Water phases in rat striated muscles as determined by T2 proton NMR relaxation times

Rumeur, Élisabeth Le; Certaines, J. de; Toulouse, P.; Rochcongar, P.

doi:10.1016/0730-725x(87)90003-8

Cited by 103 publications

(61 citation statements)

References 21 publications

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“…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.…”

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confidence: 91%

“…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.…”

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confidence: 99%

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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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mentioning

confidence: 91%

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confidence: 99%

Monitoring blood oxygen state in muscle microcirculation with transverse relaxation

Stainsby

Wright

2001

Magnetic Resonance in Med

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“…For basal and vasodilatory state intravascular volumes, we consider a range of blood volumes (5% to 12%), consistent with the literature. 20,26,27 Intravascular T 2 may be estimated from oximetry measurements within larger vessels 8 ; a basal state oxygen level of 27%O 2 maps to a vascular T 2 about 39 ms and a vasodilatory state oxygen level of 82%O 2 maps to a vascular T 2 about 183 ms. Parameters of the extravascular space include a relative volume of 1 Ϫ intravascular volume and T 2 of 40 ms. 28 A water exchange rate of 7 per second is assumed. 29 The predicted T 2 responses to adenosine are summarized in Table 3.…”

Section: Predicted T 2 Elevation During Adenosine Infusionmentioning

confidence: 99%

Vasodilator Response Assessment in Porcine Myocardium With Magnetic Resonance Relaxometry

et al. 2002

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Background-This research describes an early preclinical study of the biophysical mechanisms governing changes in myocardial T 2 during vasodilation in normal myocardium. Methods and Results-Theoretical modeling and experimental studies in an instrumented pig model (nϭ7) provided measures of changes in myocardial T 2 , relative blood volume (BV), and microcirculation oxygen levels (%O 2 ) during intracoronary adenosine infusion. Intracoronary adenosine increases perfusion without increasing blood volume or cardiac metabolic rate; thus, T 2 elevations should reflect elevated microcirculation oxygen levels. Robust strategies were used for magnetic resonance imaging (MRI) data collection. Measures of myocardial and vascular T 1 before and after Clariscan (Amersham Health) injection provided blood volume assessment. Changes in microcirculation oxygen levels were estimated via direct blood sampling from the left anterior descending (LAD) coronary vein. Perfusion changes were monitored using a Doppler flow wire within the left main coronary artery. Myocardial T 2 elevations (⌬T 2 ϭ17Ϯ8%) within the LAD arterial perfusion bed were related to elevations in perfusion (coronary velocity reserveϭ3.2Ϯ0.4) and coronary venous %O 2 [⌬(LAD CV%O 2 ) ϭ56Ϯ11%], whereas blood volume (⌬BVϭ0 Ϯ2%) and cardiac metabolic rate [⌬(heart rate x blood pressure) ϭ Ϫ4Ϯ11%] remained constant. Conclusions-Myocardial T 2 elevation during intracoronary adenosine infusion was significant and repeatable, caused by increases in microcirculation oxygen levels. Changes in microcirculation oxygen levels of approximately 40%O 2 should be detectable by this technique. This sensitivity should suffice for differentiating normal from abnormal myocardium via measurement of myocardial perfusion reserve.

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“…Furthermore, the speed of exchange between bound and free water determines if there is a mean relaxation time or two or more separately detectable relaxation times: in healthy muscle, it has been established that two spin-spin relaxation times can be separately identified expressing a slow exchange between different water phases [28,29]. Table 2 T1 and T2 frequency dependence of human skeletal muscle in-vivo measured on 13 MRI units after correction resulting from a preliminary quality assessment using Eurospin TO5 test object [26] NMR frequency 4.…”

Section: Perception Of Visual Texturesmentioning

confidence: 99%

Application of texture analysis to muscle MRI: 1-What kind of information should be expected from texture analysis?

Certaines

Larcher

Duda

et al. 2015

EPJ Nonlinear Biomed Phys

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Several previous clinical or preclinical studies using computerized texture analysis of MR Images have demonstrated much more clinical discrimination than visual image analysis by the radiologist. In muscular dystrophy, a discriminating power has been already demonstrated with various methods of texture analysis of magnetic resonance images (MRI-TA). Unfortunately, a scale gap exists between the spatial resolutions of histological and MR images making a direct correlation impossible. Furthermore, the effect of the various histological modifications on the grey level of each pixel is complex and cannot be easily analyzed. Consequently, clinicians will not accept the use of MRI-TA in routine practice if TA remains a "black box" without clinical correspondence at a tissue level. A goal therefore of the multicenter European COST action MYO-MRI is to optimize MRI-TA methods in muscular dystrophy and to elucidate the histological meaning of MRI textures. ReviewSeveral methods of image post-processing have been developed for Texture Analysis of Magnetic Resonance images (MRI-TA) and have already demonstrated stimulating results in a large range of pre-clinical or clinical applications [1]; MRI-TA usually provides much more clinical discrimination than visual analysis of MR images by the radiologist [2]; visual analysis (about 100 grey level can be discriminated) is ten times less sensitive to fine and local grey level changes than computer analysis (about 1000 grey level by using computer detection). There is presently no well-established consensus concerning the limits of texture visual perception but it is clear that texture represented by higher orders statistics can only be discriminated by computerized image analysis.In normal versus dystrophic muscles, a discriminating power at an early stage and during disease evolution has been demonstrated with various MRI-TA methods: some MRI texture parameters in healthy or diseased skeletal muscle have previously been related to fat infiltration [3,4] to the loss of orientation of muscle fibers [3], to the disturbance of perimysium [3], to the mean size of necrotic and regeneration foci [5], to the proportion of oxidative myofibers [5], to the endomysal fibrosis [5] and collagen content [4] or to the heterogeneity of myofiber size [5].

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Water phases in rat striated muscles as determined by T2 proton NMR relaxation times

Cited by 103 publications

References 21 publications

Monitoring blood oxygen state in muscle microcirculation with transverse relaxation

Monitoring blood oxygen state in muscle microcirculation with transverse relaxation

Vasodilator Response Assessment in Porcine Myocardium With Magnetic Resonance Relaxometry

Application of texture analysis to muscle MRI: 1-What kind of information should be expected from texture analysis?

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