MR tractography for stroke

The diffusion-tensor imaging (DTI) technique records the anisotropy of water molecular diffusion. By postprocessing the DTI data, one can acquire in vivo information about neuronal pathways. This process is now well known as MR tractography. This technique can depict the major fiber bundles, including the sensory tracts, pyramidal tracts, and visual pathways. To test whether tractography is reproducible and reliable, we used this technique to document the presence of acute tiny infarcts located in the supratentorial brain. We analyzed the data of 14 patients who presented to our institute with sensorimotor symptoms. There was an excellent correlation between the location of the infarct as assessed by tractography and clinical symptoms. Therefore, this study showed that MR tractography reliably depicts the sensorimotor tracts. Next, we applied the technique to patients with evolving symptoms after admission to hospital. We specifically assessed the change in the tract–infarct relationship over time. The data showed that, in most cases when there was symptomatic progression, the distance between the tract and the infarct border depicted on diffusion-weighted images (DWI) diminished. Finally, we studied whether the use of tractography could help predict a patient's prognosis. To simplify the analysis, we specifically focused on patients with lenticulostriate artery (LSA) infarcts. We analyzed the correlation between the extent of CST involvement within the infarcts and the severity of motor deficits. The data indicated that the tractographic technique could be useful in predicting a patient's outcome. Furthermore, combining this information with the apparent diffusion coefficient (ADC) and perfusion data may further refine the accuracy of the outcome prediction.