title: MR imaging and MR arthrography of paraglenoid labral cysts.
abstract: OBJECTIVE
  We investigated the pathophysiology of paraglenoid labral cysts on the basis of MR imaging, MR arthrography, and cyst aspiration.
  
  
  METHODS
  From 2211 MR imaging examinations, 51 (2.3%) cysts in 46 patients were identified. MR arthrography (n = 5), cystography (n = 1), arthroscopy (n = 17), percutaneous needle aspiration (n = 4), and medical records were also reviewed (n = 46).
  
  
  RESULTS
  On MR imaging and arthrography, cysts were best viewed on T2-weighted images. Mean cyst diameter and volume were 2.2 cm and 2.8 cm3, respectively. Fifty-seven percent of cysts were located adjacent to the posterior labrum. On MR imaging and arthroscopy, a labral tear was identified in 27 (53%) and 15 (88%) patients, respectively. Eight cysts that caused compression neuropathy were large (mean size, 3.1 cm; p = 0.04) and located next to the posterior or inferior labrum. In four of five patients, MR arthrograms showed no intraarticular contrast material in the cyst. Cystograms showed no communication with the glenohumeral joint space, and cyst aspiration resulted in temporary symptom relief; however, cysts recurred in three of four patients.
  
  
  CONCLUSIONS
  Most paralabral cysts are associated with labral tears. Paralabral cysts may be difficult to identify on MR arthrography unless a T2-weighted sequence is performed. Direct communication between a cyst and joint space rarely occurs. A posterior or inferior cyst may cause compression neuropathy of the suprascapular or axillary nerve, respectively. Cyst aspiration may result in temporary relief of symptoms, but an untreated labral tear should be suspected if cysts recur.
authors.affiliation: Department of Diagnostic Imaging, Brown University School of Medicine, Rhode Island Hospital, Providence 02903, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Tung
authors.forename: D
authors.initials: D
authors.lastname: Entzian
authors.forename: J B
authors.initials: JB
authors.lastname: Stern
authors.forename: A
authors.initials: A
authors.lastname: Green
mesh_terms: D000328:Adult; D000368:Aged; D001182:Arthroscopy; D003560:Cysts / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis / Q000628:therapy; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000473:pathology*; D013396:Suction