CT perfusion mismatch in subacute stroke: Oligemia or luxury perfusion? Response to persistent benign oligemia causes CT perfusion mismatch in patients with intracranial large artery occlusive disease during subacute stroke

摘要

We read with great interest the study of Li et al. [1] which demonstrates the existence of a mismatched area with similar characteristics to penumbra in patients with intracranial large artery occlusive disease (ICAD) during the subacute phase of stroke. The authors suggest that this area may be the result of benign oligemia rather than penumbra. CBV ratio was significantly higher in the ICAD versus the acute stroke group, and there was a trend toward higher CBF values in the ICAD group as well. MTT values were >145% in both groups. However, the authors did not consider the possibility that these data may be the result of postischemic hyper-perfusion (PH) rather than oligemia. PH refers to restoration of perfusion in a cerebrovascular territory affected by prior severe ischemia due to either spontaneous or therapeutic recanalization of the occluded vessels. This phenomenon has been termed "luxury perfusion" and may or may not progress to infarction. Luxury perfusion refers to a condition where CBF is in excess of oxygen demand. Luxury perfusion thus represents nonnutritive flow to infarcted tissue, resulting from a loss of cerebrovascular autoregu-lation. Luxury perfusion is reported to occur in up to one-third of patients by 48 h after ischemic stroke [2], With functional imaging (PET/SPBCT) [2] in animal and human studies, the pattern-of luxury perfusion is characterized by a near-normal or slight increase in CBV and CBF; however, limited data are available on this topic with respect to CT perfusion (CTP) imaging.