title: Evaluation of rectus extraocular muscles using dynamic contrast-enhanced MR imaging in patients with Graves' ophthalmopathy for assessment of disease activity.
abstract: BACKGROUND
  It is important to assess the activity of Graves' ophthalmopathy (GO) for planning optimal treatment strategy. Dynamic contrast-enhanced MR imaging (DCE-MRI) is a technique for assessment of microcirculation status. The correlation between disease activity and the microcirculation characteristics of extraocular muscles (EOMs) has been demonstrated in GO.
  
  
  OBJECTIVE
  To investigate the changes of rectus EOMs in patients with active vs. inactive GO using DCE-MRI, and to evaluate the value of DCE-MRI in assessing the activity of GO.
  
  
  METHODS
  Rectus EOMs of 20 healthy controls, 18 patients with active GO, and 16 patients with inactive GO were studied. The signal intensity (SI) of rectus EOMs on T(2)W images was evaluated. Regions of interest were placed on each rectus on DCE-MRI images. The DCE-MRI parameters including time to peak enhancement (Tpeak), enhancement ratio (ER), and wash-out ratio (WR) were calculated.
  
  
  RESULTS
  There were significant differences in SI and T(peak), ER and WR values among the three groups (P = 0.000). However, there was no significant difference in SI between the active and inactive groups (P = 0.07). T(peak) values of each rectus were significantly increased in inactive group compared with the active group (P < 0.05). ER and WR values of the inferior rectus and WR values of the superior rectus in inactive group were significantly lower than those in active group (P < 0.05). There was significant correlation between clinical activity score (CAS) and minimum T(peak) (minT(peak)), maximum ER (maxER) and maximum WR (maxWR) (P < 0.001). The cut-off values of minT(peak), maxER and maxWR were 156.98s, 1.31 and 13.50% respectively, giving positive predictive values of 68.00%, 88.90%, and 94.44% for the assessment of disease activity.
  
  
  CONCLUSIONS
  DCE-MRI could demonstrate the microcirculatory changes of rectus EOMs in both active and inactive GO, and this MRI method is a useful tool in differentiating active from inactive GO.
authors.affiliation: Department of Radiology, Beijing Tongren Hospital, Capital Medical University, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
authors.forename: Zhenchang
authors.initials: Z
authors.lastname: Wang
authors.forename: Junfang
authors.initials: J
authors.lastname: Xian
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Chen
authors.forename: Likun
authors.initials: L
authors.lastname: Ai
mesh_terms: D000328:Adult; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D049970:Graves Ophthalmopathy / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000473:pathology*; D012720:Severity of Illness Index
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA