Magnetic Resonance Pore Imaging: Overcoming the resolution limit of MRI for closed pore systems

Hertel, Stefan; Hunter, Mark; Galvosas, Petrik

doi:10.1016/j.micromeso.2014.08.024

Cited by 6 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using this phantom sample, Hertel et al (2015b) obtained images of hemi-equilateral triangular pores using their MRPI approach. Furthermore, Hertel et al (2015a) suggested the MRPI mapping experiment and experimentally confirmed it as a promising extension of MRPI towards practical applications. This technique allows one to map the MRPI signal onto MRI images as published by Hertel et al (2015a) for 1d-MRI images and by Hertel et al (2015b) for 2d-MRI images.…”

Section: Introductionmentioning

confidence: 74%

“…Furthermore, Hertel et al (2015a) suggested the MRPI mapping experiment and experimentally confirmed it as a promising extension of MRPI towards practical applications. This technique allows one to map the MRPI signal onto MRI images as published by Hertel et al (2015a) for 1d-MRI images and by Hertel et al (2015b) for 2d-MRI images. The following chapters show the implementation of these innovations on a commercially available micro-imaging NMR system and applications to selected porous materials.…”

Section: Introductionmentioning

confidence: 74%

“…A plot of the MRPI mapping data is shown in fig. 4.21 (Hertel et al (2015a)). The horizontal dimension shows the one-dimensional spin density of the sample in x-direction, which was obtained by Fourier transform of the spin-echo signal in the time domain for each step in the MRPI gradients.…”

Section: Mrpi 1d-mappingmentioning

confidence: 94%

“…Color scales are signal intensities in arbitrary units. Reprinted from Hertel et al (2015a). q space data.…”

Section: Mrpi 1d-mappingmentioning

confidence: 99%

See 3 more Smart Citations

Magnetic resonance pore imaging, a tool for porous media research

2013

View full text Add to dashboard Cite

Porous media are highly prevalent in nature and span a wide range of systems including biological tissues, chemical catalysts or rocks in oil reservoirs. Imaging of the structure of the constituent pores is therefore highly desirable for life sciences and technological applications. This thesis presents the new development and application of a nuclear magnetic resonance (NMR) technique to acquire high resolution images of closed pores. The technique is a further development of diffusive-diffraction Pulsed Gradient Spin Echo (PGSE) NMR, which has been shown to image the pore auto-correlation function averaged over all pores. Until recently it was conventional wisdom that diffusive-diffraction PGSE NMR can only measure the magnitude of the form factor, due to its similarity to diffraction techniques such as x-ray and neutron scattering. In diffraction applications the loss of phase information is commonly referred to as the "phase problem", which prevents the reconstruction of images of the pore space by inverse Fourier transform. My work is based on a recently suggested modification of the diffusive-diffraction PGSE NMR method, which creates a hybrid between Magnetic Resonance Imaging (MRI) and PGSE NMR. Therefore, we call this approach Magnetic Resonance Pore Imaging (MRPI). We provide experimental confirmation that MRPI does indeed measure the diffractive signal including its phase and thus the "phase problem" is lifted. We suggest a two-dimensional version of MRPI and obtain two-dimensional average pore images of cylindrical and triangular pores with an unprecedented resolution as compared to state of the art MRI. Utilizing a laser machined phantom sample we present images of microscopic pores with triangular shape even in the presence of wall relaxation effects. We therefore show that MRPI is able to reconstruct the pore shape without any prior knowledge or assumption about the porous system under study. Furthermore, we demonstrate i During preparation of my thesis I received help and encouragement from many people and institutions to which I would like to express my gratitude. First of all, I would like to thank my supervisor Dr. Petrik Galvosas for the guidance, stimulation and support he provided throughout the past three and a half years. His help was especially indispensable regarding the art of mastering the NMR spectrometer and the gradient hardware. Moreover, he extended his support beyond work related issues, which I experienced as exceptionally kind and which made my stay in New Zealand such an enjoyable time. I would also like to thank Professor Sir Paul Callaghan for providing such a stimulating environment and for entrusting the project for this thesis to me. He sadly passed away, but is remembered vividly in his lab. There are many people whom I would like to thank from the NMR lab at Victoria University of Wellington. Dr. Mark Hunter helped me to get going on the MRPI project and provided key simulations in the early stages of my work. My colleagues

show abstract