title: Consecutive assessment of FA and ADC values of normal lumbar nerve roots from the junction of the dura mater.
abstract: BACKGROUND
  Diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) are widely used in the evaluation of the central nervous system and recently have been reported as a potential tool for diagnosis of the peripheral nerve or the lumbar nerve entrapment. The purpose of this study was to evaluate consecutive changes in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of normal lumbar nerve roots from the junction of the dura mater.
  
  
  METHODS
  The lumbar spinal nerves were examined in 6 male healthy volunteers (mean age, 35 years) with no experiences of sciatica, with a 3.0-T MR unit using a five-element phased-array surface coil. DTI was performed with the following imaging parameters: 11084.6/73.7 ms for TR/TE; b-value, 800 s/mm2; MPG, 33 directions; slice thickness, 1.5 mm; and total scan time, 7 min 35 s. ADC and FA values at all consecutive points along the L4, L5 and S1 nerves were quantified on every 1.5 mm slice from the junction of the dura mater using short fiber tracking.
  
  
  RESULTS
  ADC values of all L4, 5, and S1 nerve roots decreased linearly up to 15 mm from the dura junction and was constant distally afterward. ADC values in the proximal portion demonstrated S1 > L5 > L4 (p < 0.05). On the other hand, FA values increased linearly up to 15 mm from the dura junction, and was constant distally afterward. FA values in the proximal portion showed L4 > L5 > S1 (p < 0.05).
  
  
  CONCLUSIONS
  Our study demonstrated that ADC and FA values of each L4, 5, and S1 at the proximal portion from the junction of the dura matter changed linearly. It would be useful to know the normal profile of DTI values by location of each nerve root so that we can detect subtle abnormalities in each nerve root.
authors.affiliation: Department of Orthopedics, The University of Tokushima Graduate School, Tokushima, Japan. yakitorinegi@yahoo.co.jp.|Department of the Radiological Sciences, University of California, Irvine, School of Medicine, Irvine, CA, 92868, USA. yakitorinegi@yahoo.co.jp.
authors.forename: Ryo
authors.initials: R
authors.lastname: Miyagi
authors.affiliation: Department of Orthopedics, The University of Tokushima Graduate School, Tokushima, Japan. norinoridowluck@yahoo.co.jp.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Sakai
authors.affiliation: Department of the Radiological Sciences, University of California, Irvine, School of Medicine, Irvine, CA, 92868, USA. yamabeeiko@gmail.com.
authors.forename: Eiko
authors.initials: E
authors.lastname: Yamabe
authors.affiliation: Department of the Radiological Sciences, University of California, Irvine, School of Medicine, Irvine, CA, 92868, USA. hiroshi@uci.edu.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yoshioka
mesh_terms: D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging; D004388:Dura Mater / Q000033:anatomy & histology*; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008160:Lumbosacral Plexus / Q000033:anatomy & histology*; D008297:Male; D011237:Predictive Value of Tests; D013126:Spinal Nerve Roots / Q000033:anatomy & histology*