NMR in biomedicine
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Randomized Controlled Trial Comparative Study
Comparison of T1 relaxation times in adipose tissue of severely obese patients and healthy lean subjects measured by 1.5 T MRI.
Subcutaneous (SAT) and visceral adipose tissue (VAT) differ in composition, endocrine function and localization in the body. VAT is considered to play a role in the pathogenesis of insulin resistance, type 2 diabetes, fatty liver disease, and other obesity-related disorders. It has been shown that the amount, distribution, and (cellular) composition of adipose tissue (AT) correlate well with metabolic conditions. ⋯ Obese subjects also showed significant (p < 0.01) T1 differences between sSAT (268 ± 11 ms) and dSAT (281 ± 19 ms). More important, T1 differences in both SAT and VAT were highly significant (p < 0.001) between obese patients and healthy subjects. The results of our pilot study suggest that T1 relaxation times differ between severely obese patients and lean controls, and may potentially provide an additional means for the non-invasive assessment of AT conditions and dysfunction.
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Randomized Controlled Trial
First-pass dynamic contrast-enhanced MRI with extravasating contrast reagent: evidence for human myocardial capillary recruitment in adenosine-induced hyperemia.
Human myocardial (1)H(2)O T(1)-weighted dynamic contrast-enhanced MRI data were acquired during the brief first-pass period after injection of a very small gadolinium diethylenetriaminepenta-acetate (GdDTPA(2-)) dose. The shutter-speed pharmacokinetic effects of both transendothelial and transcytolemmal equilibrium water exchange processes were investigated. Our results indicate that even for such a short acquisition window and relatively large pseudo-first-order rate constant (K(trans)) for plasma/interstitium contrast reagent (CR) transfer the kinetics of these water exchange processes cannot be treated as infinitely fast or slow. ⋯ We also compared resting and hyperemic cardiac conditions, the latter resulting from the volume flow increase induced by adenosine arteriolar vasodilation. We found that the P(CR)S value increases with flow probably mostly because of an S increase associated with capillary recruitment. The v(b) values also increased in hyperemia and showed a flow-dependence with a clearly identifiable component due to capillary recruitment.