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Kolouchova K, Jirak D, Groborz O, Sedlacek O, Ziolkowska N, Vit M, Sticova E, Galisova A, Svec P, Trousil J, Hajek M, Hruby M. Implant-forming polymeric 19F MRI-tracer with tunable dissolution. J Control Release 2020; 327:50-60. [PMID: 32730953 DOI: 10.1016/j.jconrel.2020.07.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 12/29/2022]
Abstract
Magnetic resonance imaging (MRI) using 19F-based tracers has emerged as a promising multi-purpose noninvasive diagnostic tool and its application requires the use of various 19F-based tracers for the intended diagnostic purpose. In this study, we report a series of double-stimuli-responsive polymers for use as injectable implants, which were designed to form implants under physiological conditions, and to subsequently dissolve with different dissolution rates (t1/2 ranges from 30 to more than 250 days). Our polymers contain a high concentration of fluorine atoms, providing remarkable signal detectability, and both a hydrophilic monomer and a pH-responsive monomer that alter the biodistribution properties of the implant. The implant location and dissolution were observed using 19F MRI, which allows the anatomic extent of the implant to be monitored. The dissolution kinetics and biocompatibility of these materials were thoroughly analyzed. No sign of toxicity in vitro or in vivo or pathology in vivo was observed, even in chronic administration. The clinical applicability of our polymers was further confirmed via imaging of a rat model by employing an instrument currently used in human medicine.
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Affiliation(s)
- Kristyna Kolouchova
- Institute of Macromolecular Chemistry CAS, Heyrovsky Square 2, 162 06 Prague 6, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 00, Czech Republic
| | - Daniel Jirak
- Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic; Department of Science and Research, Faculty of Health Studies, Technical University of Liberec, Studentska 1402/2, 461 17 Liberec, Czech Republic.
| | - Ondrej Groborz
- Institute of Macromolecular Chemistry CAS, Heyrovsky Square 2, 162 06 Prague 6, Czech Republic; Department of Organic Chemistry, Charles University, Faculty of Science, Hlavova 8, 128 43 Prague 2, Czech Republic; Institute of Biophysics and Informatics, Charles University, First Faculty of Medicine, Salmovská 1, 120 00 Prague 2, Czech Republic; Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo square 542/2, 162 06 Prague 6, Czech Republic
| | - Ondrej Sedlacek
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281-S4, 9000 Ghent, Belgium
| | - Natalia Ziolkowska
- Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic; Institute of Biophysics and Informatics, Charles University, First Faculty of Medicine, Salmovská 1, 120 00 Prague 2, Czech Republic
| | - Martin Vit
- Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic; Technical University of Liberec, Faculty of Mechatronics Informatics and Interdisciplinary Studies, Studentska 1402/2, 461 17 Liberec, Czech Republic
| | - Eva Sticova
- Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic
| | - Andrea Galisova
- Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic
| | - Pavel Svec
- Institute of Macromolecular Chemistry CAS, Heyrovsky Square 2, 162 06 Prague 6, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 2 128 00, Czech Republic
| | - Jiri Trousil
- Institute of Macromolecular Chemistry CAS, Heyrovsky Square 2, 162 06 Prague 6, Czech Republic
| | - Milan Hajek
- Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4, Czech Republic
| | - Martin Hruby
- Institute of Macromolecular Chemistry CAS, Heyrovsky Square 2, 162 06 Prague 6, Czech Republic.
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Keeley TP, Mann GE. Defining Physiological Normoxia for Improved Translation of Cell Physiology to Animal Models and Humans. Physiol Rev 2019; 99:161-234. [PMID: 30354965 DOI: 10.1152/physrev.00041.2017] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The extensive oxygen gradient between the air we breathe (Po2 ~21 kPa) and its ultimate distribution within mitochondria (as low as ~0.5-1 kPa) is testament to the efforts expended in limiting its inherent toxicity. It has long been recognized that cell culture undertaken under room air conditions falls short of replicating this protection in vitro. Despite this, difficulty in accurately determining the appropriate O2 levels in which to culture cells, coupled with a lack of the technology to replicate and maintain a physiological O2 environment in vitro, has hindered addressing this issue thus far. In this review, we aim to address the current understanding of tissue Po2 distribution in vivo and summarize the attempts made to replicate these conditions in vitro. The state-of-the-art techniques employed to accurately determine O2 levels, as well as the issues associated with reproducing physiological O2 levels in vitro, are also critically reviewed. We aim to provide the framework for researchers to undertake cell culture under O2 levels relevant to specific tissues and organs. We envisage that this review will facilitate a paradigm shift, enabling translation of findings under physiological conditions in vitro to disease pathology and the design of novel therapeutics.
