Tadimalla Sirisha, Momot Konstantin I
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland, Australia; Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia.
PLoS One. 2014 Dec 29;9(12):e115288. doi: 10.1371/journal.pone.0115288. eCollection 2014.
Anisotropy of transverse proton spin relaxation in collagen-rich tissues like cartilage and tendon is a well-known phenomenon that manifests itself as the "magic-angle" effect in magnetic resonance images of these tissues. It is usually attributed to the non-zero averaging of intra-molecular dipolar interactions in water molecules bound to oriented collagen fibers. One way to manipulate the contributions of these interactions to spin relaxation is by partially replacing the water in the cartilage sample with deuterium oxide. It is known that dipolar interactions in deuterated solutions are weaker, resulting in a decrease in proton relaxation rates. In this work, we investigate the effects of deuteration on the longitudinal and the isotropic and anisotropic contributions to transverse relaxation of water protons in bovine articular cartilage. We demonstrate that the anisotropy of transverse proton spin relaxation in articular cartilage is independent of the degree of deuteration, bringing into question some of the assumptions currently held over the origins of relaxation anisotropy in oriented tissues.
在富含胶原蛋白的组织（如软骨和肌腱）中，横向质子自旋弛豫的各向异性是一种众所周知的现象，在这些组织的磁共振图像中表现为“魔角”效应。它通常归因于与定向胶原纤维结合的水分子中分子内偶极相互作用的非零平均值。操纵这些相互作用对自旋弛豫贡献的一种方法是用重水部分替代软骨样品中的水。众所周知，氘化溶液中的偶极相互作用较弱，导致质子弛豫率降低。在这项工作中，我们研究了氘化对牛关节软骨中水质子纵向弛豫以及横向弛豫的各向同性和各向异性贡献的影响。我们证明，关节软骨中横向质子自旋弛豫的各向异性与氘化程度无关，这对目前关于定向组织中弛豫各向异性起源的一些假设提出了质疑。
