Usefulness of acceleration time ratio in diagnosis of internal carotid artery origin stenosis

PURPOSE: The acceleration time (AcT) ratio of the internal carotid artery (ICA) is increased in ICA stenosis. However, there are few reports that have directly compared the AcT ratio to digital subtraction angiography (DSA) findings. METHODS: We evaluated 177 vessels with DSA and carotid artery ultrasonography. The AcT ratio was calculated as AcT of the ICA (ICA–AcT)/AcT of the ipsilateral common carotid artery (CCA). We evaluated the correlation of DSA–NASCET stenosis with the origin of the ICA or the peak systolic velocity (ICApsv) in the stenotic region, ICApsv/peak systolic velocity of the CCA (CCApsv), ICA–AcT, and AcT ratio. Sensitivity and specificity for stenosis ≥ 70% were calculated based on the ICApsv, ICApsv/CCApsv, ICA–AcT, and AcT ratio. RESULTS: Using NASCET criteria, 34 vessels had 70% or greater stenosis. DSA–NASCET showed a significant positive correlation with ICApsv, ICApsv/CCApsv, ICA–AcT, and AcT ratio (p < 0.0001). When the cut-off value for ICApsv was set at 176 cm/s, ICApsv/CCApsv at 2.42, ICA–AcT at 0.095 s, and the AcT ratio at 1.35, the sensitivity was 97.1, 97.1, 82.4, and 97.1%, and the specificity was 94.4, 91.0, 83.2, and 83.2%, for DSA–NASCET ≥ 70%, respectively. CONCLUSION: The AcT ratio is a beneficial parameter for evaluating ICA stenosis as well as ICApsv and ICApsv/CCApsv.