Affiliation:
1. Leeds Institute for Medical Research, University of Leeds Leeds UK
2. Department of Plastic, Reconstructive and Hand Surgery Leeds Teaching Hospitals Trust Leeds UK
3. Division of Psychology, Communication & Human Neuroscience The University of Manchester Manchester UK
4. Leeds Teaching Hospitals Trust Leeds UK
5. Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds Leeds UK
Abstract
AbstractPurposeDTI characterizes tissue microstructure and provides proxy measures of nerve health. Echo‐planar imaging is a popular method of acquiring DTI but is susceptible to various artifacts (e.g., susceptibility, motion, and eddy currents), which may be ameliorated via preprocessing. There are many pipelines available but limited data comparing their performance, which provides the rationale for this study.MethodsDTI was acquired from the upper limb of heathy volunteers at 3T in blip‐up and blip‐down directions. Data were independently corrected using (i) FSL's TOPUP & eddy, (ii) FSL's TOPUP, (iii) DSI Studio, and (iv) TORTOISE. DTI metrics were extracted from the median, radial, and ulnar nerves and compared (between pipelines) using mixed‐effects linear regression. The geometric similarity of corrected b = 0 images and the slice matched T1‐weighted (T1w) images were computed using the Sörenson‐Dice coefficient.ResultsWithout preprocessing, the similarity coefficient of the blip‐up and blip‐down datasets to the T1w was 0·80 and 0·79, respectively. Preprocessing improved the geometric similarity by 1% with no difference between pipelines. Compared to TOPUP & eddy, DSI Studio and TORTOISE generated 2% and 6% lower estimates of fractional anisotropy, and 6% and 13% higher estimates of radial diffusivity, respectively. Estimates of anisotropy from TOPUP & eddy versus TOPUP were not different but TOPUP reduced radial diffusivity by 3%. The agreement of DTI metrics between pipelines was poor.ConclusionsPreprocessing DTI from the upper limb improves geometric similarity but the choice of the pipeline introduces clinically important variability in diffusion parameter estimates from peripheral nerves.
Funder
Arthritis Research UK
British Heart Foundation
Department of Health and Social Care
Medical Research Council Canada
National Institute for Health and Care Research
Leeds Biomedical Research Centre
Subject
Radiology, Nuclear Medicine and imaging