title: 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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Radiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Murayama
authors.forename: J
authors.initials: J
authors.lastname: Murakami
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
authors.forename: S
authors.initials: S
authors.lastname: Sakai
authors.forename: S
authors.initials: S
authors.lastname: Hinaga
authors.forename: H
authors.initials: H
authors.lastname: Soeda
authors.forename: H
authors.initials: H
authors.lastname: Nakata
authors.forename: K
authors.initials: K
authors.lastname: Masuda
mesh_terms: D001994:Bronchogenic Cyst / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008476:Mediastinal Cyst / Q000175:diagnosis*; D008479:Mediastinal Neoplasms / Q000175:diagnosis; D013724:Teratoma / Q000175:diagnosis