Difference between revisions of "NA"

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'''Objective:''' Developing new methods for statistical group tests of diffusion tensor data. Our goal is to be able to detect subtle white matter differences between schizophrenics and normal controls beyond what can be detected today using current methods.
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'''Objective:''' To use DTI to quantify the integrity of interhemispheric connectivity in schizophrenic patients, by measuring fractional anisotropy (FA) and other diffusion measures in both corpus collosum (CC) and anterior commissure (AC) fibers. To the best of our knowledge, no previous study has analyzed diffusion measures along the anterior commissure.
  
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'''Progress:'''
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<br />'''Progress:''' We have implemented a scanning protocol by which we obtain several midline sagittal slices, allowing high resolution data of both the midsagittal corpus callosum and the anterior commisure. Preliminary results (methods currently being improved) indicate decreased FA in the midsagittal corpus callosum in schizophrenics, and decreased overall diffusivity in both the corpus callosum and anterior commisure. We are currently utilizing fiber tracking in these structures to calculate FA (and other diffusion measures) along both CC and AC fibers. We are considering using smoothed data to create these fibers. We are also using automatic clustering to separate anatomically similar fibers, and compare diffusion measures along fibers extending to different brain regions.
  
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* We are applying our methods to the cingulum bundle data from Harvard. First, we have developed a new measure of anisotropy, called geodesic anisotropy (GA), that we are comparing with the standard fractional anisotropy (FA) to see if it gives more statistical power in group tests. Our results on the cingulum bundle data have shown similar results using FA or GA, that is, they show no advantage to using GA over FA. Another method that we are developing compares distributions of data within regions of interest rather than just a single summary measurement. Our preliminary results have not shown differences that are detectable using the mean FA, and we are working to improve upon the methodology. Finally, we are building DTI processing tools to help Core 3 researchers, including methods for interpolating, filtering, and segmenting DTI.
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<br />'''Key Investigators:'''
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* March 25, 2005. University of Utah visit of Harvard VA for collaborative work on DTMRI.
 
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** Presentation of non linear statistics for tensors by Tom Fletcher.
 
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** Possible collaboration on comparing new and old anisotropy measures in the context of Schizophrenia.
 
  
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'''Key Investigators:'''
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* Marek Kubicki, BWH
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* Lauren O'Donnell, MIT
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* Mark Dreusicke, BWH
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* Doug Markant, BWH
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* Carl-Fredrik Westin, BWH
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* Martha Shenton, BWH
  
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* Utah: Tom Fletcher, Ross Whitaker.
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<br />'''Links:'''
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* PNL: Sylvain Bouix, Marek Kubicki, Martha Shenton.
 
  
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'''Links:'''
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* Progress on improving the method used to create corpus callosum ROIs [[DBP:Harvard:Software:Bugs:Corpus_Callosum|'''here''']].
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* Images of corpus callosum fibers using smoothed vs. unsmoothed data [[DBP:Harvard:Software:Bugs:Corpus_Callosum_Fibers|'''here''']].
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* http://pnl.bwh.harvard.edu/index.html
 
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Revision as of 14:03, 18 December 2006

Home < NA

Objective: To use DTI to quantify the integrity of interhemispheric connectivity in schizophrenic patients, by measuring fractional anisotropy (FA) and other diffusion measures in both corpus collosum (CC) and anterior commissure (AC) fibers. To the best of our knowledge, no previous study has analyzed diffusion measures along the anterior commissure.


Progress: We have implemented a scanning protocol by which we obtain several midline sagittal slices, allowing high resolution data of both the midsagittal corpus callosum and the anterior commisure. Preliminary results (methods currently being improved) indicate decreased FA in the midsagittal corpus callosum in schizophrenics, and decreased overall diffusivity in both the corpus callosum and anterior commisure. We are currently utilizing fiber tracking in these structures to calculate FA (and other diffusion measures) along both CC and AC fibers. We are considering using smoothed data to create these fibers. We are also using automatic clustering to separate anatomically similar fibers, and compare diffusion measures along fibers extending to different brain regions.


Key Investigators:

  • Marek Kubicki, BWH
  • Lauren O'Donnell, MIT
  • Mark Dreusicke, BWH
  • Doug Markant, BWH
  • Carl-Fredrik Westin, BWH
  • Martha Shenton, BWH


Links:

  • Progress on improving the method used to create corpus callosum ROIs here.
  • Images of corpus callosum fibers using smoothed vs. unsmoothed data here.
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