis of image contrast and the relaxation mechanism associated with Abeta plaques in human Alzheimer's disease (AD) and transgenic APP/PS1 mouse tissues. MATERIALS AND METHODS With the aid of the previously developed histological coil, T(2) (*)-weighted images and R(2) (*) parametric maps were directly compared with histology stains acquired from the same set of Alzheimer's and APP/PS1 tissue slices. RESULTS The electron microscopy and histology images revealed significant differences in plaque morphology and associated iron concentration between AD and transgenic APP/PS1 mice tissue samples. For AD tissues, T(2) (*) contrast of Abeta-plaques was directly associated with the gradation of iron concentration. Plaques with significantly less iron load in the APP/PS1 animal tissues are equally conspicuous as the human plaques in the MR images. CONCLUSION These data suggest a duality in the relaxation mechanism where both high focal iron concentration and highly compact fibrillar beta-amyloid masses cause rapid proton transverse magnetization decay. For human tissues, the former mechanism is likely the dominant source of R(2) (*) relaxation; for APP/PS1 animals, the latter is likely the major cause of increased transverse proton relaxation rate in Abeta plaques. The data presented are essential for understanding the histopathological underpinning of MRI measurement associated with Abeta plaques in humans and animals.
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Affiliation(s)
- Mark D Meadowcroft
- Department of Radiology (Center for NMR Research), Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
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40
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Gossuin Y, Gillis P, Hocq A, Vuong QL, Roch A. Magnetic resonance relaxation properties of superparamagnetic particles. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2009; 1:299-310. [DOI: 10.1002/wnan.36] [Citation(s) in RCA: 205] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yves Gossuin
- Biological Physics Department, University of Mons‐Hainaut, Mons, Belgium
| | - Pierre Gillis
- Biological Physics Department, University of Mons‐Hainaut, Mons, Belgium
| | - Aline Hocq
- Biological Physics Department, University of Mons‐Hainaut, Mons, Belgium
| | - Quoc L Vuong
- Biological Physics Department, University of Mons‐Hainaut, Mons, Belgium
| | - Alain Roch
- Department of General, Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons‐Hainaut, Mons, Belgium
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41
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Susceptibility contrast in high field MRI of human brain as a function of tissue iron content. Neuroimage 2008; 44:1259-66. [PMID: 19027861 DOI: 10.1016/j.neuroimage.2008.10.029] [Citation(s) in RCA: 235] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2008] [Revised: 10/01/2008] [Accepted: 10/15/2008] [Indexed: 12/21/2022] Open
Abstract
Magnetic susceptibility provides an important contrast mechanism for MRI. Increasingly, susceptibility-based contrast is being exploited to investigate brain tissue microstructure and to detect abnormal levels of brain iron as these have been implicated in a variety of neuro-degenerative diseases. However, it remains unclear to what extent magnetic susceptibility-related contrast at high field relates to actual brain iron concentrations. In this study, we performed susceptibility weighted imaging as a function of field strength on healthy brains in vivo and post-mortem brain tissues at 1.5 T, 3 T and 7 T. Iron histology was performed on the tissue samples for comparison. The calculated susceptibility-related parameters R(2)(*) and signal frequency shift in four iron-rich regions (putamen, globus pallidus, caudate, and thalamus) showed an almost linear dependence (r>or=0.90 for R(2)(*); r>or=0.83 for phase, p<0.01) on field strength, suggesting that potential ferritin saturation effects are not relevant to susceptibility-weighted contrast for field strengths up to 7 T. The R(2)(*) dependence on the putative (literature-based) iron concentration was 0.048 Hz/T/ppm. The histological data from brain samples confirmed the linear dependence of R(2)(*) on field strength and showed a slope against iron concentration of 0.0099 Hz/T/ppm dry-weight, which is equivalent to 0.05 Hz/T/ppm wet-weight and closely matched the calculated value in vivo. These results confirm the validity of using susceptibility-weighted contrast as an indicator of iron content in iron-rich brain regions. The absence of saturation effects opens the way to exploit the benefits of MRI at high field strengths for the detection of iron distributions with high sensitivity and resolution.
