Original ArticleThe Utility of Middle Cerebral Artery Clot Density and Burden Assessment by Noncontrast Computed Tomography in Acute Ischemic Stroke Patients Treated with Thrombolysis
Introduction
Despite increasing availability of magnetic resonance imaging (MRI), noncontrast computed tomography (CT) continues to be the imaging modality of choice in acute stroke care in many institutions. Actually, CT-based modern stroke imaging protocols incorporating CT perfusion and CT angiography fulfill most of the requirements for management of hyperacute stroke, such as detection of early signs of parenchymal ischemia, extent of perfusion deficit, and vascular status including location of occluding thrombus. The other 2 required issues regarding acute stroke management, albeit still not fully accomplished by available CT and/or MRI techniques, are the determination of the composition and volume of occluding thrombi.
For the first issue—prediction of clot composition—the hyperdense artery sign on CT and hypointense vessel sign on T2* or susceptibility-weighted MRI have been proposed to be useful. Using histopathologic confirmation from acutely retrieved thrombotic material, a recent study showed that hyperdense/hypointense vessels signs on imaging reflect red blood cell content of the thrombi.1 More indirectly, quantified density (Hounsfield unit [HU]) of an occluding thrombus on CT has been suggested to be discriminative of artery-to-artery cerebral embolism from cardiogenic ones, in other words, presumably white and red thrombi, respectively, in 1 study2; however, this observation could not be replicated by others.3 In addition to this ambiguity, potential diagnostic and therapeutic implications of exploring the clot structure with HU quantification on prethrombolysis CT have led us to revisit not only quantitative but also qualitative aspects of the hyperdense middle cerebral artery sign (HMCAS) to clarify their clinical utility in the setting of acute stroke thrombolysis.
For the second issue—prediction of the extent of obstructing thrombus—direct measurement of intra-arterial clot length and use of several semiquantitative scores on cerebral angiography studies, where CT angiography has recently become popular, perhaps, because of its punctual availability, were proposed.4, 5 Previous studies have shown that higher thrombus volume can negatively affect functional and final tissue outcome and increase parenchymal hematoma risk following thrombolysis.5, 6, 7 Because of limited availability of acute angiography, a more available, simple, and practical alternative of clot burden assessment based on noncontrast CT may be advantageous in the emergency department setting. To accomplish this aim, we adapted, and then tested, a clot burden score (CBS)5 previously described for CT angiography to noncontrast CT (the hyperdense MCA burden score [HMCABS]).
Overall, we are in search of more dependable noncontrasted (plain) CT-derived prognosticating tools for acute middle cerebral artery (MCA) stroke thrombolysis in the current CT angiography era. If plain CT gives reliable information about the extent and composition of the occluding thrombi, impact on various components of the management and decision making would be quite advantageous in terms of safety and financial aspects.
Section snippets
Patients
A total of 105 consecutive patients (mean ± SD age: 63.3 ± 13.4 years; 52 women and 53 men) with acute MCA M1 segment occlusion (88 proximal M1; 27 distal M1; 57 left; 47 right, 1 bilateral) who received intravenous or intra-arterial thrombolysis (intravenous recombinant tissue plasminogen activator 78; intra-arterial lysis/intervention 10; combined therapy 17) between January 2006 and December 2012 were included into the present study. In 22 patients, ipsilateral internal carotid artery (ICA)
Results
Study groups were age and sex matched. MCA and vertebrobasilar circulation stroke (VBS) stroke subjects had similar relevant stroke characteristics except for higher admission NIHSS (P = .017) and longer symptom-to-needle intervals (P = .026) observed in VBS stroke group. Hematologic parameters were comparable across 3 groups (Supplementary Table 1).
In 105 patients with MCA occlusion, the mean ipsilateral MCA HU was significantly higher than those of contralateral MCA and BA tip and also those
Discussion
We found that quantification of density or extent in the affected vessel on admission plain CT had no significant role for determination of response to thrombolytic treatment as defined clinically via EDR and complication rate. In addition, neither presence of HMCAS nor its numeric indices was found to be significant predictors of the 3-month clinical outcome. At least from several aspects, these observations can be considered to contradict current understandings about HMCAS and merit further
References (29)
- et al.
Hyperdense middle cerebral artery sign and outcome after intravenous thrombolysis for acute ischemic stroke
J Neurol Sci
(2009) - et al.
Hyperdense middle cerebral artery sign is associated with increased risk of hemorrhagic transformation after intravenous thrombolysis for patients with acute ischaemic stroke
J Clin Neurosci
(2013) - et al.
CT and MRI early vessel signs reflect clot composition in acute stroke
Stroke
(2011) - et al.
Quantification of thrombus Hounsfield units on noncontrast CT predicts stroke subtype and early recanalization after intravenous recombinant tissue plasminogen activator
AJNR Am J Neuroradiol
(2012) - et al.
Prediction of thrombolytic efficacy in acute ischemic stroke using thin-section noncontrast CT
Neurology
(2006) - et al.
Thrombus burden is associated with clinical outcome after intra-arterial therapy for acute ischemic stroke
Stroke
(2008) - et al.
CT angiography clot burden score and collateral score: correlation with clinical and radiologic outcomes in acute middle cerebral artery infarct
AJNR Am J Neuroradiol
(2009) - et al.
Intracranial thrombus extent predicts clinical outcome, final infarct size and hemorrhagic transformation in ischemic stroke: the clot burden score
Int J Stroke
(2008) - et al.
Density of thrombus on admission CT predicts revascularization efficacy in large vessel occlusion acute ischemic stroke
Stroke
(2013) - et al.
Measurements of acute cerebral infarction: a clinical examination scale
Stroke
(1989)
Outcomes validity and reliability of the modified Rankin scale: implications for stroke clinical trials: a literature review and synthesis
Stroke
Is the benefit of early recanalization sustained at 3 months? A prospective cohort study
Stroke
An evidence-based causative classification system for acute ischemic stroke
Ann Neurol
Prevalence and significance of hyperdense middle cerebral artery in acute stroke
Stroke
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