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Affiliation(s)
- Thomas P Keeley
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
| | - Giovanni E Mann
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
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Jirak D, Galisova A, Kolouchova K, Babuka D, Hruby M. Fluorine polymer probes for magnetic resonance imaging: quo vadis? MAGMA (NEW YORK, N.Y.) 2019; 32:173-185. [PMID: 30498886 PMCID: PMC6514090 DOI: 10.1007/s10334-018-0724-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/19/2018] [Accepted: 11/21/2018] [Indexed: 12/26/2022]
Abstract
Over the last few years, the development and relevance of 19F magnetic resonance imaging (MRI) for use in clinical practice has emerged. MRI using fluorinated probes enables the achievement of a specific signal with high contrast in MRI images. However, to ensure sufficient sensitivity of 19F MRI, fluorine probes with a high content of chemically equivalent fluorine atoms are required. The majority of 19F MRI agents are perfluorocarbon emulsions, which have a broad range of applications in molecular imaging, although the content of fluorine atoms in these molecules is limited. In this review, we focus mainly on polymer probes that allow higher fluorine content and represent versatile platforms with properties tailorable to a plethora of biomedical in vivo applications. We discuss the chemical development, up to the first imaging applications, of these promising fluorine probes, including injectable polymers that form depots that are intended for possible use in cancer therapy.
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Affiliation(s)
- Daniel Jirak
- Institute for Clinical and Experimental Medicine, Vídeňská 9, 140 21, Prague 4, Czech Republic.
- Institute of Biophysics and Informatics, 1st Medicine Faculty, Charles University, Salmovská 1, 120 00, Prague, Czech Republic.
- Faculty of Health Studies, Technical University of Liberec, Studentská 1402/2, 461 17, Liberec 1, Czech Republic.
| | - Andrea Galisova
- Institute for Clinical and Experimental Medicine, Vídeňská 9, 140 21, Prague 4, Czech Republic
| | - Kristyna Kolouchova
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského sq. 2, 162 06, Prague 6, Czech Republic
| | - David Babuka
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského sq. 2, 162 06, Prague 6, Czech Republic
| | - Martin Hruby
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského sq. 2, 162 06, Prague 6, Czech Republic
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Kolouchova K, Sedlacek O, Jirak D, Babuka D, Blahut J, Kotek J, Vit M, Trousil J, Konefał R, Janouskova O, Podhorska B, Slouf M, Hruby M. Self-Assembled Thermoresponsive Polymeric Nanogels for 19F MR Imaging. Biomacromolecules 2018; 19:3515-3524. [PMID: 30011367 DOI: 10.1021/acs.biomac.8b00812] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Magnetic resonance imaging using fluorinated contrast agents (19F MRI) enables to achive highcontrast in images due to the negligible fluorine background in living tissues. In this pilot study, we developed new biocompatible, temperature-responsive, and easily synthesized polymeric nanogels containing a sufficient concentration of magnetically equivalent fluorine atoms for 19F MRI purposes. The structure of the nanogels is based on amphiphilic copolymers containing two blocks, a hydrophilic poly[ N-(2-hydroxypropyl)methacrylamide] (PHPMA) or poly(2-methyl-2-oxazoline) (PMeOx) block, and a thermoresponsive poly[ N(2,2difluoroethyl)acrylamide] (PDFEA) block. The thermoresponsive properties of the PDFEA block allow us to control the process of nanogel self-assembly upon its heating in an aqueous solution. Particle size depends on the copolymer composition, and the most promising copolymers with longer thermoresponsive blocks form nanogels of suitable size for angiogenesis imaging or the labeling of cells (approximately 120 nm). The in vitro 19F MRI experiments reveal good sensitivity of the copolymer contrast agents, while the nanogels were proven to be noncytotoxic for several cell lines.
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Affiliation(s)
- Kristyna Kolouchova
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic
| | - Ondrej Sedlacek
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic.,Department of Organic and Macromolecular Chemistry , Ghent University , Krijgslaan 281-S4 , 9000 Ghent , Belgium
| | - Daniel Jirak
- Institute for Clinical and Experimental Medicine , Vídeňská 9 , Prague 4 140 21 , Czech Republic.,Institute of Biophysics and Informatics, First Medicine Faculty , Charles University , Salmovská 1 , Prague 120 00 , Czech Republic
| | - David Babuka
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic
| | - Jan Blahut
- Department of Inorganic Chemistry, Faculty of Science , Charles University , Hlavova 8 , Prague 2 128 00 , Czech Republic
| | - Jan Kotek
- Department of Inorganic Chemistry, Faculty of Science , Charles University , Hlavova 8 , Prague 2 128 00 , Czech Republic
| | - Martin Vit
- Institute for Clinical and Experimental Medicine , Vídeňská 9 , Prague 4 140 21 , Czech Republic.,TU Liberec, Faculty of mechatronics, informatics and interdisciplinary studies , Studentská 1402/2 , Liberec 1 461 17 , Czech Republic
| | - Jiri Trousil
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic.,Department of Analytical Chemistry, Faculty of Science , Charles University , Hlavova 8 , Prague 2 128 43 , Czech Republic
| | - Rafał Konefał
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic
| | - Olga Janouskova
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic
| | - Bohumila Podhorska
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic
| | - Miroslav Slouf
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic
| | - Martin Hruby
- Institute of Macromolecular Chemistry AS CR , v.v.i., Heyrovského sq. 2 , Prague 6 162 06 , Czech Republic
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5
