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Bertram Schwarzschild described the important contributions made by the 2003 Nobel laureates Paul Lauterbur and Peter Mansfield during the 1970s (Physics Today, December 2003, page 24). They extended magnetic resonance imaging for applications in medicine into two and three dimensions and to faster speeds. Schwarzschild refers to an article by Felix Wehrli (Physics Today, Physics Today 0031-9228 45 6 1992 34 https://doi.org/10.1063/1.881310. June 1992, page 34 ), but Wehrli makes no mention of the earlier use of magnetic field gradients and MRI during the 1950s and 1960s (see Physics Today, January 1993, page 94).Schwarzschild does mention the early use of magnetic field gradients to correlate the nuclear signal (usually proton) with spatial coordinates. He cites work by Erwin Harm and by Edward Purcell and me, 1 1. E. L. Hahn, Phys. Rev. 80, 580 (1950); https://doi.org/10.1103/PhysRev.80.580 H. Y. Carr, E. M. Purcell, Phys Rev. 94, 630 (1954). https://doi.org/10.1103/PhysRev.94.630 but that work is not directly related to internal macroscopic imaging. Hahn used existing gradients to observe diffusion, while Purcell and I intentionally applied additional gradients to study diffusion. For modern internal MRI, another component in addition to the applied gradient is necessary. Unlike for diffusion or flow studies, the object being observed must have spatially inhomogeneous internal structure. To the best of my knowledge, the first time such a field gradient was applied to a nuclear magnetic resonance (NMR) sample having an inhomogeneously distributed internal spin system was during a demonstration I conducted for my PhD thesis. 2 2. H. Y. Carr, “Free Precession Techniques in Nuclear Magnetic Resonance,” PhD thesis, Harvard U., Cambridge, MA (1952); Encyclopedia of Nuclear Magnetic Resonance, vol. 1, Wiley and Sons, Hoboken, NJ (1996), p. 253. My motivation in that demonstration was to help faculty and other graduate students understand the recently discovered and rather complicated NMR fine structure in ethyl alcohol. A special object, built for the demonstration, consisted initially of two and later three small separated groups of protons having numbers of protons in the ratios of 3:2:1. The groups were placed in a straight line parallel to the direction of the magnetic field gradient. Thus that first MRI image or spin map was one-dimensional. Although medical applications for 1D imaging are very few, in physics there are several; the most notable was in the discovery of superfluid helium-3. The 1952 demonstration used the new and faster pulsed NMR technique 3 3. D. D. Stark, W. G. Bradley, Magnetic Resonance Imaging, C. V. Mosby, St. Louis, MO (1988), p. 9. rather than the simpler and slower continuous-wave frequency (or field) sweep technique. 4 4. C. Leon Partain et al. , Nuclear Magnetic Resonance (NMR) Imaging, W. B. Saunders, Philadelphia (1983), chap. 17. The visual observation of the three separated groups of protons provided confidence in the pulsed MRI technique with its spatial image coming from the Fourier transform of the complicated time-dependent free-induction decay. That first MRI demonstration was not reported in the 1954 paper, which concentrated on the basic techniques of the new pulsed NMR used with internally homogeneous samples. Other topics, including gradient echoes, electric shims, and the spinning of the samples to obtain narrower lines for observing very fine structure, were left for later papers.My thesis received significant distribution. In particular, Nuclear Magnetic Resonance Specialties near Pittsburgh, Pennsylvania, where Lauterbur and Raymond Damadian did their initial MRI work, received a copy in 1967. Shortly thereafter, the president of the company requested additional copies for some of the purchasers of the company’s pulsed NMR spectrometers.REFERENCESSection:ChooseTop of pageREFERENCES <<CITING ARTICLES1. E. L. Hahn, Phys. Rev. 80, 580 (1950); https://doi.org/10.1103/PhysRev.80.580 , Google ScholarCrossref, ISI H. Y. Carr, E. M. Purcell, Phys Rev. 94, 630 (1954). https://doi.org/10.1103/PhysRev.94.630 , , Google ScholarCrossref, ISI2. H. Y. Carr, “Free Precession Techniques in Nuclear Magnetic Resonance,” PhD thesis, Harvard U., Cambridge, MA (1952); Google Scholar Encyclopedia of Nuclear Magnetic Resonance, vol. 1, Wiley and Sons, Hoboken, NJ (1996), p. 253. Google Scholar3. D. D. Stark, W. G. Bradley, Magnetic Resonance Imaging, C. V. Mosby, St. Louis, MO (1988), p. 9. Google Scholar4. C. Leon Partain et al. , Nuclear Magnetic Resonance (NMR) Imaging, W. B. Saunders, Philadelphia (1983), chap. 17. Google Scholar© 2004 American Institute of Physics.
