High spatial resolution NMR imaging of polymer layers on metallic substrates

TY - JOUR

T1 - High spatial resolution NMR imaging of polymer layers on metallic substrates

AU - Zhu, Haijin

AU - Huinink, Hendrik P.

AU - Erich, Sebastiaan J.F.

AU - Baukh, Viktor

AU - Adan, Olaf C.G.

AU - Kopinga, Klaas

N1 - Funding Information: This project is funded by DPI, TU/e and TNO. The authors thank Hans Dalderop and Jef Noijen for technical support and assistance.

PY - 2012/1

Y1 - 2012/1

N2 - High spatial resolution NMR imaging techniques have been developed recently to measure the spatial inhomogeneity of a polymer coating film. However, the substrates of the polymer coatings for such experiments are generally required to be non-metallic, because metals can interact with static magnetic fields B 0 and RF fields B 1 giving rise to artifacts in NMR images. In this paper we present a systematic study on the effects of metallic substrates on 1D profiles obtained by high resolution NMR imaging. The off-resonance effect is discussed in detail in terms of the excitation profile of the RF pulses. We quantitatively show how the NMR signal intensities change with frequency offset at different RF pulse lengths. The complete NMR profiles were simulated using a Finite Element Analysis method by fully considering the inhomogeneities in both B 1 and B 0. The excellent agreement between the calculated and measured NMR profiles on both metallic and non-metallic substrates indicates that the experimental NMR profiles can be reproduced very well by numerical simulations. The metallic substrates can disturb the RF field of the coil by eddy current effect and therefore change the NMR profiles. To quantitatively interpret the NMR profile of a polymer layer on a metallic substrate, the profile has to be divided by the profile of a reference on the same metallic substrate located at the same distance from the coil.

AB - High spatial resolution NMR imaging techniques have been developed recently to measure the spatial inhomogeneity of a polymer coating film. However, the substrates of the polymer coatings for such experiments are generally required to be non-metallic, because metals can interact with static magnetic fields B 0 and RF fields B 1 giving rise to artifacts in NMR images. In this paper we present a systematic study on the effects of metallic substrates on 1D profiles obtained by high resolution NMR imaging. The off-resonance effect is discussed in detail in terms of the excitation profile of the RF pulses. We quantitatively show how the NMR signal intensities change with frequency offset at different RF pulse lengths. The complete NMR profiles were simulated using a Finite Element Analysis method by fully considering the inhomogeneities in both B 1 and B 0. The excellent agreement between the calculated and measured NMR profiles on both metallic and non-metallic substrates indicates that the experimental NMR profiles can be reproduced very well by numerical simulations. The metallic substrates can disturb the RF field of the coil by eddy current effect and therefore change the NMR profiles. To quantitatively interpret the NMR profile of a polymer layer on a metallic substrate, the profile has to be divided by the profile of a reference on the same metallic substrate located at the same distance from the coil.

KW - Eddy current

KW - GARfield NMR

KW - Metal

KW - Off-resonance

KW - Simulation

KW - Surface coil

UR - http://www.scopus.com/inward/record.url?scp=84855695220&partnerID=8YFLogxK

U2 - 10.1016/j.jmr.2011.11.009

DO - 10.1016/j.jmr.2011.11.009

M3 - 文章

C2 - 22169437

AN - SCOPUS:84855695220

SN - 1090-7807

VL - 214

SP - 227

EP - 236

JO - Journal of Magnetic Resonance

JF - Journal of Magnetic Resonance

ER -