Appendicitis

Imaging Findings of appendicitis
Abdominal plain film (abnormalities seen in <50%) pain =" 90%" color="#ff0000">US (77-94% sensitive, 90% specific, 78-96% accurate)
Useful in ovulating women (false-negative appendectomy rate in males 15%, in females 35%):
Visualization of noncompressible appendix as a blind-ending tubular aperistaltic structure (seen only in 2% of normal adults, but in 50% of normal children)
Target appearance of >6 mm in total diameter on cross section (81%)
Mural wall thickness >2 mm
Diffuse hypoechogenicity (associated with higher frequency of perforation)
Lumen may be distended with anechoic / hyperechoic material
Loss of wall layers
Visualization of appendicolith (6%)
Localized periappendiceal fluid collection
Prominent hyperechoic mesoappendix / pericecal fat
Color Doppler US:
Increased conspicuity from increase (in size + number) of vessels in and around the appendix
Decreased resistance of arterial waveforms
Continuous / pulsatile venous flow
CT (87-98% sensitive, 83-97% specific, 93% accurate)
Distended lumen
Circumferentially thickened and enhancing wall
Appendicolith = homogeneous / ringlike calcification (25%)
Periappendicular inflammation-linear streaky densities in periappendicular fat
Pericecal soft-tissue mass
Abscess
Poorly encapsulated
Single or multiple fluid collection(s) with air
Extraluminal contrast material
Focal cecal wall thickening (80%)
"Arrowhead" sign = funnel of contrast medium in cecum centering about occluded orifice of appendix

Reference:Learningradiology.com