PURPOSE: The purpose of this study was to evaluate the temporal pattern of blood volume change in cerebralinfarction and to provide guidelines for the interpretation of blood volume data known to vary according to thestage of infarction. MATERIALS AND METHODS: Thirteen patients with large infarctions attributable to proximalmiddle cerebral artery occlusion were studied at least twice after the onset of stroke using dynamiccontrast-enhanced T2*-weighted MR imaging and MR angiography. A total of 34 infarctions (11 in the acute stage[< or =7 days], 13 in the subacute stage [8-21 days], and 10 in the chronic stage [22-35 days]) were included. Afterblood volume maps were created on a pixel-by-pixel basis, blood volume ratios (blood volume of the infarctedregion divided by blood volume of the corresponding contralateral region) and findings of MR angiograms werecompared at different stages. RESULTS: A changing biphasic pattern of blood volume ratios was found: 0.73 in theacute stage, 1.45 in the subacute stage and 0.73 in the chronic stage (p < .01). Mean blood volume ratios ininfarctions with and without recanalization of occluded arteries were 1.37 and 0.42, respectively, a significantdifference (p <.001). Recanalization occurred during the acute stage in 45% of infarctions, and during the subacutestage in 77%. CONCLUSION: Blood volume that initially decreases in cerebral infarction increases during thesubacute stage, reflecting reperfusion hyperemia, and decreases again during the chronic stage. For correctinterpretation of blood volume data in cerebral infarction at various stages, the time interval between the onsetof stroke and MR examination and recanalization of arteries must be considered.