Simulation of biologic tissues by using agar gels at magnetic resonance imaging.
Simulation of biologic tissues by using agar gels at magnetic resonance imaging.
复制标题
在磁共振成像中使用琼脂凝胶模拟生物组织。
DOI：
10.3109/02841858909174735
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发表时间：
1989
期刊：
影响因子：
1.3
通讯作者：
B. Lehmann
中科院分区：
文献类型：
--
作者：
M. Bucciolini;L. Ciraolo;B. Lehmann
许多作者（5，10）出于不同的目的，例如更好地理解弛豫机制（2，3）和组织中的RF功率耗散（6，7），研究了生物组织的MR模拟问题。本研究的目的是找到一种体模材料，可用于易于控制的MR成像系统的某些性能。一般而言，目标是检查TI和T2计算图像的质量，并在使用标准脉冲序列进行的常规扫描中比较申报介质与感兴趣组织的信号强度。如前所述（1，10），选择琼脂凝胶，因为它的T2弛豫特性。事实上，由于琼脂溶于水时的半固体行为（9）。凝胶的结构表现出束缚水和自由水的受限运动。此外，如果将顺磁性离子添加到琼脂溶液中，则T1和T2值甚至比在水溶液中更强烈地降低，使得通过组合不同重量百分比的琼脂和顺磁性离子浓度，可以覆盖活组织的主要范围。事实上，尽管过渡金属水溶液的自旋-晶格和自旋-自旋弛豫速率（分别为1/T1和1R2）对离子浓度具有相同的依赖性，但它们受到琼脂百分比的不同影响（4，5，10）。因此，T1和T2可以独立地变化，使得T1可以大于或远大于T2，如在一些天然生物组织中那样。
The problem of MR simulation of biologic tissues has been approached by many authors (5, 10) with different purposes, such as a better understanding of both relaxation mechanisms (2, 3) and RF power dissipation in tissues (6, 7). The aim of this investigation was to find a phantom material which could be used for easy control of some performances of an MR imaging system. In general, the goal was to check the quality of TI and T2 computed images and to compare signal intensity of the proposed medium with that of the tissue of interest, in scans routinely performed with standard pulse sequences. As previously proposed (1, lo), an agar gel was chosen, because of its T2 relaxation properties. In fact, owing to the semisolid behaviour when agar is dissolved in water (9). the structure of the gel presents a restricted motion of bound and free water. Moreover, if paramagnetic ions are added to an agar solution, TI and T2 values are even more strongly reduced than in an aqueous solution, so that, by combining different weight percentages of agar and paramagnetic ion concentrations, the main range of living tissues can be covered. In fact, whereas spin-lattice and spin-spin relaxation rates (1/T1 and 1R2, respectively) of an aqueous solution of transition metals have the same dependence on ion concentration, they are differently affected by the percentage of agar present (4, 5, 10). TI and T2 can therefore be varied independently, so that TI can be greater or much greater than T2 as in some natural biologic tissues.