结直肠癌病变部位与单体位扫描的关系在减少CT剂量中的对照研究

The Comparative Study of the Relationship Between the Lesion Location of Colorectal Carcinomas and Single-position Scanning in Reducing CT Doses

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 discuss the relationship between the image quality of colorectal carcinomas and single-position （supine or prone）,and provide the theory evidence about how to choose the optimal single-position for reducing the X-ray dose of CT colonography （CTC）.Materials and Methods 52 pre-surgery cases with colorectal carcinoma were performed both CTC（supine and prone）and colonoscopy. CTC findings were compared with those of colonoscopy and histopathology retrospectively.Results Of the 52 patients,the tumor location of 27 cases were in rectum,9 cases in the sigmoid colon,3 cases in the ascending colon,4 cases in the transverse colon,3 cases in descending colon and 3 cases in anal canal. All cases were single lesion. Lesions of the rectum 25/27 （92.59%;χ2=32.72;P0.05） and the sigmoid colon 9/9（100%;χ2=8.42;P0.05） were more clearly revealed in prone position than that in supine,because that the rectum and the sigmoid colon were more obviously filled gas in prone. Lesions of the transverse colon 4/4 （100%;χ2=4.5;P0.05） were more clearly showed in supine position. There was no significant difference for the lesions of the ascending colon and the descending colon between prone（9/9） and supine position（9/9）,but cancers of anal canal were clearly revealed neither in the prone（0/3）or supine（0/3）.The specificity of detecting the serosa surface invasion was 85%,the false-positive ratio in detecting the lymphadenopathy was 25%,and the false-negative ratio was 13%. All remote metastasis and lymphadennopathy were clearly revealed.Conclusion There is difference between prone position and supine in revealing the lesions of colorectal carcinomas. According to the lesion location,selecting the optimal single-position can cause X-ray dose to be reduced half,and quality of CTC is not be affected. CTC has an important value in detecting the serosa surface invasion,but it is limited in detecting lymphadenopathy.