MRI diagnosis of gallbladder adenomyomatosis: optimization of various pulse sequences

Abstract

Objective To compare the detectability of Rokitansky-Aschoff sinuses (RAS) in patients with pathologically confirmed gallbladder adenomyomatosis in varied MR pulse sequences. Methods MR imaging of 35 patients (19 males and 16 females, the age ranged from 32 to 72 years, mean 52 years) with gallbladder adenomyomatosis was studied on the 1.5 T and 0.5 T MR systems. For each patient, 4 pulse sequences were performed including axial T_1WI and T_2WI with 7 mm slice thickness, axial 3 mm thin-slice T_2WI, and MRCP. MRCP was produced by breath-hold thick-slab single-shot fast spin echo (SSFSE) method and 3-dimentional fat-suppressed fast spin echo with MIP reconstruction technique. Two radiologists evaluated the MR images and scored the RAS according to a 5-point confidence scale. RAS graded as 4 or 5 was used for further statistical analysis. Finally, the MR findings were correlated with surgical specimen and histopathological results. Results In this group, gallbladder wall thickening was showed on MRI in all patients and the thickness was from 5 to 12 mm (mean 7 mm). Among them, 16 fundal type, 12 segmental type, and 7 diffuse type of gallbladder adenomyomatosis were identified. The RAS was seen in the diseased gallbladder wall and its size ranged from 2 to 7 mm (mean 4 mm). On MR imaging, RAS appeared as hyperintensity on T_2WI and MRCP, hypo-, iso- or hyperintensity on T_1WI depending on the extent of bile concentration. Thin-slice T_2WI detected RAS in 35 cases (100%), both conventional T_2WI and MPCP in 21 (60%), and T_1WI in 9 (26%). 3 mm thin-slice T_2WI was superior to T_1WI, T_2WI, and MPCP in showing RAS (χ 2= 40.88, P0.01). Conclusion 3 mm thin-slice T_2WI was optimal in showing RAS.