Shuter B, Tofts P S, Wang S C, Pope J M
Department of Radiology, Royal North Shore Hospital, St. Leonards, NSW, Australia.
Magn Reson Imaging. 1996;14(3):243-53. doi: 10.1016/0730-725x(95)02097-d.
The NMR relaxivities of Gd-EOB-DTPA and Gd-DTPA were determined in the kidney and liver of intact male Wistar rats immediately following sacrifice and in vitro in solutions and gels, at 1.5 T using a clinical MR scanner, T1 and T2 values of tissue samples were derived from spin-echo image sequences. Tissue gadolinium concentrations were determined by radioassay of Gd153, Gd-EOB-DTPA T1 and T2 relaxivities, R1 and R2 (s-1 mmole-1 kg), were found to be 10.7 +/- 0.5 and 22.5 +/- 3.2 respectively, for liver, 2.4 +/- 0.2 and 12.1 +/- 1.7 for kidney cortex, 2.7 +/- 0.2 and 14.5 +/- 1.9 for kidney outer medulla, 2.0 +/- 0.2 and 11.4 +/- 2.1 for kidney inner medulla. Gd-DTPA R1 and R2 were found to be 4.8 +/- 0.4 and 14.5 +/- 3.7 for liver, 1.2 +/- 0.1 and 7.9 +/- 0.8 for kidney cortex, 1.6 +/- 0.1 and 10.2 +/- 1.4 for kidney outer medulla, 1.3 +/- 0.1 and 10.2 +/- 1.2 for kidney inner medulla. Gd-EOB-DTPA and Gd-DTPA R1 was increased in liver compared to agarose gets at 38 degrees C (4.49 +/- 0.03 and 3.47 +/- 0.06), but reduced in kidney tissues. All R2 were elevated compared to agarose gels at 38 degrees C (5.72 +/- 0.12 and 4.12 +/- 0.03). Elevated R2 and R1 (expressed in terms of the concentration of gadolinium per kg of tissue) can be accounted for in part by the lower water content of tissues compared with gels or solutions increased microviscosity and binding to macromolecules. In addition, susceptibility effects may give rise to further increases in R2. By contrast, the reduced R1 observed in kidney may be the result of compartmentalization of the magnetopharmaceuticals. Statistically improved fits were obtained for T1 recovery curves for liver in the presence of Gd-EOB-DTPA when a dual exponential model was used. Assuming in vitro values for the relaxivities of these artificial contrast agents will lead to inaccuracies when relating observed signal enhancement factors to tissue gadolinium concentration.
在处死雄性Wistar大鼠后，立即在其肾脏和肝脏中，以及在体外溶液和凝胶中，使用临床磁共振扫描仪在1.5T场强下测定钆塞酸二钠（Gd-EOB-DTPA）和钆喷酸葡胺（Gd-DTPA）的核磁共振弛豫率。组织样本的T1和T2值由自旋回波图像序列得出。通过对Gd153进行放射性测定来确定组织中的钆浓度。发现Gd-EOB-DTPA在肝脏中的T1和T2弛豫率R1和R2（s-1 mmol-1 kg）分别为10.7±0.5和22.5±3.2，肾皮质中为2.4±0.2和12.1±1.7，肾外髓质中为2.7±0.2和14.5±1.9，肾内髓质中为2.0±0.2和11.4±2.1。发现Gd-DTPA在肝脏中的R1和R2分别为4.8±0.4和14.5±3.7，肾皮质中为1.2±0.1和7.9±0.8，肾外髓质中为1.6±0.1和10.2±1.4，肾内髓质中为1.3±0.1和10.2±1.2。与38℃的琼脂糖凝胶相比，Gd-EOB-DTPA和Gd-DTPA在肝脏中的R1升高（分别为4.49±0.03和3.47±0.06），但在肾脏组织中降低。与38℃的琼脂糖凝胶相比，所有的R2均升高（分别为5.72±0.12和4.12±0.03）。R2和R1升高（以每千克组织中钆的浓度表示）部分可归因于与凝胶或溶液相比，组织中的水含量较低、微粘度增加以及与大分子的结合。此外，磁化率效应可能导致R2进一步升高。相比之下，在肾脏中观察到的R1降低可能是磁性药物分隔的结果。当使用双指数模型时，在存在Gd-EOB-DTPA的情况下，肝脏的T1恢复曲线在统计学上拟合得更好。假设这些人工造影剂的弛豫率为体外值，在将观察到的信号增强因子与组织钆浓度相关联时会导致不准确。