2A nuclear magnetic resonance advance. Imaging fluorinated anesthetics in the brain.
A nuclear magnetic resonance advance. Imaging fluorinated anesthetics in the brain.
10Assessment of Formation Damage Potential of Novel Drilling Fluids via Integration of Fluid Loss Data with Filter Cake Quality and Filtrate Core Penetration Depth from NMR and MRI
Appropriate drilling fluid additives which can build effective filter cakes are key components to minimize formation damage. Today there exists no effective and quantitative technique which can assess the formation damage minimization potential of any novel drilling fluid. This study provides the methodology for such a technique, by integrating HP/HT fluid loss data, derived from standard API HP/HT filter press, with filter cake quality and filtrate penetration depth, derived by Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) techniques. Novel nano-based drilling fluidwas made of de-ionized water, 7 wt% commercial Na-bentonite, and addition of custom made iron oxide (CM Fe3O4) nanoparticles (NP) at 0.5 wt%. Its excellent filtration characteristics were determined at elevated pressures and temperatures using a HP/HT filter press (500 psi/350°F) with ceramic discs, mimicking the formation, as filter media of k=775 mD. NMR T2 relaxation time measurements provided the pore size distribution of the ceramic discs, and a newly developed MRI technique by our team allowed direct visualization on the core-ceramic disc of the produced filter cake and filtrate penetration depth, providing insights on filtration characteristics. Addition of 0.5 wt% Fe3O4 NP resulted in a decrease of fluid loss by 47% compared to that obtained from the base fluid (BF) without the nanoparticles. The excellent filtration characteristics were attributed to the synergistic interaction of NP with bentonite platelets producing a strong microstructure network leading to rigid and very low permeability filter cakes. Spin-spin relaxation time (T2) NMR measurements revealed different pore size distribution of the nano-enhanced drilling fluid showing its tendency to occupy the smallest pores of the filter medium (ceramic disc). MRI T2 measurements revealed the saturation profiles of the drilling fluids inside the ceramic discs, in 3-D space. This allowed the visual representation of the penetration depth of the filtrate produced in the ceramic discs of the different tested drilling fluids. Our integrated characterization approach, gives us tools to analyze inter-particle interactions in the filter cakes at HP/HT conditions in order to explain the significant improvement in fluid loss performance of novel drilling fluids. The information gained in this study is considered to be extremely significant for deriving an effective methodology for assessing formation damage potential of any newly developed drilling fluid which can lead to more efficient and cost-effective drilling activities.
Read more126Revised guidance on acceptable limits of exposure during nuclear magnetic resonance clinical imaging.
In the last few years there has been rapid progress in the application of nuclear magnetic resonance clinical imaging as a diagnostic aid (Partain et al, 1983; Steiner, 1983; Worthington, 1983). Records kept by the operators of NMR imaging equipment indicate that about 1800 individuals have now been examined without incident within the United Kingdom. In view of this progress, an advisory group (Appendix) appointed by the National Radiological Protection Board recommends some modifications to the original advice given in 1981 (NRPB, 1981). The principal modifications are that: (1) It is no longer considered necessary to exclude volunteers with a history of epilepsy or cardiac disease. (2) It is not obligatory that a registered medical practitioner trained in resuscitation techniques be present during an exposure. (3) Higher limits are recommended for rates of change of magnetic flux density when the period of change is less than 10 ms. (4) The radiofrequency limit of 15 MHz has been removed. Theoretical considerations indicate that the interaction of an applied magnetic field with the intrinsic magnetic moments of protons and electrons within a molecule could alter its rate of chemical reaction (McLauchlan, 1981). Chemical reactions involving radical pair intermediates are expected to be sensitive to magnetic fields for this reason and a number of enzyme reactions that might be expected to be affected have been identified (A. Cass, personal communication). However, there is no experimental confirmation of these theoretical possibilities at present.
