TY - JOUR
T1 - 19F spin-lattice relaxation of perfluoropolyethers
T2 - Dependence on temperature and magnetic field strength (7.0-14.1 T)
AU - Kadayakkara, Deepak K.
AU - Damodaran, Krishnan
AU - Hitchens, T. Kevin
AU - Bulte, Jeff W.M.
AU - Ahrens, Eric T.
N1 - Funding Information:
We are grateful to Dr. Paul A. Bottomley for his helpful discussion and insight into relaxation mechanisms. This work was supported in part by the National Institutes of Health (R01 CA134633, R01 EB17271 and P41EB 001977), the Maryland Stem Cell Research Foundation (MSCRFII-0161), and the California Institute for Regenerative Medicine (LA1-C12-06919).
PY - 2014/5
Y1 - 2014/5
N2 - Fluorine (19F) MRI of perfluorocarbon-labeled cells has become a powerful technique to track the migration and accumulation of cells in living organisms. It is common to label cells for 19F MRI with nanoemulsions of perfluoropolyethers that contain a large number of chemically equivalent fluorine atoms. Understanding the mechanisms of 19F nuclear relaxation, and in particular the spin-lattice relaxation of these molecules, is critical to improving experimental sensitivity. To date, the temperature and magnetic field strength dependence of spin-lattice relaxation rate constant (R1) for perfluoropolyethers has not been described in detail. In this study, we evaluated the R1 of linear perfluoropolyether (PFPE) and cyclic perfluoro-15-crown-5 ether (PCE) at three magnetic field strengths (7.0, 9.4, and 14.1 T) and at temperatures ranging from 256-323 K. Our results show that R1 of perfluoropolyethers is dominated by dipole-dipole interactions and chemical shift anisotropy. R1 increased with magnetic field strength for both PCE and PFPE. In the temperature range studied, PCE was in the fast motion regime (ωτc < 1) at all field strengths, but for PFPE, R1 passed through a maximum, from which the rotational correlation time was estimated. The importance of these measurements for the rational design of new 19F MRI agents and methods is discussed.
AB - Fluorine (19F) MRI of perfluorocarbon-labeled cells has become a powerful technique to track the migration and accumulation of cells in living organisms. It is common to label cells for 19F MRI with nanoemulsions of perfluoropolyethers that contain a large number of chemically equivalent fluorine atoms. Understanding the mechanisms of 19F nuclear relaxation, and in particular the spin-lattice relaxation of these molecules, is critical to improving experimental sensitivity. To date, the temperature and magnetic field strength dependence of spin-lattice relaxation rate constant (R1) for perfluoropolyethers has not been described in detail. In this study, we evaluated the R1 of linear perfluoropolyether (PFPE) and cyclic perfluoro-15-crown-5 ether (PCE) at three magnetic field strengths (7.0, 9.4, and 14.1 T) and at temperatures ranging from 256-323 K. Our results show that R1 of perfluoropolyethers is dominated by dipole-dipole interactions and chemical shift anisotropy. R1 increased with magnetic field strength for both PCE and PFPE. In the temperature range studied, PCE was in the fast motion regime (ωτc < 1) at all field strengths, but for PFPE, R1 passed through a maximum, from which the rotational correlation time was estimated. The importance of these measurements for the rational design of new 19F MRI agents and methods is discussed.
KW - Cell tracking
KW - Fluorine-19 MRI
KW - Perfluorocarbons
KW - Spin-lattice relaxation
UR - http://www.scopus.com/inward/record.url?scp=84897741838&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84897741838&partnerID=8YFLogxK
U2 - 10.1016/j.jmr.2014.01.014
DO - 10.1016/j.jmr.2014.01.014
M3 - Article
C2 - 24594752
AN - SCOPUS:84897741838
VL - 242
SP - 18
EP - 22
JO - Journal of Magnetic Resonance
JF - Journal of Magnetic Resonance
SN - 1090-7807
ER -