Screening CT colonography in an asymptomatic average-risk Asian population: a 2-year experience in a single institution.

Abstract

The purpose of our study was to report the results of screening CT colonography (CTC) in an asymptomatic average-risk Asian population. In 2005 and 2006, 1,015 Korean adults (609 men and 406 women; mean age, 51 years) underwent screening CTC using a 16-MDCT scanner and an automated CO2 delivery system. During the study period, the protocols were changed to use less vigorous purgation and lower radiation doses; fecal tagging (n = 890) and primary 3D interpretation (n = 966) were generally used. CTC results were categorized as C0, inadequate; C1, no significant polyp; C2, one or two 6- to 9-mm polyps; C3, polyps > or = 10 mm or > or = three 6- to 9-mm polyps; and C4, mass. Patients with positive CTC results were referred to gastroenterologists for follow-up or management planning. Categories C0-C4 were assigned to 21 (2.1%), 916 (90.2%), 54 (5.3%), 23 (2.3%), and one (0.1%) patients, respectively. Fifty-four patients with C4 (n = 1), C3 (n = 20), or C2 (n = 33) underwent subsequent optical colonoscopy: complete (n = 53) and incomplete (n = 1). Per-patient positive predictive values (PPVs) for categories C3-C4 and C2-C4 were 90% (18/20) and 74% (39/53), respectively. Per-polyp PPVs at 10- and 6-mm thresholds were 92% (22/24) and 69% (45/65), respectively. The diagnostic yield for advanced neoplasm was 1.5% (15/1,015). Our results seem comparable to Western experiences, showing that a successful screening CTC program can be reproduced in an Asian population.