title: Reduced-distortion diffusion MRI of the craniovertebral junction.
abstract: OBJECTIVE
  CVJ lesion suffers from a high sensitivity to susceptibility and distortion artifacts, which sometimes makes diffusion image difficult to interpret. Our purpose was to evaluate the potential for diffusion MR imaging using RS-EPI compared with SS-EPI in the assessment of the CVJ.
  
  
  METHODS
  RS-EPI and SS-EPI DTI images were acquired from 10 healthy volunteers using 3T MRI with a 32-channel head coil. For both sequences, the following parameters were used: 1-mm(2) in-plane resolution; 3-mm section thickness; TR = 5200 ms; 1 acquisition at b = 0 and 12 different encoding directions at b = 1000 seconds/mm(2). The RS-EPI sequence scan time was 9.44 minutes (1 average). The SS-EPI sequence was 9.37 minutes (8 averages). Diffusion tensor calculation and image analysis were performed using DTIStudio software. Diffusion trace images and color-coded fiber orientation maps were evaluated by 2 independent readers for distortion and delineation of fine structure using a semiquantitative scale in selected landmark locations. The absolute distances between the temporal base and the cerebellar contour between the T2-weighted images and the diffusion trace images obtained with RS-EPI and SS-EPI were also compared.
  
  
  RESULTS
  The contours of the temporal lobe and cerebellum were better delineated and distortion artifacts were clearly reduced with the RS-EPI sequence. More fine structures were also visible in the brain stem and cerebellum with the RS-EPI sequence. The amount of distortion was significantly reduced with RS-EPI compared with SS-EPI (P < .01).
  
  
  CONCLUSIONS
  The RS-EPI DTI sequence was less prone to geometric distortion than the SS-EPI sequence and allowed a better delineation of CVJ internal structure. Although the acquisition time is still relatively long, the RS-EPI appears as a promising approach to perform DTI studies in CVJ lesions, such as brain stem ischemia, neurodegenerative diseases, brain and skull base tumors, or inflammation.
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine and Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan. mamiiima@kuhp.kyoto-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Iima
authors.forename: A
authors.initials: A
authors.lastname: Yamamoto
authors.forename: V
authors.initials: V
authors.lastname: Brion
authors.forename: T
authors.initials: T
authors.lastname: Okada
authors.forename: M
authors.initials: M
authors.lastname: Kanagaki
authors.forename: K
authors.initials: K
authors.lastname: Togashi
authors.forename: D
authors.initials: D
authors.lastname: Le Bihan
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001270:Cervical Atlas / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008022:Ligaments / Q000033:anatomy & histology*; D008297:Male; D008954:Models, Biological; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019291:Skull Base / Q000033:anatomy & histology*