Use of the second dimension in PGSE NMR studies of porous media

Callaghan, Paul T.; Godefroy, S.; Ryland, Brett N.

doi:10.1016/s0730-725x(03)00131-0

Cited by 99 publications

(93 citation statements)

References 13 publications

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“…We therefore turned to diffusive attenuation of the water signal. Figure 7 shows a T2-D cross-correlation spectrum [14] of avocado tissue and confirms that the effective water diffusion coefficient in avocado tissue is about 30 times greater than that of the oil. This suggests that the fast, l-D, singleshot sequence shown in Fig.…”

Section: The Spin-echo T1-null (Set-i) Protocol For Oil Determinationsupporting

confidence: 54%

NMR relaxation study of avocado quality

2005

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Four nuclear magnetic resonance relaxation protocols are investigated as potential candidates for off-line and on-line determination of avocado maturity. Two-dimensional TrT 2 and T2-D correlation spectroscopy provides the most information but is only suitable for off-line quality control. The CPMG T 2 spectrum gives avocado oil content but requires intensive data processing. Suppression of the tissue water signal by Tt-Null methods is shown to be unreliable but a new, singleshot pulse sequence which uses diffusive attenuation to suppress the tissue water is shown to give a good correlation with oil content and is suitable for both off-line and on-line implementation.

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Section: The Spin-echo T1-null (Set-i) Protocol For Oil Determinationsupporting

confidence: 54%

NMR relaxation study of avocado quality

2005

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“…Both very low and very high q yielded wrong results, questioning the validity of Eq. [2] and suggesting the use of alternative approaches (4,5). While at low values the division by q 4 corrupts the result due to deviation from the q 4 proportionality, the error at high q might be due to complete attenuation of the contributions of some orientations.…”

Section: Discussionmentioning

confidence: 99%

“…In samples with restricted diffusion, the DWV-weighted MR signal can depend on the angle between the diffusion gradients applied (1). It was suggested to use this phenomenon for measuring parameters describing tissue structure, such asemploying a long delay between the two successive diffusion weightings (2)(3)(4)(5)8,9). Using this approach, eccentric microscopic compartments can be detected even if the pores have random orientation, such that the sample macroscopically appears isotropic.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of double‐wave vector experiments investigating diffusion in randomly oriented ellipsoidal pores

Koch

Finsterbusch

2009

Magnetic Resonance in Med

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Double-wave vector diffusion weighting is expected to represent a possibility to acquire information on cell size and shape. In numerical simulations, a theoretical description of the double wave vector-weighted signal is tested in a situation where the approximating assumptions (infinitely short gradient pulses, infinitely long diffusion time, infinitely long or zero delay between diffusion weightings, small gradient moment) are not strictly met. It is shown how the dependence of the signal on the angle between the diffusion gradient directions changes upon varying the delay between the second and the third gradient pulse, and how the measures of pore geometry derived from signal differences between two angles depend on the duration, temporal separation, and amplitude of the gradient pulses. The results indicate that a violation of the approximation conditions due to finite gradient pulse duration and separation generally leads to an underestimation of pore size and pore eccentricity. It is also concluded from the simulations that for pore sizes on the order of 10 µm the investigated effects are in a range that is observable even with wholebody gradient systems. Magn Reson Med 62:247-254, 2009.

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“…Techniques often used such as diffusion tensor imaging 9 can characterize the anisotropy present when pores are coherently placed within the specimen, 10 while multiple diffusion time experiments can, to a certain extent, characterize the tortuosity and surface to volume ratio 5,11,12 and fractal dimensions 13 of the specimen. Other diffusionbased methods exist to quantify flow phenomena, [14][15][16][17] the internal magnetic field of the samples, [18][19][20] and to a certain extent, exchange properties 21,22 of the porous media. The q-space approach 1,23 introduced yet another important quantifiable microstructural parameter which characterizes the pores: their average size, which is important in most diffusion NMR applications such as emulsions 24 and central nervous system tissues.…”

Section: Introductionmentioning

confidence: 99%

Detecting diffusion-diffraction patterns in size distribution phantoms using double-pulsed field gradient NMR: Theory and experiments

Shemesh

Özarslan

Basser

et al. 2010

The Journal of Chemical Physics

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NMR observable nuclei undergoing restricted diffusion within confining pores are important reporters for microstructural features of porous media including, inter-alia, biological tissues, emulsions and rocks. Diffusion NMR, and especially the single-pulsed field gradient ͑s-PFG͒ methodology, is one of the most important noninvasive tools for studying such opaque samples, enabling extraction of important microstructural information from diffusion-diffraction phenomena. However, when the pores are not monodisperse and are characterized by a size distribution, the diffusion-diffraction patterns disappear from the signal decay, and the relevant microstructural information is mostly lost. A recent theoretical study predicted that the diffusion-diffraction patterns in double-PFG ͑d-PFG͒ experiments have unique characteristics, such as zero-crossings, that make them more robust with respect to size distributions. In this study, we theoretically compared the signal decay arising from diffusion in isolated cylindrical pores characterized by lognormal size distributions in both s-PFG and d-PFG methodologies using a recently presented general framework for treating diffusion in NMR experiments. We showed the gradual loss of diffusion-diffraction patterns in broadening size distributions in s-PFG and the robustness of the zero-crossings in d-PFG even for very large standard deviations of the size distribution. We then performed s-PFG and d-PFG experiments on well-controlled size distribution phantoms in which the ground-truth is well-known a priori. We showed that the microstructural information, as manifested in the diffusion-diffraction patterns, is lost in the s-PFG experiments, whereas in d-PFG experiments the zero-crossings of the signal persist from which relevant microstructural information can be extracted. This study provides a proof of concept that d-PFG may be useful in obtaining important microstructural features in samples characterized by size distributions.

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Use of the second dimension in PGSE NMR studies of porous media

Cited by 99 publications

References 13 publications

NMR relaxation study of avocado quality

NMR relaxation study of avocado quality

Numerical simulation of double‐wave vector experiments investigating diffusion in randomly oriented ellipsoidal pores

Detecting diffusion-diffraction patterns in size distribution phantoms using double-pulsed field gradient NMR: Theory and experiments

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