Pulsed NMR relaxometry of striated muscle fibers

English, A. E.; Joy, Michael; Henkelman, R. Mark

doi:10.1002/mrm.1910210211

Cited by 68 publications

(47 citation statements)

References 28 publications

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“…The tissue samples were kept in covered containers to prevent drying and were 2 to 4 h old when experiments were performed. It has previously been established that changes in the relaxation characteristics of tissues over this time interval postexcision (26) are small. Samples of cardiac muscle (-1 cm3) and slow twitch muscle (-0.2 cm3) were obtained from adult white Wistar rats.…”

Section: Methodsmentioning

confidence: 99%

Magnetization Transfer and T₂ Relaxation Components in Tissue

Harrison

Bronskill

Henkelman

1995

Magnetic Resonance in Med

128

107

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T2 relaxation makes an important contribution to tissue contrast in magnetic resonance (MR) imaging. Many tissues are known to exhibit multicomponent T2 relaxation that suggests some compartmental segregation of mobile protons on a T2 timescale. Magnetization transfer (MT) is another relaxation mechanism that can be used to produce tissue contrast in MR imaging. The MT process depends strongly on water-macromolecular interactions. To investigate the relationship between multicomponent T2 relaxation and the MT process, multiecho T2 measurements have been combined with MT measurements for freshly excised samples of cardiac muscle, striated muscle, and white matter. For muscle, short T2 components show greater MT than long T2 components, consistent with the belief that they represent distinct water environments. For white matter, quantitative MT measurements were identical for the two major T2 components, apparently because of exchange between the T2 compartments on a time-scale characteristic of the MT experiment. Implications for accurate modeling of MT in tissue and the use of MT for MR image contrast are discussed.

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Section: Methodsmentioning

confidence: 99%

Magnetization Transfer and T₂ Relaxation Components in Tissue

Harrison

Bronskill

Henkelman

1995

Magnetic Resonance in Med

128

107

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“…27,30 Nerve tissue is not, however, unique in returning more than one relaxation component. Skeletal 33 and cardiac 34 muscle, bovine tendon and cartilage, 35 and porcine lung 36,37 have all been reported to have more than one relaxation component. Finally, it is noteworthy that the consistency of in-vitro and in-vivo measurements has been established in the cold-blooded frog sciatic nerve by Does and Snyder.…”

Section: Relaxation Modelsmentioning

confidence: 99%

Relaxation times and microstructures

2001

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A discussion is presented of the evaluation of multiple relaxation components from water protons in biological tissue. The principal focus is to draw attention to the way in which limitations in the raw NMR data, such as signal-to-noise ratio, data sampling density and acquisition window width, affect the precision and resolution in the processed multiple component solution of the return to thermal equilibrium. The second issue discussed is the interpretation of these multiple components in terms of microstructural compartments of the biological sample and, thirdly, we outline some of the successes in determining regional and pathological variations in microstructure in the human body in-vivo, using the technique of multiple relaxation components.

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“…Other investigators have studied the relaxation behavior of in vitro skeletal muscle using T 2 relaxation times. Results in various muscle types with different capillary densities indicated significant (10) or no (11) differences with monoexponential T 2 fits. Fits for multiexponential decay found two (11,12) or three (10,13,14) T 2 components in normal muscle.…”

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confidence: 96%

Monitoring blood oxygen state in muscle microcirculation with transverse relaxation

Stainsby

Wright

2001

Magnetic Resonance in Med

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Oxygen uptake from the microcirculation is a direct measure of tissue function. Magnetic resonance is capable of detecting differences between oxygenated and deoxygenated blood due to the paramagnetic properties of deoxyhemoglobin. At the level of the microcirculation, however, imaging methods cannot directly visualize the vessels. Instead, bulk MR parameters are investigated for their ability to monitor blood oxygen saturation (%O 2 ) changes in the microcirculation of tissue, specifically skeletal muscle. The ability to monitor the blood oxygenation level within the microcirculation could provide valuable insight into the question of tissue viability and the assessment of tissue function. Measurements of oxygen consumption have been shown to be correlated with organ function (1-5). A noninvasive measurement of blood oxygen state (%O 2 ) would be useful clinically in a range of disease states (6). We are interested in a bulk MR tissue parameter that is correlated to blood oxygen state and is sensitive enough to show changes in tissues where the blood volume fraction is small.Deoxyhemoglobin in blood acts as a paramagnetic contrast agent. This suggests that T 2 -based parameters are likely to be the most sensitive to changes in tissue blood oxygenation. Indeed, functional MR studies have shown that the BOLD contrast mechanism (7) can be sensitive to small changes in blood volume and oxygenation state. This contrast is T* 2 based, which is composed of T 2 Ј (reversible) and T 2 (irreversible) contributions, both of which are expected to change with blood oxygenation, following slightly different mechanisms. While this approach has proven effective in the brain, results in skeletal muscle have been mixed (8,9). Other investigators have studied the relaxation behavior of in vitro skeletal muscle using T 2 relaxation times. Results in various muscle types with different capillary densities indicated significant (10) or no (11) differences with monoexponential T 2 fits. Fits for multiexponential decay found two (11,12) or three (10,13,14) T 2 components in normal muscle. When three T 2 components were fit, the shortest T 2 component was approximately 5 msec. It was less than 5% of the total signal and was assigned to macromolecular-associated water. In vivo measurements would likely not be able to distinguish such a component since typical echo times are greater than the T 2 of this short component. Hazlewood et al. (13) hypothesized that the two longer T 2 components were associated with intra-and extracellular water. Le Rumeur et al. (11) demonstrated inconsistencies in Hazlewood's assignments, and instead related the long-T 2 component to the vascular space alone, and the short-T 2 component to the sum of interstitial and intracellular spaces. If Le Rumeur's assignments of intra-and extravascular spaces were correct, then changes in the T 2 of blood resulting from changes in its oxygen state should preferrentially affect the long-T 2 component. We have investigated the feasibility of detecting these blood oxygen...

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Pulsed NMR relaxometry of striated muscle fibers

Cited by 68 publications

References 28 publications

Magnetization Transfer and T₂ Relaxation Components in Tissue

Magnetization Transfer and T₂ Relaxation Components in Tissue

Relaxation times and microstructures

Monitoring blood oxygen state in muscle microcirculation with transverse relaxation

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Pulsed NMR relaxometry of striated muscle fibers

Cited by 68 publications

References 28 publications

Magnetization Transfer and T2 Relaxation Components in Tissue

Magnetization Transfer and T2 Relaxation Components in Tissue

Relaxation times and microstructures

Monitoring blood oxygen state in muscle microcirculation with transverse relaxation

Contact Info

Product

Resources

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Magnetization Transfer and T₂ Relaxation Components in Tissue

Magnetization Transfer and T₂ Relaxation Components in Tissue