title: Usefulness of dynamic contrast-enhanced MRI in differentiating between septic arthritis and transient synovitis in the hip joint.
abstract: OBJECTIVE
  The purpose of this study was to show the usefulness of dynamic contrast-enhanced MRI (DCE-MRI) and to determine the optimal time window in MRI for differentiating between septic arthritis and transient synovitis in painful hip joints.
  
  
  METHODS
  Eighteen patients who underwent DCE-MRI were enrolled, and the final diagnoses were septic arthritis (n = 7) and transient synovitis (n = 11). The enhancement patterns of DCE-MRI were dichotomized according to the shape of the time-signal intensity curves. The time at the maximal difference in the signal intensity between two time-signal intensity curves of both femoral heads was recorded. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated. Receiver operating characteristic curves were calculated.
  
  
  RESULTS
  Six of seven patients with septic arthritis in the hip joint had decreased enhancement during the early phase of DCE-MRI. The enhancement difference between the two patient groups was statistically significant (p = 0.0498). The time at the maximal difference in the signal intensity between two time-signal intensity curves of both femoral heads was approximately 3.5 minutes. The area under the receiver operating characteristic curve for predicting septic arthritis was 0.792.
  
  
  CONCLUSIONS
  DCE-MRI is useful in differentiating between septic hip arthritis and transient synovitis. If static contrast-enhanced coronal MRI is used, the optimal time for the acquisition of contrast-enhanced coronal MRI is approximately 3.5 minutes.
authors.affiliation: Department of Radiology, Ajou University School of Medicine, San 5, Woncheon-dong, Yeongtong-gu, Suwon 443-721, Republic of Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Kim
authors.forename: Kyu-Sung
authors.initials: KS
authors.lastname: Kwack
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Cho
authors.forename: Doo-Hyung
authors.initials: DH
authors.lastname: Lee
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Yoon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001170:Arthritis, Infectious / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D019786:Gadolinium DTPA; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013585:Synovitis / Q000175:diagnosis*
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA