Abstract
BackgroundIn acute ischemic stroke the status of collateral circulation is a critical factor in determining outcome. We propose a less invasive alternative to digital subtraction angiography for evaluating collaterals based on dynamic-susceptibility contrast magnetic resonance imaging.MethodsPerfusion maps of Tmax and cerebral blood flow (CBF) were created for 35 patients with baseline occlusion of a major cerebral artery. Volumes of hypoperfusion were defined as having a Tmax delay of > 4 seconds (Tmax4s) and > 6 seconds (Tmax6s) and a CBF drop below 80% of healthy, contralateral tissue. For each patient a ratio between the volume of the CBF and the Tmax based perfusion deficit was calculated. Associations with collateral status and radiological outcome were assessed with the Mann-Whitney-U test, uni- and multivariable logistic regression analyses as well as area under the receiver-operator-characteristic (ROC) curve.ResultsThe CBF/Tmax volume ratios were significantly associated with bad collateral status in crude logistic regression analysis as well as with adjustment for NIHSS at admission and baseline infarct volume (OR = 2.5 95% CI[1.2–5.4] p = 0.020 for CBF/Tmax 4s volume ratio and OR = 1.6 95% CI[1.0–2.6] p = 0.031 for CBF/Tmax6s volume ratio). Moreover, the ratios were significantly correlated to final infarct size (Spearman’s rho = 0.711 and 0.619, respectively for the CBF/Tmax4s volume ratio and CBF/Tmax6s volume ration, all p<0.001). The ratios also had a high area under the ROC curve of 0.93 95%CI[0.86–1.00]) and 0.90 95%CI[0.80–1.00]respectively for predicting poor radiological outcome.ConclusionsIn the setting of acute ischemic stroke the CBF/Tmax volume ratio can be used to differentiate between good and insufficient collateral circulation without the need for invasive procedures like conventional angiography.
Highlights
In the setting of acute ischemic stroke caused by an occlusion of a cerebral artery collateral circulation is a critical factor in determining infarct evolution[1] and influencing patients’ eligibility for endovascular treatment as it has the capacity to salvage penumbral tissue through redistribution of blood via leptomeningeal anastomoses
We propose a less invasive alternative to digital subtraction angiography for evaluating collaterals based on dynamic-susceptibility contrast magnetic resonance imaging
The cerebral blood flow (CBF)/Tmax volume ratios were significantly associated with bad collateral status in crude logistic regression analysis as well as with adjustment for NIHSS at admission and baseline infarct volume (OR = 2.5 95% CI[1.2–5.4] p = 0.020 for CBF/Tmax 4s volume ratio and OR = 1.6 95% CI[1.0–2.6] p = 0.031 for CBF/Tmax6s volume ratio)
Summary
In the setting of acute ischemic stroke caused by an occlusion of a cerebral artery collateral circulation is a critical factor in determining infarct evolution[1] and influencing patients’ eligibility for endovascular treatment as it has the capacity to salvage penumbral tissue through redistribution of blood via leptomeningeal anastomoses. The current gold standard for evaluating collateral status is digital subtraction angiography (DSA), a time-consuming and invasive method performed only in patients eligible for thrombectomy. Some attempts have already been made to use it in categorizing collateral status[4,5] These have relied solely on the Tmax parameter which is heavily influenced by delay and dispersion[6] and combining it with additional parameters[7], such as the delay-insensitive cerebral blood flow (CBF) might be advantageous. We propose a less invasive alternative to digital subtraction angiography for evaluating collaterals based on dynamic-susceptibility contrast magnetic resonance imaging
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