23Na MRI accurately measures fixed charge density in articular cartilage
23Na MRI accurately measures fixed charge density in articular cartilage
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DOI：
10.1002/mrm.10054
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发表时间：
2002-02-01
影响因子：
3.3
通讯作者：
Reddy, R
中科院分区：
文献类型：
--
作者：
Shapiro, EM;Borthakur, A;Reddy, R
骨关节炎的起始步骤之一是软骨基质中蛋白聚糖（PG）分子的丢失。因此，评估软骨完整性的一种方法是测量软骨的PG含量或固定电荷密度（FCD）。本报告显示了Na-23 MRI计算FCD的可行性，并介绍了人体研究的MRI协议，在体内。用Na-23 MRI测量牛髌软骨内钠离子浓度。然后通过考虑理想的唐南平衡将钠浓度转换为FCD（mM）。将这些FCD测量值与通过标准二甲基亚甲基蓝PG测定获得的FCD测量值进行比较。通过Na-23 MRI获得的FCD测量值与通过PG测定获得的FCD测量值之间具有高度相关性（斜率= 0.89，r（2）= 0.81）。这些方法，然后在体内定量的人志愿者的关节软骨的FCD。比较了两种成像协议：一种使用鸟笼线圈，另一种使用发射/接收表面线圈。两种方法都给出了相似的结果，正常人髌骨软骨的平均钠浓度范围从相似的240到260 mM。这对应于FCD为约158 mM到约182 mM。Magn Reson Med 47：284-291，2002。(C)2002 Wiley-Liss，Inc.
One of the initiating steps of osteoarthritis is the loss of proteoglycan (PG) molecules from the cartilage matrix. One method for assessing cartilage integrity, therefore, is to measure the PG content or fixed charge density (FCD) of cartilage. This report shows the feasibility of calculating FCD by Na-23 MRI and introduces MRI protocols for human studies, in vivo. Na-23 MRI was used to measure the sodium concentration inside bovine patellar cartilage. The sodium concentration was then converted to FCD (mM) by considering ideal Donnan equilibrium. These FCD measurements were compared to FCD measurements obtained through standard dimethylmethylene blue PG assays. There was a high correlation (slope = 0.89, r(2) = 0.81) between the FCD measurements obtained by Na-23 MRI and those obtained by the PG assays. These methods were then employed in quantifying the FCD of articular cartilage of human volunteers in vivo. Two imaging protocols were compared: one using a birdcage coil, the other using a transmit/receive surface coil. Both methodologies gave similar results, with the average sodium concentration of normal human patellar cartilage ranging from similar to240 to 260 mM. This corresponds to FCDs of -158 mM to -182 mM. Magn Reson Med 47:284-291, 2002. (C) 2002 Wiley-Liss, Inc.