Characteristics of proton NMR T2 relaxation of water in the normal and regenerating tendon
Characteristics of proton NMR T2 relaxation of water in the normal and regenerating tendon
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DOI：
10.2170/jjphysiol.50.569
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发表时间：
2000-12-01
期刊：
影响因子：
--
通讯作者：
Hirasawa, Y
中科院分区：
文献类型：
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作者：
Takamiya, H;Kusaka, Y;Hirasawa, Y
使用横向弛豫时间 (T-2) 分析正常肌腱和再生肌腱中水的分子行为，该横向弛豫时间 (T-2) 通过自旋回波质子核磁共振 (H-1-NMR) 光谱在 2.34 T (25 ℃) 下测量。从麻醉的日本白兔身上切下跟腱的一部分，其纵轴与静磁场成 0、35、54.7、75 和 90 度。在正常肌腱中，水的T-2弛豫在长T-2（5.41至6.21 ms）和短T-2（0.41至1.43 ms）分量中均呈现双指数弛豫和各向异性，其中最大值在54.7度处获得。然而，各向异性的范围比我们从水与肌腱中胶原纤维结合的 H-1 偶极相互作用中预期的要窄得多。水质子密度的表观分数也随方向变化：较长的 T-2 成分的分数在 54.7 度时达到最大值。这些结果表明，简单的二室模型不能适用于肌腱 T-2 值的方向依赖性，并且短 T-2 松弛分量中有序的水可能会显示出延长的 T-2 松弛时间，该时间落在长 T-2 松弛分量的 54.7 度范围内。该假设可以解释 T-2 弛豫时间的较窄范围以及对 H-1 密度表观分数的取向依赖性。通过分析 T-2 松弛时间，对跟腱的再生过程进行了 18 周的跟踪。横切后长达 3 周仅存在较长的 T-2 弛豫时间成分（21.8 至 28.0 毫秒）。在 6 周及之后显示出双指数弛豫，由此（i）T-2 弛豫时间变短，（ii）短 T-2 值和长 T-2 值存在各向异性，以及（iii）随着再生肌腱的成熟，水质子密度表观分数的方向依赖性变得明显。根据这些结果，水的 H-1 T-2 弛豫时间可用于非侵入性监测肌腱胶原结构的愈合过程。
The molecular behavior of water in normal and regenerating tendons was analyzed using the transverse relaxation time (T-2) measured by spin-echo proton nuclear magnetic resonance (H-1-NMR) spectroscopy at 2.34 T (25 degreesC). A section of the Achilles tendon was dissected from an anesthetized Japanese white rabbit, and its longitudinal axis was oriented at 0, 35, 54.7, 75, and 90 degrees to the static magnetic field. In the normal tendon, the T-2 relaxation of water presented biexponential relaxation and anisotropy in both the long T-2 (5.41 to 6.21 ms) and short T-2 (0.41 to 1.43ms) components, in which the greatest values were obtained at 54.7 degrees. However, the range of the anisotropy was much narrower than we expected from the H-1 dipolar interaction of water bound to the collagen fibers in the tendon. The apparent fractions of water proton density also varied with orientation: the fraction of the longer T-2 components was at its maximum at 54.7 degrees. These results suggest that a simple two-compartment model could not be applicable to orientational dependency of the T-2 value of the tendon, and the well ordered water in the short T-2 relaxation component may show an elongated T-2 relaxation time that falls in the range of the long T-2 relaxation component at 54.7 degrees. This hypothesis can explain both the narrower range of the T-2 relaxation time and the orientational dependency on the apparent fraction of H-1 density. Regenerating processes of the Achilles tendon were followed for 18 weeks by analyzing the T-2 relaxation time. There is only a long T-2 relaxation time component (21.8 to 28.0 ms) up to 3 weeks after transection. Biexponential relaxation is revealed at 6 weeks and thereafter, whereby (i) the T-2 relaxation times become shorter, (ii) there is anisotropy in the short and long T-2 values, and (iii) the orientational dependency of the apparent fraction of water proton density becomes evident with maturation of the regenerating tendon. From these results, the H-1 T-2 relaxation time of water might be used to monitor the healing process of collagen structures of the tendon non-invasively.