Article
Fibertracking in Deep Brain Stimulation:Comparing two sets of regions of interest to delineate cerebellar thalamic fibers
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Published: | June 9, 2017 |
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Objective: The thesis of targeting fiber tracts rather than nuclei in deep brain stimulation (DBS) has been discussed for many years now. MRI based diffusion tractography seems to be a thrilling, non invasive tool to depict the fiber tracts of interest and to improve target planning. Here, we present and compare two different methods of tracing cerebellar- thalamic connections and try to validate the methods’ anatomic accuracy.
Methods: Data of 6 patients who have received DBS in our center were analyzed. As part of the preoperative MR-imaging, diffusion weighted images (DWI) with 12 and 64 read out directions were performed. On these image data sets, we performed deterministic fiber tracking (iPlan Stereotaxy software, Brainlab) and probabilistic fiber tracking (FSL software) placing the regions of interest (ROI) in the contralateral dentate nucleus, superior cerebellar peduncle and ipsilatetal red nucleus (dentate-rubro-thalmic-tract, DRTT). For further comparison, we performed deterministic fiber tracking (12 and 64 read out directions) of the cortico-thalamic-cerebellar-tract, CTC, with ROIs set in the ipsilateral red nucleus and primary motor cortex. We compared the tracts´ center of mass and the tracts´closest distance to the atlas based VIM target-point.
Results: The deterministic algorithm could not depict the DRTT in data sets with 64 read out directions in ten of twelve hemispheres. The depiction of the CTC was successful in all hemispheres, with deterministic tractography. Probabilistic tractography presented a robust delineation of the DRTT in all hemispheres. The distance from the atlas based VIM target to the center of mass of the CTC compared to the DRTT was significantly shorter (p=0.02) when tracked deterministically with 12 read out directions.
Conclusion: The detection of the CTC with deterministic fibertracking is more robust than the detection of the DRTT especially when DWIs with higher numbers of gradient directions are used. Noteworthy, the courses of CTC and DRTT are not congruent.