Utility of hyperdense whirl sign for the diagnosis of gallbladder torsion.

The purpose of this report was to evaluate the usefulness of hyperdense whirl sign on unenhanced computed tomography (CT) for diagnosing gallbladder torsion. The CT scans of seven patients with gallbladder torsion were independently reviewed by two board-certified radiologists for locating the high-density core with twisting between the gallbladder neck and liver bed, termed hyperdense whirl sign. The sign was observed in six cases. The detection of a hyperdense whirl sign on unenhanced CT appears useful for diagnosing gallbladder torsion.