Magnetic resonance imaging of experimentally-induced sialadenitis in rat submandibular glands

Objectives: To correlate the features of magnetic resonance (MR) images of experimentally induced obstructive sialadenitis in rat submandibular glands with the histopathological changes. Methods: Changes in MR images of ligated and non-ligated rat submandibular glands were compared with the histopathological changes and wet weight ratios. Spin echo T1 weighted images (SE T1WI), fast spin echo T2 weighted images (FSE T2WI), and gradient echo T2 weighted images (GE T2WI) were obtained at 1, 2, 3, 4, 5, 7 and 21 days after duct ligation with a 0.3 T MR imaging system. Results: There was a significant difference (P < 0.05) between the signal intensity ratios of both ligated and non-ligated glands on each day, except at 21 days on GE T2WI. On SE T1 WI, small interval changes of signal intensity ratios were observed on both glands, whereas there were large interval changes at 1-2 days, 4-7 days and 21 days after duct ligation with FSE T2WI. These three periods correlated highly with three phases of histopathological changes, swelling of acinar cells at 1-2 days, atrophy of acinar cells and increase of duct-like structures at 3-7 days, and proliferation of connective tissue at 21 days, and the changes in wet weight ratios. A similar tendency was observed on GE T2WI to FSE T2WI. Conclusions: As FSE T2WI showed large changes in signal intensity that correlated highly with histopathological three phases, it is recommended as the MR sequence of choice for diagnosing the degree of damage in obstructive sialadenitis.