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39 K and 23 Na relaxation times and MRI of rat head at 21.1 T
Author(s) -
Nagel Armin M.,
Umathum Reiner,
Rösler Manuela B.,
Ladd Mark E.,
Litvak Ilya,
Gor'kov Peter L.,
Brey William W.,
Schepkin Victor D.
Publication year - 2016
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3528
Subject(s) - relaxation (psychology) , nuclear magnetic resonance , isotopes of sodium , agarose , isotopes of potassium , sodium , spin–spin relaxation , spin–lattice relaxation , chemistry , physics , analytical chemistry (journal) , potassium , medicine , chromatography , organic chemistry , nuclear quadrupole resonance
At ultrahigh magnetic field strengths ( B 0 ≥ 7.0 T), potassium ( 39 K) MRI might evolve into an interesting tool for biomedical research. However, 39 K MRI is still challenging because of the low NMR sensitivity and short relaxation times. In this work, we demonstrated the feasibility of 39 K MRI at 21.1 T, determined in vivo relaxation times of the rat head at 21.1 T, and compared 39 K and sodium ( 23 Na) relaxation times of model solutions containing different agarose gel concentrations at 7.0 and 21.1 T. 39 K relaxation times were markedly shorter than those of 23 Na. Compared with the lower field strength, 39 K relaxation times were up to 1.9‐ ( T 1 ), 1.4‐ ( T 2S ) and 1.9‐fold ( T 2L ) longer at 21.1 T. The increase in the 23 Na relaxation times was less pronounced (up to 1.2‐fold). Mono‐exponential fits of the 39 K longitudinal relaxation time at 21.1 T revealed T 1 = 14.2 ± 0.1 ms for the healthy rat head. The 39 K transverse relaxation times were 1.8 ± 0.2 ms and 14.3 ± 0.3 ms for the short ( T 2S ) and long ( T 2L ) components, respectively. 23 Na relaxation times were markedly longer ( T 1 = 41.6 ± 0.4 ms; T 2S = 4.9 ± 0.2 ms; T 2L = 33.2 ± 0.2 ms). 39 K MRI of the healthy rat head could be performed with a nominal spatial resolution of 1 × 1 × 1 mm 3 within an acquisition time of 75 min. The increase in the relaxation times with magnetic field strength is beneficial for 23 Na and 39 K MRI at ultrahigh magnetic field strength. Our results demonstrate that 39 K MRI at 21.1 T enables acceptable image quality for preclinical research. Copyright © 2016 John Wiley & Sons, Ltd.