Abstract
BackgroundAn increasing number of neurosurgeons use display of the dentato-rubro-thalamic tract (DRT) based on diffusion weighted imaging (dMRI) as basis for their routine planning of stimulation or lesioning approaches in stereotactic tremor surgery. An evaluation of the anatomical validity of the display of the DRT with respect to modern stereotactic planning systems and across different tracking environments has not been performed.MethodsDistinct dMRI and anatomical magnetic resonance imaging (MRI) data of high and low quality from 9 subjects were used. Six subjects had repeated MRI scans and therefore entered the analysis twice. Standardized DICOM structure templates for volume of interest definition were applied in native space for all investigations. For tracking BrainLab Elements (BrainLab, Munich, Germany), two tensor deterministic tracking (FT2), MRtrix IFOD2 (https://www.mrtrix.org), and a global tracking (GT) approach were used to compare the display of the uncrossed (DRTu) and crossed (DRTx) fiber structure after transformation into MNI space. The resulting streamlines were investigated for congruence, reproducibility, anatomical validity, and penetration of anatomical way point structures.ResultsIn general, the DRTu can be depicted with good quality (as judged by waypoints). FT2 (surgical) and GT (neuroscientific) show high congruence. While GT shows partly reproducible results for DRTx, the crossed pathway cannot be reliably reconstructed with the other (iFOD2 and FT2) algorithms.ConclusionSince a direct anatomical comparison is difficult in the individual subjects, we chose a comparison with two research tracking environments as the best possible “ground truth.” FT2 is useful especially because of its manual editing possibilities of cutting erroneous fibers on the single subject level. An uncertainty of 2 mm as mean displacement of DRTu is expectable and should be respected when using this approach for surgical planning. Tractographic renditions of the DRTx on the single subject level seem to be still illusive.
Highlights
MethodsStereotactic surgery for tremor of various origins has typically targeted the ventral intermediate nucleus of the thalamus (Vim) [7, 71]
Problems appear for Crossed dentato-rubro-thalamic tract (DRT)(T) (DRTx), in particular for 2 Tensor deflection algorithm (FT2), where the reconstruction fails quite often; i.e., only a very low number of streamlines is found or no streamlines at all
We show the median of the center of gravity (COG) deviations along the z-coordinate (Fig. 4) together with three distinct z-levels in Fig. 5 (z = − 22, superior cerebellar peduncle, scp, z = 6 ventral intermediate nucleus Vim, z = − 8 nucleus ruber Red nucleus (RN), Montreal Neurological Institute (MNI) coordinates) as bar plots
Summary
MethodsStereotactic surgery for tremor of various origins has typically targeted the ventral intermediate nucleus of the thalamus (Vim) [7, 71]. There is evidence that the effective target of tremor surgery might be one distinct part of the tremor network which can readily be depicted with non-invasive diffusion weighted imaging (dMRI) technology [15]. This target is the cerebello-thalamo-cortical pathway—by some authors called the dentato-rubro-thalamic tract (DRT) (Fig. 1)— which penetrates all classical stereotactic targets for tremor surgery [14, 15], namely the ventral intermediate nucleus of the thalamus [6, 7] and the posterior subthalamic region (pSTR) [33] including the caudal zona incerta (cZI) [3, 48, 49]. Tractographic renditions of the DRTx on the single subject level seem to be still illusive
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