腹部磁共振成像应用口服造影剂枸橼酸铁铵的研究

Ferric Ammonium Citrat as Oral Contrast Agent for Abdominal MR Imaging:Experimental and Clinical Study

缺乏一种理想的口服造影剂已成为腹部ＭＲＩ发展中的一大障碍。笔者选用枸橼酸铁铵（ＦＡＣ）作为ＭＲ口服造影剂，对其作用机理、增强规律、最佳浓度、造影方法、临床效果等问题进行了试管、动物实验和临床对照研究。ＦＡＣ具有较强的弛豫增强作用，低浓度时，以缩短Ｔ＿１为主，信号强度随浓度升高而增高；高浓度时，以缩短Ｔ＿２为主，信号强度随浓度升高而降低。当ＦＡＣ浓度为２．１ｍｍｏｌ／Ｌ时，Ｔ＿１Ｗ和Ｔ＿２Ｗ像均得到满意的对比增强，故为最佳浓度。ＦＡＣ口服造影可以标记胃肠道、提高邻近正常结构和病灶的解剖分辨率。造影时配合应用胃肠道松弛剂效果更好，低张造影组肝左叶、胰腺各段及胆总管下端的分辨效果明显优于平扫组。ＦＡＣ具有价格低廉、无毒副作用、造影效果良好等优点，是较理想的ＭＲ口服造影剂。

Lack of a suitable oral contrast agent is the major drawback of abdominal MR imag-ing. FAC(Ferric ammonium citrat) was chosen to use as MR oral contrast agent.Test tube,animal ex-periment and clinical study were done to resolve a series of issues,including relaxation enhancing charac-teristics,the most appropriate concentration and clinical effectiveness of FAC. FAC demonstrates strong relaxation enhancing effect.At low concentration,the signal intensity increases with concentration due to predominance of T_1 shortening。At high concentration,the signal intensity decreases with increase in concentration due to predominance of T_2 shortening. The most appropriate concentration for FAC is 2.1mmol/L, with which the signal intensity of gastro-intestinal tract can be properly enhanced both on T_1 and T_2 weighted images.Orally administered FAC can well mark the gastrointestinal tract and im-prove delineation of adjacent normal and abnormal structures。The best result was abtained for the group using hypotonic technique,in which the delineation of the left lobe of the liver, all parts of the pancreas and the lowest part of the common bile duct are all significantly improved compared to the plain-scan group.Therefore,FAC is an effective, inexpensive oral MR contrast agent with no side effects.