Objective: The purposes of this study were to evaluate the temporal pattern of blood volume change in cerebral infarction and to provide a guideline in the interpretation of blood volume data, which are known to vary according to the stage of infarction.
Subjects and methods: Thirty-three patients with large middle cerebral infarctions were examined one to three times (one time in 20 patients, two times in eight patients, and three times in five patients) after the onset of stroke by dynamic contrast-enhanced T2*-weighted MR imaging and MR angiography. A total of 54 infarctions (29 in an acute stage [up to 7 days], 15 in a subacute stage [8-21 days], and 10 in a chronic stage [22-35 days]) were included. After blood volume maps were created, blood volume ratios (blood volume of the infarcted region divided by blood volume of corresponding contralateral region) were compared at different stages. Likewise, findings on MR angiography were compared at different stages.
Results: Mean blood volume ratios in each stage of infarction were 0.46 in the acute stage, 1.48 in the subacute stage, and 0.73 in the chronic stage (p < .001). Recanalization of occluded arteries occurred in 21% of infarctions in the acute stage and 80% in the subacute stage. Infarctions with recanalization had higher blood volume ratios than did those without recanalization (p < .001). A biphasic pattern of blood volume ratios was found in 13 patients who underwent at least two MR examinations: increased blood volume in the subacute stage and decreased blood volume in the chronic stage, regardless of recanalization (p < .01).
Conclusion: Blood volume that initially decreases in cerebral infarction increases in the subacute stage, reflecting reperfusion hyperemia. Blood volume decreases again in the chronic stage. The time interval between onset of stroke and MR examination must be considered for correct interpretation of blood volume data in cerebral infarction at various stages.