Abstract W MP16: Lower Apparent Diffusion Coefficient Ratio Predicts Increased Swelling After Ischemic Stroke
Introduction: Swelling is common after acute ischemic stroke but little is known about predictors for its development. We explored several putative markers of swelling using brain magnetic resonance imaging (MRI).
Methods: We retrospectively analyzed a cohort of acute stroke subjects with serial research brain MRI at baseline, 6 hours later, and then at 24 and 48 hours after the baseline MRI. We defined swelling as the expansion in stroke volume from baseline to the follow-up scan up about 2 days after stroke onset. Change in volume was also examined between each MRI interval. Apparent diffusion coefficient (ADC) and fluid-attenuated inversion recovery (FLAIR) signal intensity ratios were developed by normalizing the average signal intensity within the stroke lesion to that of the normal contralateral hemisphere. The association between ADC ratio and FLAIR ratio with expansion was assessed.
Results: Twenty-one subjects had 71 scans available at four time points with a median baseline stroke volume of 98 mL [interquartile range (IQR) 66-135 mL]. The median increase in volume was 55 mL (IQR 35-84 mL) from baseline MRI. The changes from baseline to 24 hours (r=0.89, p<0.0001) and from 24 to 48 hrs (r=0.85, p<0.0001) were associated total expansion. FLAIR ratio exhibited a sharp elevation from baseline to 24 hours, and plateaued thereafter, but was not associated with expansion. ADC ratio decreased to a nadir between 6 and 24 hours, and then normalized at 48 hours. The nadir ADC ratio at 6 hours (r=-0.64, p=0.007) and 24 hours (r =-0.61, p=0.007) was associated with swelling.
Conclusions: Acute stroke subjects exhibit differing trajectories of expansion, and those with greater total swelling show larger increases early on. The nadir ADC ratio, a marker of stroke severity and cytotoxic injury, correlated with total swelling. FLAIR ratio, a potential marker of vasogenic edema, was not correlated to lesion expansion in this cohort. Future studies are warranted to better understand the relationship between these imaging markers and clinical outcome.
Author Disclosures: T.W.K. Battey: None. M. Karki: None. O. Wu: Research Grant; Modest; NIH-NINDS U01NS069208, R01NS051412. Research Grant; Significant; NIH-NINDS R01NS059775, P50NS051343, R01NS063925. Consultant/Advisory Board; Modest; Penumbra, Inc. A.B. Singhal: Research Grant; Significant; NIH-NINDS R01NS051412; P50NS051343; R21NS077442. K.N. Sheth: None. W.T. Kimberly: Research Grant; Significant; NIH-NINDS K23NS076597-02.
- © 2014 by American Heart Association, Inc.