急性期脳梗塞におけるischemic coreとpenumbraの同定 Identification of Ischemic Core and Penumbra in Acute Stroke

脳梗塞の成立には発症からの時間と残存脳血流量が関与しており,高度脳虚血では発症3時間以内でも脳組織のviabilityを維持することができず,中等度脳虚血では6時間以内でも維持しうる.^<133>Xe-SPECTを用いた検討では,発症3時間以内では15〜30ml/100g/min,3〜6時間では20〜30ml/100g/minの領域がischemic penumbraの領域と推定された.拡散強調画像(DWI)上の皮質高信号域(HIA)における残存脳血流量(Y)と発症からの時間(X)との間にはY=3.12X+3.61(r=0.73,p<0.05)の関係式が得られ,皮質HIAはischemic coreに相当することが示唆された.血栓溶解療法により救済されるischemic penumbraは発症から6時間以内のDWl上に皮質HIAのみられない中等度の脳虚血域に同定される.

Development of cerebral infarction was dependent on both time from stroke onset and residual cerebral blood flow (CBF), and cerebral tissue viability could not be preserved in a severe ischemic region even within 3 hours, but it could be preserved in a moderate ischemic region within 3-6 hours. Using ^<133>Xe-SPECT imaging, penumbral flow was estimated as 15-30 ml/100 g per mm within 3 hours from stroke onset and 20-30 ml/100 g per mm during 3-6 hours from stroke onset. The relationship between residual CBF (Y) and time from stroke onset (X) in an ischemic region with cortical hyperintensity area (HIA) on diffusion-weighted MRI (DWI) was expressed by linear regession(Y=3.12X+3.61, r=0.73, p<0.05), and cortical HIA on DWI was estimated as the ischemic core because cerebral tissue viability could not be preserved by residual CBF level in cortical HIA. Ischemic penumbra rescued by thrombolytic therapy was identified in a moderate ischemic region without cortical HIA on DWI within 6 hours from stroke onset.