Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
Radiographics. 2013 May;33(3):891-912. doi: 10.1148/rg.333125039. Epub 2013 Mar 11.
Electronic cleansing (EC) is an emerging technique for the removal of tagged fecal materials at fecal-tagging computed tomographic (CT) colonography. However, existing EC methods may generate various types of artifacts that severely impair the quality of the cleansed CT colonographic images. Dual-energy fecal-tagging CT colonography is regarded as a next-generation imaging modality. EC that makes use of dual-energy fecal-tagging CT colonographic images promises to be effective in reducing cleansing artifacts by means of applying the material decomposition capability of dual-energy CT. The dual-energy index (DEI), which is calculated from the relative change in the attenuation values of a material at two different photon energies, is a reliable and effective indicator for differentiating tagged fecal materials from various types of tissues on fecal-tagging CT colonographic images. A DEI-based dual-energy EC scheme uses the DEI to help differentiate the colonic lumen-including the luminal air, tagged fecal materials, and air-tagging mixture-from the colonic soft-tissue structures, and then segments the entire colonic lumen for cleansing of the tagged fecal materials. As a result, dual-energy EC can help identify partial-volume effects in the air-tagging mixture and inhomogeneous tagging in residual fecal materials, the major causes of EC artifacts. This technique has the potential to significantly improve the quality of EC and promises to provide images of a cleansed colon that are free of the artifacts commonly observed with conventional single-energy EC methods.
电子清肠 (EC) 是一种新兴的技术，用于去除粪便标记计算机断层扫描 (CT) 结肠成像中的标记粪便物质。然而，现有的 EC 方法可能会产生各种类型的伪影，严重影响清洁后的 CT 结肠成像质量。双能粪便标记 CT 结肠成像被认为是下一代成像方式。利用双能粪便标记 CT 结肠成像的 EC 有望通过应用双能 CT 的物质分解能力来有效减少清洁伪影。双能指数 (DEI) 是根据物质在两种不同光子能量下衰减值的相对变化计算得出的，它是区分粪便标记 CT 结肠成像上标记粪便物质与各种组织类型的可靠且有效的指标。基于 DEI 的双能 EC 方案利用 DEI 帮助区分包括管腔空气、标记粪便物质和空气标记混合物在内的结肠腔与结肠软组织结构，然后对整个结肠腔进行分割，以清除标记的粪便物质。因此，双能 EC 可以帮助识别空气标记混合物中的部分容积效应和残留粪便物质中的不均匀标记，这是 EC 伪影的主要原因。这项技术有可能显著提高 EC 的质量，并有望提供无传统单能 EC 方法常见伪影的清洁结肠图像。
