Relaxivity and diffusion of gadolinium agents in cartilage
Relaxivity and diffusion of gadolinium agents in cartilage
复制标题
DOI：
10.1002/mrm.10327
复制
发表时间：
2002-12-01
影响因子：
3.3
通讯作者：
Burstein, D
中科院分区：
文献类型：
--
作者：
Gillis, A;Gray, M;Burstein, D
先前的工作表明，Gd(DTPA)(2-) 的分布（通过 T-1 测量）是软骨中糖胺聚糖 (GAG) 分布的良好替代指标。除了存在 Gd(DTPA)(2-) 时测量的 T-1 之外，Gd(DTPA)(2-) 浓度测量的精度还取决于无 Gd(DTPA)(2-) 时的 T-1（T(1) 度）以及软骨中 Gd(DTPA)(2-) 的弛豫度 (r)，这些参数受软骨成分的影响。这些参数是在天然软骨和 GAG 耗尽的软骨中测量的，以便估计在任意退化状态下软骨的预期值的界限。 T(1)度的范围是0.3秒； r 的范围在 8.5 T 时为 0.6 (mM*s)(-1)，在 2 T 时为 1.4 (mM*s)(-1)。这些数据表明，如果假定 T(1) 度和 r 的值是天然软骨的值，则 Gd(DTPA)(2-) 将被低估（并且 GAG 被高估）。 （例如，在严重的情况下，90% 的 GAG 损失将被低估为 70% 损失。）Gd(HPDO3A) 作为非离子“控制剂”进行研究，发现其弛豫和扩散特性与 Gd(DTpA)(2-) 相当（r(GD(HPDO3A))/r(Gd(DTPA)) 接近 1； D-Gd(HPDO3A)/D-Gd(DTPA) 大约为 0.85)。由于 Gd(HPDO3A) 在软骨中均匀分布（独立于 GAG），因此 T-1 与 Gd(HPDO3A) 的分布可用作 T(1) 度和 r（如果存在）变化的替代测量。从运输的角度来看，如果Gd(HPDO3A)已完全渗透软骨，Gd(DTPA)(2-)也会在相同的时间范围内完全渗透。因此，数据证实了使用 Gd(HPDO3A) 作为 dGEMRIC“控制剂”的功效。
Prior work indicates that the distribution of Gd(DTPA)(2-) (as measured by T-1) is a good surrogate measure of the distribution of gycosaminoglycan (GAG) in cartilage. In addition to the measured T-1 in the presence of Gd(DTPA)(2-), the precision of the measurement of Gd(DTPA)(2-) concentration depends on the T-1 without Gd(DTPA)(2-) (T(1)degrees), and the relaxivity (r) of Gd(DTPA)(2-) in cartilage, parameters that are influenced by cartilage composition. These parameters were measured in native and GAG-depleted cartilage in order to estimate the bounds on the values one might expect for cartilage in arbitrary states of degeneration. The range of T(1)degrees was 0.3 sec; the range of r was 0.6 (mM*s)(-1) at 8.5 T and 1.4 (mM*s)(-1) at 2 T. These data suggest that Gd(DTPA)(2-) will be underestimated (and GAG overestimated) if the values for T(1)degrees, and r are assumed to be those of native cartilage. (For example, in a severe case a 90% loss of GAG would be underestimated as a 70% loss.) Gd(HPDO3A) was investigated as a nonionic "control agent" and found to have relaxivity and diffusion properties that were comparable to Gd(DTpA)(2-) (r(GD(HPDO3A))/r(Gd(DTPA)) approximate to 1; D-Gd(HPDO3A)/D-Gd(DTPA) approximate to 0.85). Since Gd(HPDO3A) distributes uniformly through cartilage (independent of GAG), the distribution of T-1 with Gd(HPDO3A) can be used as a surrogate measure of variations in T(1)degrees and r, if present. From the perspective of transport, if Gd(HPDO3A) has fully penetrated the cartilage, Gd(DTPA)(2-) would have in the same time frame. Therefore, the data confirm the efficacy of using Gd(HPDO3A) as a "control agent" for dGEMRIC.