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5Study of Pumpkin Drying Through Magnetic Resonance Imaging
Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) techniques are widely used in food science, mainly because they are non-invasive techniques. MRI, as a non-destructive technique, allows the study of intact samples and without any preparation of the samples before analysis. In food processing, the monitoring of distribution and water content is a consolidated analysis technique, frequently used on the market in order to preserve appropriate nutritional and health characteristics of food according to quality standards. In a food matrix, the variation of the water content is related to the changes in the internal structure and in the physico-chemical properties that occur during the transformation process. In this study MRI technique is used to evaluate the variation of the water content as a function of the drying time. Pumpkin samples are analyzed at four different drying temperatures of 50, 60, 65, and 70°C. The transverse relaxation time, T2, is used to assess the hydration level of the samples by comparing the information extracted from MR images with the drying kinetics measured by gravimetric method. Moreover, T2 maps are used to correlate the change in water distribution with the change in T2 values. The results show that the global weight loss curves obtained with the standard gravimetric method and with the MRI data are in excellent agreement. This work indicates that monitoring changes in the T2 profile of food (i.e., pumpkin) is a useful method for evaluating moisture profiles and changes induced on the sample during the drying process.
Read more3Characterization of Pore Structures Using NMR-Restricted Diffusion Measurements
The self-diffusional motion of fluid molecules in a porous medium is expected to be different from that in the bulk fluid due to the presence of pore boundaries which restrict the molecules diffusing within the pore space. Thus it is conceivable that the study of restricted diffusion may provide information leading to pore structure characterization. We report the use of pulsed field gradient nuclear magnetic resonance (PFG NMR) techniques to study proton restricted self-diffusion in porous media. Measurements were conducted in model porous media consisting of different sized glass bead packs, as well as porous rocks. Computational analyses were carried out to obtain apparent diffusivities and other characteristics from the experimental results.
Read more710. NMR Imaging of Fluids and Flow in Porous Media
10. NMR Imaging of Fluids and Flow in Porous Media
2Analytical Methods | Nuclear Magnetic Resonance: Principles
Analytical Methods | Nuclear Magnetic Resonance: Principles
Paul Christian Lauterbur
Paul Christian Lauterbur
4Nuclear Magnetic Resonance and Magnetic Resonance Imaging for Process Analysis
Nuclear magnetic resonance (NMR) spectroscopy is an experimental technique based on the interaction between nuclear magnetic moments and an applied magnetic field. The nuclei emit and absorb energy at a specific frequency that is proportional to the applied magnetic field. Magnetic resonance imaging (MRI) is the term used to describe the spatial resolution of NMR signals within a sample. NMR/MRI may provide information on the weight, chemical composition, physical properties, and structure of a sample. NMR is a noncontacting and noninvasive measurement. NMR and MRI are suitable for use in process control and have been applied to polymer processing, food processing and refinery processes. The response is linear from the detection limits of approximately 10 ppb to 100%. The accuracy of the technique depends on the signal‐to‐noise ratio (S/N), which is a function of the sample size, applied magnetic field strength, the radio‐frequency (rf) coil and the spectrometer hardware. Typical accuracy of the technique is 0.5% for measurements of composition and 1–5% for viscosity. NMR cannot generally be applied to magnetic or highly conductive materials.
Read more17MR imaging: its development and the recent Nobel Prize.
