Diffusion tensor imaging, permanent pyramidal tract damage, and outcome in subcortical stroke.
BACKGROUND
Studies in chronic stroke patients suggest that diffusion tensor imaging (DTI) parameters of the pyramidal tract (PT) relate to residual motor function. We performed a prospective controlled study to evaluate if the DTI parameters tract volume (TV) and fractional anisotropy (FA) in patients with acute subcortical infarcts are correlated with permanent PT damage and clinical outcome after 6 months.


METHODS
We acquired DTI in 18 stroke patients with subcortical ischemic infarcts either affecting the PT (PT group, n = 12) or not (non-PT group, n = 6) and in 7 age- and risk factor-matched controls at median times of 12 and 180 days. The PT was isolated using tractography and tract volume ratios (R(TV)) and FA ratios (R(FA)) were calculated (affected tract/unaffected tract). Ratios were compared within and between groups at initial and follow-up time points, as well as in tract portions above and below the infarcts, and were correlated to Rivermead Motor Function Test (RMFT) scores.


RESULTS
Mean R(FA) and R(TV) of the PT group were smaller than those of both non-PT and control groups initially and at follow-up (p < 0.01). Tract portions above the infarct had lower R(TV) than below (p < 0.05). There was no significant change in R(FA) and R(TV) over time for the whole tract or tract portions. R(FA) and R(TV) both were highly correlated with initial and follow-up RMFT scores.


CONCLUSIONS
DTI parameters of PT integrity acquired within the first weeks after acute subcortical stroke measure permanent ischemic PT damage and are highly correlated with residual motor function in the acute and chronic stage.
Radlinska
B
B
Neurology Department, Room E006.2, SMBD Jewish General Hospital and Lady Davis Institute for Medical Research, 3755, Chemin de la Cote St. Catherine, Montreal, QC, H3T 1E2 Canada. alexander.thiel@mcgill.ca
Ghinani
S
S
Leppert
I R
IR
Minuk
J
J
Pike
G B
GB
Thiel
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001931:Brain Mapping; D002544:Cerebral Infarction / Q000473:pathology* / Q000503:physiopathology; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009048:Motor Skills; D011446:Prospective Studies; D011712:Pyramidal Tracts / Q000473:pathology* / Q000503:physiopathology; D012720:Severity of Illness Index; D020521:Stroke / Q000473:pathology* / Q000503:physiopathology