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42
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House MJ, St Pierre TG, McLean C. 1.4T study of proton magnetic relaxation rates, iron concentrations, and plaque burden in Alzheimer's disease and control postmortem brain tissue. Magn Reson Med 2008; 60:41-52. [PMID: 18523986 DOI: 10.1002/mrm.21586] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We measured proton magnetic longitudinal (R(1)) and transverse (R(2)) relaxation rates at 1.4T, iron concentrations, water contents, and amyloid plaque densities in postmortem brain tissue samples from three Alzheimer's disease (AD), two possible AD, and five control subjects. Iron concentrations and R(1) were significantly higher in the temporal cortex region of our AD group compared to the controls. Frequency analyses showed that the observed trends of higher iron, R(1), and R(2) in AD gray matter regions were statistically significant. Simple regression models indicated that for AD and control gray matter the iron concentrations and water contents have significant linear correlations with R(1) and R(2). Multiple regression models based on iron concentrations and water contents were highly significant for all groups and tissue types and suggested that the effects of iron become more important in determining R(1) and R(2) in the AD samples. At 1.4T R(1) and R(2) are strongly affected by water content and to a lesser extent by variations in iron concentrations. The AD plaque density did not correlate with iron concentrations, water contents, R(1), or R(2), suggesting that increases in AD brain iron are not strongly related to the accumulation of amyloid plaques.
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Affiliation(s)
- Michael J House
- School of Physics, University of Western Australia, Perth, WA 6009, Australia.
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43
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Gálvez N, Fernández B, Sánchez P, Cuesta R, Ceolín M, Clemente-León M, Trasobares S, López-Haro M, Calvino JJ, Stéphan O, Domínguez-Vera JM. Comparative Structural and Chemical Studies of Ferritin Cores with Gradual Removal of their Iron Contents. J Am Chem Soc 2008; 130:8062-8. [DOI: 10.1021/ja800492z] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Natividad Gálvez
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Belén Fernández
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Purificación Sánchez
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Rafael Cuesta
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Marcelo Ceolín
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Miguel Clemente-León
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Susana Trasobares
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Miguel López-Haro
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Jose J. Calvino
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - Odile Stéphan
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
| | - José M. Domínguez-Vera
- Departamento de Química Inorgánica, Universidad de Granada, 18071 Granada, Spain, Departamento de Química Inorgánica y Orgánica, EPS Linares, Universidad de Jaén, 23700 Linares, Spain, Instituto de Físico-Química Teórica y Aplicada, Universidad Nacional de La Plata, Argentina, Instituto de Ciencia Molecular, Universidad de Valencia, Fundació General de la Universitat de València (FGUV), Polígono de la Coma s/n, 46980 Paterna, Spain, Departamento Ciencia de Materiales e Ingeniería Metalúrgica y Química
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Bartzokis G, Lu PH, Tishler TA, Fong SM, Oluwadara B, Finn JP, Huang D, Bordelon Y, Mintz J, Perlman S. Myelin breakdown and iron changes in Huntington's disease: pathogenesis and treatment implications. Neurochem Res 2007; 32:1655-64. [PMID: 17484051 DOI: 10.1007/s11064-007-9352-7] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Accepted: 04/05/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND Postmortem and in vivo imaging data support the hypothesis that premature myelin breakdown and subsequent homeostatic remyelination attempts with increased oligodendrocyte and iron levels may contribute to Huntington's Disease (HD) pathogenesis and the symmetrical progress of neuronal