Mapping the ischemic penumbra and predicting stroke progression in acute ischemic stroke: the overlooked role of susceptibility weighted imaging

Abstract

Objectives Asymmetrically prominent veins (APVs) detected on susceptibility weighted imaging (SWI) in acute stroke patients are assumed to signify compromised cerebral perfusion. We aimed to explore the role of APVs in identifying the ischemic penumbra and predicting stroke progression in acute stroke patients Methods Twenty patients with a middle cerebral artery ischemic infarction presenting within 24 h of symptoms onset underwent SWI following our standard MR stroke protocol imaging sequences which included diffusion-weighted imaging (DWI). Follow-up (FUP) FLAIR images were obtained at least 5 days after the initial MRI study. The Alberta Stroke Program Early CT Score (ASPECTS) was used to determine the initial infarct size, extent of APVs and final infarct size on initial DWI, SWI, and FUP images respectively. For each patient, SWI was compared with DWI images to determine match/mismatch of their respective ASPECTS values and calculate mismatch scores, whereas acute DWI findings were compared with follow-up images to identify infarct growth (IG) and calculate infarction growth scores (IGS). Results IG occurred in 6/10 patients with a positive DWI-SWI mismatch and in none of the patients without a positive DWI-SWI mismatch. A positive DWI/SWI mismatch was significantly associated with IG (χ2 = 8.57, p = 0.0138, Cramer’s V = 0.65). A significant inverse correlation was found between SWI ASPECTS and IGS (rs = − 0.702, p = 0.001). DWI-SWI mismatch scores were strongly correlated with IGS. (rs = 0.788, p = 0.000) Conclusion A positive DWI-SWI mismatch is an indicator of the ischemic penumbra and a predictor of infarct expansion if left untreated.

The ischemic penumbra: From concept to reality

“…Using this technique, the positive DWI/SWI mismatch has also been shown to represent severely hypoxic tissue, consistent with the ischemic penumbra, although again, this is not widely used due to complex and lengthy MRI sequences. 82,83…”

“…Using this technique, the positive DWI/SWI mismatch has also been shown to represent severely hypoxic tissue, consistent with the ischemic penumbra, although again, this is not widely used due to complex and lengthy MRI sequences. 82,83 Arterial spin labeling (ASL) is another perfusion MRI technique that can quantify CBF without the injection of a contrast agent. The accuracy of ASL at detecting the infarcted regions was shown on a small subset of patients with acute ischemic stroke, where the hypoperfused regions obtained from ALS were compared to those obtained from dynamic susceptibility contrast on PWI and found to be consistent.…”

The Prognostic Impact of Susceptibility-Weighted Imaging Prominent Veins in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

“…26 PVS-SWI can be a valid marker of acute ischemic stroke progression 32,[39][40][41][42] A timely assessment of the ischemic penumbra and a successful reperfusion therapy are critical to avoid irreversible brain damage. 43 Meanwhile, this present study showed that the risk of hemorrhagic transformation after stroke was independent of the presence of PVS-SWI. Therefore, thrombolysis should not be delayed due to the presence of PVS-SWI.…”

FLAIR and ADC Image-Based Radiomics Features as Predictive Biomarkers of Unfavorable Outcome in Patients With Acute Ischemic Stroke

“…Acute ischemic stroke (AIS) is a critical cerebrovascular disorder worldwide with high morbidity and disability and accounts for 60–80% of all strokes ( Darwish et al, 2020 ). The cerebral infarct in the middle cerebral artery (MCA) territory represents the most frequent AIS ( Sommer et al, 2018 ).…”

“…By intravenous injection of contrast agent, enhanced MRI can provide further information, and the lesion mismatch on perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) has been employed to estimate the ischemic penumbra ( Darwish et al, 2020 ). Whereas, enhanced MRI is not a universally accepted method in the routine workup in AIS patients due to an intravenous injection of gadolinium agent, it is time consuming, and the patient’s cooperation.…”