Pulsed field gradient NMR and nuclear magnetic relaxation studies of water mobility in hydrated collagen II

Knauss, Robert; Fleischer, G.; Gründer, Wilfried; Kärger, Jörg; Werner, Annett

doi:10.1002/mrm.1910360211

Cited by 48 publications

(55 citation statements)

References 21 publications

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“…The dermis, on the other hand, is characterized by its high collagen content. The hypointensity of the dermis is probably due to both the reduced cellular density and the shortened T2 of water resulting from a significant portion of water that is tightly bound to collagen (18 Figures 5a and 5b show two contiguous slices from a 12-slice GRASS data set obtained with Prescription 1 (Table I), by means of the 1-cm surface coil. Hair follicles in the dermis of these 400-pm sections are clearly visualized.…”

Section: Resultsmentioning

confidence: 98%

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In vivo MR microscopy of the human skin

Song

Wehrli

1997

Magnetic Resonance in Med

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The requirements for imaging the skin are dictated by the organ's layered structure, which extends only a few millimeters from the surface and thus demands extremely high resolution in this direction. While less critical, resolution in the remaining two dimensions determines whether the skin's accessory structures can be resolved. The problem is compounded by short transverse relaxation times, in particular of the dermis, the structure of most clinical interest. In this work images of the normal human skin were obtained in vivo at voxel sizes as small as 19 x 78 x 800 microm3, by means of customized 3D gradient and partial flip-angle spin-echo pulse sequences and very small transmit/receive coils on a 1.5T clinical imager equipped with high-power whole-body gradients. Structures resolved include hair follicles and the sublayers of the dermis. The very short time constant for the major component (91%) for transverse relaxation in the dermis (T2* approximately 10 ms) suggests the potential of substantial gains in achievable signal-to-noise ratio by shortening the echo time.

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Section: Resultsmentioning

confidence: 98%

“…The high-intensity layer below is the epidermis. The SNR of the stratum corneum, epidermis, and the dermis was 18, 33, and 6, respectively.…”

Section: Resultsmentioning

confidence: 99%

In vivo MR microscopy of the human skin

Song

Wehrli

1997

Magnetic Resonance in Med

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“…24,25 The macromolecular structure of the collagen in the cap could create a barrier to molecular motion, thereby creating a T 2 * mechanism as water molecules traverse across layers. 22,23,26,27 The T 2 * sensitivity of the GRE-weighted 3D TOF sequence would then allow detection of disruptions or absence of the collagen layers in the fibrous cap that would be caused by plaque rupture or the presence of proteoglycan-rich regions. 28 Because T 1 relaxation is less dependent on the static component of dipole-dipole coupling, this effect is not evident in T 1 -weighted images.…”

Section: Discussionmentioning

confidence: 99%

Identification of Fibrous Cap Rupture With Magnetic Resonance Imaging Is Highly Associated With Recent Transient Ischemic Attack or Stroke

