Korean J Radiol.  2007 Dec;8(6):484-491. 10.3348/kjr.2007.8.6.484.

Diagnostic Performance of CT Colonography for the Detection of Colorectal Polyps

• Yun JY
• Ro HJ
• Park JB
• Choi JB
• Chung JE
• Kim YJ
• Suh WH
• Lee JK

• KMID: 1089435
• DOI: http://doi.org/10.3348/kjr.2007.8.6.484

Abstract

OBJECTIVE: To investigate the diagnostic value of CT colonography for the detection of colorectal polyps. MATERIALS AND METHODS: From December 2004 to December 2005, 399 patients underwent CT colonography and follow-up conventional colonoscopy. We excluded cases of advanced colorectal cancer. We retrospectively analyzed the CT colonography findings and follow-up conventional colonoscopy findings of 113 patients who had polyps more than 6 mm in diameter. Radiologists using 3D and 2D computer generated displays interpreted the CT colonography images. The colonoscopists were aware of the CT colonography findings before the procedure. RESULTS: CT colonography detected 132 polyps in 107 of the 113 patients and conventional colonoscopy detected 114 colorectal polyps more than 6 mm in diameter in 87 of the 113 patients. The sensitivity of CT colonography analyzed per polyp was 91% (41/45) for polyps more than 10 mm in diameter and 89% (101/114) for polyps more than 6 mm in diameter. Thirteen polyps were missed by CT colonography and were detected on follow-up conventional colonoscopy. CONCLUSION: CT colonography is a sensitive diagnostic tool for the detection of colorectal polyps and adequate bowel preparation, optimal bowel distention and clinical experience are needed to reduce the rate of missing appropriate lesions.

Keyword

Colon, CT; Colon neoplasm; Computed tomography (CT) colonography; Virtual colonoscopy

MeSH Terms

Adult
Aged
Aged, 80 and over
Colonic Polyps/*diagnosis
Colonography, Computed Tomographic/*methods
Colonoscopy/methods
Colorectal Neoplasms/*diagnosis
Contrast Media/administration & dosage
False Negative Reactions
False Positive Reactions
Follow-Up Studies
Humans
Image Processing, Computer-Assisted
Imaging, Three-Dimensional
Iohexol/analogs & derivatives/diagnostic use
Middle Aged
Observer Variation
Predictive Value of Tests
Radiographic Image Enhancement/methods
Retrospective Studies
Sensitivity and Specificity

Figure

• 

  Fig. 1 An 8 mm flat-elevated rectal lesion in a 50-year-old man. A. A three-dimensional lumen view of the proximal rectum revealing an 8 mm, flat-elevated lesion with central depression (arrow) on CT colonography. B. A contrast-enhanced axial CT image at the level of the proximal rectum shows a small enhancing flat-elevated lesion (arrow). C. A photograph from conventional colonoscopy displays a flat-elevated lesion with central depression in the proximal rectum. Histological examination revealed that the lesion was an adenocarcinoma.

• 

  Fig. 2 A pseudopolyp at the appendiceal orifice in 35-year-old asymptomatic woman. A. A three-dimensional view of the cecal lumen revealing a 15 mm, polypoid lesion (arrow) at the appendiceal orifice. This lesion was misinterpreted as a cecal polyp on CT colonography. B. A contrast-enhanced axial CT image at the level of the cecum, shows an enhancing polypoid lesion (arrow) at the appendiceal orifice. This lesion was constant and non-movable in the prone, supine, and decubitus positions. C. A photograph from a conventional colonoscopy displaying the nodular endoluminal protrusion at the appendiceal base (not an intussusception of the appendix). The woman underwent pelvic surgery for a cesarean section and pelvic endometriosis a few years earlier. The endoluminal protrusion at the appendiceal base into the air-inflated cecum is thought to be due to pelvic adhesions.

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