الفهرس 
Radiological anatomy of the cerebral cortex using MRIOnly 14 pages are availabe for public view
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Abstract
Cerebral stroke is a worldwide concern, it’s classified as the most second cause of death. Annually, 5.7 million deaths & about nine million patients had cerebral strokes events in 2008 with resultant variable degrees of disabilities.
The primary goal in stroke management is to reach an early accurate diagnosis for the patients, which will affect the choice of the treatment lines among the newly developed programs and the end stage recovery.
The DTI & the DT based tractography are new techniques depend on the directional movement of water which is determined by the brain micro-structures and imaged on the diffusion sensitive MRI to generate virtual, three dimensional representations of the white matter fiber tracts. The ability of the trace of the white matter pathway in non-invasive way is the reason why the tractography has generated much enthusiasm and high expectations.
The diffusion tensor is a mathematical description of the magnitude and directionality (anisotropy) of the movement of water molecules in a three-dimensional space. In the brain white matter, diffusion is directional (anisotropic) along the fibres because molecules move more easily parallel to tracts and are mostly hindered or restricted in their movement perpendicular to tracts. Therefore, the diffusion tensor gives two important pieces of information in each imaging voxel: the magnitude of diffusion anisotropy and the orientation of the maximum diffusion. Tractography algorithms use this information to track the whole white matter pathway by inferring the continuity of fibre paths from voxel to voxel in the brain.
This study is aiming to evaluate this new technique in ischemic cerebral strokes patients and its effectiveness in predicting the clinical outcome in such cases.
One hundered patients with ischemic cerebral strokes were recruited in this study which was done in the Kobery Elkobah Military compound.
These patients were evaluated clinically at the time of the admission by using the NIHSS, then imaging of these patients within one week of the admission by conventional MRI and adding DTI sequence to the study.
The DTI was transferred to workstation where all tracts related to the infarction site were reconstructed.
The evaluation method for this study was by measuring the fractional anisotropy & the tract fiber numbers on the affected side and comparing with the similar results on the healthy contra-lateral side and calculating a ratio between these results.
Then the patients were examined again by NIHSS after 14th day of admission or at the time of the discharge.
In this study we reconstructed 261 tracts for the patients mainly the CST and we also reconstruction for the thalamic radiation and some association tracts related to the infarction site.
All tracts were classified into three groups according the FA ratio and the degree of tract involvements with the infarction.
Then we made a comparison between the radiological results by the DTI & the DTT with the clinical outcome & patient improvement measured by the NIHSS.
We compared our results to the recent publications in the same subject and made a comparison as regard the agreement and the disagreement points.
We met some limitations during the study which was also compared to the recently published similar studies.
The important points we reached in this study could be summarized in points as follows:-
• The DTI is a trustable technique that is similar in physical idea and diagnostic criteria to the DWI, yet it provides more per-voxel information that allows the more white matter micro-structural & the virtual reconstruction of the fiber tracts.
• Reconstruction of the CST in the acute & subacute phases is a feasible technique that allows the direct visualization the relationship between that important tract and the site of the infarction as well as the degree of involvement and the expected motor prognostic outcome.
• The reconstruction of the association fibers in the acute stage was of little value, as their evaluation needs longer time of follow up & concentrated studies on each of them separately.
• The FA & FA ratio are solid measurement tools which are more dependable than the fiber numbers and the fiber number ratio.
• The results of the FN and the FNr are more similar & convergent with the FA results in the projection tracts than the association tracts.
• The MR tractography carries a future hopes and promising technique for better understanding the anatomy of the brain tracts and the functions of each as well as opening a window to diagnose many non-understandable neurological and psychiatric symptoms.