- Accordion sign
- Appearance of bowel that may be seen with pseudomembranous colitis.
|Marked submucosal edema (arrows) is present in the right colon. Oral contrast material (arrowhead) is trapped within the lumen|
- Air crescent sign
- Appearance of cavitation that may be seen with invasive apergillosis.
|On healing, interval development of at least two air crescent signs (arrowheads), which coincided with recovery of the patient’s white blood cell count.|
- Anteater's nose sign
- Sign of calcaneonavicular tarsal coalition.
- Apple Core lesion
- Circumferential narrowing of the lumen secondary to colon cancer.