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Nuclear magnetic relaxation dispersion of murine tissue for development of T 1 ( R 1 ) dispersion contrast imaging
Author(s) -
Araya Yonathan T.,
MartínezSantiesteban Francisco,
Handler William B.,
Harris Chad T.,
Chronik Blaine A.,
Scholl Timothy J.
Publication year - 2017
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.3789
Subject(s) - dispersion (optics) , nuclear magnetic resonance , spin–lattice relaxation , relaxation (psychology) , materials science , in vivo , physics , optics , medicine , biology , microbiology and biotechnology , nuclear quadrupole resonance
This study quantified the spin–lattice relaxation rate ( R 1 ) dispersion of murine tissues from 0.24 mT to 3 T. A combination of ex vivo and in vivo spin–lattice relaxation rate measurements were acquired for murine tissue. Selected brain, liver, kidney, muscle, and fat tissues were excised and R 1 dispersion profiles were acquired from 0.24 mT to 1.0 T at 37 °C, using a fast field‐cycling MR (FFC‐MR) relaxometer . In vivo R 1 dispersion profiles of mice were acquired from 1.26 T to 1.74 T at 37 °C, using FFC‐MRI on a 1.5 T scanner outfitted with a field‐cycling insert electromagnet to dynamically control B 0 prior to imaging. Images at five field strengths (1.26, 1.39, 1.5, 1.61, 1.74 T) were acquired using a field‐cycling pulse sequence, where B 0 was modulated for varying relaxation durations prior to imaging. R 1 maps and R 1 dispersion (Δ R 1 /Δ B 0 ) were calculated at 1.5 T on a pixel‐by‐pixel basis. In addition, in vivo R 1 maps of mice were acquired at 3 T. At fields less than 1 T, a large R 1 magnetic field dependence was observed for tissues. ROI analysis of the tissues showed little relaxation dispersion for magnetic fields from 1.26 T to 3 T. Our tissue measurements show strong R 1 dispersion at field strengths less than 1 T and limited R 1 dispersion at field strengths greater than 1 T. These findings emphasize the inherent weak R 1 magnetic field dependence of healthy tissues at clinical field strengths. This characteristic of tissues can be exploited by a combination of FFC‐MRI and T 1 contrast agents that exhibit strong relaxivity magnetic field dependences (inherent or by binding to a protein), thereby increasing the agents' specificity and sensitivity. This development can provide potential insights into protein‐based biomarkers using FFC‐MRI to assess early changes in tumour development, which are not easily measureable with conventional MRI.