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Nair G, Sun R, Merkle H, Xu Q, Hoskin K, Bree K, Dodd S, Koretsky AP. A method to image brain tissue frozen at autopsy. Neuroimage 2024; 296:120680. [PMID: 38857819 PMCID: PMC11220777 DOI: 10.1016/j.neuroimage.2024.120680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/04/2024] [Accepted: 06/07/2024] [Indexed: 06/12/2024] Open
Abstract
Magnetic Resonance Imaging (MRI) can provide the location and signal characteristics of pathological regions within a postmortem tissue block, thereby improving the efficiency of histopathological studies. However, such postmortem-MRI guided histopathological studies have so far only been performed on fixed samples as imaging tissue frozen at the time of extraction, while preserving its integrity, is significantly more challenging. Here we describe the development of cold-postmortem-MRI, which can preserve tissue integrity and help target techniques such as transcriptomics. As a first step, RNA integrity number (RIN) was used to determine the rate of tissue biomolecular degradation in mouse brains placed at various temperatures between -20 °C and +20 °C for up to 24 h. Then, human tissue frozen at the time of autopsy was immersed in 2-methylbutane, sealed in a bio-safe tissue chamber, and cooled in the MRI using a recirculating chiller to determine MRI signal characteristics. The optimal imaging temperature, which did not show significant RIN deterioration for over 12 h, at the same time giving robust MRI signal and contrast between brain tissue types was deemed to be -7 °C. Finally, MRI was performed on human tissue blocks at this optimal imaging temperatures using a magnetization-prepared rapid gradient echo (MPRAGE, isotropic resolution between 0.3-0.4 mm) revealing good gray-white matter contrast and revealing subpial, subcortical, and deep white matter lesions. RINs measured before and after imaging revealed no significant changes (n = 3, p = 0.18, paired t-test). In addition to improving efficiency of downstream processes, imaging tissue at sub-zero temperatures may also improve our understanding of compartment specificity of MRI signal.
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Affiliation(s)
- Govind Nair
- Quantitative MRI Core, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Dr, Bethesda, MD 20893, USA.
| | - Roy Sun
- Quantitative MRI Core, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Dr, Bethesda, MD 20893, USA
| | - Hellmut Merkle
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
| | - Qing Xu
- Human Brain Collection Core, National Institute of Mental Health, National Institutes of Health, Bethesda, USA
| | - Kyra Hoskin
- Quantitative MRI Core, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Dr, Bethesda, MD 20893, USA
| | - Kendyl Bree
- Quantitative MRI Core, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Dr, Bethesda, MD 20893, USA
| | - Stephen Dodd
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
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Nair G, Sun R, Merkle H, Hoskin K, Bree K, Dodd S, Koretsky A. Postmortem MRI of Tissue Frozen at Autopsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.20.576456. [PMID: 38313300 PMCID: PMC10836069 DOI: 10.1101/2024.01.20.576456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
Introduction Postmortem MRI provides insight into location of pathology within tissue blocks, enabling efficient targeting of histopathological studies. While postmortem imaging of fixed tissue is gaining popularity, imaging tissue frozen at the time of extraction is significantly more challenging. Methods Tissue integrity was examined using RNA integrity number (RIN), in mouse brains placed between -20 °C and 20 °C for up to 24 hours, to determine the highest temperature that could potentially be used for imaging without tissue degeneration. Human tissue frozen at the time of autopsy was sealed in a tissue chamber filled with 2-methylbutane to prevent contamination of the MRI components. The tissue was cooled to a range of temperatures in a 9.4T MRI using a recirculating aqueous ethylene glycol solution. MRI was performed using a magnetization-prepared rapid gradient echo (MPRAGE) sequence with inversion time of 1400 ms to null the signal from 2-methylbutane bath, isotropic resolution between 0.3-0.4 mm, and scan time of about 4 hours was used to study the anatomical details of the tissue block. Results and Discussion A temperature of -7 °C was chosen for imaging as it was below the highest temperature that did not show significant RIN deterioration for over 12 hours, at the same time gave robust imaging signal and contrast between brain tissue types. Imaging performed on various human tissue blocks revealed good gray-white matter contrast and revealing subpial, subcortical, and deep white matter lesions typical of multiple sclerosis enabling further spatially targeted studies. Conclusion Here, we describe a new method to image cold tissue, while maintaining tissue integrity and biosafety during scanning. In addition to improving efficiency of downstream processes, imaging tissue at sub-zero temperatures may also improve our understanding of compartment specificity of MRI signal.
