The origin of biexponential T2 relaxation in muscle water

Cole, William C.; LeBlanc, Adrian; Jhingran, Satish G.

doi:10.1002/mrm.1910290106

Cited by 98 publications

(100 citation statements)

References 23 publications

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“…Indeed, prior to considering an interpretation for the two components of the diffusion decay curves, we shall argue that the most likely assignments for the fast and slow relaxing components of the T 2 decay curves are the intra-and extracellular water compartments. This proposition is based upon the following arguments from in vitro (8) and in vivo (10) experiments by others as well as our own previous study of a similar rat muscle edema model (23).…”

Section: Discussionmentioning

confidence: 99%

“…In vitro, Cole and coworkers demonstrated that complete maceration of rat muscle was required to eliminate multiexponential T 2 decay, implicating membrane integrity and resultant water compartmentation for the phenomenon (8). In vivo, Saab and colleagues (10) used high signal-to-noise, non-imaging CPMG methods on a clinical scanner and were able to detect 4 T 2 components in healthy human muscle at 1.5 T. They attributed the small amplitude first component with T2 Ͻ 5 ms to water asso- Table 2 Biexponential Parameters of Fits to the Decay Curves in Fig.…”

Section: Discussionmentioning

confidence: 99%

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Biexponential parameterization of diffusion and T₂ relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

Ababneh

Beloeil

Berde

et al. 2005

Magnetic Resonance in Med

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Quantitative T 2 relaxation and diffusion imaging studies of a rat muscle edema model were performed in order to determine the effects of intra-and extracellular water compartmentation on the respective decay curves. The right hind paw of rats was injected with a carrageenan solution to generate edematous muscle. A Carr-Purcell-Meiboom-Gill (CPMG) imaging sequence was used to acquire T 2 relaxation decay curves from both paws. A line scan diffusion imaging (LSDI) sequence was then used to acquire diffusion decay curves from the same paws over a wide b-factor range. Measurements were made from both edematous muscle (EM) and control muscle (CM). The EM and CM T 2 relaxation decay curves were best fit with biexponential functions. The fraction of the fast T 2 component dropped dramatically from approximately 0.95 in CM to 0.45 in EM, consistent with a water compartmentation model in which the fast and slow T 2 components reflect intra-and extracellular water, respectively. Both CM and EM diffusion decay curves required biexponential fitting functions, and the diffusion coefficients of the fast and slow components were substantially larger in EM than CM. The fraction of the fast diffusion component, however, was not radically altered between CM and EM conditions (0.84 versus 0.89 for CM versus EM). Assuming a model in which intra-and extracellular water compartments are responsible for the fast and slow T 2 -decay components and for the slow and fast diffusion decay components, respectively, leads to fractional sizes of the diffusion components that are not supported by experiment. We conclude that intra-and extracellular water compartmentation is a reasonable interpretation for the two T 2 -decay components in both CM and EM but that other factors, such as restricted diffusion and/or alternate forms of water compartmentation like surface versus volume water, most probably have profound influences on the precise shapes of the diffusion decay curves, a complete understanding of which will require significant theoretical work. The sensitivity of proton relaxation and diffusion measurements to the chemical and physical environment of water molecules has long been exploited for studying the organization and distribution of water in living tissues. Early transverse relaxation time, T 2 , studies performed with non-imaging based Carr-Purcell-Meiboom-Gill (CPMG) sequences (1) or Hahn spin echo sequences (2) on tissue specimens often described the T 2 relaxation decay curves as non-monoexponential in nature and well-suited to multiexponential analyses, with the components generally interpreted in terms of different water compartments with some contributions from macromolecules, particularly for the very short T 2 components (3-10). Most imaging studies of T 2 relaxation with magnetic resonance imaging scanners, however, have been performed with more stringent limitations on minimal echo spacings due to the need for frequency encoded readouts. Also, unless specifically optimized for single slice imaging, measurements are oft...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Biexponential parameterization of diffusion and T₂ relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

Ababneh

Beloeil

Berde

et al. 2005

Magnetic Resonance in Med

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“…there is a rapid exchange of protons between tissue water and macromolecules, proving that the water compartments are interdependent (20,21). We applied biexponential fitting for estimation of the bound and free water compartments.…”

Section: Lung Water and Hyaluronan In Rabbit Pupsmentioning

confidence: 99%

Lung Water and Proton Magnetic Resonance Relaxation in Preterm and Term Rabbit Pups: Their Relation to Tissue Hyaluronan

