Accelerated magnetic resonance diffusion tensor imaging of the median nerve using simultaneous multi-slice echo planar imaging with blipped CAIPIRINHA
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To investigate the feasibility of MR diffusion tensor imaging (DTI) of the median nerve using simultaneous multi-slice echo planar imaging (EPI) with blipped CAIPIRINHA.
Materials and methods
After federal ethics board approval, MR imaging of the median nerves of eight healthy volunteers (mean age, 29.4 years; range, 25–32) was performed at 3 T using a 16-channel hand/wrist coil. An EPI sequence (b-value, 1,000 s/mm2; 20 gradient directions) was acquired without acceleration as well as with twofold and threefold slice acceleration. Fractional anisotropy (FA), mean diffusivity (MD) and quality of nerve tractography (number of tracks, average track length, track homogeneity, anatomical accuracy) were compared between the acquisitions using multivariate ANOVA and the Kruskal-Wallis test.
Acquisition time was 6:08 min for standard DTI, 3:38 min for twofold and 2:31 min for threefold acceleration. No differences were found regarding FA (standard DTI: 0.620 ± 0.058; twofold acceleration: 0.642 ± 0.058; threefold acceleration: 0.644 ± 0.061; p ≥ 0.217) and MD (standard DTI: 1.076 ± 0.080 mm2/s; twofold acceleration: 1.016 ± 0.123 mm2/s; threefold acceleration: 0.979 ± 0.153 mm2/s; p ≥ 0.074). Twofold acceleration yielded similar tractography quality compared to standard DTI (p > 0.05). With threefold acceleration, however, average track length and track homogeneity decreased (p = 0.004–0.021).
Accelerated DTI of the median nerve is feasible. Twofold acceleration yields similar results to standard DTI.
• Standard DTI of the median nerve is limited by its long acquisition time.
• Simultaneous multi-slice acquisition is a new technique for accelerated DTI.
• Accelerated DTI of the median nerve yields similar results to standard DTI.
KeywordsDiffusion tensor imaging Diffusion tractography Simultaneous multi-slice Echo-planar imaging Median nerve
Controlled aliasing in parallel imaging results in higher acceleration
Distal radio-ulnar joint
Diffusion tensor imaging
Echo planar imaging
Fibre density index
Intra-class correlation coefficient
Region of interest
Simultaneous multi-slice acquisition
The authors kindly thank Heiko Meyer and Thomas Beck (both Siemens Healthcare, Erlangen, Germany) for providing them with the software for simultaneous multi-slice acquisition. The scientific guarantor of this publication is Roman Guggenberger, MD. Gustav Andreisek, MD, MBA, and Val M. Runge, MD, declare relationships with Siemens Healthcare, Erlangen, Germany. Himanshu Bhat, PhD is an employee of Siemens Medical Solutions USA Inc, Charlestown, MA, United States. These companies had no influence on the present study. The authors state that this work has not received any funding. No complex statistical methods were necessary for this paper. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects in this study. Methodology: prospective, experimental, performed at one institution.