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Lee AL, Gee CT, Weegman BP, Einstein SA, Juelfs A, Ring HL, Hurley KR, Egger SM, Swindlehurst G, Garwood M, Pomerantz WCK, Haynes CL. Oxygen Sensing with Perfluorocarbon-Loaded Ultraporous Mesostructured Silica Nanoparticles. ACS NANO 2017; 11:5623-5632. [PMID: 28505422 PMCID: PMC5515277 DOI: 10.1021/acsnano.7b01006] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Oxygen homeostasis is important in the regulation of biological function. Disease progression can be monitored by measuring oxygen levels, thus producing information for the design of therapeutic treatments. Noninvasive measurements of tissue oxygenation require the development of tools with minimal adverse effects and facile detection of features of interest. Fluorine magnetic resonance imaging (19F MRI) exploits the intrinsic properties of perfluorocarbon (PFC) liquids for anatomical imaging, cell tracking, and oxygen sensing. However, the highly hydrophobic and lipophobic properties of perfluorocarbons require the formation of emulsions for biological studies, though stabilizing these emulsions has been challenging. To enhance the stability and biological loading of perfluorocarbons, one option is to incorporate perfluorocarbon liquids into the internal space of biocompatible mesoporous silica nanoparticles. Here, we developed perfluorocarbon-loaded ultraporous mesostructured silica nanoparticles (PERFUMNs) as 19F MRI detectable oxygen-sensing probes. Ultraporous mesostructured silica nanoparticles (UMNs) have large internal cavities (average = 1.8 cm3 g-1), facilitating an average 17% loading efficiency of PFCs, meeting the threshold fluorine concentrations needed for imaging studies. Perfluoro-15-crown-5-ether PERFUMNs have the highest equivalent nuclei per PFC molecule and a spin-lattice (T1) relaxation-based oxygen sensitivity of 0.0032 mmHg-1 s-1 at 16.4 T. The option of loading PFCs after synthesizing UMNs, rather than traditional in situ core-shell syntheses, allows for use of a broad range of PFC liquids from a single material. The biocompatible and tunable chemistry of UMNs combined with the intrinsic properties of PFCs makes PERFUMNs a MRI sensor with potential for anatomical imaging, cell tracking, and metabolic spectroscopy with improved stability.
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Affiliation(s)
- Amani L. Lee
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Clifford T. Gee
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Bradley P. Weegman
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN 55455, United States
| | - Samuel A. Einstein
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN 55455, United States
| | - Adam Juelfs
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Hattie L. Ring
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN 55455, United States
| | - Katie R. Hurley
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Sam M. Egger
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Garrett Swindlehurst
- Department of Chemical Engineering & Material Science, University of Minnesota, Minneapolis, MN 55455, United States
| | - Michael Garwood
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN 55455, United States
| | | | - Christy L. Haynes
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
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Roussakis E, Li Z, Nichols AJ, Evans CL. Sauerstoffmessung in der Biomedizin - von der Makro- zur Mikroebene. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201410646] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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7
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Roussakis E, Li Z, Nichols AJ, Evans CL. Oxygen-Sensing Methods in Biomedicine from the Macroscale to the Microscale. Angew Chem Int Ed Engl 2015; 54:8340-62. [DOI: 10.1002/anie.201410646] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/05/2015] [Indexed: 12/15/2022]
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8
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Yu JX, Hallac RR, Chiguru S, Mason RP. New frontiers and developing applications in 19F NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 70:25-49. [PMID: 23540575 PMCID: PMC3613763 DOI: 10.1016/j.pnmrs.2012.10.001] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 10/23/2012] [Indexed: 05/06/2023]
Affiliation(s)
- Jian-Xin Yu
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
| | - Rami R. Hallac
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
| | - Srinivas Chiguru
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
| | - Ralph P. Mason
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
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Tran LBA, Bol A, Labar D, Jordan B, Magat J, Mignion L, Grégoire V, Gallez B. Hypoxia imaging with the nitroimidazole 18F-FAZA PET tracer: a comparison with OxyLite, EPR oximetry and 19F-MRI relaxometry. Radiother Oncol 2012; 105:29-35. [PMID: 22677038 DOI: 10.1016/j.radonc.2012.04.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 04/02/2012] [Accepted: 04/16/2012] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND PURPOSE (18)F-FAZA is a nitroimidazole PET tracer that can provide images of tumor hypoxia. However, it cannot provide absolute pO(2) values. To qualify (18)F-FAZA PET, we compared PET images to pO(2) measured by OxyLite, EPR oximetry and (19)F-MRI. MATERIALS AND METHODS Male WAG/Rij rats grafted with rhabdomyosarcoma were used. Tumor oxygenation was modified by gas breathing (air or carbogen). The same day of PET acquisition, the pO(2) was measured in the same tumor either by OxyLite probes (measurement at 10 different sites), EPR oximetry using low frequency EPR or (19)F-relaxometry using 15C5 on an 11.7T MR system. RESULTS There was a good correlation between the results obtained by PET and EPR (R = 0.93). In the case of OxyLite, although a weaker correlation was observed (R = 0.55), the trend for two values to agree was still related to the inverse function theoretically predicted. For the comparison of (18)F-FAZA PET and (19)F-MRI, no change in T(1) was observed. CONCLUSIONS A clear correlation between (18)F-FAZA PET image intensities and tumor oxygenation was demonstrated, suggesting that (18)F-FAZA PET is a promising imaging technique to guide cancer therapy.
