Application Of Dual-energy CT Immediately In The Diagnosis Of Intracranial Hemorrhage And The Evaluation Of Early Infarction After Endovascular Treatment Of Acute Ischemic Stroke

Objective:To explore the clinical value of dual-energy CT(DECT)in distinguishing cerebral hemorrhage from contrast medium extravasation and evaluating the progression of early infarction immediately after(AIS)endovascular treatment of acute ischemic stroke,so as to better guide the selection of clinical follow-up treatment and prognosis judgment.Methods:50 patients with acute ischemic stroke who underwent endovascular treatment and follow-up DECT immediately were included.Mixed energy images(MIX),virtual non-contrast images(VNC),iodine overlay maps(IOM)and virtual non-calcium images(VNCa)and brain edema map(X-Map)were obtained and evaluated after post-processing.Taking the conventional CT or MR susceptibility weighted angiography(SWAN)images within 24～48h after operation as the reference standard.The sensitivity,specificity,positive and negative predictive value,accuracy of dual energy CT in the diagnosis of hemorrhage were calculated.In addition,with reference to the acute ischemic regions on follow-up CT or MRI DWI,the average density of early infarcted areas on MIX,VNC and X-Map and the contralateral side to infarction differences(CID)were measured and calculated.ROC analyses were performed and the respective Youden indices calculated for cut-off analysis and the sensitivity and specificity of each sequence to the detection of early infarction progression.Two physicians independently evaluated the visual infarction contrast,image noise and Aspect score of acute infarction area on each sequence,compared the consistency with the Aspect score of follow-up CT or MRI DWI.Results:Among the 50 patients,41 patients had high density on MIX.29 cases were diagnosed as contrast medium extravasation by DECT,24 of them were confirmed by follow-up scan,the other 5 cases were identified as hemorrhagic transformation.12 cases were diagnosed as intracranial hemorrhage complicated with contrast medium extravasation by DECT,all were confirmed by follow-up scan.10 were diagnosed as atypical calcification by DECT,all were confirmed by follow-up or former scan.The sensitivity,specificity,positive and negative predictive value,accuracy of DECT in the diagnosis of hemorrhage after endovascular treatment of AIS were 70.6%(12/17),100%(36/36),100%(12/12),87.8%(36/41)and 90.6%(48/53),respectively.Compared with MIX and VNC,X-Map has the lowest average infarct area density(X-Map:21.95±6.73 HU;VNC:25.00±3.90 HU;MIX:30.83±6.86 HU),the highest CID(X-Map:13.21±5.92 HU;VNC:7.09±3.24 HU;MIX:3.05±5.78 HU)and subjective visual infarction contrast,but its image noise is also the most serious;X-Map has the highest infarct detection rate(AUC=0.96),the sensitivity was 93%,the specificity was 88%,and the cutoff value was<30.5Hu.Compared with the follow-up CT or MRI DWI,the ICC of Aspect score of acute infarction area on VNC was higher than that of X-Map and MIX(0.88 vs 0.70 vs 0.20;0.86 vs 0.72 vs 0.14).Conclusions:DECT can be used to accurately diagnose intracranial hemorrhage immediately after endovascular treatment of AIS,combined with VNC and X-Map can better evaluate the progression of early infarction than conventional CT images.