Abstract WP44: Acute Damage to Corticospinal Tract Detected by Diffusional Kurtosis Correlates with Motor Outcome at 3 Months After Stroke - A Preliminary Report

Abstract

Background: Diffusional kurtosis imaging (DKI) is a recently developed diffusion MRI method that yields, in addition to conventional diffusion information, the diffusional kurtosis (K) and white-matter-specific metrics (WMM) that may better characterize tissue microstructure after stroke. This study aims to quantitatively test the hypothesis that motor impairment 3 months post- stroke is correlated with the acute damage to the corticospinal tract (CST) measured by kurtosis metrics. Methods: DKI was acquired from 15 first-time acute ischemic stroke patients in the acute phase (within 48 hours) with various degrees of motor deficit. Patients were assessed at baseline (between 2 to 5 days from onset of symptom) and at 90 days (+/- 14 days) after stroke using the Fugl-Meyer Motor Scale (FMMS). Kurtosis metrics, including WMM (intra-axonal diffusivity (D a ), extra-axonal axial (D e,// ) and radial (D e,// ) diffusivity ) as well as fractional anisotropy (FA), mean diffusivity (MD), mean Kurtosis (MK) were measured in the lesional CST. Correlation analyses were applied among these metrics and FMMS at 90 days. Results: Corticospinal tract intra-axonal environment was altered by acute ischemia. D a ( r = 0.75, p = 0.001) and D e,// ( r = 0.52, p=0.048) measured in the acute phase correlated with motor outcome at 3 months. FA, MD, MK and D e,// showed no significant correlations. Conclusions: The preliminary data supports acute damage to CST detected by WMM with DKI correlated with motor outcome at 3 months. The WMM has potential to be an early imaging biomarker for motor outcome prediction.