Vascular Territorial Classification and Etiologies of Acute MCA Infarct by Diffusion-Weighted MRI

Abstract

P42 Background and Purpose - The purpose of this study is to classify infarct subtypes of middle cerebral artery distribution (MCA) seen on diffusion-weighted MRI (DWI) and investigate infarct mechanisms and etiologies of MCA infarct subtypes. Method - We analysed 187 consecutive patients with acute MCA infarct who were studied by DWI/MRA within the first 4 days of stroke onset between 1997 and 1999, and stroke mechanism was determinedaccording to the criteria of the Trial of Org 10172 in Acute Stroke Treatment (TOAST). Infarct patterns from 128 patients except for lacunar infarcts (patients) were classified by the two types of multiple infarcts and large single infarcts: 2 types of multipleinfarcts; subcortical/cortical and cortical/cortical infarcts, 3 types of large single infarcts; subcortical, cortical and large infarcts including cortical and subcortical lesions Results -TOAST diagnostic subtypes were 78 large vessel strokes, 22 cardioembolic strokes, 59 lacune strokes, 4 other strokes, and 26strokes of unknown cause. We identified multiple infarcts (MI) in 41 patients: subcortical/cortical, 29 including 14 MCA disease (p=0.03); cortical/cortical, 7 including 6 ICA disease (p=0.005), and 87 large single infarcts (SI): subcortical, 32 including 13 MCA disease (p=0.02); cortical, 5 including 3 cardioembolism (p=0.03); large infarcts (cortical/subcortical), 50. There was no difference of etiologies among large infarcts (cortical/subcortical) in SI. Conclusion -MCA disease is the most important cause of subcortical and cortical multiple infarcts, and subcortical single infarcts. ICA disease is most frequent cause of cortical multiple infarcts and cardioembolism is more common cause in cortical single infarcts. We conclude that our classificationof MCA Infarct patterns using early DWI in acute ischemic stroke is useful to identify the causes of stroke according to subtypes and to consider the clinical decisions of etiologic investigations and to decide the early treatment modality in acute ischemic stroke.