Usefulness of spectral computed tomography for evaluation of intestinal activity and severity in ileocolonic Crohn's disease

Background: Assessment of intestinal activity and severity of Crohn's disease (CD) is crucial to guide treatment. In this study, we aimed to investigate the accuracy of spectral computed tomography (CT) in this assessment and make a comparison with conventional CT. Methods: A total of 50 patients with ileocolonic CD underwent spectral CT scanning. Conventional CT and spectral CT images were reconstructed. Endoscopic lesions were classified as absent, mild lesions and severe lesions. Qualitative and quantitative findings in CT images were compared in these segments. Logistic regressions were established, based on conventional and spectral CT parameters, to predict intestinal activity and severity. Comparisons were made by receiver operating characteristic (ROC) curve. Results: The results showed that bowel wall hyperenhancement, ulcers on CT images, comb sign, bowel wall thickness, normalized iodine concentration (NIC) and slope of HU curve (lambda(HU)) increased significantly (p < 0.01) with endoscopic severity. In predicting intestinal activity, spectral CT demonstrated higher accuracy (99.6% versus 94.7%), sensitivity (99.1% versus 93.4%) and specificity (99.9% versus 94.4%) than conventional CT. In predicting intestinal severity, spectral CT also had higher accuracy (96.5% versus 91.9%), sensitivity (96.5% versus 92.1%) and specificity (95.8% versus 89.8%) than conventional CT. Besides, both NIC and lambda(HU) correlated significantly with Simple Endoscopic Score for CD (r = 0.833 and r = 0.771; both p < 0.001), but their correlations with C-reactive protein (r = 0.578 and r = 0.513; both p < 0.01) and Harvey-Bradshaw Index (r = 0.545 and r = 0.522; both p < 0.01) were moderate. Conclusions: Compared with conventional CT, spectral CT had higher accuracy in detecting intestinal activity and severity of CD, which could be an alternative choice in evaluation of CD.