gms | German Medical Science

Objective: The aim of the present study was to find out a simple and reproducible strategy that enables especially clinicians to track a variety of fibers with little effort in a short time but with a high anatomical precision. White matter anatomy should provide additional information during preoperative planning or intraoperative neuronavigation, e.g. for resection of tumors in eloquent areas. Up to now, this technique is subject to several restrictions, the quality of results often seems to be insufficient for intraoperative application. For example, most fiber tracking tools only depict parts of the motor fibers when tracking the corticospinal tract. However, precise anatomical information about the 3-D course and extension of a fiber tract is essential for the neurosurgeon. Therefore we tried to enhance anatomical accuracy by exploiting the possibilities of the line propagation tracking algorithm.

Methods: We recorded a 32-direction DTI EPI data set including a T1-weighted anatomical reference of a normal subject. After distortion correction fiber tracking was performed with the recently developed program “StealthDTI”. For each of the eleven fiber tracts of the motor, visual, speech, limbic and association systems we varied the regions of interest as well as the tracking parameters to achieve results which come close to their anatomical templates. Fiber tracts were visualized in 2-D and 3-D revealing their topographic relations.

Results: Anatomy of the corticospinal tract, optic radiation and arcuate fascicle as well as the cingulum and fornix is known. The medial forebrain bundle can be assigned to the limbic system and has gained new interest especially in the field of functional sterotactic neurosurgery since several patients have suffered from psychiatric symptoms after deep brain stimulation. These might be explained by accidental stimulation of this tract due to slightly misplaced electrodes. We additionally show the course of 5 major association pathways, the superior and inferior longitudinal, the superior and inferior occipitofrontal and uncinate fascicles and their topographical relations / intermingling with e.g. the corticospinal tract.

Conclusions: We could show that despite the limitations of the line propagation technique the program here used enables visualization of anatomically precise fiber tract information with sufficient accuracy for neurosurgical purposes and intraoperative neuronavigation.