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Affiliation(s)
- Govind Nair
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Roy Sun
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Hellmut Merkle
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Kyra Hoskin
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Kendyl Bree
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Stephen Dodd
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Alan Koretsky
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
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Lachowicz D, Kmita A, Gajewska M, Trynkiewicz E, Przybylski M, Russek SE, Stupic KF, Woodrum DA, Gorny KR, Celinski ZJ, Hankiewicz JH. Aqueous Dispersion of Manganese-Zinc Ferrite Nanoparticles Protected by PEG as a T 2 MRI Temperature Contrast Agent. Int J Mol Sci 2023; 24:16458. [PMID: 38003646 PMCID: PMC10671015 DOI: 10.3390/ijms242216458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/03/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023] Open
Abstract
Mixed manganese-zinc ferrite nanoparticles coated with PEG were studied for their potential usefulness in MRI thermometry as temperature-sensitive contrast agents. Particles in the form of an 8.5 nm core coated with a 3.5 nm layer of PEG were fabricated using a newly developed, one-step method. The composition of Mn0.48Zn0.46Fe2.06O4 was found to have a strong thermal dependence of magnetization in the temperature range between 5 and 50 °C. Nanoparticles suspended in an agar gel mimicking animal tissue and showing non-significant impact on cell viability in the biological test were studied with NMR and MRI over the same temperature range. For the concentration of 0.017 mg/mL of Fe, the spin-spin relaxation time T2 increased from 3.1 to 8.3 ms, while longitudinal relaxation time T1 shows a moderate decrease from 149.0 to 125.1 ms. A temperature map of the phantom exposed to the radial temperature gradient obtained by heating it with an 808 nm laser was calculated from T2 weighted spin-echo differential MR images. Analysis of temperature maps yields thermal/spatial resolution of 3.2 °C at the distance of 2.9 mm. The experimental relaxation rate R2 data of water protons were compared with those obtained from calculations using a theoretical model incorporating the motion averaging regime.
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Affiliation(s)
- Dorota Lachowicz
- Academic Centre for Materials and Nanotechnology, AGH University of Krakow, 30-059 Krakow, Poland; (D.L.); (M.G.); (E.T.); (M.P.)
| | - Angelika Kmita
- Academic Centre for Materials and Nanotechnology, AGH University of Krakow, 30-059 Krakow, Poland; (D.L.); (M.G.); (E.T.); (M.P.)
| | - Marta Gajewska
- Academic Centre for Materials and Nanotechnology, AGH University of Krakow, 30-059 Krakow, Poland; (D.L.); (M.G.); (E.T.); (M.P.)
| | - Elżbieta Trynkiewicz
- Academic Centre for Materials and Nanotechnology, AGH University of Krakow, 30-059 Krakow, Poland; (D.L.); (M.G.); (E.T.); (M.P.)
| | - Marek Przybylski
- Academic Centre for Materials and Nanotechnology, AGH University of Krakow, 30-059 Krakow, Poland; (D.L.); (M.G.); (E.T.); (M.P.)
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, 30-059 Krakow, Poland
| | - Stephen E. Russek
- National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305, USA; (S.E.R.)
| | - Karl F. Stupic
- National Institute of Standards and Technology, 325 Broadway St, Boulder, CO 80305, USA; (S.E.R.)
| | - David A. Woodrum
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; (D.A.W.); (K.R.G.)
| | - Krzysztof R. Gorny
- Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; (D.A.W.); (K.R.G.)
| | - Zbigniew J. Celinski
- Center for the BioFrontiers Institute, University of Colorado Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918, USA; (Z.J.C.); (J.H.H.)
| | - Janusz H. Hankiewicz
- Center for the BioFrontiers Institute, University of Colorado Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918, USA; (Z.J.C.); (J.H.H.)
