Mamoru Iimuro

Virtual endoscopy: current perspectives.

Virtual endoscopy is a new method for evaluating the gastrointestinal tract using either thin-section computed tomography (CT) or magnetic resonance imaging (MRI). The acquired data are then subjected to computer manipulation to render images simulating the conventional endoscopic view. CT and MR imaging data can provide information that is not accessible endoscopically. These important features include information on tissue extending through and beyond organ walls and the anatomic context of the entire gastrointestinal tract, which permits correct anatomic localization of the lesion. Many clinical studies have shown that it is a safe, noninvasive, well-tolerated alternative to conventional endoscopy. Virtual endoscopy may have potential as a method of screening for colorectal cancer. This review describes the technique, reviews reported results, and discusses the present and future applications of this technique, focusing on CT colography (CTC).

3489 Virtual colography compared to endoscopic colonoscopy in detecting ascending colon and cecal lesions.

Introduction: Virtual colography (VC) is being studied as a potential screening tool for colorectal polyps and cancers that is less invasive than endoscopic colonoscopy (EC). VC performance characteristics have been assessed only in small numbers of patients who had known lesions. The ascending colon and cecum are not visualized in up to 10% of EC.We therefore chose to evaluate the performance of VC, in compariosn with EC as a gold standard, in the ascending colon and cecum of all patients undergoing EC. Methods: Patients scheduled for EC for any reason were prospectively recruited for the study. 58 consecutive patients who agreed and gave informed consent were enrolled. EC was performed by a single gastroenterologist (12 yrs postgraduate) who was blinded as to VC results. All underwent VC immediately or within a week after EC, and the exams were done in separate areas of the hospital by different staff members. After standard EC prep, VC was performed with air insufflation to tolerance, and by single breath-hold thin section helical CT. GE Navigator software was used to generate interactive 3D images. Images were coded and in a blinded fashion. Results: 58 patients, mean age 58, range 31-83, and 72% were male. Reasons for EC were FOBT/rectal bleeding 49%, unexplained abdominal pain 11%, and others 40%. EC reached the cecum in 53/58 (91%). 26 polypoid lesions were detected, 12 were 10 mm. 2 flat lesions were detected and confirmed on histology to be flat adenomas. Of the 26 polypoid lesions detected by EC, VC detected 11 (42%), 2/12 10 mm (83%). VC detected 4 lesions not seen on EC, 0 10 mm. However, VC detected 0/2 of the flat adenomas seen on EC. Thus, overall sensitivity of VC was 42% (95% CI: 23%-63%) with 85% (95% CI: 66%- 96%) specificity. Conclusion: VC has comparable or higher sensitivity than EC for polypoid lesions >10mm, comparable sensitivity to EC for polypoid lesions of 5-9 mm, but has lower sensitivity for lesions 10mm suggest that VC may have potential for routine clinical screening, especially in those patients in whom the ascending colon or cecum was not reached by EC.