loss from earlier-myelinating striatum to later-myelinating regions. A unique combination of in vivo tissue integrity and iron level assessments was used to examine the hypothesis. METHODS A method that uses two Magnetic resonance imaging (MRI) instruments operating at different field-strengths was used to quantify the iron content of ferritin molecules (ferritin iron) as well as tissue integrity in eight regions in 11 HD and a matched group of 27 healthy control subjects. Three white matter regions were selected based on their myelination pattern (early to later-myelinating) and fiber composition. These were frontal lobe white matter (Fwm) and splenium and genu of the corpus callosum (Swm and Gwm). In addition, gray matter structures were also chosen based on their myelination pattern and fiber composition. Three striatum structures were assessed [caudate, putamen, and globus pallidus (C, P, and G)] as well as two comparison gray matter regions that myelinate later in development and are relatively spared in HD [Hippocampus (Hipp) and Thalamus (Th)]. RESULTS Compared to healthy controls, HD ferritin iron levels were significantly increased in striatum C, P, and G, decreased in Fwm and Gwm, and were unchanged in Hipp, Th, and Swm. Loss of tissue integrity was observed in C, P, Fwm, and especially Swm but not Hipp, Th, G, or Gwm. This pattern of findings was largely preserved when a small subset of HD subjects early in the disease process was examined. CONCLUSIONS The data suggest early in the HD process, myelin breakdown and changes in ferritin iron distribution underlie the pattern of regional toxicity observed in HD. Prospective studies are needed to verify myelin breakdown and increased iron levels are causal factors in HD pathogenesis. Tracking the effects of novel interventions that reduce myelin breakdown and iron accumulation in preclinical stages of HD could hasten the development of preventive treatments.
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Affiliation(s)
- George Bartzokis
- Department of Neurology, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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45
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Gilad AA, Winnard PT, van Zijl PCM, Bulte JWM. Developing MR reporter genes: promises and pitfalls. NMR IN BIOMEDICINE 2007; 20:275-90. [PMID: 17451181 DOI: 10.1002/nbm.1134] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
MR reporter genes have the potential to monitor transgene expression non-invasively in real time at high resolution. These genes can be applied to interrogate the efficacy of gene therapy, to assess cellular differentiation, cell trafficking, and specific metabolic activity, and also assess changes in the microenvironment. Efforts toward the development of MR reporter genes have been made for at least a decade, but, despite these efforts, the field is still in its early developmental stage. This reflects the fact that there are potential pitfalls, caused by the low sensitivity of detection, the need for substrates with their associated undesirable pharmacokinetics, and/or the difficult and, in some cases, delayed interpretation of signal changes. Nevertheless, significant progress has been made during the last few years. Whereas enzyme-based reporters were initially applied to NMR spectroscopic monitoring of changes in phosphor and fluorine metabolism, MRI-based approaches are now emerging that rely on: (1) enzyme-based cleavage of functional groups that block water (proton) exchange or protein binding of MR contrast agents; (2) expression of surface receptors that enable binding of specific MR contrast agents; (3) expression of para- and anti-ferromagnetic (metallo)proteins involved with iron metabolism, such as tyrosinase, transferrin receptor, and ferritin. After an introduction to the basic principles of designing promoters, expression vectors, and cloning of transgenes, a fresh look is provided on the use of reporter genes for optical (including bioluminescent) and nuclear imaging, with which MR reporter genes compete. Although progress in the use of MR reporter genes has been slow, newer strategies that use metalloproteins or alternative contrast mechanisms, with no need for substrates, promise rapid growth potential for this field.
