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Motor pathway degeneration in young ataxia telangiectasia patients: A diffusion tractography study.

Sahama I, Sinclair K, Fiori S, Doecke J, Pannek K, Reid L, Lavin M, Rose S - Neuroimage Clin (2015)

Bottom Line: White matter fiber tracking and whole tract statistical analyses were used to assess quantitative fractional anisotropy and mean diffusivity differences along the cortico-ponto-cerebellar, cerebellar-thalamo-cortical, somatosensory and lateral corticospinal tract length in patients using a linear mixed effects model.Mean diffusivity was significantly elevated in anterior tract locations but was reduced within cerebellar peduncle regions of all patient tracts (p < 0.001).In addition, reduced apparent fiber density in the left and right corticospinal and right somatosensory tracts (p < 0.006) occurred in patients.

View Article: PubMed Central - PubMed

Affiliation: University of Queensland, School of Medicine, Brisbane, Australia.

ABSTRACT

Background: Our understanding of the effect of ataxia-telangiectasia mutated gene mutations on brain structure and function is limited. In this study, white matter motor pathway integrity was investigated in ataxia telangiectasia patients using diffusion MRI and probabilistic tractography.

Methods: Diffusion MRI were obtained from 12 patients (age range: 7-22 years, mean: 12 years) and 12 typically developing age matched participants (age range 8-23 years, mean: 13 years). White matter fiber tracking and whole tract statistical analyses were used to assess quantitative fractional anisotropy and mean diffusivity differences along the cortico-ponto-cerebellar, cerebellar-thalamo-cortical, somatosensory and lateral corticospinal tract length in patients using a linear mixed effects model. White matter tract streamline number and apparent fiber density in patient and control tracts were also assessed.

Results: Reduced fractional anisotropy along all analyzed patient tracts were observed (p < 0.001). Mean diffusivity was significantly elevated in anterior tract locations but was reduced within cerebellar peduncle regions of all patient tracts (p < 0.001). Reduced tract streamline number and tract volume in the left and right corticospinal and somatosensory tracts were observed in patients (p < 0.006). In addition, reduced apparent fiber density in the left and right corticospinal and right somatosensory tracts (p < 0.006) occurred in patients.

Conclusions: Whole tract analysis of the corticomotor, corticospinal and somatosensory pathways in ataxia telangiectasia showed significant white matter degeneration along the entire length of motor circuits, highlighting that ataxia-telangiectasia gene mutation impacts the cerebellum and multiple other motor circuits in young patients.

No MeSH data available.


Related in: MedlinePlus

Region of interest (ROI) placement for representative somatosensory motor cortex tracts for a control participant (age 23): corticospinal (CST), somatosensory (Somato), cortico-ponto-cerebellar (CPC) and cerebellar-thalamo-cortical (CTC) tract ROIs in the cerebral cortex (first row) and cerebellar peduncles (second row). Coloration is based on the direction of water diffusion (Blue: ascending–descending diffusion; Red: left–right diffusion; Green: anterior–posterior diffusion).
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f0005: Region of interest (ROI) placement for representative somatosensory motor cortex tracts for a control participant (age 23): corticospinal (CST), somatosensory (Somato), cortico-ponto-cerebellar (CPC) and cerebellar-thalamo-cortical (CTC) tract ROIs in the cerebral cortex (first row) and cerebellar peduncles (second row). Coloration is based on the direction of water diffusion (Blue: ascending–descending diffusion; Red: left–right diffusion; Green: anterior–posterior diffusion).

Mentions: Probabilistic tractography was performed using MRtrix3. To extract WM fiber tracks of interest, anatomically constrained tractography (ACT) (Smith et al., 2012) was performed. T1 co-registration to the diffusion imaging series, and subsequent FSL BET/FAST/FIRST processing on structural data as per the MRtrix 3 ‘act_anat_prepare_fsl’ script were conducted to produce a five tissue types mask, to generate whole brain tractograms comprising fifty million streamlines (Tournier et al., 2012). Wholebrain tractograms were subsequently processed using the Spherical-deconvolution Informed Filtering of Tractograms (SIFT) procedure introduced in MRtrix3, resulting in twenty-five million streamlines (Smith et al., 2013), to reduce false positive streamlines. The MRtrix package was used to select regions-of-interest (ROIs) to enable extraction of the CPC, CTC, CST and somatosensory fiber tracks from SIFTed wholebrain tractograms. ROIs, particularly for the CST and somatosensory tracts, were identified using established target regions specific to children (Kamali et al., 2010; Kumar et al., 2009) and verified manually by an expert child neurologist (SF). ROIs were placed in the precentral and postcentral gyri and spinal cord for CST, postcentral gyrus and spinal cord for the somatosensory tracts and cerebral hemispheres and opposing medial cerebellar peduncle and superior cerebellar peduncle regions for the CPC and CTC tracts respectively (Fig. 1).


