The efficacy of intravenous contrast-enhanced 16-raw multidetector CT colonography for detecting patients with colorectal polyps in an asymptomatic population in Korea.

PURPOSE: The purpose of this study is to compare the sensitivity of computed tomography (CT) colonography (CTC) with that of colonoscopy for detecting patients with colorectal polyps in an asymptomatic screening population in Korea, thus to evaluate a possibility, whether CTC could be used as a screening tool for colorectal polyps. METHODS: A total of 241 asymptomatic adults underwent intravenous contrast-enhanced CTC and colonoscopy successively on the same day. Bowel preparation was performed by 4 L of polyethylene glycol (n=172) or 90 mL of sodium phosphate (n=69). The CTC findings were released to the colonoscopists after the first examination of each segment, a procedure known as segmental unblinded colonoscopy, and were used as the reference standard. The diagnostic performance of CTC for colorectal polyps was calculated. RESULTS: The per-patient sensitivities of CTC were 68.5% (37/54) and 86.7% (13/15) for polyp > or = 6 and > or = 10 mm, inferior to those of colonoscopy, 92.6% (50/54) and 100% (15/15), respectively. The per-polyp sensitivities of CTC were 60.4% (61/101) and 72.7% (16/22) for polyp > or = 6 and > or = 10 mm, respectively. The low sensitivity of CTC was related with flat morphology. CTC detected only 37.5% (9/24) of flat polyps > or = 6 mm. Bowel preparation by sodium phosphate further decreased the positive predictive value and specificity than by polyethylene glycol. CONCLUSIONS: Screening by CTC with asymptomatic population was not promising in Korea despite using advanced CT technology (16-row detector). Bowel preparation was one of the key determinants of the specificity of CTC.

Extracolonic findings in an asymptomatic screening population undergoing intravenous contrast-enhanced computed tomography colonography.

BACKGROUND AND AIM: The purpose of this study was to evaluate extracolonic findings that could be encountered with computed tomography colonography (CTC) using intravenous (IV) contrast material in an asymptomatic screening population. METHODS: Intravenous contrast medium-enhanced CTC was performed in 2230 asymptomatic adults (mean age, 57.5 years). Axial images were prospectively examined for extracolonic lesions. These findings were classified into three categories: potentially important findings, likely unimportant findings, and clinically unimportant findings. Potentially important extracolonic findings were defined as those which required immediate further diagnostic studies and treatment. Clinical and radiologic follow up, missed lesions and clinical outcomes were assessed using medical records (mean duration of follow up, 1.6 years). RESULTS: A total of 115 new potentially important findings in 5.2% of subjects (115/2230) were found. Subsequent medical or surgical intervention was performed in 2.0% (45/2230). New extracolonic cancer was detected in 0.5% (12/2230), and the majority of them (83.3%) were not metastasized. Computed tomography colonography missed eight potentially important extracolonic findings in eight subjects (0.4%, 8/2230): 0.8-cm early-stage prostatic cancer, six adrenal mass and one intraductal papillary mucinous tumor. There were no severe life-threatening complications related to contrast medium. CONCLUSION: Intravenous contrast-enhanced CTC could safely detect asymptomatic early-stage extracolonic malignant diseases without an unreasonable number of additional work-ups, thus reducing their morbidity or mortality.