Magnetic Resonance–Based Prediction of Poststroke Motor Recovery

Fractional anisotropy and FA ratio correlated with later functional scores in patients with middle cerebral artery infarction.

Can newer magnetic resonance (MR)-based measurements that reflect the structural integrity of the pyramidal tract predict the extent of functional motor recovery after stroke? To find out, investigators used diffusion tensor imaging (DTI) to measure the apparent diffusion coefficient (ADC) and the fractional anisotropy (FA) values of the pyramidal tract in 29 patients between 20 and 185 days after middle cerebral artery (MCA) stroke. The researchers compared the absolute FA and ADC values of the ipsilateral pyramidal tract, as well as the FA ratio (ipsilateral FA/contralateral FA) and ADC ratio of the pyramidal tract, with Brunnstrom scores of functional motor recovery at 8 months after stroke onset.

Both the ipsilateral FA value and the FA ratio correlated significantly with Brunnstrom scores. Using an internally defined threshold value of 0.45 for ipsilateral pyramidal tract FA, the sensitivity was 90% and the specificity was 89% in discriminating patients with poor motor function outcomes (Brunnstrom score of 1 or 2). No such correlation was evident with ADC measurements. The authors conclude that measurement of FA values of the ipsilateral pyramidal tract in patients following MCA strokes can provide useful structural and functional information regarding the extent of motor system injury in adults.


Citation(s):

Liu X et al. Quantitative diffusion tensor imaging for evaluation of motor function in patients with brain infarcts. Acta Neurol Scand 2010 May; 121:315.