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Affiliation(s)
- Ly-Binh-An Tran
- Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
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10
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Goh F, Long R, Simpson N, Sambanis A. Dual perfluorocarbon method to noninvasively monitor dissolved oxygen concentration in tissue engineered constructs in vitro and in vivo. Biotechnol Prog 2011; 27:1115-25. [PMID: 21608139 DOI: 10.1002/btpr.619] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 01/17/2011] [Indexed: 11/06/2022]
Abstract
Noninvasive in vivo monitoring of tissue implants provides important correlations between construct function and the observed physiologic effects. As oxygen is a key parameter affecting cell and tissue function, we established a monitoring method that utilizes (19) F nuclear magnetic resonance (NMR) spectroscopy, with perfluorocarbons (PFCs) as oxygen concentration markers, to noninvasively monitor dissolved oxygen concentration (DO) in tissue engineered implants. Specifically, we developed a dual PFC method capable of simultaneously measuring DO within a tissue construct and its surrounding environment, as the latter varies among animals and with physiologic conditions. In vitro studies using an NMR-compatible bioreactor demonstrated the feasibility of this method to monitor the DO within alginate beads containing metabolically active murine insulinoma βTC-tet cells, relative to the DO in the culture medium, under perfusion and static conditions. The DO profiles obtained under static conditions were supported by mathematical simulations of the system. In vivo, the dual PFC method was successful in tracking the oxygenation state of entrapped βTC-tet cells and the surrounding peritoneal DO over 16 days in normal mice. DO measurements correlated well with the extent of cell growth and host cell attachment examined postexplantation. The peritoneal oxygen environment was found to be variable and hypoxic, and significantly lower in the presence of metabolically active cells. The significance of the dual PFC system in providing critical DO measurements for entrapped cells and other tissue constructs, in vitro and in vivo, is discussed.
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Affiliation(s)
- Fernie Goh
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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12
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Baete SHU, Vandecasteele J, Colman L, De Neve W, De Deene Y. An oxygen-consuming phantom simulating perfused tissue to explore oxygen dynamics and (19)F MRI oximetry. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2010; 23:217-26. [PMID: 20577778 DOI: 10.1007/s10334-010-0219-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 05/31/2010] [Accepted: 06/01/2010] [Indexed: 11/28/2022]
Abstract
OBJECTIVE This study presents a reproducible phantom which mimics oxygen-consuming tissue and can be used for the validation of (19)F MRI oximetry. MATERIALS AND METHODS The phantom consists of a haemodialysis filter of which the outer compartment is filled with a gelatin matrix containing viable yeast cells. Perfluorocarbon emulsions can be added to the gelatin matrix to simulate sequestered perfluorocarbons. A blood-substituting perfluorocarbon fluid is pumped through the lumen of the fibres in the filter. (19)F relaxometry MRI is performed with a fast 2D Look-Locker imaging sequence on a clinical 3T scanner. RESULTS Acute and perfusion-related hypoxia were simulated and imaged spatially and temporally using the phantom. CONCLUSIONS The presented experimental setup can be used to simulate oxygen consumption by somatic cells in vivo and for validating computational biophysical models of hypoxia, as measured with (19)F MRI oximetry.
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Affiliation(s)
- Steven H Ubert Baete
- Department of Radiation Oncology and Experimental Cancer Research, Ghent University, Gent, Belgium.
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Scholz AWK, Eberle B, Heussel CP, David M, Schmittner MD, Quintel M, Schreiber LM, Weiler N. Ventilation-Perfusion Ratio in Perflubron During Partial Liquid Ventilation. Anesth Analg 2010; 110:1661-8. [DOI: 10.1213/ane.0b013e3181d3e1d5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Díaz-López R, Tsapis N, Fattal E. Liquid perfluorocarbons as contrast agents for ultrasonography and (19)F-MRI. Pharm Res 2009; 27:1-16. [PMID: 19902338 DOI: 10.1007/s11095-009-0001-5] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Accepted: 10/22/2009] [Indexed: 12/22/2022]
Abstract
Perfluorocarbons (PFCs) are fluorinated compounds that have been used for many years in clinics mainly as gas/oxygen carriers and for liquid ventilation. Besides this main application, PFCs have also been tested as contrast agents for ultrasonography and magnetic resonance imaging since the end of the 1970s. However, most of the PFCs applied as contrast agents for imaging were gaseous. This class of PFCs has been recently substituted by liquid PFCs as ultrasound contrast agents. Additionally, liquid PFCs are being tested as contrast agents for (19)F magnetic resonance imaging (MRI), to yield dual contrast agents for both ultrasonography and (19)F MRI. This review focuses on the development and applications of the different contrast agents containing liquid perfluorocarbons for ultrasonography and/or MRI: large and small size emulsions (i.e. nanoemulsions) and nanocapsules.
