The use of computed tomographic colonography in predicting the difficulty of endoscopic treatment for large protruding neoplasms

Abstract

Dear Editor: Submucosal fibrosis is considered a major hurdle in endoscopic submucosal dissection (ESD), which is an effective technique for treating colorectal neoplasms. Although it is relatively easy to predict the difficulty of endoscopic resection for laterally spreading tumors (LST), it is more difficult in the case of large protruding lesions (Paris type 0-Is, >20 mm in diameter) such as villous tumors, which are often eventually removed by multiple piecemeal resection. However, considering the high incidence of recurrent or residual tumors and the difficulty of precise histopathological evaluation, piecemeal endoscopic mucosal resection (EMR) should be avoided. Instead, when endoscopic resection is predicted to be difficult, laparoscopic assisted colectomy is a viable treatment option; therefore, the objective evaluation of fibrotic changes in the submucosal layer is important. Although this evaluation may be accomplished using endoscopic miniprobe ultrasonography (mEUS), which is effective in assessing the depth of invasion in both gastric cancer and colorectal neoplasms as well as that of submucosal fibrosis for flat or depressed lesions, its limited depth of penetration is a disadvantage in assessing protruding lesions. Moreover, the observation of lesions located on the oral side of folds using mEUS is also considered difficult, and a different method may be more suitable for identifying these cases. Computed tomographic colonography (CTC) is currently an established technique for colorectal imaging that allows the evaluation of both endoluminal and transluminal features and has good diagnostic performance in T staging of colorectal cancer. Using CTC, images can be reconstructed in almost any plane and can be used to create three-dimensional images while maintaining diagnostic image resolution and without influencing the location of the lesion. It can also be used to evaluate both lesion morphology and intratumoral features, including those of protruding lesions and lesions located on the oral side of folds. Moreover, several studies have shown that the degree of fibrosis contributes to an enhancement pattern in contrast-enhanced CTC (CE-CTC). Thus, CECTC may potentially be used for evaluating the shape and morphological changes of the bowel wall, including the degree of fibrotic changes in the submucosal layer. In this letter, we describe the use of CTC in the identification of patients with intramucosal protruded-type neoplasm predicted to present endoscopic difficulties. All patients who had undergone preoperative colonoscopy and same day CE-CTC at our institution from January 2006 to December 2008 were identified through retrospective analysis. After pretreatment colonoscopy and standard preparation, patients underwent CE-CTC examination for staging using a 64-multidetector row CT scanner (Aquilion; Toshiba Medical Systems, Tokyo, Japan). The scan range was from the abdomen to the pelvis, with the following parameters: 120 kV; 200–400 mA with automatic exposure control; 64 rows×0.5 mm collimation; and helical pitch, 53 (pitch factor, 0.828). Anticholinergic drugs were injected intravenously immediately before each examination, and gas insufflation was performed via the anus with an T. Sakamoto (*) : T. Nakajima : T. Matsuda :Y. Saito Endoscopy Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan e-mail: tasakamo@ncc.go.jp