title: Validation of tractography: Comparison with manganese tracing.
abstract: In this study, we used invasive tracing to evaluate white matter tractography methods based on ex vivo diffusion-weighted magnetic resonance imaging (dwMRI) data. A representative selection of tractography methods were compared to manganese tracing on a voxel-wise basis, and a more qualitative assessment examined whether, and to what extent, certain fiber tracts and gray matter targets were reached. While the voxel-wise agreement was very limited, qualitative assessment revealed that tractography is capable of finding the major fiber tracts, although there were some differences between the methods. However, false positive connections were very common and, in particular, we discovered that it is not possible to achieve high sensitivity (i.e., few false negatives) and high specificity (i.e., few false positives) at the same time. Closer inspection of the results led to the conclusion that these problems mainly originate from regions with complex fiber arrangements or high curvature and are not easily resolved by sophisticated local models alone. Instead, the crucial challenge in making tractography a truly useful and reliable tool in brain research and neurology lies in the acquisition of better data. In particular, the increase of spatial resolution, under preservation of the signal-to-noise-ratio, is key.
authors.affiliation: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Knösche
authors.affiliation: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Anwander
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.|Department of Computer Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Matthew
authors.initials: M
authors.lastname: Liptrot
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.
authors.forename: Tim B
authors.initials: TB
authors.lastname: Dyrby
mesh_terms: D000465:Algorithms; D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology; D001931:Brain Mapping / Q000379:methods*; D003287:Contrast Media; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005188:False Negative Reactions; D005189:False Positive Reactions; D066128:Gray Matter / Q000033:anatomy & histology; D007091:Image Processing, Computer-Assisted; D008345:Manganese; D008959:Models, Neurological; D009044:Motor Cortex / Q000033:anatomy & histology / Q000502:physiology; D009412:Nerve Fibers; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000502:physiology; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology; D013552:Swine; D013556:Swine, Miniature
chemical_list: D003287:Contrast Media; D008345:Manganese
keywords: DTI; MRI; brain connections; crossing fibers; tracking; white matter