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Affiliation(s)
- Raquel Díaz-López
- Univ Paris Sud, UMR CNRS 8612, Faculté de Pharmacie, 5 rue Jean-Baptiste Clément, 92296, Châtenay-Malabry, France
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15
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Janjic JM, Ahrens ET. Fluorine-containing nanoemulsions for MRI cell tracking. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2009; 1:492-501. [PMID: 19920872 PMCID: PMC2777673 DOI: 10.1002/wnan.35] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this article we review the chemistry and nanoemulsion formulation of perfluorocarbons used for in vivo(19)F MRI cell tracking. In this application, cells of interest are labeled in culture using a perfluorocarbon nanoemulsion. Labeled cells are introduced into a subject and tracked using (19)F MRI or NMR spectroscopy. In the same imaging session, a high-resolution, conventional ((1)H) image can be used to place the (19)F-labeled cells into anatomical context. Perfluorocarbon-based (19)F cell tracking is a useful technology because of the high specificity for labeled cells, ability to quantify cell accumulations, and biocompatibility. This technology can be widely applied to studies of inflammation, cellular regenerative medicine, and immunotherapy.
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Affiliation(s)
- Jelena M. Janjic
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Eric T. Ahrens
- Department of Biological Sciences and Pittsburgh NMR Center for Biomedical Research, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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van Faassen EE, Bahrami S, Feelisch M, Hogg N, Kelm M, Kim-Shapiro DB, Kozlov AV, Li H, Lundberg JO, Mason R, Nohl H, Rassaf T, Samouilov A, Slama-Schwok A, Shiva S, Vanin AF, Weitzberg E, Zweier J, Gladwin MT. Nitrite as regulator of hypoxic signaling in mammalian physiology. Med Res Rev 2009; 29:683-741. [PMID: 19219851 PMCID: PMC2725214 DOI: 10.1002/med.20151] [Citation(s) in RCA: 321] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this review we consider the effects of endogenous and pharmacological levels of nitrite under conditions of hypoxia. In humans, the nitrite anion has long been considered as metastable intermediate in the oxidation of nitric oxide radicals to the stable metabolite nitrate. This oxidation cascade was thought to be irreversible under physiological conditions. However, a growing body of experimental observations attests that the presence of endogenous nitrite regulates a number of signaling events along the physiological and pathophysiological oxygen gradient. Hypoxic signaling events include vasodilation, modulation of mitochondrial respiration, and cytoprotection following ischemic insult. These phenomena are attributed to the reduction of nitrite anions to nitric oxide if local oxygen levels in tissues decrease. Recent research identified a growing list of enzymatic and nonenzymatic pathways for this endogenous reduction of nitrite. Additional direct signaling events not involving free nitric oxide are proposed. We here discuss the mechanisms and properties of these various pathways and the role played by the local concentration of free oxygen in the affected tissue.
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Affiliation(s)
- Ernst E van Faassen
- Department of Interface Physics, Debye Institute, Utrecht University, Princetonplein 1, 3508 TA Utrecht, The Netherlands.
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Abstract
Hypoxia, a condition of insufficient O2 to support metabolism, occurs when the vascular supply is interrupted, as in stroke or myocardial infarction, or when a tumor outgrows its vascular supply. When otherwise healthy tissues lose their O2 supply acutely, the cells usually die, whereas when cells gradually become hypoxic, they adapt by up-regulating the production of numerous proteins that promote their survival. These proteins slow the rate of growth, switch the mitochondria to glycolysis, stimulate growth of new vasculature, inhibit apoptosis, and promote metastatic spread. The consequence of these changes is that patients with hypoxic tumors invariably experience poor outcome to treatment. This has led the molecular imaging community to develop assays for hypoxia in patients, including regional measurements from O2 electrodes placed under CT guidance, several nuclear medicine approaches with imaging agents that accumulate with an inverse relationship to O2, MRI methods that measure either oxygenation directly or lactate production as a consequence of hypoxia, and optical methods with NIR and bioluminescence. The advantages and disadvantages of these approaches are reviewed, along with the individual strategies for validating different imaging methods. Ultimately the proof of value is in the clinical performance to predict outcome, select an appropriate cohort of patients to benefit from a hypoxia-directed treatment, or plan radiation fields that result in better local control. Hypoxia imaging in support of molecular medicine has become an important success story over the last decade and provides a model and some important lessons for development of new molecular imaging probes or techniques.
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Affiliation(s)
- Kenneth A Krohn
- Department of Radiology, University of Washington, Seattle, Washington 98195-6004, USA.
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18
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Abstract
Oxygen plays a major role as a substrate in metabolic processes in numerous signaling pathways, in redox metabolism, and in free radical metabolism. To study the role of oxygen in normal and pathophysiological states, methods that can be used noninvasively are required. This review examines the potential of nuclear magnetic resonance techniques to study tissue oxygenation. It is written from a systems perspective, looking at detection methods with respect to the path that oxygen takes in the mammalian system-from the lungs, through the vascular system, into the interstitial space, and finally into the cell. Methods discussed range from those that are quantifiable, such as the assessment of spin lattice relaxation time in fluorocarbon solutions, to those that are more correlative, such as assessment of lactate and high energy phosphates. Since the methods vary in their site of application, sensitivity, and specificity to the quantification of oxygen, this review provides examples of how each method has been applied. This may facilitate the reader's understanding of how to optimally apply different methods to study specific biomedical problems.
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Affiliation(s)
- J F Dunn
- Department of Radiology, Physiology, and Biophysics, University of Calgary, Faculty of Medicine, Calgary, Alberta, Canada.
