Abstract: Objective To analyze the value of quantitative electroencephalogram (qEEG) combined with magnetic resonance arterial spin labeling (ASL) perfusion imaging in evaluating unilateral middle cerebral artery (MCA) stenosis. 
Methods The patients with unilateral MCA stenosis were prospectively included as the research subjects. All patients underwent qEEG, ASL perfusion imaging and CT angiography (CTA). According to the results of CTA, patients were divided into mild stenosis group, moderate stenosis group and severe stenosis group. The qEEG and ASL perfusion imaging parameters ［delta and theta/alpha+beta ratio (DTABR), temporal brain symmetry index (tBSI), spatial brain symmetry index (sBSI), cerebral blood flow (CBF)］ of the three groups were compared, and the evaluation value of qEEG combined with ASL perfusion imaging for unilateral MCA stenosis was analyzed. 
Results Among 82 patients with unilateral MCA stenosis, CTA examination showed 28 cases of mild stenosis, 32 cases of moderate stenosis, and 22 cases of severe stenosis. The sBSI and tBSI values in the moderate and severe stenosis groups were higher than those in the mild stenosis group, while the sBSI and tBSI values in the severe stenosis group were higher than those in the moderate stenosis group (P＜0.05). The CBF value, CBF ratio on the affected side and the healthy side, Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) scores of the moderate and severe stenosis groups were lower than those of the mild stenosis group, while the scores of the severe stenosis group were lower than those of the moderate stenosis group (P＜0.05). Receiver operating characteristic (ROC) curve was drawn, and the results showed the area under the ROC curve (AUC) of sBSI, tBSI, CBF on the affected side, and CBF ratio on the affected side and the healthy side alone and in combination in evaluating mild to moderate and moderate to severe MCA stenosis was all greater than 0.7, indicating moderate evaluation value, with the best evaluation value by combination. 
Conclusion qEEG combined with ASL perfusion imaging has high evaluation value for unilateral MCA stenosis, and can accurately reflect the degree of MCA stenosis. 

Key words: cerebral arterial diseases, quantitative electroencephalogram, magnetic resonance arterial spin labeling perfusion imaging