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 g allbladder 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-A schoff 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 separa tely rated on a 5-point scale by two radiologists for comparison. Interobse rver differences were evaluated. Other MR findings were also analyzed. RESULTS. Among the six pulse sequences studied, three T2-weighted with brea th-holding sequences were found to be superior to the other three sequences in showing Rokitansky-Aschoff sinuses. In particular, the half-Fourier rap id acquisition with relaxation enhancement was scored the highest by the tw o observers and received the highest kappa coefficient in our statistical a nalysis of the scoring. Diffuse-type adenomyomatosis typically showed early mucosal and subsequent serosal enhancement. Localized adenomyomatosis exhi bited homogenous enhancement, showing smooth continuity with the surroundin g gallbladder epithelium. CONCLUSION. MR imaging may be able to provide important information in the diagnosis of adenomyomatosis.