title: Diffusion tensor imaging of extraocular muscle using two-dimensional single-shot interleaved multiple inner volume imaging diffusion-weighted EPI at 3 tesla.
abstract: OBJECTIVE
  To evaluate the feasibility of diffusion tensor imaging (DTI) for the medial and lateral rectus extraocular muscle (EOM) evaluation, to investigate the normal DTI parameters of the medial and lateral rectus EOM, and to compare with other skeletal muscle.
  
  
  METHODS
  Seven multiple sclerosis patients and five normal subjects (M:F = 5:7, mean age = 31.6 ± 9.2) without EOM disorder were included. The orbital DTIs using 2D-ss-IMVI-DWEPI were scanned with b = 500 s/mm(2) and 12 directions. The mean diffusivity (MD) and fractional anisotrophy (FA) of medial and lateral rectus EOMs in both orbits, and temporalis muscles were measured in regions of interest on two consecutive axial slices. Student t-test was performed to compare the mean apparent diffusion coefficient and FA values between medial and lateral rectus EOMs, and between EOMs and temporalis muscles.
  
  
  RESULTS
  The MDs in medial (0.58 ± 0.18 × 10(-3) mm(2) /s) and lateral rectus EOMs (0.71 ± 0.18 × 10(-3) mm(2) /s) were significantly lower than temporalis muscle (0.84 ± 0.14 × 10(-3) mm(2) /s) (P < 0.001, respectively). The MD in medial rectus EOM was significantly lower than lateral rectus EOM (P = 0.001). The FAs in medial (0.40 ± 0.05) and lateral rectus EOMs (0.40 ± 0.05) were significantly higher than temporalis muscle (0.25 ± 0.05) (P < 0.001, respectively). There was no significant difference between the FAs in medial and lateral rectus EOMs (P > 0.05).
  
  
  CONCLUSIONS
  The MDs of EOMs were lower and the FAs were higher than those of skeletal muscle. These are well correlated to the unique characteristics of EOMs.
authors.affiliation: Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA; Department of Radiology, Korea University, Ansan, Korea.
authors.forename: Hyung Suk
authors.initials: HS
authors.lastname: Seo
authors.forename: Seong-Eun
authors.initials: SE
authors.lastname: Kim
authors.forename: John
authors.initials: J
authors.lastname: Rose
authors.forename: J Rock
authors.initials: JR
authors.lastname: Hadley
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Parker
authors.forename: Eun-Kee
authors.initials: EK
authors.lastname: Jeong
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D056324:Diffusion Tensor Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D009801:Oculomotor Muscles / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: diffusion tensor imaging; muscle; orbit