title: False-negative results at multi-detector row CT colonography: multivariate analysis of causes for missed lesions.
abstract: OBJECTIVE
  To determine causes of false-negative results at multi-detector row computed tomographic (CT) colonography and determine presumptive causes with logistic regression analysis.
  
  
  METHODS
  Institutional review board approval and informed consent were obtained. The study included 394 colonic segments in 31 men and 25 women at high risk for colorectal cancer (mean age +/- standard deviation, 60.2 years +/- 9.3 for men and 56.8 years +/- 13.3 for women). Multi-detector row CT colonography and colonoscopy (reference standard) were performed in a blinded manner, and the results were compared. CT colonographic findings were interpreted in consensus by two readers using a primary two-dimensional with three-dimensional problem-solving approach. Adequacy of colonic preparation and distention was recorded. Sensitivity and specificity were obtained with 95% confidence intervals (CIs). Lesions missed at CT colonography were retrospectively reassessed to identify why they were missed, and, if the causes were not apparent, logistic regression analysis was performed to determine the presumptive causes.
  
  
  RESULTS
  Colonic preparation and distention were optimal in 17 patients (30%) but suboptimal in 37 (66%) and poor enough to make the results nondiagnostic in two (4%). Twenty-nine of 63 lesions were missed at CT colonography. When all flat, sessile, and pedunculated lesions (n = 63) were included, sensitivities were 75% (nine of 12; 95% CI: 48%, 100%) for lesions 10 mm or larger and 79% (19 of 24; 95% CI: 65%, 93%) for those 6 mm or larger. When only sessile and pedunculated lesions (n = 60) were included, corresponding sensitivities were 100% (nine of nine; 73%, 100%) and 90% (19 of 21; 78%, 100%), respectively. All three missed lesions larger than 10 mm were flat, and all three flat lesions were missed. Two 3-mm high lesions, including one invasive adenocarcinoma, were misinterpreted as feces at blinded image review; one 1-mm high tubular adenoma with adenocarcinoma foci could not be visualized even in retrospect. Sessile or pedunculated polyps 5 mm or smaller were significantly more likely to be missed than those 6 mm or larger (adjusted odds ratio, 11.6; P = .027).
  
  
  CONCLUSIONS
  Aside from inadequate bowel preparation and/or distention, flat lesions and small polyps are the two main causes for missed lesions at multi-detector row CT colonography.
authors.affiliation: Departments of Radiology and Internal Medicine, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-Dong, Songpa-Gu, 138-040 Seoul, Korea.
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Park
authors.forename: Hyun Kwon
authors.initials: HK
authors.lastname: Ha
authors.forename: Min-Jeong
authors.initials: MJ
authors.lastname: Kim
authors.forename: Kyoung Won
authors.initials: KW
authors.lastname: Kim
authors.forename: Ah Young
authors.initials: AY
authors.lastname: Kim
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Yang
authors.forename: Moon-Gyu
authors.initials: MG
authors.lastname: Lee
authors.forename: Pyo Nyun
authors.initials: PN
authors.lastname: Kim
authors.forename: Yong Moon
authors.initials: YM
authors.lastname: Shin
authors.forename: Suk-Kyun
authors.initials: SK
authors.lastname: Yang
authors.forename: Seung-Jae
authors.initials: SJ
authors.lastname: Myung
authors.forename: Young Il
authors.initials: YI
authors.lastname: Min
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging*; D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000473:pathology; D023881:Colonography, Computed Tomographic / Q000706:statistics & numerical data*; D003113:Colonoscopy / Q000706:statistics & numerical data; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D003937:Diagnosis, Differential; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data*; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data*; D007413:Intestinal Mucosa / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013673:Technology Assessment, Biomedical; D036542:Tomography, Spiral Computed / Q000706:statistics & numerical data*