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Exchange‐mediated contrast agents for spin‐lock imaging
Author(s) -
Cobb Jared G.,
Xie Jingping,
Li Ke,
Gochberg Daniel F.,
Gore John C.
Publication year - 2012
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.23130
Subject(s) - contrast (vision) , nuclear magnetic resonance , lock (firearm) , computer science , physics , artificial intelligence , engineering , mechanical engineering
Measurements of relaxation rates in the rotating frame with spin‐locking techniques are sensitive to substances with exchanging protons with appropriate chemical shifts. The authors develop a novel approach to exchange‐rate selective imaging based on measured T 1ρ dispersion with applied locking field strength, and demonstrate the method on samples containing the X‐ray contrast agent Iohexol with and without cross‐linked bovine serum albumin. T 1ρ dispersion of water in the phantoms was measured with a Varian 9.4‐T magnet by an on‐resonance spin‐locking pulse with fast spin‐echo readout, and the results used to estimate exchange rates. The Iohexol phantom alone gave a fitted exchange rate of ∼1 kHz, bovine serum albumin alone was ∼11 kHz, and in combination gave rates in between. By using these estimated rates, we demonstrate how a novel spin‐locking imaging method may be used to enhance contrast due to the presence of a contrast agent whose protons have specific exchange rates. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.