Motor pathway degeneration in young ataxia telangiectasia patients: A diffusion tractography study.

Sahama I, Sinclair K, Fiori S, Doecke J, Pannek K, Reid L, Lavin M, Rose S - Neuroimage Clin (2015)

Region of interest (ROI) placement for representative somatosensory motor cortex tracts for a control participant (age 23): corticospinal (CST), somatosensory (Somato), cortico-ponto-cerebellar (CPC) and cerebellar-thalamo-cortical (CTC) tract ROIs in the cerebral cortex (first row) and cerebellar peduncles (second row). Coloration is based on the direction of water diffusion (Blue: ascending–descending diffusion; Red: left–right diffusion; Green: anterior–posterior diffusion).
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561673&req=5

f0005: Region of interest (ROI) placement for representative somatosensory motor cortex tracts for a control participant (age 23): corticospinal (CST), somatosensory (Somato), cortico-ponto-cerebellar (CPC) and cerebellar-thalamo-cortical (CTC) tract ROIs in the cerebral cortex (first row) and cerebellar peduncles (second row). Coloration is based on the direction of water diffusion (Blue: ascending–descending diffusion; Red: left–right diffusion; Green: anterior–posterior diffusion).
Mentions: Probabilistic tractography was performed using MRtrix3. To extract WM fiber tracks of interest, anatomically constrained tractography (ACT) (Smith et al., 2012) was performed. T1 co-registration to the diffusion imaging series, and subsequent FSL BET/FAST/FIRST processing on structural data as per the MRtrix 3 ‘act_anat_prepare_fsl’ script were conducted to produce a five tissue types mask, to generate whole brain tractograms comprising fifty million streamlines (Tournier et al., 2012). Wholebrain tractograms were subsequently processed using the Spherical-deconvolution Informed Filtering of Tractograms (SIFT) procedure introduced in MRtrix3, resulting in twenty-five million streamlines (Smith et al., 2013), to reduce false positive streamlines. The MRtrix package was used to select regions-of-interest (ROIs) to enable extraction of the CPC, CTC, CST and somatosensory fiber tracks from SIFTed wholebrain tractograms. ROIs, particularly for the CST and somatosensory tracts, were identified using established target regions specific to children (Kamali et al., 2010; Kumar et al., 2009) and verified manually by an expert child neurologist (SF). ROIs were placed in the precentral and postcentral gyri and spinal cord for CST, postcentral gyrus and spinal cord for the somatosensory tracts and cerebral hemispheres and opposing medial cerebellar peduncle and superior cerebellar peduncle regions for the CPC and CTC tracts respectively (Fig. 1).

Bottom Line: White matter fiber tracking and whole tract statistical analyses were used to assess quantitative fractional anisotropy and mean diffusivity differences along the cortico-ponto-cerebellar, cerebellar-thalamo-cortical, somatosensory and lateral corticospinal tract length in patients using a linear mixed effects model.Mean diffusivity was significantly elevated in anterior tract locations but was reduced within cerebellar peduncle regions of all patient tracts (p < 0.001).In addition, reduced apparent fiber density in the left and right corticospinal and right somatosensory tracts (p < 0.006) occurred in patients.

View Article: PubMed Central - PubMed

Affiliation: University of Queensland, School of Medicine, Brisbane, Australia.

ABSTRACT

Background: Our understanding of the effect of ataxia-telangiectasia mutated gene mutations on brain structure and function is limited. In this study, white matter motor pathway integrity was investigated in ataxia telangiectasia patients using diffusion MRI and probabilistic tractography.

Methods: Diffusion MRI were obtained from 12 patients (age range: 7-22 years, mean: 12 years) and 12 typically developing age matched participants (age range 8-23 years, mean: 13 years). White matter fiber tracking and whole tract statistical analyses were used to assess quantitative fractional anisotropy and mean diffusivity differences along the cortico-ponto-cerebellar, cerebellar-thalamo-cortical, somatosensory and lateral corticospinal tract length in patients using a linear mixed effects model. White matter tract streamline number and apparent fiber density in patient and control tracts were also assessed.

Results: Reduced fractional anisotropy along all analyzed patient tracts were observed (p < 0.001). Mean diffusivity was significantly elevated in anterior tract locations but was reduced within cerebellar peduncle regions of all patient tracts (p < 0.001). Reduced tract streamline number and tract volume in the left and right corticospinal and somatosensory tracts were observed in patients (p < 0.006). In addition, reduced apparent fiber density in the left and right corticospinal and right somatosensory tracts (p < 0.006) occurred in patients.

Conclusions: Whole tract analysis of the corticomotor, corticospinal and somatosensory pathways in ataxia telangiectasia showed significant white matter degeneration along the entire length of motor circuits, highlighting that ataxia-telangiectasia gene mutation impacts the cerebellum and multiple other motor circuits in young patients.

No MeSH data available.


Related in: MedlinePlus