Quantitative measures of comb sign in Crohn's disease: correlation with disease activity and laboratory indications.

To determine retrospectively if quantitative measures of the comb sign at CT enterography correlated with laboratory indications in Crohn's disease. We retrospectively included 72 known CD patients (47 male and 25 female patients) and 41 normal controls who had undergone CT enterography (CTE) from 2008 to 2010 and had high-sensitive C reaction protein (Hs-CRP) and erythrocyte sedimentation rate (ESR) results. We divided the 72 CD patients into two groups based on disease activity which was determined by Rutgeerts' score. 41 patients were characterized as active disease while 31 patients were as inactive disease. For each individual, one reformatted coronal CTE image in which the comb sign (vasa recta) was most obviously displayed was selected by two experienced radiologists in a double blind manner. For each image, 20 regions of interest (ROI) with area of 1 cm(2) were drawn and placed over the site where the comb sign exists; the comb sign amount was counted in each ROI and recorded. Total amount of the comb sign were assessed from 20 ROI data. Quantitative comb sign results were compared with Hs-CRP and ESR level. Quantitative comb sign score is significantly higher in the CD group than in the control group at both the arterial stage and venous stage (P < 0.001). Quantitative comb sign score is obviously higher in active CD patients than in inactive CD patients both at arterial stage and venous stage (3.63 vs. 2.86 at arterial stage; 3.53 vs. 2.90 at venous stage). ESR level was well correlated with quantitative comb sign score both at arterial and venous stage whereas Hs-CRP has no significant correlation at either stage. Quantitative comb sign results did well in predicting CD activity with the accuracy rate of 78.4% at arterial stage and 80% at venous stage when using 3.33 as the cutoff of quantitative comb sign score. Quantitative comb sign score is a promising CTE parameter in predicting CD activity and be well correlates with the ESR level.