Value of Distal High Signal Vessel Sign of FLAIR Sequence in the Establishment of Secondary Collateral Circulation after Cerebral Infarction
In patients with acute stroke, the intensity of fluid attenuation and reversal recovery (FLAIR) in the diffusion-limited area was correlated with the onset time of symptoms. We hypothesized that collateral status assessed by low perfusion intensity ratio (HIR) could alter the correlation between stroke onset time and FLAIR lesion intensity. The aim of this study was to determine the effect of FLAIR sequence on secondary collateral circulation after cerebral infarction.From the AX200 ischemic stroke test, 141 patients had FLAIR, diffusion and perfusion images. In the non-reperfusion core region, we calculated the relative FLAIR signal intensity based on voxels. Perfusion intensity ratio is defined as the ratio of Tmax > 10s lesion to Tmax > 6S lesion volume. The HIR threshold (<0.4) is used to distinguish good and inconsistent collaterals. We investigated the interaction between secondary collateral circulation status and duration of symptoms and FLAIR intensity. The onset time of symptoms was correlated with the relative FLAIR intensity in the non-reperfusion core region (B = 1.05; 95% CI: 1.0-1.1). We determined the interaction between this correlation and the collateral circulation state. In patients with poor resistance, there was a correlation between time and rFLAIR intensity (r = 0.53), but not in patients with good secondary collateral circulation (r= 0.17, P = 0.04). Our results suggest that the relationship between the onset time of cerebral infarction symptoms and the intensity of rFLAIR lesions depends on the collateral circulation. For patients with good collateral circulation, the development of rFLAIR-positive lesions is less dependent on the onset time of symptoms than those with poor collateral circulation.