FLAIR-hyperintense vessel sign, diffusion-perfusion mismatch and infarct growth in acute ischemic stroke without vascular recanalisation therapy

Background and purpose: To investigate the relation between DWI-PWI mismatch and FLAIR-hyperintense vessel (FHV) sign and their influence on the prediction of the infarct growth in stroke patients without vessel recanalising therapy.

Patients and methods: Thirty-three patients with non-lacunar acute stroke and not eligible for recanalisation therapy received cerebral MRI at the day of admission and after 7±1 days. DWI and PWI lesion volumes, DWI-PWI mismatch volumes, infarct growth, relative mismatch and relative infarct growth were assessed. FHV sign was subdivided into (i) proximal or (ii) distal, the latter graded as either (i) prominent or (ii) subtle.

Results: FHV sign did not predict absolute or relative infarct growth. Significantly larger DWI lesions, PWI lesions and mismatch volumes were observed in FHV-positive infarcts. There were significant correlations between the degree of FHV sign and PWI lesion volume (r=0.52; P<0.01) as well as mismatch volume (r=0.49; P<0.01), whereas FHV sign did not correlate with the initial DWI lesion size (r=0.33; P=0.059). We found a strong correlation between relative DWI-to-PWI mismatch and relative infarct growth (r=0.91; P<0.01) yet no correlation between absolute mismatch volumes and infarct growth was evident (r=0.18, P=0.35).

Conclusion: The FHV sign is associated with larger PWI lesion volumes and DWI-to-PWI mismatch volumes in acute stroke and thus seems to be an indicator of collateral flow. However, it is unsuitable to predict infarct growth. The latter occurred when DWI-to-PWI mismatches were present with bigger relative mismatch volumes making subsequent infarct growth more likely.