目的探讨不同部位结直肠癌病变显示清晰程度与扫描体位(仰卧位和俯卧位)的关系,为减少CT结肠成像(CT colonography,CTC)检查剂量、选择最佳单体位扫描提供理论依据。资料与方法对52例结直肠癌患者术前行CTC,均行仰卧位及俯卧位检查,将CTC结果与纤维肠镜和手术病理对照。结果52例结直肠癌中,病变位于直肠27例,肛管3例,乙状结肠9例,降结肠3例,横结肠4例,升结肠6例,均为单发病灶。病变位于直肠25例(92.59%)(χ2=32.72,P<0.05),位于乙状结肠9例(100%)(χ2=8.42,P<0.05)。俯卧位上肠管充气明显,病变显示清晰,优于仰卧位,差异具有统计学意义;病变位于横结肠4例(100%)(χ2=4.5,P<0.05),仰卧位肠管充气明显,病变显示清晰,优于俯卧位,差异具有统计学意义。升降结肠病变在仰卧位(9/9)及俯卧位(9/9)上肠管充气效果相同,均显示清晰,差异无统计学意义;肛管癌在仰卧位(0/3)及俯卧位(0/3)上均显示欠佳,由于病例数少,差异无统计学意义。CT显示浆膜面受侵的诊断正确率为85.71%,CT诊断淋巴结转移的假阳性率为25%,假阴性率为12.90%,远处转移及腹膜后淋巴结肿大均显示清晰。结论不同体位上位于结直肠不同位置上的病变显示的效果不同,根据病变的位置,采取最佳单体位,可使患者受辐射量减半,而不影响CTC的效果。CTC对浆膜面受侵的判定有一定意义,但诊断结肠壁周围淋巴结有无转移有一定的局限性。 Objective To explore the relationship between the clearness of colorectal lesions and the scanning position (supine position and prone position) in different sites, and to provide a theoretical basis for reducing the CT colonography (CTC) examination dose and selecting the best single-unit scanning. Materials and Methods 52 patients with colorectal cancer undergoing preoperative CTC were examined in supine and prone positions. The CTC results were compared with fibroenteroscope and surgical pathology. Results In 52 cases of colorectal cancer, 27 cases were located in the rectum, 3 in the anal canal, 9 in the sigmoid colon, 3 in the descending colon, 4 in the transverse colon, and 6 in the ascending colon. All were single lesions. The lesions were located in the rectum in 25 cases (92.59%) (χ2=32.72, P<0.05) and in the sigmoid colon in 9 cases (100%) (χ2=8.42, P<0.05). In the inflated position, the intestine was inflated and the lesions were clearly displayed, which was superior to the supine position. The difference was statistically significant. The lesions were located in the transverse colon in 4 patients (100%) (χ2=4.5, P<0.05). The intestine was inflated in the supine position and the lesions were clearly visible. , better than the prone position, the difference was statistically significant. Lifting colon lesions had the same bowel inflation effect in supine position (9/9) and prone position (9/9), all showing clear, no statistically significant difference; anal canal cancer was in supine position (0/3) and prone position ( 0/3) showed poor results. The difference was not statistically significant due to the small number of cases. CT showed that the diagnostic accuracy of serosal surface involvement was 85.71%, the false positive rate of CT diagnosis of lymph node metastasis was 25%, and the false negative rate was 12.90%. Distant metastasis and retroperitoneal lymph node enlargement were all clearly shown. Conclusions Different lesions located on different positions of the colorectal lesion show different effects. According to the position of the lesion, taking the best single position can reduce the radiation dose by half, without affecting the effect of CTC. CTC has some significance in determining the invasion of serosal surface, but it has certain limitations in diagnosing the metastasis of lymph nodes around the colon wall.