Focal sparing around the gallbladder in fatty liver

In evaluating fatty liver with CT, the residual normal liver tissues without fat deposits are occasionally detected on CT as high attenuation regions, especially surrounding the gallbladder. This study examined the incidence of this phenomenon in terms of the diagnostic value of CT in fatty liver. Fifty-seven patients with fatty liver were examined with CT. The incidence of focal sparing area was the highest in the gallbladder bed (42/57, 74%), followed by the interlobar fissure or subcapsular area (13, 23%), quadrate lobe (8, 14%), caudate lobe (2, 4%), and right lobe (one, 1.8%). These CT appearances were of spot, band, ring, and the mixed type. In 38 patients, fatty liver was too moderate to be detected without CT attenuation numbers. Among them, 27 patients (71%) had focal sparing area surrounding the gallbladder. This CT appearance seemed to be of significance in preventing the missing of moderate fatty liver. (Namekawa, K)