HomeRadiologyVol. 231, No. 3 PreviousNext EditorialsMR Imaging: Its Development and the Recent Nobel PrizeStephen J. RiedererStephen J. RiedererAuthor Affiliations1From the MR Laboratory, Mayo Clinic, 200 First Street SW, Rochester, MN 55905. Received January 19, 2004; accepted January 21. Address correspondence to the author (e-mail: [email protected]).Stephen J. RiedererPublished Online:Jun 1 2004https://doi.org/10.1148/radiol.2313040114MoreSectionsFull textPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In References 1 Lauterbur PC. Image formation by induced local interactions: examples employing nuclear magnetic resonance. Nature 1973; 242:190-191. Crossref, Google Scholar2 USA MRI market Mountain View, Calif: Frost and Sullivan Market Research, 2002. Google Scholar3 Mansfield P, Grannell PK. NMR “diffraction” in solids? J Phys C Solid State Phys 1973; 6:L422. Crossref, Google Scholar4 Mansfield P. Multi-planar image formation using NMR spin echoes. J Phys C 1977; 10:L55. Crossref, Google Scholar5 Haase A, Frahm J, Matthaei D, Hanicke W, Merboldt KD. FLASH imaging: rapid NMR imaging using low flip-angle pulses. J Magn Reson 1986; 67:258-266. Google Scholar6 Masaryk TJ, Modic MT, Ross JS, et al. Intracranial circulation: preliminary clinical results with three-dimensional (volume) MR angiography. Radiology 1989; 171:793-799. Link, Google Scholar7 Parker DL, Yuan C, Blatter DD. MR angiography by multiple thin slab 3D acquisition. Magn Reson Med 1991; 17:434-451. Crossref, Medline, Google Scholar8 Prince MR, Yucel EK, Kaufman JA, Harrison DC, Geller SC. Dynamic gadolinium-enhanced 3D abdominal MR arteriography. J Magn Reson Imaging 1993; 3:877-881. Crossref, Medline, Google Scholar9 Hennig J, Nauerth A, Friedburg H. RARE imaging: a fast imaging method for clinical MR. Magn Reson Med 1986; 3:823-833. Crossref, Medline, Google Scholar10 Mulkern RV, Wong STS, Winalski C, Jolesz FA. Contrast manipulation and artifact assessment of 2D and 3D RARE sequences. Magn Reson Imaging 1990; 8:557-566. Crossref, Medline, Google Scholar11 Hayes CE, Edelstein WA, Schenck JR, Mueller OM, Eash M. An efficient, highly homogeneous radiofrequency coil for whole-body NMR imaging at 1.5T. J Magn Reson 1985; 63:622-628. Google Scholar12 Roemer PB, Edelstein WA, Hayes CE, Souza SP, Mueller OM. The NMR phased array. Magn Reson Med 1990; 16:192-225. Crossref, Medline, Google Scholar13 Roemer PB, Edelstein WA. Self-shielded gradient coils (abstr) In: Book of abstracts: Society of Magnetic Resonance in Medicine 1986. Berkeley, Calif: Society of Magnetic Resonance in Medicine, 1986; 1067. Google Scholar14 Le Bihan D, Breton E, Lallemand D, Grenier P, Cabanis E, Laval-Jeantet M. MR imaging of intravoxel incoherent motions: application to diffusion and perfusion in neurologic disorders. Radiology 1986; 161:401-407. Link, Google Scholar15 Turner R, Le Bihan D, Maier J, Vavrek R, Hedges LK, Pekar J. Echo-planar imaging of intravoxel incoherent motion. Radiology 1990; 177:407-414. Link, Google Scholar16 Basser PJ, Mattiello J, Le Bihan D. MR diffusion tensor spectroscopy and imaging. Biophys J 1994; 66:259-267. Crossref, Medline, Google Scholar17 Wakana S, Jiang H, Nagae-Poetscher LM, van Zijl P, Mori S. Fiber tract-based atlas of human white matter anatomy. Radiology 2004; 230:77-87. Link, Google Scholar18 Belliveau JW, Kennedy DN, McKinstry RC, et al. Functional mapping of the human visual cortex by magnetic resonance imaging. Science 1991; 254:716-718. Crossref, Medline, Google Scholar19 Bandettini PA, Wong EC, Hinks RS, Tikofsky RS, Hyde JS. Time course EPI of human brain function during task activation. Magn Reson Med 1992; 25:390-397. Crossref, Medline, Google Scholar20 Kwong KK, Belliveau JW, Chesler DA, et al. Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation. Proc Natl Acad Sci U S A 1992; 89:5675-5679. Crossref, Medline, Google Scholar21 Ogawa S, Tank D, Menon R, et al. Intrinsic signal changes accompanying sensory stimulation: functional brain mapping using MRI. Proc Natl Acad Sci U S A 1992; 89:5951-5955. Crossref, Medline, Google Scholar22 Ogawa S, Lee TM, Kay AR, Tank DW. Brain magnetic resonance imaging with contrast dependent on blood oxygenation. Proc Natl Acad Sci U S A 1990; 87:9868-9872. Crossref, Medline, Google Scholar23 Johnson GA, Benveniste H, Black RD, Hedlund LW, Maronpot RR, Smith BR. Histology by magnetic-resonance microscopy. Magn Reson Q 1993; 9:1-30. Medline, Google Scholar24 Paulus MJ, Sari-Sarraff H, Gleason SS, et al. A new x-ray computed tomography system for laboratory mouse imaging. IEEE Trans Nucl Sci 1999; 46:558-564. Crossref, Google Scholar25 Kruger RA, Mistretta CA, Houk TL, et al. Computerized fluoroscopy in real time for noninvasive visualization of the cardiovascular system: preliminary studies. Radiology 1979; 130:49-57. Link, Google ScholarArticle HistoryPublished in print: June 2004 FiguresReferencesRelatedDetailsCited ByMedicine, Vol. 93, No. 28Skeletal Radiology, Vol. 40, No. 9Medicine - Programa de Formaci?n M?dica Continuada Acreditado, Vol. 9, No. 92Magnetic Resonance Imaging, Vol. 24, No. 4Applied Magnetic Resonance, Vol. 29, No. 1Pacing and Clinical Electrophysiology, Vol. 28, No. 10Magnetic Resonance Imaging, Vol. 22, No. 10Recommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 231, No. 3 Metrics Altmetric Score PDF download
