Article

Reproducibility of thalamic segmentation based on probabilistic tractography.

King's College London Institute of Psychiatry, Department of Clinical Neuroscience, England, UK.
NeuroImage (impact factor: 5.89). 08/2010; 52(1):69-85. DOI:10.1016/j.neuroimage.2010.04.024 pp.69-85
Source: PubMed

ABSTRACT Reliable identification of thalamic nuclei is required to improve targeting of electrodes used in Deep Brain Stimulation (DBS), and for exploring the role of thalamus in health and disease. A previously described method using probabilistic tractography to segment the thalamus based on connections to cortical target regions was implemented. Both within- and between-subject reproducibility were quantitatively assessed by the overlap of the resulting segmentations; the effect of two different numbers of target regions (6 and 31) on reproducibility of the segmentation results was also investigated. Very high reproducibility was observed when a single dataset was processed multiple times using different starting conditions. Thalamic segmentation was also very reproducible when multiple datasets from the same subject were processed using six cortical target regions. Within-subject reproducibility was reduced when the number of target regions was increased, particularly in medial and posterior regions of the thalamus. A large degree of overlap in segmentation results from different subjects was obtained, particularly in thalamic regions classified as connecting to frontal, parietal, temporal and pre-central cortical target regions.

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    Article: Target identification for stereotactic thalamotomy using diffusion tractography.
    Zsigmond Tamás Kincses, Nikoletta Szabó, István Valálik, Zsolt Kopniczky, Lívia Dézsi, Péter Klivényi, Mark Jenkinson, András Király, Magor Babos, Erika Vörös, Pál Barzó, László Vécsei
    [show abstract] [hide abstract]
    ABSTRACT: Stereotactic targets for thalamotomy are usually derived from population-based coordinates. Individual anatomy is used only to scale the coordinates based on the location of some internal guide points. While on conventional MR imaging the thalamic nuclei are indistinguishable, recently it has become possible to identify individual thalamic nuclei using different connectivity profiles, as defined by MR diffusion tractography. Here we investigated the inter-individual variation of the location of target nuclei for thalamotomy: the putative ventralis oralis posterior (Vop) and the ventral intermedius (Vim) nucleus as defined by probabilistic tractography. We showed that the mean inter-individual distance of the peak Vop location is 7.33 mm and 7.42 mm for Vim. The mean overlap between individual Vop nuclei was 40.2% and it was 31.8% for Vim nuclei. As a proof of concept, we also present a patient who underwent Vop thalamotomy for untreatable tremor caused by traumatic brain injury and another patient who underwent Vim thalamotomy for essential tremor. The probabilistic tractography indicated that the successful tremor control was achieved with lesions in the Vop and Vim respectively. Our data call attention to the need for a better appreciation of the individual anatomy when planning stereotactic functional neurosurgery.
    PLoS ONE 01/2012; 7(1):e29969. · 4.09 Impact Factor
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Keywords

between-subject reproducibility
 
Brain Stimulation
 
cortical target regions
 
described method
 
different subjects
 
electrodes
 
large degree
 
medial
 
multiple times
 
pre-central cortical target regions
 
probabilistic tractography
 
Reliable identification
 
resulting segmentations
 
segmentation results
 
single dataset
 
target regions
 
thalamic nuclei
 
Thalamic segmentation
 
thalamus
 
Within-subject reproducibility