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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Diffusion tensor imaging detects early Wallerian degeneration of the pyramidal tract after ischemic stroke
Götz Thomalla1, Volkmar Glauche, Martin A Koch
1Klinik und Poliklinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany. thomalla@uke.uni-hamburg.de
Abstract:
We used diffusion tensor imaging (DTI) to assess Wallerian degeneration of the pyramidal tract within the first 2 weeks after ischemic stroke, and correlated the extent of Wallerian degeneration with the motor deficit. Nine patients with middle cerebral artery stroke were examined 2-16 days after stroke by DTI and T2-weighted MRI. We measured fractional anisotropy (FA), averaged diffusivity (Dav), eigenvalues of the diffusion tensor and T2-weighted signal in the cerebral peduncle and compared these values between the affected and the unaffected side and between patients and six controls. FA was significantly reduced on the affected side compared to the unaffected side and compared to the control group. The largest eigenvalue was reduced, whereas the smallest eigenvalue was elevated on the affected side. There was no significant difference in T2-weighted signal and Dav. The decrease of anisotropy correlated positively with the motor deficit at the time of DTI study and 90 days after stroke. The reduction of anisotropy mirrors the disintegration of axonal structures, as it occurs in the early phase of Wallerian degeneration. DTI detects changes of water diffusion related to beginning pyramidal tract degeneration within the first 2 weeks after stroke that are not yet visible in conventional T2-weighted or orientationally averaged diffusion weighted MRI. We demonstrated for the first time a correlation of early DTI findings of pyramidal tract damage with the motor deficit. DTI can help prognosing recovery of motor function after stroke within the early subacute phase.
Insights
Diffusion tensor imaging (DTI) detects early Wallerian degeneration of the pyramidal tract after ischemic stroke. This early DTI finding correlates with motor deficits, aiding in prognosing motor function recovery.
Area of Science:
- Neuroimaging
- Neurology
- Biomedical Engineering
Background:
- Ischemic stroke causes Wallerian degeneration, a process affecting motor pathways.
- Early detection of pyramidal tract damage is crucial for motor function prognosis.
- Conventional MRI may not detect early degenerative changes.
Purpose of the Study:
- To assess early Wallerian degeneration of the pyramidal tract using DTI within two weeks post-stroke.
- To correlate the extent of degeneration with motor deficits.
- To evaluate DTI's potential for early prognosis of motor recovery.
Main Methods:
- Diffusion tensor imaging (DTI) and T2-weighted MRI were used in nine middle cerebral artery stroke patients (2-16 days post-stroke).
- Fractional anisotropy (FA), averaged diffusivity (Dav), and eigenvalues were measured in the cerebral peduncle.
- Affected and unaffected sides were compared, along with a control group.
Main Results:
- Significantly reduced FA was observed on the affected side compared to the unaffected side and controls.
- The largest eigenvalue decreased, while the smallest eigenvalue increased on the affected side.
- Reduced anisotropy correlated positively with motor deficits at the time of study and 90 days post-stroke.
Conclusions:
- DTI detects early Wallerian degeneration of the pyramidal tract, not visible with conventional MRI.
- Early DTI findings of pyramidal tract damage correlate with motor deficits.
- DTI shows promise for prognosing motor function recovery in the early subacute phase after stroke.
