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Quantifying iron‐oxide nanoparticles at high concentration based on longitudinal relaxation using a three‐dimensional SWIFT look‐locker sequence
Author(s) -
Zhang Jinjin,
Chamberlain Ryan,
Etheridge Michael,
Idiyatullin Djaudat,
Corum Curtis,
Bischof John,
Garwood Michael
Publication year - 2014
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.25181
Subject(s) - iron oxide nanoparticles , nanoparticle , materials science , analytical chemistry (journal) , chemistry , nuclear magnetic resonance , nanotechnology , physics , chromatography
Purpose Iron‐oxide nanoparticles (IONPs) have proven utility as contrast agents in many MRI applications. Previous quantitative IONP mapping has been performed using mainly T 2 * mapping methods. However, in applications requiring high IONP concentrations, such as magnetic nanoparticles based thermal therapies, conventional pulse sequences are unable to map T 2 * because the signal decays too rapidly. In this article, sweep imaging with Fourier transformation (SWIFT) sequence is combined with the Look‐Locker method to map T 1 of IONPs in high concentrations. Methods T 1 values of agar containing IONPs in different concentrations were measured with the SWIFT Look‐Locker method and with inversion recovery spectroscopy. Precisions of Look‐Locker and variable flip angle (VFA) methods were compared in simulations. Results The measured R 1 (=1/T 1 ) has a linear relationship with IONP concentration up to 53.6 mM of Fe. This concentration exceeds concentrations measured in previous work by almost an order of magnitude. Simulations show SWIFT Look‐Locker method is also much less sensitive to B 1 inhomogeneity than the VFA method. Conclusion SWIFT Look‐Locker can accurately measure T 1 of IONP concentrations ≤53.6 mM. By mapping T 1 as a function of IONP concentration, IONP distribution maps might be used in the future to plan effective magnetic nanoparticle hyperthermia therapy. Magn Reson Med 71:1982–1988, 2014. © 2014 Wiley Periodicals, Inc.