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Optic radiation structure and anatomy in the normally developing brain determined using diffusion MRI and tractography.

Dayan M, Munoz M, Jentschke S, Chadwick MJ, Cooper JM, Riney K, Vargha-Khadem F, Clark CA - Brain Struct Funct (2013)

Bottom Line: Left lateralization of DTI metrics was observed that showed a gender effect in lateralization.Sexual dimorphism of DTI metrics in the right hemisphere was also found.The anatomical results presented for the OR have potentially important applications for neurosurgical planning.

View Article: PubMed Central - PubMed

Affiliation: Imaging and Biophysics Unit, UCL Institute of Child Health, London, UK, mdayan.research@gmail.com.

ABSTRACT
The optic radiation (OR) is a component of the visual system known to be myelin mature very early in life. Diffusion tensor imaging (DTI) and its unique ability to reconstruct the OR in vivo were used to study structural maturation through analysis of DTI metrics in a cohort of 90 children aged 5-18 years. As the OR is at risk of damage during epilepsy surgery, we measured its position relative to characteristic anatomical landmarks. Anatomical distances, DTI metrics and volume of the OR were investigated for age, gender and hemisphere effects. We observed changes in DTI metrics with age comparable to known trajectories in other white matter tracts. Left lateralization of DTI metrics was observed that showed a gender effect in lateralization. Sexual dimorphism of DTI metrics in the right hemisphere was also found. With respect to OR dimensions, volume was shown to be right lateralised and sexual dimorphism demonstrated for the extent of the left OR. The anatomical results presented for the OR have potentially important applications for neurosurgical planning.

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Example of probabilistic map of the OR to which is applied a PICo threshold of 1 % represented in a coronal (a), sagittal (b) and axial (c) plane. The OR reconstruction is displayed in a linear hot colour scale ranging from just above 0 (red) to 1 (yellow). The background FA map is shown in greyscale and the main diffusion directions in each voxel are shown as small red segments
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Fig6: Example of probabilistic map of the OR to which is applied a PICo threshold of 1 % represented in a coronal (a), sagittal (b) and axial (c) plane. The OR reconstruction is displayed in a linear hot colour scale ranging from just above 0 (red) to 1 (yellow). The background FA map is shown in greyscale and the main diffusion directions in each voxel are shown as small red segments

Mentions: An example of a probability map with PICo threshold 1 % obtained for one representative subject is shown in Fig. 6. The greyscale background image is an FA map, while the red segments indicate the main diffusion direction. The value of the tractography probability in each voxel is displayed on a linear scale from just above 0 in pure red (one track went through that voxel) to 1 in pure yellow (all the tracts generated passed through that voxel). The reconstruction of the OR was satisfactory in all subjects. The distinctive shape of ML was clearly visible in all subjects, and the entirety of the OR—from the LGN to the occipital lobe—could be systematically segmented. The reconstructed tracts run along the lateral ventricles as expected, before curving medially towards the mid-sagittal plane. Also the exclusion masks were particularly efficient at removing most artefactual tracts as only very few of these were visible in the final segmentation.Fig. 6


Optic radiation structure and anatomy in the normally developing brain determined using diffusion MRI and tractography.

Dayan M, Munoz M, Jentschke S, Chadwick MJ, Cooper JM, Riney K, Vargha-Khadem F, Clark CA - Brain Struct Funct (2013)

Example of probabilistic map of the OR to which is applied a PICo threshold of 1 % represented in a coronal (a), sagittal (b) and axial (c) plane. The OR reconstruction is displayed in a linear hot colour scale ranging from just above 0 (red) to 1 (yellow). The background FA map is shown in greyscale and the main diffusion directions in each voxel are shown as small red segments
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4286633&req=5

Fig6: Example of probabilistic map of the OR to which is applied a PICo threshold of 1 % represented in a coronal (a), sagittal (b) and axial (c) plane. The OR reconstruction is displayed in a linear hot colour scale ranging from just above 0 (red) to 1 (yellow). The background FA map is shown in greyscale and the main diffusion directions in each voxel are shown as small red segments
Mentions: An example of a probability map with PICo threshold 1 % obtained for one representative subject is shown in Fig. 6. The greyscale background image is an FA map, while the red segments indicate the main diffusion direction. The value of the tractography probability in each voxel is displayed on a linear scale from just above 0 in pure red (one track went through that voxel) to 1 in pure yellow (all the tracts generated passed through that voxel). The reconstruction of the OR was satisfactory in all subjects. The distinctive shape of ML was clearly visible in all subjects, and the entirety of the OR—from the LGN to the occipital lobe—could be systematically segmented. The reconstructed tracts run along the lateral ventricles as expected, before curving medially towards the mid-sagittal plane. Also the exclusion masks were particularly efficient at removing most artefactual tracts as only very few of these were visible in the final segmentation.Fig. 6

Bottom Line: Left lateralization of DTI metrics was observed that showed a gender effect in lateralization.Sexual dimorphism of DTI metrics in the right hemisphere was also found.The anatomical results presented for the OR have potentially important applications for neurosurgical planning.

View Article: PubMed Central - PubMed

Affiliation: Imaging and Biophysics Unit, UCL Institute of Child Health, London, UK, mdayan.research@gmail.com.

ABSTRACT
The optic radiation (OR) is a component of the visual system known to be myelin mature very early in life. Diffusion tensor imaging (DTI) and its unique ability to reconstruct the OR in vivo were used to study structural maturation through analysis of DTI metrics in a cohort of 90 children aged 5-18 years. As the OR is at risk of damage during epilepsy surgery, we measured its position relative to characteristic anatomical landmarks. Anatomical distances, DTI metrics and volume of the OR were investigated for age, gender and hemisphere effects. We observed changes in DTI metrics with age comparable to known trajectories in other white matter tracts. Left lateralization of DTI metrics was observed that showed a gender effect in lateralization. Sexual dimorphism of DTI metrics in the right hemisphere was also found. With respect to OR dimensions, volume was shown to be right lateralised and sexual dimorphism demonstrated for the extent of the left OR. The anatomical results presented for the OR have potentially important applications for neurosurgical planning.

Show MeSH
Related in: MedlinePlus