title: Evaluating the Microcirculation of Normal Extraocular Muscles Using Quantitative Dynamic Contrast-Enhanced Magnetic Resonance Imaging.
abstract: OBJECTIVE
  The purpose of this work was to evaluate the microcirculation of normal extraocular muscles using quantitative dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) (DCE-MRI).
  
  
  METHODS
  The institutional review board approved the study. Forty-eight eyes were examined using quantitative DCE-MRI on a 3-T MRI system. Quantitative parameters, including the volume transfer constant (Ktrans), the fractional volume of extravascular extracellular space (Ve), and the rate constant (Kep) of each extraocular muscles, were analyzed. The type of DEC time-intensity curve (TIC) was evaluated. The parameters of bilateral extraocular muscles were compared using the Wilcoxon test. The difference in quantitative values of different extraocular muscles was compared using independent-samples Kruskal-Wallis test.
  
  
  RESULTS
  No statistical differences of parameters were found between the left and right extraocular muscles (P > 0.05). Volume transfer constant values in medial rectus (MR) muscles and inferior rectus (IR) muscles were significantly higher than those in the lateral rectus (LR) muscles and superior rectus (SR) muscles (P < 0.05). The median Ktrans value of the MR (0.170) was higher than that of the IR (0.151); however, the difference was not significant (P > 0.05). In the 4 extraocular muscles, the Ve values of MR are the largest, followed by the IR, LR, and SR values. The DCE time-intensity curves of extraocular muscles are type II or type III. Medial rectus and IR are mainly type III, and LR and SR are mainly type II.
  
  
  CONCLUSIONS
  The quantitative DCE-MRI can be used as an important and noninvasive technique to evaluate the microcirculation of extraocular muscles. Further investigations for other extraocular muscles diseases by using quantitative DCE-MRI are warranted.
authors.affiliation: From the *Department of Radiology, Tianjin First Center Hospital, Tianjin, China; †Department of Radiology, Da Gang Community Hospital, Tianjin Binghai New Area, Tianjin, China; and ‡Department of Ophthalmology, Tianjin First Center Hospital, Tianjin, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.forename: Lei
authors.initials: L
authors.lastname: Huo
authors.forename: Penghui
authors.initials: P
authors.lastname: Wang
authors.forename: Lixiang
authors.initials: L
authors.lastname: Huang
authors.forename: Chao
authors.initials: C
authors.lastname: Chai
authors.forename: Fengyuan
authors.initials: F
authors.lastname: Sun
authors.forename: Shuang
authors.initials: S
authors.lastname: Xia
authors.forename: Wen
authors.initials: W
authors.lastname: Shen
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D003198:Computer Simulation; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000493:pharmacokinetics; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted; D018810:Magnetic Resonance Angiography; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D055806:Microvessels / Q000000981:diagnostic imaging* / Q000502:physiology*; D008875:Middle Aged; D008955:Models, Cardiovascular; D009801:Oculomotor Muscles / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA