Limits...
Patient-tailored connectomics visualization for the assessment of white matter atrophy in traumatic brain injury.

Irimia A, Chambers MC, Torgerson CM, Filippou M, Hovda DA, Alger JR, Gerig G, Toga AW, Vespa PM, Kikinis R, Van Horn JD - Front Neurol (2012)

Bottom Line: Specifically, we introduce a graphically driven approach for the assessment of trauma-related atrophy of white matter connections between cortical structures, with relevance to the quantification of TBI chronic case evolution.In addition, it allows one to relate the findings supplied by our workflow to the existing body of research that focuses on the functional roles of the cortical structures being targeted.A graphical means for representing patient TBI status is relevant to the emerging field of personalized medicine and to the investigation of neural atrophy.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neuro Imaging, Department of Neurology, University of California Los Angeles Los Angeles, CA, USA.

ABSTRACT
Available approaches to the investigation of traumatic brain injury (TBI) are frequently hampered, to some extent, by the unsatisfactory abilities of existing methodologies to efficiently define and represent affected structural connectivity and functional mechanisms underlying TBI-related pathology. In this paper, we describe a patient-tailored framework which allows mapping and characterization of TBI-related structural damage to the brain via multimodal neuroimaging and personalized connectomics. Specifically, we introduce a graphically driven approach for the assessment of trauma-related atrophy of white matter connections between cortical structures, with relevance to the quantification of TBI chronic case evolution. This approach allows one to inform the formulation of graphical neurophysiological and neuropsychological TBI profiles based on the particular structural deficits of the affected patient. In addition, it allows one to relate the findings supplied by our workflow to the existing body of research that focuses on the functional roles of the cortical structures being targeted. A graphical means for representing patient TBI status is relevant to the emerging field of personalized medicine and to the investigation of neural atrophy.

No MeSH data available.


Related in: MedlinePlus

Connectogram of the atrophy profile for patient 1. Links displayed indicate connections that suffered large atrophy from the acute baseline to the chronic follow-up time point. Link transparency encodes the percentage change Δ in fiber density (see Methods), in the range [min{/Δ/}, max{/Δ/}], with larger changes (more negative values of Δ) being encoded by more opaque hues of blue. The lowest color opacity corresponds to the smallest absolute value of the percentage change that is greater than the chosen threshold of 20%, and the highest opacity corresponds to the maximum absolute value of the change in fiber density.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3275792&req=5

Figure 7: Connectogram of the atrophy profile for patient 1. Links displayed indicate connections that suffered large atrophy from the acute baseline to the chronic follow-up time point. Link transparency encodes the percentage change Δ in fiber density (see Methods), in the range [min{/Δ/}, max{/Δ/}], with larger changes (more negative values of Δ) being encoded by more opaque hues of blue. The lowest color opacity corresponds to the smallest absolute value of the percentage change that is greater than the chosen threshold of 20%, and the highest opacity corresponds to the maximum absolute value of the change in fiber density.

Mentions: To calculate inter-region connectivity, the location of each fiber tract extremity was identified and each fiber extremity was associated with the appropriate parcelation. This was performed for all fibers that both originated and ended within any two distinct parcelations. Appropriate connectivity matrix entries were updated as necessary to reflect fiber count increments (Hagmann et al., 2008, 2010). To validate the accuracy of the connectivity matrix algorithm, its results were reproduced by individually counting in 3D Slicer all fibers that had exactly one extremity within the volumetric extent of some given parcelation, and by repeating this procedure over several test subjects. Each entry in the connectivity matrix was normalized by the total number of fibers in the entire brain based on the MR volume acquired at each time point and the resulting normalized fiber counts were used for ulterior calculations. Whenever fibers existed between a cortical region affected by pathology and another that was unaffected, the color of the corresponding link was brown. Similarly, links between parcelations that were both affected by pathology were drawn in gray. Thus, one can distinguish between connections that involve only one affected region (brown links) or two affected regions (gray links). Above and throughout, regions affected by pathology are understood to represent regions that contain pathological tissue of any type as obviated by MRI. For connectograms displaying WM atrophy that occurred between the acute and chronic time points, links associated with atrophy (decrease in fiber density) were drawn in blue. The transparency level was directly proportional to the percentage change in fiber density (see also section below). In the case of connectograms displaying atrophy measures (Figures 7–9), the colors on the five inner rings of each connectogram indicate percentage differences in each measure m (where m can be cortical area, cortical thickness, curvature, or GM volume), computed between the acute and chronic time points (t1 and t2, respectively). Percentage differences were computed using the formula [m(t2) − m(t1)] × 100/m(t1), i.e., as percentage changes with respect to the acute baseline time point.