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Affiliation(s)
- Dawen Zhao
- Department of The University of Texas Southwestern Medicial Center at Dallas, 75390, USA
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Heussel CP, Scholz A, Schmittner M, Laukemper-Ostendorf S, Schreiber WG, Ley S, Quintel M, Weiler N, Thelen M, Kauczor HU. Measurements of Alveolar pO2 Using 19F-MRI in Partial Liquid Ventilation. Invest Radiol 2003; 38:635-41. [PMID: 14501491 DOI: 10.1097/01.rli.0000077056.41954.eb] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES Partial liquid ventilation using Perfluorcarbon (PFC) is an innovative treatment of acute respiratory distress syndrome. However, the underlying mechanisms are not totally clear. The aim was to investigate the distribution of oxygen partial pressure within the PFC-filled lung (ppO2). METHODS Nine pigs underwent partial liquid ventilation, receiving 20 mL PFC/kg bodyweight (bw). Measurements were obtained by a chemical shift selective TurboFLASH sequence at different axial lung levels. ppO2 was calculated from 19F-MRI by nonlinear curve T1-fitting technique after noise correction. RESULTS Quantification and distribution of ppO2 was performed successfully. A narrow relationship of the inspiratory O2 fraction and ppO2, as well as a significant ventral-to-dorsal gradient of ppO2 (ventral:dependent lung = 1.9:1) were detected in all subjects and slice positions. CONCLUSIONS In vivo measurement of local ppO2 gains new and clinical important insights into the physiology of PLV. The previously unknown ppO2 gradient within PFC fits to distribution of perfusion. Dependent lung regions appear to have limited access to O2 from central airways.
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Mills GH, Wild JM, Eberle B, Van Beek EJR. Functional magnetic resonance imaging of the lung. Br J Anaesth 2003; 91:16-30. [PMID: 12821562 DOI: 10.1093/bja/aeg149] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- G H Mills
- Unit of Academic Anaesthesia, University of Sheffield and The Directorate of Critical Care Medicine, Royal Hallamshire Hospital, Glossop Road, UK.
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22
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Biederer J, Schoene A, Freitag S, Reuter M, Heller M. Simulated pulmonary nodules implanted in a dedicated porcine chest phantom: sensitivity of MR imaging for detection. Radiology 2003; 227:475-83. [PMID: 12649421 DOI: 10.1148/radiol.2272020635] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the diagnostic accuracy of common magnetic resonance (MR) imaging sequences for detection of small pulmonary nodules by using a chest phantom and porcine lungs containing simulated lesions. MATERIALS AND METHODS Fourteen porcine lungs containing 366 porcine myocardial tissue implants were inflated inside a phantom. Two-dimensional (2D) and three-dimensional (3D) gradient-echo (GRE), T2-weighted turbo spin-echo (SE), and T2-weighted single-shot SE train MR sequences were performed. Spiral computed tomography (CT) was performed for comparison. Blinded observers read the images and recorded the sizes and locations of visible nodules by consensus. The sensitivity of each imaging method for depicting single nodules of given sizes was calculated. Specificities, positive predictive values (PPVs), and negative predictive values (NPVs) for detection of one or more nodules of various sizes were calculated. RESULTS Sensitivities of 3D GRE, 2D GRE, T2-weighted turbo SE, and T2-weighted single-shot SE train MR imaging and of CT were 0.50, 0.40, 0.12, 0.00, and 0.55, respectively, for detection of 1.4-mm nodules and 0.88, 0.84, 0.69, 0.06, and 0.96, respectively, for detection of 4.2-mm nodules. The 95% CIs for CT and GRE MR imaging overlapped, but those for turbo SE and single-shot SE train MR imaging differed significantly (P <.05). For detection of nodules larger than 5 mm, all examinations except single-shot SE train MR imaging yielded a specificity, PPV, and NPV of 1.00 each. For detection of nodules smaller than 5 mm, diagnostic accuracy of 3D GRE MR imaging was high: Specificity, PPV, and NPV all were approximately 0.90. Two-dimensional GRE MR imaging results were influenced by false-positive findings: Specificity was 0.64; PPV, 0.74; and NPV, 1.00. CONCLUSION Common MR imaging sequences such as 3D GRE have high diagnostic accuracy in depicting small pulmonary nodules when artifacts from cardiac and respiratory motion are absent.
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Affiliation(s)
- Jürgen Biederer
- Department of Diagnostic Radiology, University Hospital Kiel, Arnold-Heller-Strasse 9, Germany.