Read more170Selective Saturation NMR Imaging
The application of selective saturation (or solvent suppression) techniques in nuclear magnetic resonance (NMR) imaging offers the opportunity to significantly expand the range of NMR studies. Data acquired at 1.44 T are presented using a two-dimensional spin-echo sequence preceded by a selective (saturating) radiofrequency pulse. Individual water or lipid proton resonances were eliminated (greater than 90% reduction in signal intensity) resulting in images of H2O or -CH2- distribution with resolution and imaging time equivalent to conventional proton images. Data are also presented demonstrating the feasibility of using selective saturation to image proton metabolites at low concentrations with a three-dimensional chemical shift imaging approach. Lactate was investigated because of its importance in the pathophysiology of ischemic insult. Phantom studies without solvent suppression failed to detect lactate at 80 mM; however, with solvent suppression, lactate at 40 mM was imaged in a reasonable time (approximately 50 min). With the favorable NMR characteristics of the methyl protons of lactate and with improvements in imaging systems, this technique may play an important role in the noninvasive evaluation of tissue ischemia using 1H NMR.
Read more2The Latest Developments of Laboratory NMR Techniques in Unconventional Shale Characterization
The complexity of the microstructure and fluids in unconventional reservoirs presents a significant challenge to the traditional approaches to the evaluation of geological formations and petrophysical properties due to the low porosity, ultralow permeability, complex lithology, and fluid composition. Nuclear magnetic resonance (NMR) techniques have been playing major roles in unconventional shale characterization in the last decades as NMR can provide critical information about the reservoirs for quantifying their petrophysical parameters and fluid properties and estimating productivity. Laboratory higher frequency (HF), e.g., 23-MHz NMR techniques, especially two-dimensional (2D) T1-T2 mapping, and applications have been essential for the noninvasive characterization of tight rock samples for identifying kerogen, bitumen, heavy or light hydrocarbons, and bound or capillary water. The traditional T2 cutoffs need new definitions to reflect the inferences from water and hydrocarbons separately. The legendary crushed rock analysis method, as applied to unconventional formations, has shown great success in evaluating total porosity and water saturation but suffers from inconsistency in results due to desiccation and solvent effects. The industry has witnessed significant development of HF-NMR techniques that couple advances in petrophysics, petroleum engineering, and geochemistry with a broad range of applications. This article will summarize key advances in laboratory NMR applications in unconventional shale characterization, including monitoring processes of liquids equilibrium, desiccation, and imbibition in fresh shale samples, determination of activation energy of hydrocarbons in shales, monitoring changes in a shale sample during liquid flooding experiment, and direct measurements on kerogen. Future NMR applications, such as in EOR, gas condensation, and saturation profile, will be discussed. In this article, we will review the following techniques: laboratory NMR, especially 23 MHz, techniques for unconventional shale sample measurements, 2D NMR T1-T2 mapping with an inter-echo spacing time of 0.7 ms at various sample temperatures, and early-time NMR signals acquired using the solid-echo pulse sequence together with pyrolysis results in kerogen studies. We will review the necessaries and advantages of the HF-NMR techniques and applications, explain the importance of the inter-echo spacing time in shale NMR experiments, give examples of monitoring liquid redistribution and desiccation in fresh shale samples, compare the results from NMR, Dean-Stark, and pyrolysis, examine the multidiscipline approaches as better tools to solve petrophysical problems. Examples include kerogen study using the solid-type NMR measurement combined with geochemical pyrolysis and NMR combined with capillary pressure. There has been significant advancement of NMR techniques in unconventional shale evaluation over the last decade. It is time for us to summarize such technological advances and draw conclusions to help us in planning unconventional core analysis programs.
Read more99Nuclear magnetic resonance imaging and spectroscopy in experimental brain edema in a rat model.
