title: MR imaging of transient synovitis: differentiation from septic arthritis.
abstract: BACKGROUND
  Transient synovitis is the most common cause of acute hip pain in children. However, MR imaging findings in transient synovitis and the role of MR imaging in differentiating transient synovitis from septic arthritis have not been fully reported.
  
  
  OBJECTIVE
  To describe the MR findings of transient synovitis and to determine whether the MR characteristics can differentiate this disease entity from septic arthritis.
  
  
  METHODS
  Clinical findings and MR images of 49 patients with transient synovitis (male/female 36/13, mean age 6.1 years) and 18 patients with septic arthritis (male/female 10/8, mean age 4.9 years) were retrospectively reviewed.
  
  
  RESULTS
  MR findings of transient synovitis were symptomatic joint effusion, synovial enhancement, contralateral joint effusion, synovial thickening, and signal intensity (SI) alterations and enhancement in surrounding soft tissue. Among these, SI alterations and enhancement in bone marrow and soft tissue, contralateral joint effusion, and synovial thickening were statistically significant MR findings in differentiating transient synovitis from septic arthritis.
  
  
  CONCLUSIONS
  The statistically significant MR findings in transient synovitis are contralateral (asymptomatic) joint effusions and the absence of SI abnormalities of the bone marrow. It is less common to have SI alterations and contrast enhancement of the soft tissues. The statistically significant MR findings in septic arthritis are SI alterations of the bone marrow, and SI alterations and contrast enhancement of the soft tissue. Ipsilateral effusion and synovial thickening and enhancement are present in both diseases.
authors.affiliation: Department of Radiology, Kangnam St. Mary's Hospital, The Catholic University of Korea, 505 Banpo-dong, Seocho-gu, Seoul 137-701, South Korea.
authors.forename: Wan Jik
authors.initials: WJ
authors.lastname: Yang
authors.forename: Soo Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Gye-Yeon
authors.initials: GY
authors.lastname: Lim
authors.forename: Ho Jong
authors.initials: HJ
authors.lastname: Chun
authors.forename: Na Young
authors.initials: NY
authors.lastname: Jung
authors.forename: Mi Sook
authors.initials: MS
authors.lastname: Sung
authors.forename: Byung Gil
authors.initials: BG
authors.lastname: Choi
mesh_terms: D000293:Adolescent; D001170:Arthritis, Infectious / Q000175:diagnosis*; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D005334:Fever / Q000209:etiology; D006621:Hip Joint / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007964:Leukocytosis / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D010146:Pain / Q000209:etiology*; D013585:Synovitis / Q000150:complications / Q000175:diagnosis* / Q000276:immunology
chemical_list: D002097:C-Reactive Protein