The rim sign in acute cholecystitis. Comparison of radionuclide, surgical, and pathologic findings.

Nonvisualization of the gallbladder associated with the rim sign of enhanced pericholecystic hepatic activity has been established as a useful and highly specific sign of acute cholecystitis. This study's purpose was to determine the pathophysiologic cause of the rim sign. Thirty-seven surgery-bound patients with a clinical diagnosis of acute cholecystitis were studied. A group of 20 patients with a definite rim sign were compared to a group of 17 patients without a rim sign; all with nonvisualization of the gallbladder. Radionuclide, surgical, and pathologic findings were correlated. In patients with the rim sign and in those without the rim sign, microscopic review of all surgical specimens revealed transmural reaction of the gallbladder wall in 95% and 59% of cases, respectively. The surgeon found inflammation extending beyond the gallbladder wall in 75% of rim sign cases, but in only 35% of case without the rim sign. Liver tissue was attached to the gallbladder specimen in three cases, and the findings support the association of hepatic inflammation with the presence of a rim sign. Pathologic correlation and surgical evidence suggest that the rim sign is caused by the spread of inflammation through the gallbladder wall and into adjacent liver tissue. Transmural reaction is required before the inflammatory process can reach the liver. A high-count, high-intensity technique seems to best demonstrate the rim sign. Once demonstrated, further delayed imaging is unnecessary.