Capabilities of perfusion ASPECTS in predicting the efficiency of intravenous thrombolytic therapy

Perfusion computed tomography (PCT) is increasingly used to diagnose ischemic stroke (IS), as well as to identify candidates for thrombolytic therapy (TLT). The feasibility of using this technique in all patients within the therapeutic window has not yet been established.
Objective: to investigate cerebral blood flow according to PCT findings and its relationship to clinical and instrumental indicators and functional status of patients who had received TLT in the acute period of IS.
Patients and methods. 62 patients with acute IS who had received TLT were examined. All the patients underwent clinical, laboratory, and instrumental examinations and PCT, by assessing cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) in 10 brain regions in accordance with the Alberta Score Program Early CT Score (ASPECTS). The total result of perfusion ASPECTS was calculated separately for CBV, CBF and MTT, as well as combinations of these parameters. The penumbra size was calculated as CBV minus MTT (CBV - MTT) ASPECTS, the infarct core size was measured as CBV + MTT ASPECTS.
Results. There was an increase in MTT in most regions of interest of the affected hemisphere as compared to the intact one and a predominance of reversible perfusion disorders. The averaged penumbra size constituted three zones according to ASPECTS. No relationship was found between ASPECTS scores and time after the onset of symptoms prior to hospital admission. Perfusion parameters, particularly penumbra size (CBV - MTT), were associated with the degree of stenosis in the contralateral common carotid artery, body mass index, and blood triglyceride level. Cerebral blood flow indices were also influenced by red blood cell counts and heart ejection fraction. The scores of the perfusion scales were correlated with those of the non-contrast scale. The data of the investigated ASPECTS variants correlated with the level of neurological deficit in patients, its course, and the functional outcome of acute IS.
Conclusion. The perfusion variants of ASPECTS have a high predictive value for patients' neurologic and functional status upon completion of the first treatment stage. The penumbra size (CBV - MTT ASPECTS) is a marker for the expected regression of neurological impairment during TLT. The infarct core size (CBV + MTT ASPECTS) determines the degree of neurologic deficit at a patient's discharge.

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