CT perfusion imaging and stages of regional cerebral hypoperfusion in pre-infarction period

Objective: To investigate the applicative value in stages of pre-infarction period using dynamic perfusion CT. Methods: Dynamic perfusion CT was performed in 32 cases of cerebral hypoperfusion. The ratios of side-to-side were measured at hypoperfusion areas in the regional cerebral ischemia. The stages of pre-infarction period were made as the following: (I1) TTP was delayed, MTT, rCBF and rCBV were normal; (I2) TTP and MTT were delayed, rCBF was normal, and rCBV was normal or slightly increased; (II1) TTP and MTT were delayed, rCBF was decreased, and rCBV was normal or slightly decreased; (II2) TTP and MTT were delayed, rCBF and rCBV were decreased. Results: There were 4 cases in stage I1. Regional hypoperfusion was revealed only by TTP map. The mean ratios of rCBF, rCBV, MTT, and TTP were 1.00, 1.00, 1.00, and 1.30, respectively. In stage I2, the areas of delayed TTP and MTT were found in all 13 cases. The rCBF and rCBV maps appeared normal in 8 cases. Another 5 cases showed normal rCBF and slightly increased rCBV areas. The mean ratios of rCBF, rCBV, MTT, and TTP were 1.00, 1.03, 1.38, and 1.30, respectively. In stage II1, the areas of delayed TTP and MTT were revealed in all 8 cases. The depiction of decreased rCBF was also found in 8 cases. The areas of decreased rCBV were showed in 5 cases, and normal rCBV maps were revealed in 3. The mean ratios of rCBF, rCBV, MTT, and TTP were 0.56, 0.94, 1.49, and 1.47, respectively. In stage II2, the areas of delayed TTP and MTT were revealed in all 4 cases, in whom depiction of decreased rCBF and rCBV was also found. The mean ratios of rCBF, rCBV, MTT, and TTP were 0.42, 0.59, 1.57, and 1.55, respectively. Conclusion: CT perfusion imaging and its parameters' analysis may play an increasing role to delineate the depiction of cerebral hypoperfusion in pre-infarction period. Analyzing the relationship of rCBF, rCBV, MTT, and TTP is very helpful to know the status of the capillary vessels in regional cerebral hypoperfusion area and to provide functional information with our stages of pre-infarction period