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Stoll JA, Lachowicz D, Kmita A, Gajewska M, Sikora M, Berent K, Przybylski M, Russek SE, Celinski ZJ, Hankiewicz JH. Synthesis of Manganese Zinc Ferrite Nanoparticles in Medical-Grade Silicone for MRI Applications. Int J Mol Sci 2023; 24:ijms24065685. [PMID: 36982758 PMCID: PMC10059734 DOI: 10.3390/ijms24065685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/06/2023] [Accepted: 03/13/2023] [Indexed: 03/19/2023] Open
Abstract
The aim of this project is to fabricate hydrogen-rich silicone doped with magnetic nanoparticles for use as a temperature change indicator in magnetic resonance imaging-guided (MRIg) thermal ablations. To avoid clustering, the particles of mixed MnZn ferrite were synthesized directly in a medical-grade silicone polymer solution. The particles were characterized by transmission electron microscopy, powder X-ray diffraction, soft X-ray absorption spectroscopy, vibrating sample magnetometry, temperature-dependent nuclear magnetic resonance relaxometry (20 °C to 60 °C, at 3.0 T), and magnetic resonance imaging (at 3.0 T). Synthesized nanoparticles were the size of 4.4 nm ± 2.1 nm and exhibited superparamagnetic behavior. Bulk silicone material showed a good shape stability within the study’s temperature range. Embedded nanoparticles did not influence spin–lattice relaxation, but they shorten the longer component of spin–spin nuclear relaxation times of silicone’s protons. However, these protons exhibited an extremely high r2* relaxivity (above 1200 L s−1 mmol−1) due to the presence of particles, with a moderate decrease in the magnetization with temperature. With an increased temperature decrease of r2*, this ferro–silicone can be potentially used as a temperature indicator in high-temperature MRIg ablations (40 °C to 60 °C).
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Affiliation(s)
- Joshua A. Stoll
- Colorado Springs Center for the BioFrontiers Institute, University of Colorado, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, USA
| | - Dorota Lachowicz
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland
- Correspondence:
| | - Angelika Kmita
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland
| | - Marta Gajewska
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland
| | - Marcin Sikora
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland
| | - Katarzyna Berent
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland
| | - Marek Przybylski
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland
| | - Stephen E. Russek
- National Institute of Standards and Technology, 325 Broadway St., Boulder, CO 80305, USA
| | - Zbigniew J. Celinski
- Colorado Springs Center for the BioFrontiers Institute, University of Colorado, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, USA
| | - Janusz H. Hankiewicz
- Colorado Springs Center for the BioFrontiers Institute, University of Colorado, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, USA
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Stroud J, Hao Y, Read TS, Hankiewicz JH, Bilski P, Klodowski K, Brown JM, Rogers K, Stoll J, Camley RE, Celinski Z, Przybylski M. Magnetic particle based MRI thermometry at 0.2 T and 3 T. Magn Reson Imaging 2023; 100:43-54. [PMID: 36933774 DOI: 10.1016/j.mri.2023.03.004] [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: 12/03/2022] [Revised: 02/28/2023] [Accepted: 03/12/2023] [Indexed: 03/18/2023]
Abstract
This study provides insight into the advantages and disadvantages of using ferrite particles embedded in agar gel phantoms as MRI temperature indicators for low-magnetic field scanners. We compare the temperature-dependent intensity of MR images at low-field (0.2 T) to those at high-field (3.0 T). Due to a shorter T1 relaxation time at low-fields, MRI scanners operating at 0.2 T can use shorter repetition times and achieve a significant T2⁎ weighting, resulting in strong temperature-dependent changes of MR image brightness in short acquisition times. Although the signal-to-noise ratio for MR images at 0.2 T MR is much lower than at 3.0 T, it is sufficient to achieve a temperature measurement uncertainty of about ±1.0 °C at 37 °C for a 90 μg/mL concentration of magnetic particles.
