Sodium Ions in Ordered Environments in Biological Systems: Analysis of 23Na NMR Spectra

Kemp-Harper, Richard; Wickstead, Bill; Wimperis, Stephen

doi:10.1006/jmre.1999.1834

Cited by 15 publications

(16 citation statements)

References 25 publications

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“…Using isolated models of cartilage, it was shown that the contribution to RQC in cartilage was due to the ordering of collagen bundles and that PG did not contribute to the RQC. A similar model provided the best fit for Jeener-Broekaert spectra obtained from bovine articular cartilage (144).…”

Section: Sodium Nmr Of Cartilagementioning

confidence: 84%

“…The theory of NMR of quadrupolar nuclei (74,75,(77)(78)(79)(80), relaxation-induced sodium single and multiple quantum coherences (MQC) and their applications in the studies of biological systems has been extensively discussed in several original and review articles (81)(82)(83)(84)(85)(86)(87)(88)(89)(90)(91). Here a brief overview of steps involved in the calculation of spin dynamics using the density matrix approach is presented.…”

Section: Sodium Nmrmentioning

confidence: 99%

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Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

et al. 2006

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In this article, both sodium magnetic resonance (MR) and T 1r relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T 1r , a brief description of (i) principles of measuring T 1r relaxation, (ii) pulse sequences for computing T 1r relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T 1r in biological tissues and (v) effects of exchange and dipolar interaction on T 1r dispersion are discussed. Correlation of T 1r relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokineinduced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T 1r data from osteoarthritic specimens, animal models, healthy human subjects and as well from osteoarthritic patients are provided. The current status of T 1r relaxation mapping of cartilage and future directions is also discussed. Copyright # 2006 John Wiley & Sons, Ltd. KEYWORDS: cartilage; arthritis; spin-lock; T1rho; sodium; MRI OSTEOARTHRITIS Osteoarthritis (OA) affects more than half of the population above the age of 65 (1,2) and has a significant negative impact on the quality of life of elderly individuals (3). The economic costs in the USA from OA have been estimated to be more than 1% of the gross domestic product (4). OA is now increasingly viewed as a metabolically active joint disorder of diverse etiologies. The biochemistry of the disease is characterized by the following changes in cartilage: reduced proteoglycan (PG) concentration, possible changes in the size of collagen fibril and aggregation of PG, increased water content and increased rate of synthesis and degradation of matrix macromolecules. The earliest changes in the cartilage due to OA result in a partial breakdown in the proteoglyc...

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Section: Sodium Nmr Of Cartilagementioning

confidence: 84%

Section: Sodium Nmrmentioning

confidence: 99%

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

et al. 2006

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“…7(b) demonstrates that applying a /2 y pulse will create double quantum coherence T 3,2,0 . In some experiments, it is necessary to suppress any signal arising from T 3,1,0 because this coherence can arise through pathways other than quadrupolar evolution (16).…”

Section: Flip Angle: Dqf Experimentsmentioning

confidence: 99%

A way of visualizing NMR experiments on quadrupolar nuclei

Philp

Kuchel

2005

Concepts Magn. Reson.

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ABSTRACT:A graphical representation of the spin states of quadrupolar nuclei in NMR experiments is described. The spherical harmonics represent the irreducible spherical tensor operator basis set, and therefore any density matrix can be illustrated with computer graphics by converting it to a sum of spherical harmonics. Using a multiple quantum-filtered experiment as an example, we demonstrate how the phase and flip angle of RF pulses can be used to create multiple quantum coherences, to suppress the creation of particular coherences, and to select coherences by exploiting their symmetry. This visual approach complements the algebraic description of pulse sequences, providing an intuitive way of designing and analyzing pulse sequences.

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“…Fortunately, there are other experiments which work in the presence of strong field inhomogeneities. As an example, the Jeener-Broekaert experiment (21), producing multipolar states of dipolar or quadrupolar order, does not relay upon the flip-angle effect to suppress the unwanted signal components (22)(23)(24). The required discrimination arises as a result of the nominal 90…”

Section: Introductionmentioning

confidence: 96%