Relationship between the degree of recanalization and functional outcome in acute ischemic stroke is mediated by penumbra salvage volume

Abstract

Background The presence of metabolically viable brain tissue that may be salvageable with rapid cerebral blood flow restoration is the fundament rationale for reperfusion therapy in patients with large vessel occlusion stroke. The effect of endovascular treatment (EVT) on functional outcome largely depends on the degree of recanalization. However, the relationship of recanalization degree and penumbra salvage has not yet been investigated. We hypothesized that penumbra salvage volume mediates the effect of thrombectomy on functional outcome. Methods 99 acute anterior circulation stroke patients who received multimodal CT and underwent thrombectomy with resulting partial to complete reperfusion (modified thrombolysis in cerebral infarction scale (mTICI) ≥ 2a) were retrospectively analyzed. Penumbra volume was quantified on CT perfusion and penumbra salvage volume (PSV) was calculated as difference of penumbra and net infarct growth from admission to follow-up imaging. Results In patients with complete reperfusion (mTICI ≥ 2c), the median PSV was significantly higher than the median PSV in patients with partial or incomplete (mTICI 2a–2b) reperfusion (median 224 mL, IQR: 168–303 versus 158 mL, IQR: 129–225; p < 0.01). A higher degree of recanalization was associated with increased PSV (+ 63 mL per grade, 95% CI: 17–110; p < 0.01). Higher PSV was also associated with improved functional outcome (OR/mRS shift: 0.89; 95% CI: 0.85–0.95, p < 0.0001). Conclusions PSV may be an important mediator between functional outcome and recanalization degree in EVT patients and could serve as a more accurate instrument to compare treatment effects than infarct volumes.

Comparison of two computed tomography perfusion post-processing software to assess infarct volume in patients with acute ischemic stroke

“…Baseline CTP ( Hoving et al, 2018 ) to assess ischemic damage is the most common method recommended by the guide in the clinical management of AIS patients, given its rapidity and ease ( Powers et al, 2019 ). Accurate quantification of the IC and penumbra in the acute phase is critical, because the volume of the tissue that can be saved and the tissue that currently identifies the infarct directly affects appropriate treatment decisions and clinical outcomes ( Gasparotti et al, 2009 ; Albers et al, 2017 ; Broocks et al, 2021 ; Chen et al, 2021 ). However, discrepancies between the predicted infarct volume and true FIV are prevalent, and accurate assessment of IC and penumbra remain challenging ( Schaefer et al, 2015 ; Albers et al, 2016 ; Koopman et al, 2019 ; Chen et al, 2021 ).…”

Pretreatment CT perfusion collateral parameters correlate with penumbra salvage in middle cerebral artery occlusion

“…Penumbra salvage indices have shown to predict both short-term and long-term good functional and clinical outcomes in patients with AIS. [27][28][29][30][31] Hence, PSI may be an important prognostic marker in anterior circulation AIS-LVO. The major limitation in using PSI as a prognostic marker is that it is not available at presentation, and it needs subsequent imaging follow-up.…”

Penumbra salvage in extensive stroke: exploring limits for reperfusion therapy

“…Second, net infarct growth from admission to follow-up CT was calculated defined as the difference between the total infarct volume at follow-up CT and ischemic core at admission CT. Finally, we subtracted the net infarct growth volume from penumbra volume to determine PSV as previously described6 (equation 1).…”

“…Penumbra salvage volume (PSV) has recently been introduced as a CT perfusion (CTP)-based imaging biomarker to compare treatment effects, being significantly associated with the degree of recanalization 6. Yet, the relationship of penumbral salvage and the degree of early ischemic changes, as well as baseline ischemic core volumes, remains uncertain.…”