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

Andreisek, Gustav ; White, Lawrence ; Kassner, Andrea ; Tomlinson, George ; Sussman, Marshall

In: Skeletal Radiology, 2009, vol. 38, no. 1, p. 51-59

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    Titre
    • Diffusion tensor imaging and fiber tractography of the median nerve at 1.5T: optimization of b value
    Auteur
    • Andreisek, Gustav. Division of Musculoskeletal Imaging, Department of Medical Imaging, Mount Sinai Hospital and the University Health Network, University of Toronto, 600 University Ave, M5G 1X5, Toronto, Ontario, Canada
    • White, Lawrence. Division of Musculoskeletal Imaging, Department of Medical Imaging, Mount Sinai Hospital and the University Health Network, University of Toronto, 600 University Ave, M5G 1X5, Toronto, Ontario, Canada
    • Kassner, Andrea. Department of Medical Imaging, University Health Network, University of Toronto, 180 Dundas Street, 4th Floor, Suite 430, Room 428, M5G 1X5, Toronto, Canada
    • Tomlinson, George. Division of Clinical Decision-Making & Health Care, Department of Public Health Sciences, University of Toronto, Toronto General Hospital, Eaton North Wing, 13th Floor, Rm 13EN238, 200 Elizabeth St., M5G 2C4, Toronto, Ontario, Canada
    • Sussman, Marshall. Department of Medical Imaging, Toronto General Hospital, University of Toronto, 585 University Ave., NCSB 1C-572, M5G 1X5, Toronto, Canada
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:314224
    Summary
    Objective: 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 1.5T. 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, 31.2years) underwent diffusion tensor imaging of the wrist. A single-shot spin-echo-based echo-planar imaging sequence (TR/TE, 7000/103ms) was performed in each subject at eight different b values ranging from 325 to 1,550s/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). Results: Longest fibers were observed for b values between 675 and 1,025s/mm2. Maximum FDi was found at b values of 1,025s/mm2. FA was between 0.5 and 0.6 for all b values. ADC gradually decreased from 1.44 × 10−3 to 0.92 × 10−3mm2/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 1,025s/mm2 was 48.5% of the maximum SNR. Optimal fiber tract image quality was found for b values of 1,025s/mm2. Conclusions: The optimal b value for diffusion tensor imaging and fiber tractography of the median nerve at 1.5T was 1,025s/mm2