title: MR imaging of Pellegrini-Stieda disease.
abstract: OBJECTIVE
  To describe the MR imaging of Pellegrini-Stieda disease, a post-traumatic ossification of the medial collateral ligament with typical radiographic findings.
  
  
  METHODS
  Coronal and/or axial T2*-weighted field echo and T1-weighted conventional spin echo MR images were obtained with 1.5-Tesla or 0.5-Tesla units. Four patients with radiographic and clinical diagnoses of Pellegrini-Stieda disease were examined. Surgery was performed on one patient, and histopathologic correlation was obtained.
  
  
  CONCLUSIONS
  Delineating it as a signal void, T2*-weighted MR imaging indicated the precise extent of the osseous fragment in relation to the medial collateral ligament. T1-weighted imaging showed the presence of fatty marrow as a high signal region within the fragment, indicating maturity of the fragment. These findings may help to determine preoperative planning for resection of massive fragments around the ligament. Pellegrini-Stieda disease cannot be considered rare, since it is often encountered in daily MRI examinations.
authors.affiliation: Department of Radiology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Niitsu
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: T
authors.initials: T
authors.lastname: Iijima
authors.forename: N
authors.initials: N
authors.lastname: Ochiai
authors.forename: M
authors.initials: M
authors.lastname: Noguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Itai
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000150:complications*; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D009999:Ossification, Heterotopic / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery; D011859:Radiography