MR diagnosis of adenomyomatosis of the gallbladder and differentiation from gallbladder carcinoma: importance of showing Rokitansky-Aschoff sinuses.

OBJECTIVE: We evaluated the MR imaging features of adenomyomatosis of the gallbladder with particular emphasis on Rokitansky-Aschoff sinuses.

MATERIALS AND METHODS: MR images of 17 patients with histologically proven adenomyomatosis were retrospectively reviewed. The presence of Rokitansky-Aschoff sinuses was evaluated and analyzed; four T2-weighted (fast spin-echo with a surface coil, with or without breath-holding, fast spin-echo with a phased-array coil with breath-holding, and half-Fourier rapid acquisition with relaxation enhancement with breath-holding) and two contrast-enhanced dynamic pulse sequences were studied. These six pulse sequences were separately rated on a 5-point scale by two radiologists for comparison. Interobserver differences were evaluated. Other MR findings were also analyzed.

RESULTS: Among the six pulse sequences studied, three T2-weighted with breath-holding sequences were found to be superior to the other three sequences in showing Rokitansky-Aschoff sinuses. In particular, the half-Fourier rapid acquisition with relaxation enhancement was scored the highest by the two observers and received the highest kappa coefficient in our statistical analysis of the scoring. Diffuse-type adenomyomatosis typically showed early mucosal and subsequent serosal enhancement. Localized adenomyomatosis exhibited homogeneous enhancement, showing smooth continuity with the surrounding gallbladder epithelium.

CONCLUSION: MR imaging may be able to provide important information in the diagnosis of adenomyomatosis.