Patient-tailored connectomics visualization for the assessment of white matter atrophy in traumatic brain injury.

Irimia A, Chambers MC, Torgerson CM, Filippou M, Hovda DA, Alger JR, Gerig G, Toga AW, Vespa PM, Kikinis R, Van Horn JD - Front Neurol (2012)

Connectogram of the atrophy profile for patient 1. Links displayed indicate connections that suffered large atrophy from the acute baseline to the chronic follow-up time point. Link transparency encodes the percentage change Δ in fiber density (see Methods), in the range [min{/Δ/}, max{/Δ/}], with larger changes (more negative values of Δ) being encoded by more opaque hues of blue. The lowest color opacity corresponds to the smallest absolute value of the percentage change that is greater than the chosen threshold of 20%, and the highest opacity corresponds to the maximum absolute value of the change in fiber density.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3275792&req=5

Figure 7: Connectogram of the atrophy profile for patient 1. Links displayed indicate connections that suffered large atrophy from the acute baseline to the chronic follow-up time point. Link transparency encodes the percentage change Δ in fiber density (see Methods), in the range [min{/Δ/}, max{/Δ/}], with larger changes (more negative values of Δ) being encoded by more opaque hues of blue. The lowest color opacity corresponds to the smallest absolute value of the percentage change that is greater than the chosen threshold of 20%, and the highest opacity corresponds to the maximum absolute value of the change in fiber density.
Mentions: To calculate inter-region connectivity, the location of each fiber tract extremity was identified and each fiber extremity was associated with the appropriate parcelation. This was performed for all fibers that both originated and ended within any two distinct parcelations. Appropriate connectivity matrix entries were updated as necessary to reflect fiber count increments (Hagmann et al., 2008, 2010). To validate the accuracy of the connectivity matrix algorithm, its results were reproduced by individually counting in 3D Slicer all fibers that had exactly one extremity within the volumetric extent of some given parcelation, and by repeating this procedure over several test subjects. Each entry in the connectivity matrix was normalized by the total number of fibers in the entire brain based on the MR volume acquired at each time point and the resulting normalized fiber counts were used for ulterior calculations. Whenever fibers existed between a cortical region affected by pathology and another that was unaffected, the color of the corresponding link was brown. Similarly, links between parcelations that were both affected by pathology were drawn in gray. Thus, one can distinguish between connections that involve only one affected region (brown links) or two affected regions (gray links). Above and throughout, regions affected by pathology are understood to represent regions that contain pathological tissue of any type as obviated by MRI. For connectograms displaying WM atrophy that occurred between the acute and chronic time points, links associated with atrophy (decrease in fiber density) were drawn in blue. The transparency level was directly proportional to the percentage change in fiber density (see also section below). In the case of connectograms displaying atrophy measures (Figures 7–9), the colors on the five inner rings of each connectogram indicate percentage differences in each measure m (where m can be cortical area, cortical thickness, curvature, or GM volume), computed between the acute and chronic time points (t1 and t2, respectively). Percentage differences were computed using the formula [m(t2) − m(t1)] × 100/m(t1), i.e., as percentage changes with respect to the acute baseline time point.

Bottom Line: Specifically, we introduce a graphically driven approach for the assessment of trauma-related atrophy of white matter connections between cortical structures, with relevance to the quantification of TBI chronic case evolution.In addition, it allows one to relate the findings supplied by our workflow to the existing body of research that focuses on the functional roles of the cortical structures being targeted.A graphical means for representing patient TBI status is relevant to the emerging field of personalized medicine and to the investigation of neural atrophy.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neuro Imaging, Department of Neurology, University of California Los Angeles Los Angeles, CA, USA.

ABSTRACT
Available approaches to the investigation of traumatic brain injury (TBI) are frequently hampered, to some extent, by the unsatisfactory abilities of existing methodologies to efficiently define and represent affected structural connectivity and functional mechanisms underlying TBI-related pathology. In this paper, we describe a patient-tailored framework which allows mapping and characterization of TBI-related structural damage to the brain via multimodal neuroimaging and personalized connectomics. Specifically, we introduce a graphically driven approach for the assessment of trauma-related atrophy of white matter connections between cortical structures, with relevance to the quantification of TBI chronic case evolution. This approach allows one to inform the formulation of graphical neurophysiological and neuropsychological TBI profiles based on the particular structural deficits of the affected patient. In addition, it allows one to relate the findings supplied by our workflow to the existing body of research that focuses on the functional roles of the cortical structures being targeted. A graphical means for representing patient TBI status is relevant to the emerging field of personalized medicine and to the investigation of neural atrophy.

No MeSH data available.


Related in: MedlinePlus