Tractography of Association Fibers Associated with Language Processing.
BACKGROUND
Several major association fiber tracts are known to be part of the language processing system. There is evidence that high angular diffusion-based MRI is able to separate these fascicles in a constant way. In this study, we wanted to proof this thesis using a novel whole brain "global tracking" approach and to test for possible lateralization.


METHODS
Global tracking was performed in six healthy right-handed volunteers for the arcuate fascicle (AF), the medial longitudinal fascicle (MdLF), the inferior fronto-occipital fascicle (IFOF), and the inferior longitudinal fascicle (ILF). These fiber tracts were characterized quantitatively using the number of streamlines (SL) and the mean fractional anisotropy (FA).


RESULTS
We were able to characterize the AF, the MdLF, the IFOF, and the ILF consistently in six healthy volunteers using global tracking. A left-sided dominance (LI > 0.2) for the AF was found in all participants. The MdLF showed a left-sided dominance in four participants (one female, three male). Regarding the FA, no lateralization (LI > 0.2) could be shown in any of the fascicles.


CONCLUSIONS
Using a novel global tracking algorithm we confirmed that the courses of the primary language processing associated fascicles can consistently be differentiated. Additionally we were able to show a streamline-based left-sided lateralization in the AF of all right-handed healthy subjects.
Department of Neuroradiology, University Medical Centre Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany. karl.egger@uniklinik-freiburg.de.
K
K
Egger
Department of Neuroradiology, University Medical Centre Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany.
S
S
Yang
Department of Medical Physics, University Medical Centre Freiburg, 79106, Freiburg, Germany.
M
M
Reisert
Department of Neurology, University Medical Centre Freiburg, 79106, Freiburg, Germany.
C
C
Kaller
Department of Neuroradiology, University Medical Centre Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany.
I
I
Mader
Department of Neurology, University Medical Centre Freiburg, 79106, Freiburg, Germany.
L
L
Beume
Department of Neurology, University Medical Centre Freiburg, 79106, Freiburg, Germany.
C
C
Weiller
Department of Neuroradiology, University Medical Centre Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany.
H
H
Urbach
D000368:Aged; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D008297:Male; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D066127:White Matter / Q000033:anatomy & histology* / Q000502:physiology
DTI; Global tracking; IFOF; ILF; Keywords; MdLF; SLF; association fibers; language processing; streamline; tractography