胃肠道影像学检查的新进展

Current Advances in Gastrointestinal Imaging

随着高速、高效计算机技术发展，一大批新兴的医学检查设备与技术的开发和在临床应用成功，包括电子纤维内镜；超声与内镜超声；ＣＴ 与ＣＴＥ；ＭＲＩ ＤＳＡ……。极大地提高了胃肠道疾病的检出能力与诊断水平。然任一高、精、新的检查方法均各有其长处与不足（ 限度） 。多相胃和结肠造影检查仍应是胃肠道疾病理想的初选检查方法。运用数字摄影成像系统，更能连续、快速获取多幅图像；进行图像后处理；缩短检查时间；减少射线曝射量；图像储存与传输……，使高质量的双对比胃肠造影检查更有保证。胃肠道ＣＴ 检查能直接显示胃肠道各器官本身及其病变的横断面像，因此特别适用于胃肠道占位性病变的诊断；肿瘤病变的分期；手术切除可能性的预测……。运用专门软件，进行三维重建（ 表面遮盖显示法或容积再现法） 可获得胃肠道仿真内镜三维图像。ＥＵＳ 能判别胃肠壁各层组织结构，故对胃、直肠癌肿侵入胃肠壁的深度和邻近脏器直接侵润的判断，要优于其它影像学方法，还可在ＥＵＳ 导引入下作细针抽吸活检和介入治疗。ＭＲＩ 随着快速扫描和消除伪影序列的开发；呼吸、心脏门控技术的应用；胃肠道腔内造影剂的研制，再加上ＭＲＩ 自身固有的多方位成像及较高的组织对比分辩能力，有助于淋巴结。

Thanks to the development of computer techniques, a lot of new medical equipments and technologies have been exploited and applied satisfactorily, including endoscopy, ultrasonography, CT, CTE, MRI, DSA etc. All of these have greatly improved the diagnostic ability for gastrointestinal lesions, but it is very important for us to know that evey one of advanced high quality modalities has its own advantages and disadvantages(limitation).Multiphasic gastrointestinal radiography is still the ideal and the first choice in diagnosing gastrointestinal diseases. Compared with conventional GI, digital imaging system is capable of providing the clarity and resolution needed to perform high-quality double contrast examination of the GI tract.CT can display the entity of organ directly, thus, it is very beneficial for occuping space lesions to assess the presence of extra-organic spread, to find the distance metastases, and to predict the resectability of malignant tumors before operation. Using customized computer software, helical CT volumetric data can be adopted to produce reformatted three-dimensional images of the inner walls of hollow organ to reproduce the simulated endoscopic views(CT Endoscopy, CTE, CTVE).EUS not only can it be able to visualize the component layers of the bowel wall, to judge the depth of infiltration more accurately, which were caused by malignant lesions, but also it is possible to perform EUS guided fine needle aspiration biopsy of target lesions located within and beyond the gastrointestinal wall. Until recently, the development of faster imaging sequences with breath-hold and cardiac gating techniques has significantly reduced the problem of motion artifact. By the use of surface and intraluminal coils as well as the administration of a variety of oral contrast agents,signal-to-noise and spatial resolution have been effectively improved. In combination with its high inherent soft tissue contrast and multiplannar imaging, MRI has been found to be particularly useful in the detection and differentiation of metastases, including lymph node, retroperitoneum and distance viscera.