新型磁共振体模材料的研制

THE RESEARCH OF NEW MRI PHANTOM MATERIAL

磁共振成像（ＭＲＩ）体模已成为评价成像质量的一种必不可少的工具。理想的体模材料应该是其质子密度、Ｔ１和Ｔ２值与人体组织的应尽可能接近；能分别调节Ｔｌ、Ｔ２；具有长久稳定性及简便的制作工艺。作者以聚乙烯醇（ＰＶＡ）为基质，先后制备了一系列含有Ｃｏ２＋、Ｎｉ２＋、Ｃｕ２＋、Ｇｄ３＋、Ｃ等添加剂的ＰＶＡ凝胶作为体模材料。摸索了在实验室制备ＰＶＡ体模材料的条件。在２０ＭＨｚ和８０ＭＨｚ的核磁共振波谱仪上测量Ｔ１、Ｔ２驰豫时间。研究结果表明：（１）顺磁性离子能缩短ＰＶＡ凝胶的Ｔ１、Ｔ２值。其中以Ｇｄ３＋的作用最大。（２）活性炭能单独地缩短ＰＶＡ凝胶的Ｔ２值，而对Ｔ１值作用甚微。（３）乙醇作为辅助性溶剂能消除ＰＶＡ凝胶中的气泡，提高材料的均匀度，而对Ｔ１、Ｔ２值没有多大的影响。（４）在不同的共振频率下测定ＰＶＡ凝胶的Ｔ１、Ｔ２，有较大的差别。

The MRI phantom has become a necessary tool of evaluating image quality,Ideal phantom materials should at least have the following characteristics :their proton densi-ty and T1,T2 values should be close to those of human tissues, T1 and T2 values can be adjust-ed respectively, and they should be steady and simple in preparation. The phantom materialshave been made by adopting PVA gel with different additives as Co2+,Ni2+,Cu2+,Gd3+ andC. We also have measured T1,T2 relaxation time by MR spectroscopy(20MHz,80MHz). Theresult is:1)Paramagnetic ions can shorten Tl and T2 values of PVA gel,among which Gd3+has the most powerful effects; 2)Active carbon can shorten T2 values of PVA gel,while T1value still remains the same;3)Alcohol as a supplementary solution can eliminate the air bub-bles in the PVA gel and improve the material homogeneity,but not basically affect Tl and T2values;4)Difference of T1 and T2 will be obtained by MR measuring under the different fre-quencies.