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Biederer J, Both M, Graessner J, Liess C, Jakob P, Reuter M, Heller M. Lung morphology: fast MR imaging assessment with a volumetric interpolated breath-hold technique: initial experience with patients. Radiology 2003; 226:242-9. [PMID: 12511697 DOI: 10.1148/radiol.2261011974] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To prospectively evaluate the clinical feasibility of magnetic resonance (MR) imaging of the lungs with fast volumetric interpolated three-dimensional (3D) gradient-recalled-echo (GRE) sequences and to compare this examination with standard computed tomography (CT) in patients with lung abnormalities. MATERIALS AND METHODS Twenty-five patients with different lung abnormalities were examined with 3D GRE MR imaging. The small pulmonary nodules in seven, TNM stage of large intrapulmonary tumors in eight, and benign bronchial disease in five patients were evaluated. MR imaging-based diagnoses were compared with diagnoses made at CT and at discharge from the hospital. Contingency tables and the McNemar test were used to evaluate the significance of differences between MR imaging- and CT-based diagnoses. RESULTS The MR imaging- and CT-based diagnoses were identical in 24 of 25 patients. In the remaining patient, clinical findings confirmed the accuracy of the MR imaging finding of pleural empyema. Ten of 15 solid pulmonary nodules smaller than 10 mm in diameter were detected at MR imaging (P >.1). Tumor stages at MR imaging and CT were identical, but lymph node stages at the two examinations differed in two of eight patients owing to overestimation of lymph node size at MR imaging (P >.2). In the five patients with bronchiectasis, MR imaging depicted 26 of 33 affected lung segments; differences between MR imaging and CT findings of bronchial dilatation (P >.05) and bronchial wall thickening (P >.2) were not significant. Peribronchial fibrosis was overestimated at MR imaging owing to image artifacts (P <.05). CONCLUSION Study results confirmed the feasibility of fast breath-hold 3D GRE MR imaging of the lung.
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Affiliation(s)
- Jürgen Biederer
- Department of Diagnostic Radiology, University Hospital Kiel, Arnold-Heller-Strasse 9, 24105 Kiel 1, Germany.
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Abstract
A double-walled magnetic resonance (MR) imaging-compatible container with a flexible diaphragm was designed to hold freshly excised porcine heart-lung preparations. The saline contents simulate MR signal of an actual chest wall. Continuous evacuation keeps the lung inflated. A variety of experiments with different imaging modalities, including angiography, under close to in vivo conditions are feasible. Access to bronchial system and lung vessels allows for various studies.
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Affiliation(s)
- Jürgen Biederer
- Department of Diagnostic Radiology, University Hospital Kiel, Arnold-Heller-Strasse 9, 24105 Kiel 1, Germany.
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Murugesan R, English S, Reijnders K, Yamada KI, Cook JA, Mitchell JB, Subramanian S, Krishna MC. Fluorine electron double resonance imaging for 19F MRI in low magnetic fields. Magn Reson Med 2002; 48:523-9. [PMID: 12210918 DOI: 10.1002/mrm.10221] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This work demonstrates the feasibility of generating fluorine NMR images at a very low magnetic field of 0.015 T by making use of the Overhauser enhancement of (19)F NMR signal brought about by a stable, water-soluble, narrow-line paramagnetic contrast agent. The enhancement in the (19)F NMR images depends on the concentration of the single electron contrast agent, the pO(2), and the electron paramagnetic resonance (EPR) irradiation power. The applicability of this technique for (19)F NMR imaging is demonstrated with phantom samples, where a time resolution of 4-10 min is achieved. Proton electron double resonance imaging (PEDRI) and fluorine electron double resonance imaging (FEDRI) images were also obtained from rat kidneys ex vivo, perfused with 10 mM Oxo63 and 10 M trifluoroacetic acid. The spatial and temporal resolutions of these images are comparable to those obtained at magnetic fields 2-3 orders of magnitude larger. Constant NMR frequency (628 kHz) operation permits both FEDRI and PEDRI of identical slices without removing the object under investigation. This feasibility of coregistration of proton-based anatomical PEDRI image with physiological FEDRI image offers good potential for studying fluorine-containing tracers.
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Affiliation(s)
- Ramachandran Murugesan
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Le D, Mason RP, Hunjan S, Constantinescu A, Barker BR, Antich PP. Regional tumor oxygen dynamics: 19F PBSR EPI of hexafluorobenzene. Magn Reson Imaging 1997; 15:971-81. [PMID: 9322216 DOI: 10.1016/s0730-725x(97)00035-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We demonstrate a novel approach to measuring regional tumor oxygen tension using 19F pulse burst saturation recovery echo planar imaging (EPI) relaxometry of hexafluorobenzene. Hexafluorobenzene offers exceptional sensitivity to changes in oxygen tension, and has a single resonance making it ideal for imaging studies. By combining a pulse burst saturation recovery preparation sequence with EPI, the relaxation experiments were performed in approximately 20 min facilitating measurements of dynamic changes in pO2 accompanying interventions. Direct intratumoral administration of hexafluorobenzene permitted labeling of specific regions of interest, and imaging provided maps of pO2, confirming distinct intra tumoral heterogeneity. For a group of three Dunning prostate adenocarcinoma R3327-AT1 tumors interrogation of the central tumor region showed skewed pO2 distributions with considerable radiobiological hypoxia (approximately 90% voxels had pO2 < 15 torr) when rats breathed 33% O2. Altering the inspired gas to pure oxygen caused distributions to shift towards increased pO2 with significant increases in mean oxygen tension (p < 0.05) in two cases. Interrogation of both central and peripheral regions in a fourth tumor showed bimodal distribution for tumor oxygenation including approximately 75% voxels with pO2 > 15 torr. EPI allows the fate of individual voxels to be traced: upon altering the inspired gas to pure oxygen those voxels with baseline pO2 > 30 torr showed significant changes (p < 0.05), whereas those with pO2 < 16 torr showed minimal response. The precision of the measurements, together with the ability to simultaneously examine dynamic changes in multiple regions should provide a useful technique for investigating tumor hypoxia with respect to therapy.