et al. 2000

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The present study was performed to investigate simultaneously total lung water, T 1 and T 2 relaxation times, and hyaluronan (HA) in preterm and term rabbits. Attempts were also made to establish the relationship of HA to total lung water and to T 2 -derived motionally distinct water fractions. Experiments were performed in fetal Pannon white rabbit pups at gestational ages of 25, 27, 29, and 31 d and at a postnatal age of 4 d. Lung tissue water content (desiccation method), T 1 and T 2 relaxation times (H 1 -NMR method), and HA concentration (radioassay) were measured, and free and bound water fractions were calculated by using multicomponent fits of the T 2 relaxation curves. Lung water content and T 1 and T 2 relaxation times were highest at a gestational age of 27 d and then declined steadily during the whole study period. Similar trends and time courses were seen for the fast and slow components of the T 2 relaxation curve. The T 2 -derived free water fraction remained unchanged at a gestational age of 25-29 d (ϳ67%), but increased progressively to a value of 78.5 Ϯ 7. During fetal life the potential air space of the lung is filled with fluid, which is generated by continuous epithelial secretion driven by active chloride transport. As parturition approaches, the lung fluid secretion decreases, and sodium transport-dependent reabsorption begins. This switch in transepithelial water movement culminates at birth and results in rapid clearance of lung fluid, which is critical for successful transition to air breathing (1-4).The osmotic water permeability of the alveolar epithelium is developmentally regulated by and related to the expression of water-transporting proteins, called AQPs. Three AQPs have been identified in the lung: AQP1 in the capillary endothelium, AQP4 in the basolateral membrane of the airway epithelium, and AQP5 in the apical membrane of alveolar epithelial type I cells (5-8).The specific localization of AQPs to endothelial and epithelial cells suggests water movement between the air space and the interstitial and capillary compartments. It takes place through individual water channels. The mRNA and protein expression of AQPs appears late in gestation, increases markedly at birth, and remains elevated during early postnatal life (9, 10). This developmental pattern of AQP expression parallels perinatal changes in the osmotic water permeability of the lung and the rate of lung water removal that occurs around birth (11).In addition to active ion transport-driven AQP-mediated water transport, the physical state of tissue water is also an important determinant of perinatal lung water clearance. Namely, a fraction of tissue water is motionally constrained, i.e. bound to macromolecules and thus made unavailable for immediate transport across alveolar, microvascular, and airway barriers (12).

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“…Previous T2 modelling studies have described living tissues as bi-or multi-exponential components, with the components interpreted as intra-and extracellular water [207][208][209]. In this case, T2 short and long components determined from bi-exponential decay curves are attributed to liver water and fat components, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Previous T2 studies describing living tissues containing bi-or multi-exponential components, generally interpreted the separate components as unique water compartments [207][208][209] usually ascribed to intra-and extracellular water. The T2 values of fat is longer than that of liver water and will contribute significantly to the tissue T2 due to the high fat content.…”

Section: Mono-versus Bi-exponential Modelsmentioning

confidence: 99%

Magnetic resonance characterisation of developing hepatocellular carcinoma in a diet induced model of liver cancer in the rat

Alghamdi¹

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Non-alcoholic fatty liver disease (NAFLD), a disorder associated with abnormal lipid accumulation within hepatocytes, is considered benign disorder in nature. However, in some cases it may progress to inflammation, nonalcoholic steatohepatitis (NASH), then cirrhosis, precancerous nodules and finally to hepatocellular carcinoma (HCC). NAFLD and NASH are both reversible with appropriate clinical intervention and lifestyle changes. In developed countries, the non-alcoholic fatty liver disease (NAFLD) is becoming one of the most common causes of precancerous and HCC lesions [1]. Unfortunately, most nodular lesions are detected too late with a poor prognosis. The discovery of markers that can predict which livers may progress to HCC would allow early intervention and potentially halting progress to HCC. This would be of great benefit at any stage up to precancerous lesions, however the earlier the better.Development of end stage liver malignancy would be decreased, resulting in decreased mortality from this disease.Histology is considered the reference standard for the assessment of fatty disease and nodular lesion in liver. However, there are significant drawbacks including invasiveness, small sample size and observer-dependence which limits its usefulness in evaluating liver disease.Magnetic resonance imaging is a non-invasive modality that can provide information on anatomical and physiological changes in the liver (e.g. fatty liver disease and HCC). MRI images are primarily assessed visually by expert radiologists looking for anatomical and contrast changes in the images compared to normal tissue. This qualitative method requires inspection of all datasets for abnormalities. Visual interpretation is subjective, labour intensive, and depends on the experience of the radiologist. This can introduce inter-observer variation and is suitable only when the pathology leads to sufficient contrast changes in the images acquired.MRI also allows the calculation of quantitative parameters like T1, T2 and diffusion values. These parameters are dependent on physical, chemical and microstructural properties of the tissue. When standard protocols are used, the calculation of these parameters should be independent of the observer. This has the potential for more precise characterization of changes that occur over time. Clinically, here has been limited utilization of these methods, as they generally require longer acquisition times and significant post processing of the images. Declaration by authorThis thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text.

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The origin of biexponential T2 relaxation in muscle water

Cited by 98 publications

References 23 publications

Biexponential parameterization of diffusion and T₂ relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

Biexponential parameterization of diffusion and T₂ relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

Lung Water and Proton Magnetic Resonance Relaxation in Preterm and Term Rabbit Pups: Their Relation to Tissue Hyaluronan

Magnetic resonance characterisation of developing hepatocellular carcinoma in a diet induced model of liver cancer in the rat

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The origin of biexponential T2 relaxation in muscle water

Cited by 98 publications

References 23 publications

Biexponential parameterization of diffusion and T2 relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

Biexponential parameterization of diffusion and T2 relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

Lung Water and Proton Magnetic Resonance Relaxation in Preterm and Term Rabbit Pups: Their Relation to Tissue Hyaluronan

Magnetic resonance characterisation of developing hepatocellular carcinoma in a diet induced model of liver cancer in the rat

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Biexponential parameterization of diffusion and T₂ relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

Biexponential parameterization of diffusion and T₂ relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments