Peripheral nerve diffusion tensor imaging (DTI): normal values and demographic determinants in a cohort of 60 healthy individuals
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To identify demographic determinants of peripheral nerve diffusion tensor imaging (DTI) and to establish normal values for fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD).
Sixty subjects were examined at 3 Tesla by single-shot DTI. FA, AD, RD, and MD were collected for the sciatic, tibial, median, ulnar, and radial nerve and were correlated with demographic variables.
Mean FA of all nerves declined with increasing age (r = −0.77), which could be explained by RD increasing (r = 0.56) and AD declining (r = −0.40) with age. Moreover, FA was inversely associated with height (r = −0.28), weight (r = −0.38) and BMI (r = −0.35). Although FA tended to be lower in men than women (p = 0.052), this difference became completely negligible after adjustment to body weight. A multiple linear regression model for FA was calculated with age and weight as predictors (defined by backward variable selection), yielding an R 2 = 0.71 and providing a correction formula to adjust FA for age and weight.
Peripheral nerve DTI parameters depend on demographic variables. The most important determinants age and weight should be considered in all studies employing peripheral nerve DTI.
• Peripheral nerve diffusion tensor imaging (DTI) parameters depend on demographic variables.
• Fractional anisotropy (FA) declines with increasing age and weight.
• Gender does not systematically affect peripheral nerve DTI.
• The formula presented here allows adjustment of FA for demographic variables.
KeywordsDiffusion tensor imaging Magnetic resonance imaging Peripheral nervous system Aging Reference values
We are grateful to Thorsten Feiweier from Siemens Healthcare for providing the work-in-progress package which included the DTI sequence that we used for imaging. This study was supported by the Deutsche Forschungsgemeinschaft (SFB 1118).
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Moritz Kronlage.
Conflict of interest
The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
One of the authors (Dr. Lorenz Uhlmann) has significant statistical expertise.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional review board approval was obtained.
Study subjects or cohorts overlap
Normal values of nerve calibre and T2 relaxometry in the same cohort were published separately in Kronlage M, Schwehr V, Schwarz D et al (2017) Normal Values and Demographic Determinants of Nerve Caliber and T2 Relaxometry in 60 healthy individuals. Clin Neuroradiol. [Epub ahead of print] Eighteen of 60 subjects were used in a control group for
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• cross-sectional study/observational
• performed at one institution
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