Trial Information

Diffusion Tensor Imaging (DTI) and Susceptibility Weighted Imaging (SWI) as a Predictor of Functional Outcome in Acute Ischemic Stroke

Stroke is the second leading cause of death in Taiwan. The morbidity and mortality of stroke
is also very high worldwide. In the United States, about one third of 800,000 stoke
patients became disabled; while in Taiwan, 13,000 out of 68,000 stroke patients died each
year.

Diffusion tensor imaging (DTI) characterizes the three-dimensional distribution of water
diffusion, which is highly anisotropic. Previous studies utilized DTI derived mean
diffusivity (MD) and fractional anisotropy (FA) have found correlation between pathological
changes of white matter and prognosis of stroke. However, the result was not specific due to
the reason that any change at either axon or myelin sheath resulted in FA reduction. DTI, on
the other hand, differentiate morphological change at axon and myelin sheath with axial and
radial diffusivity, respectively. With this data, we hypothesized that the prognosis might
be more relevant to pathological change with axon post-stroke when compare to
Diffusion-Weighted imaging (DWI)/Apparent Diffusion Coefficient (ADC).

Susceptibility-weighted imaging (SWI) is a newer technique which use fully velocity
compensation gradient echo sequence to receive magnitude and phase imaging. SWI can be used
to detect early phase bleed, intra-arterial thrombus, cerebral venous thrombosis, thus
evaluate the prognosis of patients by detect leptomeningeal collateral circulation and
intravascular deoxygenation changes. We hypothesized that the prognosis is better in
post-stroke patients with preserved leptomeningeal collateral circulation and venous
circulation of large blood vessel. Therefore, we conduct the study to use DTI derived axial
diffusivity and SWI to evaluate the severity and to predict the functional outcome in acute
ischemic stroke patient.