Adiabatic pulse preparation for imaging iron oxide nanoparticles

Abstract

*Superparamagnetic iron oxide nanoparticles produce changes in the surrounding microscopic magnetic field. A method for generating contrast based on the application of an adiabatic preparation pulse and the failure of the adiabatic condition surrounding the nanoparticles is introduced in this article. Images were obtained in the presence and absence of an adiabatic preparation pulse and the difference was obtained. With the use of an adiabatic full passage pulse, the contrast in the difference image depends linearly on iron concentration up to 1 mM. The use of an adiabatic zero passage pulse resulted in higher sensitivity to nanoparticles compared to the adiabatic full passage, while maintaining linear concentration dependence to 0.1 mM. This technique was shown to be insensitive to magnetization transfer and B 0 inhomogeneity. With its linearity with iron concentration and insensitivity to changes in the main magnetic field, the new method is well suited for quantitative iron oxide nanoparticle imaging. Magn

Theoretical and experimental study of ON-Resonance Saturation, an MRI sequence for positive contrast with superparamagnetic nanoparticles

“…Indeed, local field inhomogeneities (expected for tissue interfaces, implants and external field heterogeneities) could lead to erroneous positive contrast in area without SPM particles. However, good shimming and/or the use of an adiabatic pulse to saturate the off-resonance water protons [58] could minimize this problem. An appropriate choice of the saturation pulse bandwidth (not too small) and echo time (as small as possible) can also reduce these artefacts.…”

Tracking and Quantification of Magnetically Labeled Stem Cells Using Magnetic Resonance Imaging

“…These techniques can be divided into two groups. The first group of techniques makes uses of modified pulse sequences to directly or indirectly produce “positive” contrast, such as the white marker technique [61] , GRASP [62] , spectrally selective RF pulses to excite water off-resonance [63] or to saturate water on-resonance [64] , adiabatic pulse preparation [65] , ultra-short echo time imaging [66] , sweep imaging with Fourier Transform [67, 68] , off-resonance saturation [69] , and zero echo time imaging [70] . The second group of techniques employs post-processing methods to generate “positive” contrast from data acquired from regular gradient echo sequences.…”

Ultrashort Echo Time (UTE) imaging of receptor targeted magnetic iron oxide nanoparticles in mouse tumor models

“…A number of approaches have been investigated to obtain positive contrast from IONPs, including ultrashort echo time (UTE) imaging , off‐resonance saturation (ORS) techniques , sweep imaging with Fourier transformation (SWIFT) , phase contrast and, most recently, adiabatic imaging . Among them, UTE imaging offers a relatively simple strategy by taking advantage of high longitudinal relaxivity r1 of IONPs while reducing the contribution of predominant T2 and T2* and spin dephase effects of IONPs that are also sources of imaging artifacts.…”