Probing the reproducibility of quantitative estimates of structural connectivity derived from global tractography

Lena V Schumacher; Marco Reisert; Kai Nitschke; Karl Egger; Horst Urbach; Jürgen Hennig; Cornelius Weiller; Christoph P Kaller

doi:10.1016/j.neuroimage.2018.01.086

Probing the reproducibility of quantitative estimates of structural connectivity derived from global tractography

Neuroimage. 2018 Jul 15:175:215-229. doi: 10.1016/j.neuroimage.2018.01.086. Epub 2018 Feb 10.

Authors

Lena V Schumacher¹, Marco Reisert², Kai Nitschke³, Karl Egger⁴, Horst Urbach⁴, Jürgen Hennig², Cornelius Weiller⁵, Christoph P Kaller⁶

Affiliations

¹ Dept. of Neurology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106 Freiburg, Germany; Medical Psychology and Medical Sociology, Faculty of Medicine, University of Freiburg, Rheinstrasse 12, 79104 Freiburg, Germany; Dept. of Neuroradiology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106 Freiburg, Germany; Freiburg Brain Imaging Center, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany. Electronic address: lena.schumacher@mps.uni-freiburg.de.
² Freiburg Brain Imaging Center, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany; Medical Physics, Dept. of Radiology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 60a, 79106 Freiburg, Germany.
³ Dept. of Neurology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106 Freiburg, Germany; Freiburg Brain Imaging Center, University of Freiburg, Germany.
⁴ Dept. of Neuroradiology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106 Freiburg, Germany; Freiburg Brain Imaging Center, University of Freiburg, Germany.
⁵ Dept. of Neurology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106 Freiburg, Germany; Freiburg Brain Imaging Center, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany.
⁶ Dept. of Neurology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 64, 79106 Freiburg, Germany; Freiburg Brain Imaging Center, University of Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Germany. Electronic address: christoph.kaller@uniklinik-freiburg.de.

PMID: 29438843
DOI: 10.1016/j.neuroimage.2018.01.086

Abstract

As quantitative measures derived from fiber tractography are increasingly being used to characterize the structural connectivity of the brain, it is important to establish their reproducibility. However, no such information is as yet available for global tractography. Here we provide the first comprehensive analysis of the reproducibility of streamline counts derived from global tractography as quantitative estimates of structural connectivity. In a sample of healthy young adults scanned twice within one week, within-session and between-session test-retest reproducibility was estimated for streamline counts of connections based on regions of the AAL atlas using the intraclass correlation coefficient (ICC) for absolute agreement. We further evaluated the influence of the type of head-coil (12 versus 32 channels) and the number of reconstruction repetitions (reconstructing streamlines once or aggregated over ten repetitions). Factorial analyses demonstrated that reproducibility was significantly greater for within- than between-session reproducibility and significantly increased by aggregating streamline counts over ten reconstruction repetitions. Using a high-resolution head-coil incurred only small beneficial effects. Overall, ICC values were positively correlated with the streamline count of a connection. Additional analyses assessed the influence of different selection variants (defining fuzzy versus no fuzzy borders of the seed mask; selecting streamlines that end in versus pass through a seed) showing that an endpoint-based variant using fuzzy selection provides the best compromise between reproducibility and anatomical specificity. In sum, aggregating quantitative indices over repeated estimations and higher numbers of streamlines are important determinants of test-retest reproducibility. If these factors are taken into account, streamline counts derived from global tractography provide an adequately reproducible quantitative measure that can be used to gauge the structural connectivity of the brain in health and disease.

Keywords: DTI; Reproducibility; Streamline counts; Structural connectivity; Tractography.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Brain / diagnostic imaging*
Diffusion Tensor Imaging / methods*
Diffusion Tensor Imaging / standards
Female
Humans
Image Processing, Computer-Assisted / methods*
Image Processing, Computer-Assisted / standards
Male
Models, Theoretical*
Nerve Fibers*
Reproducibility of Results
Young Adult