Abstract
Objectives
To assess the frequency of oral contrast coating of flat polyps, which may promote detection, and influencing factors within a screening CT colonography (CTC) population.
Methods
This was a retrospective, observational study performed at one institution. From 7,426 individuals, 123 patients with 160 flat polyps were extracted. Flat polyps were defined as plaque-like, raised at most 3 mm in height and reviewed for contrast coating. Factors including demographic variables such as age and sex, and polyp variables such as polyp size, location and histology were analysed for effect on coating.
Results
Of 160 flat polyps (mean size 9.4 mm ± 3.6), 78.8 % demonstrated coating. Mean coat thickness was 1.5 mm ± 0.6; 23.8 % (n = 30) demonstrated a thin film of contrast. Large size (≥10 mm) and proximal colonic location (relative to splenic flexure) were predictive variables by univariate logistic regression [OR (odds ratio) 3.4 (CI 1.3–8.9; p = 0.011), 2.0 (CI 1.2–3.5; p = 0.011), respectively]. Adenomas (OR 0.37, CI 0.14–1.02; p = 0.054) and mucosal polyps or venous blebs (OR 0.07, CI 0.02–0.25; p < 0.001) were less likely to coat than serrated/hyperplastic lesions. Age and sex were not predictive for coating (p = 0.417, p = 0.499, respectively).
Conclusions
Surface contrast coating is common for flat polyps at CTC, promoted by large size, proximal location and serrated/hyperplastic histology. Given the difficulty in detection, recognition may aid in flat polyp identification.
Key points
• Oral contrast coats the surface of most flat colorectal polyps at CT colonography.
• Large size, proximal colonic location and serrated/hyperplastic histology increase polyp coating.
• Contrast coating increases diagnostic confidence for flat polyps.
• Contrast coating may help in flat polyp detection at CTC.
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Acknowledgements
The scientific guarantor of this publication is David H. Kim, MD. The authors of this manuscript declare relationships with the following companies: D. Kim is a consultant for Viatronix, co-founder of VirtuoCTC, and is on the medical advisory board for Digital Artforms; P. Pickhardt is a consultant for Viatronix, Mindways and Braintree, and a co-founder of VirtuoCTC. This study has received funding in part by 1R01CA144835-01 (National Cancer Institute/National Institutes of Health, NIH/NCI). One of the authors has significant statistical expertise. Institutional review board approval was obtained. Written informed consent was waived by the institutional review board. Some study subjects or cohorts have been previously reported in Pickhardt PJ et al. Acad Radiol 17:784–790, 2010.
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Kim, D.H., Hinshaw, J.L., Lubner, M.G. et al. Contrast coating for the surface of flat polyps at CT colonography: a marker for detection. Eur Radiol 24, 940–946 (2014). https://doi.org/10.1007/s00330-014-3095-z
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DOI: https://doi.org/10.1007/s00330-014-3095-z