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Affiliation(s)
- D Le
- Advanced Radiological Sciences, U.T. Southwestern Medical Center, Dallas, Texas 75235-9058, USA
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Pratt RG, Zheng J, Stewart BK, Shiferaw Y, McGoron AJ, Samaratunga RC, Thomas SR. Application of a 3D volume 19F MR imaging protocol for mapping oxygen tension (pO2) in perfluorocarbons at low field. Magn Reson Med 1997; 37:307-13. [PMID: 9001157 DOI: 10.1002/mrm.1910370229] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A limited flip angle gradient-echo 3D volume acquisition imaging protocol for mapping partial pressure of oxygen (pO2) in perfluorocarbon compounds (PFCs) at low field (0.14 T) is presented. The PO2 measurement method is based on the paramagnetic effect of dissolved molecular oxygen (O2) which reduces the PFC 19F T1. Specific objectives related to imaging of PFCs through use of the protocol include improved image signal-to-noise characteristics and elimination of 19F chemical shift artifacts. A parametric Wiener deconvolution filtering algorithm is used for suppression of 19F chemical shift artifacts. Application of the protocol is illustrated in a series of calculated PO2 maps of a gas equilibrated, multi-chamber phantom containing perfluorotributylamine (FC-43). The utility of the protocol is demonstrated in vivo through images of a commercially available perfluorocarbon based blood substitute emulsion containing FC-43 sequestered in the liver and spleen of a rat.
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Affiliation(s)
- R G Pratt
- Department of Radiology, University of Cincinnati Medical Center, Ohio 45267-0579, USA
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Thomas SR, Gradon L, Pratsinis SE, Pratt RG, Fotou GP, McGoron AJ, Podgorski AL, Millard RW. Perfluorocarbon compound aerosols for delivery to the lung as potential 19F magnetic resonance reporters of regional pulmonary pO2. Invest Radiol 1997; 32:29-38. [PMID: 9007645 DOI: 10.1097/00004424-199701000-00005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
RATIONALE AND OBJECTIVES Perfluorocarbon (PFC) aerosols present the opportunity for simultaneous analysis of lung structure and pulmonary oxygenation patterns. The authors investigated techniques to nebulize neat liquid PFCs for inhalation as a new method of PFC administration and tested the hypothesis that PFC aerosols may be developed for efficient delivery to the lung in an experimental rat model allowing the potential for sequential monitoring of pulmonary status via quantitative fluorine-19 (19F) magnetic resonance (MR) partial pressure of oxygen (pO2) imaging. METHODS Pneumatic aerosol generators were configured to produce a neat liquid PFC perfluorotributylamine (FC-43) aerosol. Perfluorocarbon inhalation breathing protocols for the rat model included: spontaneous direct breathing from an aerosol chamber, and use of a tracheotomy tube to bypass nasal breathing. The PFC aerosol delivery into the rat lung was documented through 19F MR imaging in correlation with high-resolution anatomic proton MR images. Theoretical model calculations for PFC mass deposition were compared with experimental results. RESULTS The pneumatic generator produced a PFC aerosol droplet within the theoretically targeted range (geometric mean particle diameter of 1.2 microns; concentration of approximately 4 x 10(7) droplets per cm3). No measurable aerosol reached the lungs during spontaneous breathing because of the efficient filtering capabilities of the turbinated nasal passages. With tracheotomy, aerosol depositions within the lung were achieved in mass quantities consistent with theoretical expectations; however, the distribution patterns were nonuniform and unpredictable. Oxygen-enhanced 19F imaging was demonstrated. CONCLUSIONS Perfluorocarbon aerosols of controlled size distribution can be produced at sufficient concentration with pneumatic generators for distribution to the terminal pulmonary architecture and visualization using 19F MR imaging. The potential exists for in vivo oxygen-sensitive imaging in the pulmonary system and development of sophisticated experimental animal models of systemic oxygen transport as a function of pulmonary status.
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Affiliation(s)
- S R Thomas
- Department of Radiology, University of Cincinnati, Ohio 45267-0579, USA.
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29
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Abstract
We have surveyed the sensitivity of the spin lattice relaxation rates of the 19F resonances of several perfluorocarbons to changes in oxygen tension and temperature. Hexafluorobenzene was found to exhibit exceptional sensitivity to changes in oxygen tension, and we have exploited this phenomenon to measure tumor oxygen tension following intratumoral injection. When 20 microliters hexaflourobenzene were injected they remained localized and the biodistribution was readily assessed on the basis of combined 1H and 19F three-dimensional MRI. Relaxation measurements indicated a typical baseline oxygen tension of 4.0 +/- 1.5 torr in the central region of a Dunning prostate R3327-AT1 tumor when the rat breathed 66% oxygen. Altering the inspired oxygen concentration to 100% produced a modest increase in pO2 (5.6 +/- 0.7 torr; p < 0.1). Significantly, the precision of these measurements should facilitate NMR investigations of radiobiological hypoxia. Intra-tumoral injection allowed measurements from regions not normally accessible to infused perfluorocarbons and provides an additional approach to measuring tumor oxygenation.
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Affiliation(s)
- R P Mason
- Advanced Radiological Sciences, U.T. Southwestern Medical Center, Dallas, TX 75235-9058, USA
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