Diagnostic Value Of Transcranial Doppler Ultrasound For Basilar Artery Stenosis And Occlusion

Objective:We aim to explore the diagnostic value of transcranial Doppler ultrasound(TCD)for stenosis and occlusion of basilar artery(BA)which use digital subtractive angiography(DSA)as the gold standard.methods:We collect patients who were admitted to the Department of Neurology,the First Hospital of Jilin University from May 2013 to June2018 in order to have a retrospective analysis.DSA and TCD were performed and the time interval was no more than 7 days.At the same time,the patients who with carotid artery disease,bilateral vertebral artery disease(including atherosclerotic stenosis,dissection,aneurysm,subclavian artery stealing blood,etc.),atrial fibrillation and severe arrhythmia were excluded.Patients were divided into normal group and stenosis group according to DSA results.The stenosis group was further divided into four groups: mild stenosis group(<50%),moderate stenosis group(50 ~ 69%),severe stenosis group(70 ~ 99%)and occlusion Group.we record the peak systolic Velocity(PSV),End Diastolic Velocity(EDV),Mean Flow Velocity(MFA),Pulsitility Index(PI),spectrummorphology and audio characteristics of each BA,respectively.The ranksum test was used to compare the differences of hemodynamic parameters between different groups(P<0.05).Kappa value was used to measure the consistency of TCD and DSA results.The optimal blood flow truncation of normal and stenosis was calculated by plotting ROC curve.Finally,we calculate the sensitivity,specificity,positive predictive value,negative predictive value,and accuracy of BA by TCD.ResultsA total of 232 patients were enrolled,including 169 males and 63 females.Their ages were between 15 and 84,and the average age was54.2±10.8 years.The time interval between TCD and DSA was 0 to 7days,with an average of 3 days.There were 232 BA,the normal vessels were 146(62.9%),the stenotic vessels were 86(37.1%),including 17 mild stenosis(7.3%),moderate stenosis 21(9.1%),moderate stenosis 35(15.1%)and occlusion 13(5.8%).There were 62 proximal stenosis(72.1%),19 middle stenosis(22.1%),and 5 distal stenosis(5.8%)of BA.Most of the stenosis BA showed spectrum and audio changes.The medium and severe stenosis showed eddy current,turbulence,unclear envelope of the upper spectrum,rough audio,and loud sound.There was a significant difference between the normal group and the stenosis group in PSV,EDV and MFV(P<0.001).and no significant difference in PI(P>0.05).When the overall comparison,there were significantdifferences between the normal,mild,moderate,severe and occluded groups in PSV,EDV and MFV(P<0.001),and was a statistical difference between the five groups in PI(P<0.05).And when the five groups are compared,there were no significant differences in PSV,EDV,MFVand PI between the mild stenosis group and the severe stenosis group,P>0.005.There were statistical differences between the other 9 groups(P<0.005).But the comparison between PIs is always statistically insignificant(P>0.005).The consistency of TCD and DSA was better.Kappa value was 0.74 when the normal group was compared with the stenosis group,and compared between different groups of stenosis,Kappa value was0.72.The sensitivity of TCD in diagnosing BA stenosis and occlution was74.4%,the specificity was 96.6%,the false positive rate(misdiagnosis rate)was 3.4%,the false negative rate(missing diagnosis rate)was 25.6%,the positive predictive value was 92.8%,and the negative predictive value was 86.5%.The accuracy rate was 88.4%.The optimal blood flow velocity demarcation values for TCD diagnosis of normal and stenosis were PSV=94cm/s,EDV=43cm/s,MFV=65cm/s,and the area under the curve were 0.743,0.734,0.740,the sensitivity were 64.4%.60.3%,60.3%,the specificity were 93.8%,93.2%,96.6%,the positive predictive value were 83.9%,81.5%,89.8%,the negative predictive values were84.0%,82.4%,80.9%,respectively.And the accuracy rate of TCD is84.0%,82.2%,and 84.5%.The area under the PI curve was 0.494,whichwas considered to be incapable of distinguishing between normal vessels and stenotic vessels.Conclusion:BA stenosis and occlusion tend to occur in the proximal and middle segments.TCD can be used as a preliminary screening tool for BA stenosis with high sensitivity,high specificity and moderate accuracy.MFV is the most accurate diagnostic criterion for BA stenosis,while PI has little value in diagnosing BA stenosis and occlusion.The change of spectrum morphology and audio frequency can assist the diagnosis of basilar artery stenosis by TCD.