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Spin‐lock MR enhances the detection sensitivity of superparamagnetic iron oxide particles
Author(s) -
Moonen Rik P. M.,
van der Tol Pieternel,
Hectors Stefanie J. C. G.,
Starmans Lucas W. E.,
Nicolay Klaas,
Strijkers Gustav J.
Publication year - 2015
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.25544
Subject(s) - iron oxide , superparamagnetism , dispersion (optics) , chemistry , oxide , nanoparticle , materials science , iron oxide nanoparticles , nuclear magnetic resonance , analytical chemistry (journal) , nanotechnology , chromatography , optics , physics , magnetization , magnetic field , organic chemistry , quantum mechanics
Purpose To evaluate spin‐lock MR for detecting superparamagnetic iron oxides and compare the detection sensitivity of quantitative T 1ρ with T 2 imaging. Methods In vitro experiments were performed to investigate the influence of iron oxide particle size and composition on T 1ρ . These comprise T 1ρ and T 2 measurements (B 0 = 1.41T) of agar (2%) with concentration ranges of three different iron oxide nanoparticles (IONs) (Sinerem, Resovist, and ION‐Micelle) and microparticles of iron oxide (MPIO). T 1ρ dispersion was measured for a range of spin‐lock amplitudes (γB 1 = 6.5–91 kHz). Under relevant in vivo conditions (B 0 = 9.4T; γB 1 = 100–1500 Hz), T 1ρ and T 2 mapping of the liver was performed in seven mice pre‐ and 24 h postinjection of Sinerem. Results Addition of iron oxide nanoparticles decreased T 1ρ as well as the native T 1ρ dispersion of agar, leading to increased contrast at high spin‐lock amplitudes. Changes of T 1ρ were highly linear with iron concentration and much larger than T 2 changes. MPIO did not show this effect. In vivo, a decrease of T 1ρ was observed with no clear influence on T 1ρ dispersion. Conclusion By suppression of T 1ρ dispersion, iron oxide nanoparticles cause enhanced T 1ρ contrast compared to T 2 . The underlying mechanism appears to be loss of lock. Spin‐lock MR is therefore a promising technique for sensitive detection of iron oxide contrast agents. Magn Reson Med 74:1740–1749, 2015. © 2014 Wiley Periodicals, Inc.