Acute reperfusion without recanalization: Serial assessment of collaterals within 6 h of using perfusion-weighted magnetic resonance imaging

Abstract

Acute reperfusion despite persistent arterial occlusion may occur in up to 30% of ischemic stroke patients. Recruitment of leptomeningeal collaterals may explain this phenomenon. Using dynamic susceptibility-contrast perfusion imaging (DSC-PI), we assessed acute changes in collateral flow among patients without recanalization. From a multicenter prospective database (I-KNOW), 46 patients with magnetic resonance angiography visible occlusion in whom both reperfusion and recanalization were assessed within 6 h of onset were identified. Maps of collateral flow at arterial, capillary and late venous phases were generated from DSC-PI through inter-frame registration, baseline signal subtraction and temporal summation, and graded blind to all other relevant clinical and radiological data using the Higashida scale. Flow direction and the acute evolution of collaterals were evaluated against the reperfusion status. Among patients without recanalization ( n = 33), flow direction remained retrograde. Collateral grades significantly improved between admission and acute follow-up in patients who reperfused (OR: 4.57; 95% CI: 1.1-22.7; p = 0.048), but not in those without reperfusion (OR: 1.34; 95% CI: 0.4-4.5; p = 0.623). Our study confirmed that acute reperfusion without recanalization is associated with a significant improvement of retrograde collateral flow. DSC-PI can detect acute changes in collateral flow, and may help evaluate novel treatments targeting leptomeningeal collaterals.

The Association Between Recanalization, Collateral Flow, and Reperfusion in Acute Stroke Patients: A Dynamic Susceptibility Contrast MRI Study

“…Thus, far, few studies have investigated the interaction between MR-based measures of reperfusion, recanalization, and collateral flow. Studying 33 patients within 6 h of stroke onset, Makris et al found that patients without vessel recanalization but with good collateral flow (Higashida score 3–4) had higher degrees of reperfusion than patients with poor collaterals (10). Our study confirms this finding (Figure 1B), despite the fact that our study design differed from that of Makris et al, with the first examination taking place within 24 h after stroke onset and follow-up measurements 24 h later.…”

“…These include the quality of collateral flow, which is important for maintaining perfusion in critically hypoperfused brain tissue (9). Tissue reperfusion, which often but not inevitably follows vessel recanalization (10–13), also affects stroke outcome beyond the effect of recanalization (12, 14). Reperfusion itself is influenced by the patency of the vessel feeding the affected area, the cerebral perfusion pressure, and the blood's flow properties (14).…”

“…Instead, they are operationalized using measurements that are as non-invasive and convenient as possible. What is unclear is how these operationalized measurements are related to stroke outcome, as evidence regarding this has thus far been mixed (10, 15, 16).…”

Fingolimod enhances the efficacy of delayed alteplase administration in acute ischemic stroke by promoting anterograde reperfusion and retrograde collateral flow

“…4,5 In addition, such microvascular failure hampers collateral circulation and results in infarct growth. [6][7][8] Cerebral ischemia-induced cell death swiftly activates the immune system and initiates inflammation within the brain. [9][10][11][12] In an early phase, these immune responses appear to exacerbate neurovascular dysfunction by promoting thrombus formation and accumulation of blood components in the cerebral microvasculature.…”

Prediction contribution of the cranial collateral circulation to the clinical and radiological outcome of ischemic stroke

“…Our data shed a new light on several clinical trials that demonstrated the importance of collateral status on clinical outcome using different grading techniques to evaluate patients' collateral status [11][12][13][14][15]. Most of these studies only included patients with large artery occlusion that were potentially eligible for thrombectomy whereas in our study, median infarct volume and the rate of clinically severe stroke (i.e., NIHSS > 17) was rather small representing an actual natural cohort.…”