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Affiliation(s)
- Assaf A Gilad
- Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA
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46
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Cohen B, Ziv K, Plaks V, Israely T, Kalchenko V, Harmelin A, Benjamin LE, Neeman M. MRI detection of transcriptional regulation of gene expression in transgenic mice. Nat Med 2007; 13:498-503. [PMID: 17351627 DOI: 10.1038/nm1497] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Accepted: 09/28/2006] [Indexed: 12/25/2022]
Abstract
Ferritin, the iron storage protein, was recently suggested to be a candidate reporter for the detection of gene expression by magnetic resonance imaging (MRI). Here we report the generation of TET:EGFP-HAferritin (tet-hfer) transgenic mice, in which tissue-specific inducible transcriptional regulation of expression of the heavy chain of ferritin could be detected in vivo by MRI. We show organ specificity by mating the tet-hfer mice with transgenic mice expressing tetracycline transactivator (tTA) in liver hepatocytes and in vascular endothelial cells. Tetracycline-regulated overexpression of ferritin resulted in specific alterations of the transverse relaxation rate (R(2)) of water. Transgene-dependent changes in R(2) were detectable by MRI in adult mice, and we also found fetal developmental induction of transgene expression in utero. Thus, the tet-hfer MRI reporter mice provide a new transgenic mouse platform for in vivo molecular imaging of reporter gene expression by MRI during both embryonic and adult life.
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Affiliation(s)
- Batya Cohen
- Department of Biological Regulation, Weizmann Institute, Rehovot 76100, Israel
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47
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House MJ, St Pierre TG, Kowdley KV, Montine T, Connor J, Beard J, Berger J, Siddaiah N, Shankland E, Jin LW. Correlation of proton transverse relaxation rates (R2) with iron concentrations in postmortem brain tissue from alzheimer's disease patients. Magn Reson Med 2007; 57:172-80. [PMID: 17191232 DOI: 10.1002/mrm.21118] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Iron accumulates in the Alzheimer's disease (AD) brain and is directly associated with beta-amyloid pathology. The proton transverse relaxation rate (R(2)) has a strong linear relationship with iron concentrations in healthy brain tissue; however, an independent test of this relationship has not been extended to AD brain tissue. In this study in vitro single spin-echo (SE) measurements were made on tissue samples from four human AD brains using a 4.7T MRI research scanner. R(2) values were calculated for 14 cortical and subcortical gray matter (GM) and white matter (WM) regions. Atomic absorption spectroscopy was used to measure iron concentrations in the corresponding excised brain regions. Significant positive linear correlations were observed between R(2) values and iron concentrations in GM regions assessed across individual tissue samples and data averaged by brain region. With the use of a predictive model for R(2), a threshold iron concentration of 55 microg Fe/g wet tissue was determined above which R(2) appears to be dominated by the affects of iron in AD brain tissue. High-field MRI may therefore be a useful research tool for assessing brain iron changes associated with AD.
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Affiliation(s)
- Michael J House
- School of Physics, University of Western Australia, Perth, Australia.
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48
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Deans AE, Wadghiri YZ, Bernas LM, Yu X, Rutt BK, Turnbull DH. Cellular MRI contrast via coexpression of transferrin receptor and ferritin. Magn Reson Med 2006; 56:51-9. [PMID: 16724301 PMCID: PMC4079558 DOI: 10.1002/mrm.20914] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recently there has been growing interest in the development and use of iron-based contrast agents for cellular imaging with MRI. In this study we investigated coexpression of the transferrin receptor and ferritin genes to induce cellular contrast in a biological system. Expression of transgenic human transferrin receptor and human ferritin H-subunit was induced in a stably transfected mouse neural stem cell line. When grown in iron-rich medium, the transgenic cells accumulated significantly more iron than control cells, with a trend toward an increase in reactive oxygen species, but no detrimental effects on cell viability. This cellular iron significantly increased the transverse relaxivities, R2 and R2*, at 1.5 T and 7 T. By comparing measurements in the same cell samples at 1.5 T and 7 T, we confirmed the expected increase in relaxivity with increasing field strength. Finally, supplemented transgenic cells transplanted into mouse brain demonstrated increased contrast with surrounding neural tissue on T2*-weighted MR brain images compared to controls. These results indicate that dual expression of proteins at different critical points in the iron metabolism pathway may improve cellular contrast without compromising cell viability.
