CT has 87-100% sensitive and89-98% specific of diagnosis acute appendicitis.
CT findings of normal appendix
- Visualized in 67-100%.
- AT posteromedial aspect of cecum.
- Diameter of up to 10 mm.
CT findings of Abnormal appendix
-
Distended lumen (appendix >7 mm in diameter).
-
Circumferential wall thickening.
-
Target sign: homogeneously enhancing wall with mural stratification.
-
Appendicolith: homogeneous/ringlike calcification (25%).
-
Distal appendicitis: abnormal tip of appendix + normal proximal appendix and normal cecal apex.
Signs of periappendicular inflammation
-
Linear streaky densities in periappendicular/pericecal/mesenteric/pelvic fat.
- Arrowhead sign: circumferential/focal cecal apical thickening = funnel of contrast medium in cecum symmetrically centering about occluded orifice of appendix (30% sensitive, 100% specific)
-
Free peritoneal fluid.
-
Mesenteric lymphadenopathy.
False-negative CT:
-
overlapping range in maximal appendiceal diameter between inflamed + uninflamed appendix
-
appendix mistaken for unopacified bowel
-
inflammation limited to appendiceal tip
Reference : Radiology Review Manual, Radiographics, Radiology Rounds
Advertisement
Filed under: Acute Appendicitis, Gastrointestinal Emergency, Acute Appendicitis, Arrowhead sign, CT Findings, normal appendix, Target sign