et al. 2002

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Background-High-resolution MRI has been shown to be capable of distinguishing intact, thick fibrous caps from thin and ruptured caps in human carotid atherosclerosis in vivo. The aim of this study was to determine whether MRI identification of fibrous cap thinning or rupture is associated with a history of recent transient ischemic attack (TIA) or stroke. Methods and Results-Fifty-three consecutive patients (mean age, 71 years; 49 male) scheduled for carotid endarterectomy were recruited after obtaining informed consent. Twenty-eight subjects had a recent history of TIA or stroke on the side appropriate to the index carotid lesion, and 25 were asymptomatic. Preoperative carotid MRI was performed in a 1.5-T GE Signa scanner that generated T 1 -, PD-, and T 2 -weighted and three-dimensional time-of-flight images. Using previously reported MRI criteria, the fibrous cap was categorized as intact-thick, intact-thin, or ruptured for each carotid plaque by blinded review. There was a strong and statistically significant trend showing a higher percentage of symptomatic patients for ruptured caps (70%) compared with thick caps (9%) (Pϭ0.001 Mann-Whitney test for cap status versus symptoms). Compared with patients with thick fibrous caps, patients with ruptured caps were 23 times more likely to have had a recent TIA or stroke (95% CIϭ3, 210). Conclusions-MRI identification of a ruptured fibrous cap is highly associated with a recent history of TIA or stroke.Ongoing prospective studies will determine the predictive value fibrous cap characteristics, as visualized by MRI, for risk of subsequent ischemic events. Key Words: magnetic resonance imaging Ⅲ atherosclerosis Ⅲ carotid arteries Ⅲ stroke R upture of the fibrous cap that overlies the thrombogenic necrotic core is presently believed to play an important role in acute ischemic events, such as stroke, transient ischemic attack, myocardial infarction, and unstable angina. [1][2][3][4] Several histological studies have revealed that lesions associated with the development of ischemic symptoms typically contain a large necrotic core that is separated from the lumen by a fibrous cap that is thin or disrupted. 5,6 Because the detection of these morphological features could identify the plaques that represent a higher risk for thromboembolic complications, the development of a noninvasive method capable of assessing the state of the fibrous cap would not only improve patient stratification to medical or surgical treatment but would also provide a means of monitoring disease progression or evaluating the efficacy of therapeutic interventions.Of the clinical imaging modalities presently used to study atherosclerosis, MRI is unique because it is noninvasive, capable of identifying plaque tissue components with submillimeter resolution, able to provide quantitative measures of disease severity, and suitable for serial investigations. [7][8][9][10][11][12][13][14] Recent studies demonstrated that high-resolution MRI is capable of distinguishing intact, thick fibrous caps from thin o...

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“…63 The authors concluded that the slowly diffusing but locally highly mobile water fraction represents water molecules that traverse the collagen fibers or, in other words, they advance to the molecular sites of the protein. We conclude that these hydration water molecules are the molecules that bind to polar groups of collagen, thereby increasing the local dynamics of these segments.…”

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confidence: 99%

A solid‐state NMR study of the fast and slow dynamics of collagen fibrils at varying hydration levels

Reichert¹,

Pascui²,

deAzevedo³

et al. 2004

Magnetic Reson in Chemistry

123

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We report solid-state NMR investigations of the effect of temperature and hydration on the molecular mobility of collagen isolated from bovine achilles tendon. (13)C cross-polarization magic angle spinning (MAS) experiments were performed on samples at natural abundance, using NMR methods that detect motionally averaged dipolar interactions and chemical shift anisotropies and also slow reorientational processes. Fast motions with correlation times much shorter than 40 micro s scale dipolar couplings and chemical shift anisotropies of the carbon sites in collagen. These motionally averaged anisotropic interactions provide a measure of the amplitudes of the segmental motions expressed by a molecular order parameter. The data reveal that increasing hydration has a much stronger effect on the amplitude of the molecular processes than increasing temperature. In particular, the Cgamma carbons of the hydroxyproline residues exhibit a strong dependence of the amplitude of motion on the hydration level. This could be correlated with the effect of hydration on the hydrogen bonding structure in collagen, for which this residue is known to play a crucial role. The applicability of 1D MAS exchange experiments to investigate motions on the millisecond time-scale is discussed and first results are presented. Slow motions with correlation times of the order of milliseconds have also been detected for hydrated collagen.

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Pulsed field gradient NMR and nuclear magnetic relaxation studies of water mobility in hydrated collagen II

Cited by 48 publications

References 21 publications

In vivo MR microscopy of the human skin

In vivo MR microscopy of the human skin

Identification of Fibrous Cap Rupture With Magnetic Resonance Imaging Is Highly Associated With Recent Transient Ischemic Attack or Stroke

A solid‐state NMR study of the fast and slow dynamics of collagen fibrils at varying hydration levels

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