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Pescatore et al. (2000) performed a prospective study of 50 high-risk patients. CTC was performed in the supine position using 5-mm collimation, 1.5 pitch, 200 mA, and 2.5-mm reconstructions. 2D and complete 3D surface-rendered evaluation was performed by two investigator teams consisting of a radiologist and a gastroenterologist. Each team read out the first 24 patients, followed by evaluation of results. Then, each team read out the remaining patients. Per-patient sensitivity for 10-mm or...

B

Effect of slice thickness (1.25 mm vs 5.0 mm) on image quality. (A) Axial CT images reconstructed from same data set using 4- X 1-mm detector configuration. The image on the left is reconstructed as a 1.25-mm-thick slice with 1-mm overlap. The image on the right is reconstructed as a 5-mm-thick slice with 2.5-mm overlap. In both images, arrows point to a 3-mm polyp in the descending colon, which is seen with less volume averaging with the thin slice (left). (B) Same data set now...

Background and Significance

Colorectal cancer is the second leading cause of cancer deaths. The mortality from this disease has improved slightly as a result of several factors, including earlier diagnosis, progress in therapeutic interventions, and, possibly, prevention. However, the impact has not been dramatic. The primary explanation is that our advances in knowledge and technology have not been implemented on a programmatic population basis. This deficiency has resulted from slow and insufficient dissemination of...

Patient Preparation

As is the case with many radiological examinations, computer tomography (CT) colonography (CTC) requires adequate preparation of the patient prior to imaging to achieve its full diagnostic potential. Properly performed, the preparatory steps of CTC contribute to high sensitivity for detection of polyps and can be obtained with a minimum of patient discomfort. In this chapter, we will focus on two topics central to achieving a high-quality exam patient education and bowel preparation. Our review...

D

Effect of the volumetric shape index in differentiation among polyps, folds, and the colonic wall. In each pair of images, an axial or coronal CT image that contains a polyp indicated by arrow is shown on the left and its 3D endoscopic views by perspective volume rendering is shown on the right (A) 6-mm polyp in sigmoid, (B) 9-mm polyp in sigmoid, (C) 8-mm polyp in sigmoid, (D) 9-mm polyp in sigmoid. With the coloring scheme shown in Fig 8.4, polyps, folds, and the colonic wall are...

Advanced 3D Display Methods

Paik, Sandy Napel, and R. Brooke Jeffrey, Jr. With conventional 2D computed tomography (CT) sections, polyps may be difficult to detect and, conversely, normal structures such as haustra may appear polypoid and be mistaken as pathology. This provides the rationale for 3D displays such as virtual endoscopy, which depicts more intuitively the topographical features of the colon. At the same time, 3D displays in and of themselves are insufficient to fully...

How to Perform and Interpret a Virtual Colonoscopic Examination

Colonography Air Adequate Topogram

Dachman In this chapter, we discuss computed tomography CT of the cleansed colon performed in a manner to detect polyps and masses. The use of CT colonography CTC in the partially prepared or unprepared colon is discussed in chapter 5. Technical considerations critical to the successful performance and interpretation of CTC are reviewed. This chapter presents an overview of how to perform and interpret an examination and will touch on some of the controversies....