Sonography of acute cholecystitis: comparison of color and power Doppler sonography in detecting a hypervascularized gallbladder wall.

OBJECTIVE

We evaluated the sensitivity and specificity of power Doppler sonography compared with conventional color Doppler sonography and gray-scale sonography in diagnosing patients with acute cholecystitis.

SUBJECTS AND METHODS

Seventy-six patients with right upper quadrant pain and 72 healthy volunteers underwent gray-scale sonography, conventional color Doppler sonography, and power Doppler sonography of the gallbladder. The vascularity of the gallbladder wall was scored on a scale of 0 to +3. Histology revealed acute cholecystitis in 55 patients. Histologic specimens and clinical workups showed that the remaining 21 patients suffered from other diseases.

RESULTS

Sensitive sonographic features such as the positive Murphy's sign (in 96% of patients with acute cholecystitis), calculi (95%), and a thickened gallbladder wall (73%) lacked specificity (71%, 38%, 67%, respectively) for diagnosing acute cholecystitis. In our study, the sensitivity of power Doppler sonography was 95% compared with 33% for color Doppler sonography in revealing a hypervascularized gallbladder wall. Power Doppler sonography revealed hyperemia within a nonthickened gallbladder wall in four patients with surgically proven acute cholecystitis. Specificity of power Doppler sonography was 86% compared with 95% for conventional color Doppler sonography. False-positive results with power Doppler sonography were caused by pancreatitis, duodenal ulcer, and gallbladder carcinoma. Interobserver variability seemed to play no significant role. No intramural hypervascularity was detected in the volunteer group. In four (4%) of 89 symptomatic patients we could not use power Doppler sonography because of the patients noncompliance. Mean values of the resistive index assessed within intramural vessels of the gallbladder showed no significant differences (p < .001) between patients with acute cholecystitis (0.73) and patients with other diseases (0.71).

CONCLUSIONS

Although the sensitivity of power Doppler sonography in diagnosing acute cholecystitis was similar to that of gray-scale sonography, the specificity of power Doppler sonography was significantly higher, which may substantially improve diagnostic confidence. However, the high susceptibility of power Doppler sonography to motion artifacts makes appropriate adjustment of technical parameters much more relevant than with other sonographic imaging. The resistive index within intramural vessels has no clinical use in the diagnosis of acute cholecystitis.