Thrombus Permeability Is Associated With Improved Functional Outcome and Recanalization in Patients With Ischemic Stroke

Abstract

T reatment of patients with acute ischemic stroke (AIS) is aimed at reopening occluded arteries and reestablishment of intracranial perfusion. Determining pivotal characteristics about the occluding thrombus using available imaging has the potential to improve patient's diagnostics and prognostics.Background and Purpose-Preclinical studies showed that thrombi can be permeable and may, therefore, allow for residual blood flow in occluded arteries of patients having acute ischemic stroke. This perviousness may increase tissue oxygenation, improve thrombus dissolution, and augment intra-arterial treatment success. We hypothesize that the combination of computed tomographic angiography and noncontrast computed tomography imaging allows measurement of contrast agent penetrating a permeable thrombus, and it is associated with improved outcome. Methods-Thrombus and contralateral artery attenuations in noncontrast computed tomography and computed tomographic angiography images were measured in 184 Multicenter Randomized Clinical trial of Endovascular treatment of acute ischemic stroke in the Netherlands (MR CLEAN) patients with thin-slice images. Two quantitative estimators of the thrombus permeability were introduced: computed tomographic angiography attenuation increase (Δ) and thrombus void fraction (ε). Patients were dichotomized as having a pervious or impervious thrombus and associated with outcome, recanalization, and final infarct volume. Results-Patients with Δ≥10.9 HU (n=81 [44%]) and ε≥6.5% (n=77 [42%]) were classified as having a pervious thrombus.These patients were 3.2 (95% confidence interval, 1.7-6.4) times more likely to have a favorable outcome, and 2.5 (95% confidence interval, 1.3-4.8) times more likely to recanalyze, for Δ based classification, and similarly for ε. These odds ratios were independent from intravenous or intra-arterial treatment. Final infarct volume was negatively correlated with both perviousness estimates (correlation coefficient, −0.39 for Δ and −0.40 for ε). Conclusions-This

Value of Thrombus CT Characteristics in Patients with Acute Ischemic Stroke

“…13 Location of the thrombus (M1, M2, A1, A2, ICA, or ICA-T) was determined on CTA by expert neuroradiologists. 1 The length of the thrombus was measured on NCCT with the aid of coregistered CTA, with an inhouse-developed MeVisLab interface (www.mevislab.de).…”

“…Density measurement of the thrombus and contralateral vessel segment was performed on NCCT and coregistered CTA by a trained observer (M.d.B., with 1 year of experience), blinded to clinical information, with the in-house-developed MeVisLab interface. 13 The mean thrombus density was calculated by averaging the Hounsfield units of 3 manually placed ROIs of the thrombus. Relative density was calculated by dividing the mean Hounsfield unit of the thrombus by the mean Hounsfield unit of the contralateral vessel segment.…”

“…[9][10][11][12] Moreover, it was recently shown that thrombus perviousness, which is a measure of the amount of contrast penetration in the thrombus on CTA, is strongly associated with functional outcome. 13 On the basis of these observations, we hypothesized that thrombus CT characteristics have the potential to be used for selection of patients who are likely to benefit from IAT. We aimed to determine which thrombus CT characteristics are associated with functional outcome in patients with acute ischemic stroke due to a proximal intracranial occlusion enrolled in the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute ischemic stroke in the Netherlands (MR CLEAN) study.…”

Proximal flow to middle cerebral artery is associated with higher thrombus density in terminal internal carotid artery occlusion

“…Indeed, thrombus perviousness as evidenced by higher clot density is strongly associated with recanalization after intravenous recombinant tissue‐plasminogen activator (rt‐PA) treatment and favorable functional outcome 3. Our study disclosed that MCA clots in the context of terminal ICA occlusion differ in terms of density based on the presence of proximal collateral flow.…”

“…Understanding the composition of the thrombus may provide additional information to determine the potential success of reperfusion efforts and individual prognosis. Several studies confirmed that a higher thrombus density is associated with improved reperfusion rates and better outcome, regardless of systemic or endovascular recanalization techniques 3, 4, 5, 6. Thrombus density can be determined noninvasively on noncontrast enhanced CT (NECT) and was shown to be dependent on source, time, and hematocrit, and is altered by treatment with antiplatelets 7, 8.…”