Computed tomography enterography findings correlate with tissue inflammation, not fibrosis in resected small bowel Crohn's disease.

BACKGROUND: It has become commonplace to categorize small intestinal Crohn's disease (CD) as "active" vs. "inactive" or "inflammatory" vs. "fibrotic" based on computed tomography enterography (CTE) findings. Data on histologic correlates of CTE findings are lacking. We aimed to compare CTE findings with histology from surgically resected specimens. We tested the hypothesis that CTE findings can distinguish tissue inflammation from fibrosis.
METHODS: Patients who underwent CTE within 3 months before intestinal resection for CD were retrospectively studied. Radiologists blinded to history and histology scored findings on CTE. Pathologists blinded to history and imaging scored resected histology. We compared histology with CTE findings and radiologists assessment of whether the stricture was likely "active" or "inactive."
RESULTS: In all, 22 patients met inclusion criteria. Inflammatory CTE findings correlated with histologic inflammation (rho = 0.52). Strictures believed to be "active" on CTE were more inflamed at histology (P = 0.0002). Strictures lacking inflammatory findings on CTE or considered "inactive" were not associated with greater histologic fibrosis or significant histologic inflammation. Upstream dilation was associated with greater tissue fibrosis in univariate (P = 0.014) but not in multivariate analysis (P = 0.53). Overall, histologic fibrosis correlated best with histologic inflammation (rho = 0.52). Strictures on CTE with the most active disease activity also had the most fibrosis on histology.
CONCLUSIONS: CTE findings of mesenteric hypervascularity, mucosal hyperenhancement, and mesenteric fat stranding predict tissue inflammation. However, small bowel stricture without CTE findings of inflammation does not predict the presence of tissue fibrosis. Therefore, caution should be used when using CTE criteria to predict the presence of scar tissue.