Background: Multiple hypointense vessels (MHV) on susceptibility-weighted imaging (SWI) are frequently observed in patients with acute cerebral ischemia, but their implication has not been clearly established. To elucidate the clinical significance of MHV on SWI, we investigated the association of MHV on SWI with clinical data and other MR markers in patients with acute ischemic stroke. Methods: We enrolled acute stroke patients with internal carotid or proximal middle cerebral artery occlusion who underwent MRI including SWI within 3 days from stroke onset. Baseline clinical data were reviewed. Stroke severity was measured by the National Institutes of Health Stroke Scale (NIHSS). We graded the degree of MHV on SWI as four groups of none, subtle, relative, or extensive by the modified Alberta Stroke Program Early CT Scan (ASPECTS) system. To evaluate the degree of collateral flow, distal hyperintense vessels (DHV) on FLAIR and vessels on post-contrast time-of-flight MR angiography (TOF MRA) source images were graded respectively as 3 groups: none/subtle/prominent and poor/moderate/good. Diffusion and perfusion lesion volume and diffusion-perfusion mismatch (DPM) ratio were measured in all patients. We analyzed the association of the degree of MHV on SWI with clinical data and MR markers. Results: Eighty patients were included in the study. The mean MR time from stroke onset was 12.4 h (range 0.5-63.0). There is no difference in MR time from stroke onset between groups of MHV on SWI. MHV were observed in 68 (85%) of 80 patients: none in 12, subtle in 11, relative in 13, and extensive in 44. There were no statistically significant associations between MHV on SWI and vascular risk factors. Patients with more extensive MHV on SWI had a smaller diffusion volume (p < 0.001), larger DPM (p < 0.001), and lower initial NIHSS scores (p = 0.022). Prominent DHV was presented in 29 of 44 patients with extensive MHV (p < 0.001). Good collateral flow on TOF MRA source images was presented in 37 of 44 patients with extensive MHV (p < 0.001). Conclusions: More extensive MHV on SWI in acute ischemic stroke is associated with lower initial NIHSS scores, smaller diffusion lesion volume, better collateral flow, and larger DPM. Our results show the possibility that MHV on SWI may be a useful surrogate marker for predicting increased oxygen extraction fraction and diffusion-perfusion mismatch in acute ischemic hemisphere.

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Background and PurposeSusceptibility-weighted imaging (SWI) can show an intravascular thrombus as a hypointense susceptibility vessel sign (SVS). In this study, we investigated the usefulness of SWI in the detection of an intravascular thrombus in acute cardioembolic stroke by comparing the SVS on SWI to the vessel status on time-of-flight magnetic resonance angiography (MRA).MethodsWe consecutively enrolled patients with cardioembolic stroke in the anterior circulation within 3 days from stroke onset. The frequency and location of the SVS on SWI were compared with those of occlusion on MRA.ResultsOne hundred and twenty-two patients were conclusively enrolled in this study. The SVS was observed in 75.4% (92/122) of the enrolled patients. MRA showed occlusion in 57% (70/122) of the enrolled patients. The SVS was identified in all 70 patients with occlusion on MRA. The SVS was observed in 22 (42.3%) of 52 patients without occlusion on MRA (P<0.001), which was identified mainly in post-bifurcation segments of the middle cerebral artery: the M2 segment in 4 patients, M3 segment in 10 patients, M4 segment in 4 patients, A3 segment in 1 patient, and multiple segments in 2 patients. The mean length of the SVS in the M1 segment was 13.65 mm (median: 12.39 mm, length range: 2.70–39.50 mm).ConclusionsSWI can provide useful information about the thrombus location, the presence of a single thrombus or multiple thrombi especially in distal intracranial arteries, and the thrombus burden, all in acute cardioembolic stroke.

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