G 3-3 Diagnostic criteria of intracranial ICA stenosis using transorbital TCD

Background and Purpose：It is sometimes difficult to evaluate the siphon ICA(S-ICA)on MRA, because of overestimate of stenosis. We investigated the diagnostic criteria of S-ICA using transorbital TCD. Methods：205 vessels of 110 patients(median age ; 61, male ; 72)were enrolled. We performed transorbital TCD in order to assess the blood flow velocity on S-ICA in stroke patients, who carried out angiography. Results：The stenosis was confirmed in 24(51%)of the 205 vessels on angiography. The mean flow velocity(MFV)of the S-ICA on transorbital TCD was 31(25-41)cm/sec(median, [25th-75th percentile])in no-stenosis group, 39(33-53)cm/sec in＜50 stenosis group, and 48(30-70)cm/sec in 50% stenosis group(p=0.03). The peak systolic velocity(PSV)was 53(4064)cm/sec in no-stenosis group, 68(44-96)cm/sec in＜50 stenosis group, and 74(44-112)cm/sec in 50% stenosis group(p=0.03). The optimal cut-off MFV and PSV to differentiate S-ICA stenosis from non S-ICA stenosis was 40 cm/sec(sensitivity of 63% and specificity of 70%)and 60 cm/sec(sensitivity of 63% and specificity of 77%), respectively. Conclusion：Diagnostic flow velocity of S-ICA stenosis using transorbital TCD is＞40 cm/sec in MFV or＞60 cm/sec in PSV.