Many aspects of the use of high-resolution nuclear magnetic resonance (NMR) imaging in the examination of brain edema have not been fully explored. These include the quantitation of edema fluid, the ability to distinguish between various types of edema, and the extent to which tissue changes other than a change in water content can affect NMR relaxation times. The authors have compared NMR relaxation times obtained by both in vivo magnetic resonance imaging (MRI) and in vitro NMR spectroscopy of brain-tissue samples from young adult rats with cold lesions, fluid-percussion injury, hypoxic-ischemic injury, bacterial cerebritis, and cerebral tumor. Changes in relaxation times were compared with changes in brain water content, cerebral blood volume, and the results of histological examination. In general, both in vivo and in vitro longitudinal relaxation times (T1) and transverse relaxation times (T2) were prolonged in the injured hemispheres of all experimental groups. Water content of tissue from the injured hemispheres was increased in all groups. A linear correlation between T2 (but not T1) and water content was found. Changes in the values of T1 and T2 could be used to distinguish tumor from cold-injured tissue. Cerebral blood volume was reduced in the injured hemispheres and correlated inversely with prolongation of T1 and T2. The results of this study suggest that, in a clinical setting, prolongation of T2 is a better indicator of increased water content than prolongation of T1, yet quantitation of cerebral edema based solely upon prolongation of in vivo or in vitro T1 and T2 should be undertaken with caution.
Read more23Processing of Data From an NMR Logging Tool
A new pulsed nuclear magnetic resonance (NMR) logging tool, known as the CMR* Combinable Magnetic Resonance tool, is being used worldwide. During the CMR tool development phase, one challenge was to design a robust and economical data acquisition and signal processing scheme for the hundreds or thousands of spin-echo amplitudes that can be acquired during the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence. This challenge was met by developing a new signal processing and associated downhole data compression algorithm. Data compression is essential to reducing the processing times so that formation T2-distributions can be estimated in real time. Compression of the digital data is possible, without loss of information, because the linear dependency of the NMR measurement kernels results in gross redundancy of the measured spin-echo amplitudes. An attractive feature of the algorithm described in this paper is that the compression can be performed in the downhole tool, thus substantially reducing the telemetry requirements. The raw spin echoes can also be sent uphole and made available for additional processing. Logs of CMR porosity, free-fluid porosity, mean relaxation time and rock permeability are computed from the estimated T2-distributions. The accuracy and precision of the CMR log outputs are demonstrated by repetitive Monte Carlo computer simulations in which noisy, synthetic spin-echo amplitudes are generated from known T2-distributions and then processed to obtain log outputs. Monte Carlo simulations are used to elucidate CMR log responses in typical clean sand, shaly sand, and carbonate rocks. The relative insensitivity of the measurements to short relaxation times (e.g., those less than a few milliseconds) is discussed and used to explain the differences between CMR log porosity and "total" formation porosity in shaly formations. We show that CMR porosity is an "effective porosity" that does not include clay bound water and microporosity having relaxation times less than a few milliseconds. We give examples of statistical fluctuations that can occur on estimated T2-distributions to assist log analysts in recognizing artifacts that are not indicative of actual reservoir rock properties. Field logs that display many of the features of CMR log responses revealed by the simulations are also presented.
Read more9Magnetic Resonance Imaging of Plants: Water Balance and Water Transport in Relation to Photosynthetic Activity
Nuclear magnetic resonance (NMR) and nuclear magnetic resonance imaging (MRI) techniques are described in relation to applications on intact plants. These techniques are non-destructive and non-invasive and can be used to study the dynamics of plant water relations and water transport, e.g., as a function of environmental (stress) conditions. Non-spatially resolved NMR as well as two-dimensional or even three-dimensional imaging strategies can be applied. The relevant NMR parameters that can be used to discriminate between water in sub-cellular compartments are the relaxation times T 1 and T 2, and (restricted) diffusion. The information within MRI images can be manipulated in such a way that in addition to anatomical information physico-chemical information like cell compartment size, water membrane permeability, water diffusion and flow, information on chemical composition (water, oils, sugars and other metabolites) are obtained. This information is also available in non-spatially resolved NMR with a much higher signal-to-noise ratio, but the interpretation of such non-spatially resolved measurements can be hampered by heterogeneity of the plant tissue (sub-cellular compartments, tissue heterogeneity and different types of tissue). Here we present a number of 1H NMR and MRI techniques that can be used to study plant performance in relation to its photosynthetic activity. In addition, dedicated hardware for intact plant studies is discussed.
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