| Objective:To evaluate the brain oxygen extraction fraction（OEF）,cerebral blood flow（CBF）and collateral circulation status of patients with unilateral middle cerebral artery（MCA）occlusion using quantitative susceptibility mapping（QSM）and arterial spin label（ASL）.Methods:From March 2021 to October 2022,27 patients with unilateral MCA occlusion without cerebral infarction were scanned by QSM and ASL using a 3.0 T magnetic resonance scanner.QSM were processed to obtain OEF maps.The OEF and CBF values of each region were delineated according to the Alberta Stroke Project Early CT Score method（ASPECTS）.The differences of CBF and OEF between the affected side and the normal side were compared.The arterial transit artifact（ATA）in ASL was evaluated to obtain the ATA collateral circulation score.According to the ATA collateral circulation score,each region OEF and CBF were grouped and compared whether there were differences between each group OEF and CBF.The deep venous oxygen saturation（Sv O2）of the brain was evaluated.Correlation and regression analysis were used to analyze various parameters,with bilateral P<0.05considered statistically significant.Results:The OEF values of the cortex in M1,M2 and M6 regions on the affected side were greater than that on the normal side,and the differences were statistically significant（P<0.05）.There was no statistical difference in OEF values of the cortex in other regions between the affected side and the normal side（P>0.05）.The CBF values in M2 area and M5 area on the affected side were greater than that in the contralateral side（P<0.05）,and there were no significant differences in CBF values among other regions and the overall blood-supplying region of MCA（P>0.05）.According to the collateral circulation classification of ATA,the OEF values of ATA grade 3 were lower than those of ATA grade 2 and ATA grade 1（P<0.05）.The CBF values of ATA grade 3 and ATA grade 2 were significantly higher than those of ATA grade 0（P<0.01）,while the CBF value of ATA grade 2 was higher than that of ATA grade 1（P<0.05）.There was no statistical difference in OEF and CBF values among other groups when compared with each other（P>0.05）.Linear regression showed that there was a linear correlation between OEF in the affected M2 region and the total ATA score in the affected MCA region（b=-16.933,β=-0.574,P=0.002）.There was no statistical difference between the two sides of the deep cerebral Sv O2 in patients.Conclusion:1.QSM-OEF can detect the changes of cortical OEF values in patients with unilateral MCA occlusion in a non-invasive manner,and provides a feasible imaging means for monitoring OEF changes in patients with cerebrovascular diseases in clinic.2.After unilateral MCA occlusion,the OEF of M1,M2,and M6 cortex on the affected side of the patient was increased according to ASPECTS partition,and the OEF in M2 region has a negative linear correlation with the collateral circulation obtained by ATA.3.There is no significant difference between the affected side and the contralateral side of Sv O2,the main deep cerebral vein,in patients with unilateral MCA occlusion. |
