White Matter Tractography By Diffusion Tensor Imaging Play An Important Role In Prognosis Estimation Of Acute Ischaemia Stroke

Background and purposeInfarcts (eg, small capsular strokes, or those located in the corona Radiata) are difficult to assess with regard to the precise location and the extent of pyramidal tract damage with conventional brain imaging (T₁WI, T₂WI, DWI). Color-coded diffusion tensor imaging (CDTI) and 3D (three dimmension) diffusion tensor tractography (DTT) provide a means to visualize the course of the corticospinal tract within the white matter. The aim is to evaluate the anatomic and clinical relationship between the Infarctions and the corticospinal tract(CST) in patients with acute infarcts and predict clinical outcome. Materials and methodsWe examined 28 patients of pyramidal tract strokes at the acute phase (< 3 days) with a marked motor deficit. In order to assess involvement of the tract, lesions were identified on diffusion weighted imaging and isotropic imaging of DTI superimposed on CDTI images, infarcts and the tractwere shown on the DTT images simultaneously. The anatomic location and pattern of the lesion were visualized on DTT with regard to the corticospinal tract, all patients are devided into three clinical subgroups: group 1 lesions were showed the CST in close proximity to the infarct but not to pass through it. Group 2 showed the CST partly passed through it (CST partial involvement), Group 3 had long lesions centered in the pyramidal tract. Subsequently, they are compared with the National Institutes of Health Stroke Scale (NIHSS) scores at acute phase (< 3 days), chronic phase (8-14 days), and outcome (30-60 days). ResultsNIHSS scores of group 1 (12/28)were not significantly lower than that of group 2 (1 l/28)at the acute phase(U=-1.430,P>0.05), and group 2 were significantly lower than that of group 3 (5/28 ) ( U=-2.676, P < 0.01) . Group 1 lesions often located anteriorly and medially (periventricular anterior choroidal artery territory, thalamogeniculate , tuberothalamic, lateral striate branches). In the outcome, group 1 all have good recovery (H= 15.94, P<0.01) , group 2 also have good recovery (H=7.077, P<0.05 ) but sometimes keep some mild motor disfunction, and group 3 always have been marked deficits and minor improvement. Both rADC value and rFA value were induced in the acute ischemic lesion. Discussions This study had a major findings, the degree of CST involvement withindie infaicts was shown to have significant correlation with stroke severity and the outcome measured by NIHSS. The anatomic location of the CST relative to the infarcts is an important clinical issue. Our study have pointed out these with the close proximity of the CST to the infarcts will have a good recovery, but those with the CST crossing the infarcts willhave a bad prognosis.