title: Imaging features of ischial bursitis with an emphasis on ultrasonography.
abstract: OBJECTIVE
  The aim of this study was to evaluate the imaging features of ischial bursitis with an emphasis on ultrasonography (US).
  
  
  METHODS
  Our study included 31 patients with a painful mass or tenderness in their buttock who underwent US (n=27), CT (n=1), or MR imaging (n=4). A needle aspiration (n=6) or a bursal excision (n=5) was performed in those patients who had no clinical improvement in spite of the conservative treatment. Evaluation included lesion location, size, wall of the bursae, and intrinsic characteristics on US, CT and MR imaging.
  
  
  RESULTS
  Ischial bursitis was superficial to the ischial tuberosity in all patients (n=31). The lesion ranged from 1.5 cm to 7 cm (average 3.8 cm) in diameter. The bursal wall was identifiable in 25 cases (81%). Internal septa and mural nodules were seen in 12 (39%) and 17 cases (55%), respectively. Sonography showed that fluid within the bursa was hypoechoic (59%), hyperechoic (26%), or of mixed echogenicity (15%). The bursae were compressible by the transducer. Power Doppler examination (n=7) showed hypervascularity of the bursal wall. All lesions imaged with contrast-enhanced CT and MR imaging had an enhancing thin wall and mural nodule.
  
  
  CONCLUSIONS
  Ischial bursitis, superficial to the ischial tuberosity, can be clearly demonstrated on sonography and appears as a thin-walled cystic lesion, with or without internal septa and mural nodules.
authors.affiliation: Department of Radiology, Asan Medical Center, College of Medicine, University of Ulsan, 388-1, Poongnab-dong, Songpa-ku, Seoul 13-736, South Korea.
authors.forename: S M
authors.initials: SM
authors.lastname: Kim
authors.forename: M J
authors.initials: MJ
authors.lastname: Shin
authors.forename: K S
authors.initials: KS
authors.lastname: Kim
authors.forename: J M
authors.initials: JM
authors.lastname: Ahn
authors.forename: K H
authors.initials: KH
authors.lastname: Cho
authors.forename: J S
authors.initials: JS
authors.lastname: Chang
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: R K
authors.initials: RK
authors.lastname: Chhem
mesh_terms: D000328:Adult; D000368:Aged; D002062:Bursitis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007512:Ischium; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D018608:Ultrasonography, Doppler