FIGURE 2.

Dual‐energy computed tomography enterography images of a 32‐year‐old (a, b) and a 28‐year‐old man (c–e) with Crohn's disease. Axial contrast‐enhanced image (reconstructed conventional polychromatic image at 120 kVp) shows mild bowel thickening on terminal ileum with iso‐enhancement or mild hyper‐enhancement (arrow), which mimics the normal bowel and results in a misdiagnosis (a). Under axial mono energetic 45 keV scanning, the bordering of inflamed terminal ileum (arrow) is more clearly depicted due to the improved tissue enhancement from the inflamed to normal bowel, facilitating the improvement of diagnostic accuracy (b). Similarly, axial contrast‐enhanced image (reconstructed conventional polychromatic image at 120 kVp) shows active Crohn's disease in terminal ileum (arrowhead) with suspected bowel fistula and abscess (arrows; c), and these penetrating diseases are confirmed on the axial and sagittal mono energetic 45 keV images (d, e) due to the direct imaging evidence of penetrating diseases (i.e. fistula and/or ring‐enhancement; arrows) are more clearly illustrated.