Signal intensity characteristics of mediastinal cystic masses on T1-weighted MRI

Abstract

Objective: We evaluated the intracystic MR signal intensity of mediastinal cystic masses to identify characteristic intensity patterns according to histologic type.

Materials and methods: Magnetic resonance imaging was performed on 26 cystic mediastinal masses consisting of 8 thymic cysts, 5 bronchogenic cysts, 4 pericardial cysts, 5 cystic teratomas, and 4 cystic neurogenic tumors. Signal intensity ratios of each cyst to muscle were calculated on T1-weighted imaging. Surgical records were reviewed to document the presence of intracystic hemorrhage. Chemical analysis of intracystic fluid was performed in three cases.

Results: Bronchogenic cysts, cystic teratomas, and cystic neurogenic tumors had relatively high levels of signal intensities. Each pericardial cyst had a lower signal intensity than muscle. The signal intensities of thymic cysts were variable. Intracystic hemorrhage was present in 1 bronchogenic cyst, 2 cystic neurogenic tumors, 4 cystic teratomas, and 3 thymic cysts. No hemorrhage was found in any of the pericardial cysts. Sebaceous fluid was present in 1 cystic teratoma.

Conclusion: The varying intensities of different cysts were considered to reflect the nature of the intracystic fluid. Since the nature of the fluid can reflect the histology to some extent, T1-weighted MRI will help to differentiate cystic mediastinal masses.