What are six radiographic signs of Crohn's disease?

1. Fold thickening or nodules (as a result of bowel wall edema)
2. Aphthous ulcers (can progress to deep ulcers)
3. Fistulas (may lead to abscess formation)
4. Skip lesions (not contiguous)
5. Stranding (inflammation) in mesenteric fat and fatty proliferation
6. Filiform polyps as the mucosa heals