title: CT attenuation of colorectal polypoid lesions: evaluation of contrast enhancement in CT colonography.
abstract: The aim of this study was to calculate pre- and postcontrast CT attenuation values of benign colorectal polyp and carcinoma lesions detected by virtual colonoscopy, and to investigate whether contrast enhancement of these lesions can be potentially used for differentiation from residual fluid in the colon. Fifteen benign polyps and 21 colorectal carcinoma lesions detected by virtual colonoscopy in 18 patients were included in our study. All of the polyps and carcinoma lesions were confirmed by colonoscopic biopsy. Measurement of CT attenuation values was performed in precontrast (supine) and postcontrast (prone) scans for each polyp and carcinoma. The CT attenuation values of residual fluid in the colon was also measured from the same location before and after intravenous contrast administration. On unenhanced CT scan mean attenuation values of benign polyps and colorectal carcinomas were 32.4 and 42.6 HU, respectively. Following contrast enhancement, mean attenuation value increased to 78.9 HU for polyps and 90.7 HU for carcinomas. Increase in the CT attenuation values of these lesions was significant ( p<0.0001). Mean CT attenuation value of residual fluid before and after administration of IV contrast were 14.6 and 13.8 HU, respectively. The difference between CT attenuation value of residual fluid in the colon before and after contrast material was not significant ( p=0.29). Colorectal benign polyps and carcinomas demonstrate significant enhancement following contrast administration and use of intravenous contrast material during virtual colonoscopy may help in some cases in differentiating these solid lesions from residual colonic fluid that does not enhance.
authors.affiliation: Department of Radiology, Hacettepe University School of Medicine, Sihhiye, 06100 Ankara, Turkey. ayoto@utmb.edu.tr
authors.forename: Aytekin
authors.initials: A
authors.lastname: Oto
authors.forename: Veli
authors.initials: V
authors.lastname: Gelebek
authors.forename: Berna Sayan
authors.initials: BS
authors.lastname: Oguz
authors.forename: Bülent
authors.initials: B
authors.lastname: Sivri
authors.forename: Ahmet
authors.initials: A
authors.lastname: Deger
authors.forename: Okan
authors.initials: O
authors.lastname: Akhan
authors.forename: Aytekin
authors.initials: A
authors.lastname: Besim
mesh_terms: D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D003287:Contrast Media; D006801:Humans
chemical_list: D003287:Contrast Media