Rogier E Van Gelder | Search PubMed

PubMed2006

Computed tomography colonography: current issues.

OBJECTIVE: Direct and indirect evidence supports the concept of screening for adenomas and early stage colorectal cancer in reducing the incidence and disease-specific mortality. Controversy remains as to the appropriateness of and preferred methods for screening an asymptomatic population. METHODS: Review of computed tomography (CT) colonography based on the literature and personal experience. RESULTS AND CONCLUSIONS: Current discrepancies in the data on accuracy and patient acceptance of CT colonography reflect differences in the performance and evaluation of this examination. Before CT colonography can be implemented in colorectal cancer screening, factors that cause this variability must be elucidated. Studies in which high-resolution scanning, three-dimensional review methods and an enhanced colonoscopic reference are used achieve an accuracy that is similar to colonoscopy. At the same time the evidence that ultra-low radiation dose CT colonography is feasible is mounting, a development that dramatically reduces one of the largest obstacles for large-scale application of this technique.

Adenoma↗

PubMed2004

Computed tomographic colonography compared with colonoscopy in patients at increased risk for colorectal cancer.

BACKGROUND & AIMS: To date, computed tomographic (CT) colonography has been compared with an imperfect test, colonoscopy, and has been mainly assessed in patients with positive screening test results or symptoms. Therefore, the available data may not apply to screening of patients with a personal or family history of colorectal polyps or cancer (increased risk). We prospectively investigated the ability of CT colonography to identify individuals with large (>or=10 mm) colorectal polyps in consecutive patients at increased risk for colorectal cancer. METHODS: A total of 249 consecutive patients at increased risk for colorectal cancer underwent CT colonography before colonoscopy. Two reviewers interpreted CT colonography examinations independently. Sensitivity, specificity, and predictive values were determined after meticulous matching of CT colonography with colonoscopy. Unexplained large false-positive findings were verified with a second-look colonoscopy. RESULTS: In total, 31 patients (12%) had 48 large polyps at colonoscopy. This included 8 patients with 8 large polyps that were overlooked initially and detected at the second-look colonoscopy. In 6 of 8 patients, the missed polyp was the only large lesion. With CT colonography, 84% of patients (26/31) with large polyp(s) were identified, paired for a specificity of 92% (200-201/218). Positive and negative predictive values were 59%-60% (26/43-44) and 98% (200-201/205-206), respectively. CT colonography detected 75%-77% (36-37/48) of large polyps, with 9 of the missed lesions being flat. CONCLUSIONS: CT colonography and colonoscopy have a similar ability to identify individuals with large polyps in patients at increased risk for colorectal cancer. The large proportion of missed flat lesions warrants further study.

Aged↗