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Affiliation(s)
- Abby E. Deans
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA
| | - Youssef Zaim Wadghiri
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA
- Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Lisa M. Bernas
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Xin Yu
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA
| | - Brian K. Rutt
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Daniel H. Turnbull
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA
- Department of Radiology, New York University School of Medicine, New York, New York, USA
- Department of Pathology, New York University School of Medicine, New York, New York, USA
- Correspondence to: Daniel H. Turnbull, Ph.D., Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Ave., New York, NY 10016.
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Pawelczyk E, Arbab AS, Pandit S, Hu E, Frank JA. Expression of transferrin receptor and ferritin following ferumoxides-protamine sulfate labeling of cells: implications for cellular magnetic resonance imaging. NMR IN BIOMEDICINE 2006; 19:581-92. [PMID: 16673357 DOI: 10.1002/nbm.1038] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Ferumoxides-protamine sulfate (FE-Pro) complexes are used for intracellular magnetic labeling of cells to non-invasively monitor cell trafficking by in vivo MRI. FE-Pro labeling is non-toxic to cells; however, the effects of FE-Pro labeling on cellular expression of transferrin receptor (TfR-1) and ferritin, proteins involved in iron transport and storage, has not been reported. FE-Pro-labeled human mesenchymal stem cells (MSCs), HeLa cells and primary macrophages were cultured from 1 week to 2 months and evaluated for TfR-1 and ferritin gene expression by RT-PCR and protein levels were determined using Western blots. MTT (proliferation assay) and reactive oxygen species (ROS) analysis were performed. FE-Pro labeling of HeLa and MSCs resulted in a transient decrease in TfR-1 mRNA and protein levels. In contrast, Fe-Pro labeling of primary macrophages resulted in an increase in TfR-1 mRNA but not in TfR-1 protein levels. Ferritin mRNA and protein levels increased transiently in labeled HeLa and macrophages but were sustained in MSCs. No changes in MTT and ROS analysis were noted. In conclusion, FE-Pro labeling elicited physiological changes of iron metabolism or storage, validating the safety of this procedure for cellular tracking by MRI.
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Affiliation(s)
- Edyta Pawelczyk
- Laboratory of Diagnostic Radiology Research, Experimental Neuroimaging Section, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
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Brain ferritin iron may influence age- and gender-related risks of neurodegeneration. Neurobiol Aging 2006; 28:414-23. [PMID: 16563566 DOI: 10.1016/j.neurobiolaging.2006.02.005] [Citation(s) in RCA: 263] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 02/02/2006] [Accepted: 02/09/2006] [Indexed: 12/14/2022]
Abstract
BACKGROUND Brain iron promotes oxidative damage and protein oligomerization that result in highly prevalent age-related proteinopathies such as Alzheimer's disease (AD), Parkinson's disease (PD), and Dementia with Lewy Bodies (DLB). Men are more likely to develop such diseases at earlier ages than women but brain iron levels increase with age in both genders. We hypothesized that brain iron may influence both the age- and gender-related risks of developing these diseases. METHODS The amount of iron in ferritin molecules (ferritin iron) was measured in vivo with MRI by utilizing the field dependent relaxation rate increase (FDRI) method. Ferritin iron was measured in four subcortical nuclei [caudate (C), putamen (P), globus pallidus (G), thalamus (T)], three white matter regions [frontal lobe (Fwm), genu and splenium of the corpus callosum (Gwm, Swm)] and hippocampus (Hipp) in 165 healthy adults aged 19-82. RESULTS There was a high correlation (r>0.99) between published post-mortem brain iron levels and FDRI. There were significant age-related changes in ferritin iron (increases in Hipp, C, P, G, and decreases in Fwm). Women had significantly lower ferritin iron than men in five regions (C, T, Fwm, Gwm, Swm). CONCLUSIONS This is the first demonstration of gender differences in brain ferritin iron levels. It is possible that brain iron accumulation is a risk factor that can be modified. MRI provides the opportunity to assess brain iron levels in vivo and may be useful in targeting individuals or groups for preventive therapeutic interventions.
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