Diffuse microvascular dysfunction and loss of white matter integrity predict poor outcomes in patients with acute ischemic stroke.

We sought to investigate the relationship between blood–brain barrier (BBB) permeability and microstructural white matter integrity, and their potential impact on long-term functional outcomes in patients with acute ischemic stroke (AIS). We studied 184 AIS subjects with perfusion-weighted MRI (PWI) performed <9 h from last known well time. White matter hyperintensity (WMH), acute infarct, and PWI-derived mean transit time lesion volumes were calculated. Mean BBB leakage rates (K2 coefficient) and mean diffusivity values were measured in contralesional normal-appearing white matter (NAWM). Plasma matrix metalloproteinase-2 (MMP-2) levels were studied at baseline and 48 h. Admission stroke severity was evaluated using the NIH Stroke Scale (NIHSS). Modified Rankin Scale (mRS) was obtained at 90-days post-stroke. We found that higher mean K2 and diffusivity values correlated with age, elevated baseline MMP-2 levels, greater NIHSS and worse 90-day mRS (all p < 0.05). In multivariable analysis, WMH volume was associated with mean K2 (p ¼ 0.0007) and diffusivity (p ¼ 0.006) values in contralesional NAWM. In summary, WMH severity measured on brain MRI of AIS patients is associated with metrics of increased BBB permeability and abnormal white matter microstructural integrity. In future studies, these MRI markers of diffuse cerebral microvascular dysfunction may improve prediction of cerebral tissue infarction and functional post-stroke outcome

Use of decrease in apparent diffusion coefficient values to predict infarct age

The purpose of the study was to determine the ability to predict infarct age based on decrease in apparent diffusion coefficient (ADC) values. We retrospectively identified 94 individuals (age range 16 years to 91 years; mean 63.7 + 14.1 years) who underwent magnetic resonance diffusion-weighted imaging at our institution over a course of 14 months whose infarct age could be reliably determined within 1 h. A single observer measured ADC values within the center of the infarct and compared them against values in contralateral normal tissue. We examined the ability of four ADC decrease thresholds (i.e., 24 and >48 h. Levels of ADC decrease in infarcts were as follows: >20%, n = 9; 20-29%, n = 21; 30-39%, n = 25; 40-49%, n = 23; 24 h, sensitivity for the four ADC decrease thresholds ranged from 25% to 94%, specificity ranged from 10% to 85%, positive predictive value (PPV) ranged from 18% to 25%, and negative predictive value (NPV) ranged from 85% to 89%. For prediction of infarct age >48 h, sensitivity ranged from 23% to 98%, specificity ranged from 15% to 87%, PPV ranged from 46% to 56%, and NPV ranged from 60% to 89%. Test performance characteristics for predicting infarct age of >24 and >48 h were relatively poor. In particular, PPV was very low for predicting infarcts >24 h old