Evaluation of the ischemic penumbra focusing on the venous drainage: the role of susceptibility weighted imaging (SWI) in pediatric ischemic cerebral stroke.

BACKGROUND AND PURPOSE: Susceptibility weighted imaging (SWI) allows the study of the intracranial venous vasculature based on the paramagnetic susceptibility effects of deoxygenated blood. Prominent hypointense draining veins have been revealed in ischemic brain tissue by SWI. The goal of our study was to evaluate whether a match or mismatch between territorial changes in the venous drainage of ischemic brain tissue, as identified by SWI and diffusion restriction, can show a 'venous ischemic penumbra'.

MATERIALS AND METHODS: Eight children with a confirmed diagnosis of acute pediatric arterial ischemic stroke (PAIS) were included in this preliminary study. All had undergone an acute standard magnetic resonance imaging (MRI) study with diffusion-weighted imaging (DWI) and SWI sequences. SWI scans were semi-quantitatively evaluated for signal intensity and caliber of both the intramedullary and sulcal veins. In addition, SWI abnormalities were compared with DWI images for match/mismatch of signal alterations, and the acute MRI data were compared with follow-up scans.

RESULTS: A total of 17 vascular territories showed infarction. SWI hypointensity in sulcal and intramedullary veins was found in 77% and 94% of the infarcted territories, respectively, while the caliber of the sulcal and intramedullary veins was increased in 64% and 88% of the infarcted areas, respectively. SWI/DWI match was observed in 88% of the vascular territories, whereas mismatch was noted in two; follow-up neuroimaging showed infarct progression into the mismatch areas.

CONCLUSION: Our study showed that, in children, high-quality SWI studies focused on venous drainage can provide important non-invasive data on critically perfused brain tissue at risk of infarct progression. SWI is therefore a valuable MR tool that can be added to the battery of neuroimaging techniques for acute PAIS.