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Affiliation(s)
- John Stroud
- UCCS BioFrontiers Center, University of Colorado, Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States; Department of Physics and Energy Science, University of Colorado, Colorado Springs 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States
| | - Yu Hao
- UCCS BioFrontiers Center, University of Colorado, Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States; Department of Physics and Energy Science, University of Colorado, Colorado Springs 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States
| | - Tim S Read
- UCCS BioFrontiers Center, University of Colorado, Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States
| | - Janusz H Hankiewicz
- UCCS BioFrontiers Center, University of Colorado, Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States
| | - Pawel Bilski
- Department of Physics, A. Mickiewicz University, Uniwersytetu Poznanskiego St. 2, 61-614 Poznan, Poland
| | - Krzysztof Klodowski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Mickiewicza Ave. 30, 30-059 Kraków, Poland
| | - Jared M Brown
- Colorado Center for Nanomedicine and Nanosafety, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Keegan Rogers
- Colorado Center for Nanomedicine and Nanosafety, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Josh Stoll
- UCCS BioFrontiers Center, University of Colorado, Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States; Department of Physics and Energy Science, University of Colorado, Colorado Springs 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States
| | - Robert E Camley
- UCCS BioFrontiers Center, University of Colorado, Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States; Department of Physics and Energy Science, University of Colorado, Colorado Springs 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States
| | - Zbigniew Celinski
- UCCS BioFrontiers Center, University of Colorado, Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States; Department of Physics and Energy Science, University of Colorado, Colorado Springs 1420 Austin Bluffs Pkwy, Colorado Springs, CO 80918, United States
| | - Marek Przybylski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Mickiewicza Ave. 30, 30-059 Kraków, Poland; Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Mickiewicza Ave. 30, 30-059 Kraków, Poland.
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Motovilova E, Aronowitz E, Vincent J, Shin J, Tan ET, Robb F, Taracila V, Sneag DB, Dyke JP, Winkler SA. Silicone-based materials with tailored MR relaxation characteristics for use in reduced coil visibility and in tissue-mimicking phantom design. Med Phys 2023. [PMID: 36737839 DOI: 10.1002/mp.16255] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 12/24/2022] [Accepted: 01/15/2023] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The development of materials with tailored signal intensity in MR imaging is critically important both for the reduction of signal from non-tissue hardware, as well as for the construction of tissue-mimicking phantoms. Silicone-based phantoms are becoming more popular due to their structural stability, stretchability, longer shelf life, and ease of handling, as well as for their application in dynamic imaging of physiology in motion. Moreover, silicone can be also used for the design of stretchable receive radio-frequency (RF) coils. PURPOSE Fabrication of materials with tailored signal intensity for MRI requires knowledge of precise T1 and T2 relaxation times of the materials used. In order to increase the range of possible relaxation times, silicone materials can be doped with gadolinium (Gd). In this work, we aim to systematically evaluate relaxation properties of Gd-doped silicone material at a broad range of Gd concentrations and at three clinically relevant magnetic field strengths (1.5 T, 3 T, and 7 T). We apply the findings for rendering silicone substrates of stretchable receive RF coils less visible in MRI. Moreover, we demonstrate early stage proof-of-concept applicability in tissue-mimicking phantom development. MATERIALS AND METHODS Ten samples of pure and Gd-doped Ecoflex silicone polymer samples were prepared with various Gd volume ratios ranging from 1:5000 to 1:10, and studied using 1.5 T and 3 T clinical and 7 T preclinical scanners. T1 and T2 relaxation times of each sample were derived by fitting the data to Bloch signal intensity equations. A receive coil made from Gd-doped Ecoflex silicone polymer was fabricated and evaluated in vitro at 3 T. RESULTS With the addition of a Gd-based contrast agent, it is possible to significantly change T2 relaxation times of Ecoflex silicone polymer (from 213 ms to 20 ms at 1.5 T; from 135 ms to 17 ms at 3 T; and from 111.4 ms to 17.2 ms at 7 T). T1 relaxation time is less affected by the introduction of the contrast agent (changes from 608 ms to 579 ms; from 802.5 ms to 713 ms at 3 T; from 1276 ms to 979 ms at 7 T). First results also indicate that liver, pancreas, and white matter tissues can potentially be closely mimicked using this phantom preparation technique. Gd-doping reduces the appearance of the silicone-based coil substrate during the MR scan by up to 81%. CONCLUSIONS Gd-based contrast agents can be effectively used to create Ecoflex silicone polymer-based phantoms with tailored T2 relaxation properties. The relative low cost, ease of preparation, stretchability, mechanical stability, and long shelf life of Ecoflex silicone polymer all make it a good candidate for "MR invisible" coil development and bears promise for tissue-mimicking phantom development applicability.
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Affiliation(s)
- Elizaveta Motovilova
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA.,Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | - Eric Aronowitz
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | | | - James Shin
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | - Ek Tsoon Tan
- Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | | | | | - Darryl B Sneag
- Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | - Jonathan P Dyke
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
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