Skeletal Radiology

, Volume 38, Issue 1, pp 51–59 | Cite as

Diffusion tensor imaging and fiber tractography of the median nerve at 1.5T: optimization of b value

  • Gustav AndreisekEmail author
  • Lawrence M. White
  • Andrea Kassner
  • George Tomlinson
  • Marshall S. Sussman
Scientific Article



The objective of this study was to systematically assess the optimal b value for diffusion tensor imaging and fiber tractography of the median nerve at 1.5 T.

Materials and methods

This is a prospective study which was carried out with institutional review board approval and written informed consent from the study subjects. Fifteen healthy volunteers (seven men, eight women; mean age, 31.2 years) underwent diffusion tensor imaging of the wrist. A single-shot spin-echo-based echo-planar imaging sequence (TR/TE, 7000/103 ms) was performed in each subject at eight different b values ranging from 325 to 1,550 s/mm2. Number and length of reconstructed fiber tracts, fiber density index (FDi), fractional anisotropy (FA), and apparent diffusion coefficient (ADC) were calculated for the median nerve. Signal-to-noise ratio (SNR) was also calculated for each acquisition. The overall image quality was assessed by two readers in consensus by ranking representative fiber tract images for each subject using a scale range from 1 to 8 (1 = best to 8 = worst image quality).


Longest fibers were observed for b values between 675 and 1,025 s/mm2. Maximum FDi was found at b values of 1,025 s/mm2. FA was between 0.5 and 0.6 for all b values. ADC gradually decreased from 1.44 × 10−3 to 0.92 × 10−3 mm2/s with increasing b values. Maximum SNR ± standard deviation (175.4 ± 72.6) was observed at the lowest b value and decreased with increasing b values. SNR at b values of 1,025 s/mm2 was 48.5% of the maximum SNR. Optimal fiber tract image quality was found for b values of 1,025 s/mm2.


The optimal b value for diffusion tensor imaging and fiber tractography of the median nerve at 1.5 T was 1,025 s/mm2.


MRI Diffusion tensor imaging Fiber tractography Median nerve 


Disclosure statements

Dr. Gustav Andreisek is supported by a grant from the Holcim Foundation for the Advancement of Scientific Research, Switzerland.


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Copyright information

© ISS 2008

Authors and Affiliations

  • Gustav Andreisek
    • 1
    • 2
    Email author
  • Lawrence M. White
    • 1
  • Andrea Kassner
    • 3
  • George Tomlinson
    • 4
  • Marshall S. Sussman
    • 5
  1. 1.Division of Musculoskeletal Imaging, Department of Medical Imaging, Mount Sinai Hospital and the University Health NetworkUniversity of TorontoTorontoCanada
  2. 2.Institute of Diagnostic RadiologyUniversity Hospital ZürichZürichSwitzerland
  3. 3.Department of Medical Imaging, University Health NetworkUniversity of TorontoTorontoCanada
  4. 4.Division of Clinical Decision-Making & Health Care, Department of Public Health Sciences, University of TorontoToronto General HospitalTorontoCanada
  5. 5.Department of Medical Imaging, Toronto General HospitalUniversity of TorontoTorontoCanada

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