Are systolic velocity duplex metrics negatively affected by flow aliasing in areas of critical internal carotid artery stenosis

Purpose: Duplex scanning is a useful noninvasive screening tool for the detection of carotid bifurcation disease. Internal carotid artery (ICA) peak systolic velocity (PSV) and ICA/common carotid artery (CCA) PSV ratios are proven metrics determining 70%-99% ICA stenosis. A potential disadvantage of using dramatically increasing systolic velocity measurements in areas of critical arterial stenosis is flow aliasing. Diastolic velocity should be less influenced by this flow artifact. We evaluate ICA and CCA end diastolic velocity (EDV) metrics in predicting severe ICA stenosis and document the prevalence of an aliasing artifact in a population of patients with critical ICA stenosis. Methods: Consecutive patients undergoing carotid duplex assessments and contrast angiography were compared (n = 140). ICA and CCA PSV and EDV were recorded as was evidence of the flow aliasing of ICA waveforms. ICA/CCA PSV and EDV ratios were calculated. Duplex parameters were compared with angiographic ICA measurements. Receiver-operator characteristic curve (ROC) analysis was used to determine optimal criteria to identify ICA stenosis of 70% to 99%. Results: Of 256 carotid bifurcation duplex studies, critical angiographic stenosis was present in 105 arteries. Only four completed arterial duplex scans demonstrated flow aliasing. In three of these patients, systolic metrics were non-diagnostic versus ICA/CCA EDV ratios. An ICA/CCA EDV ratio of 2.3 provided the best combination of sensitivity 73.8% and specificity 75.18%. Conclusion: ICA/CCA diastolic ratios reliably determine 70% or greater ICA stenosis. Flow aliasing infrequently complicates ICA PSV.

Reversed ophthalmic artery flow following ischemic stroke: a possible predictor of outcomes following carotid artery stenting

Stroke is the leading cause of death worldwide and stenosis of the carotid artery accounts for more than half of all cases. Carotid duplex is an effective non-invasive ultrasound test which identifies stroke patients with moderate to severe carotid stenosis who are candidates for preventative intervention to reduce the risk of recurrence. In patients with moderate to severe carotid stenosis, reversed ophthalmic artery flow (ROAF) is often observed at the time of the carotid duplex scan. In this study, we investigated whether ROAF, denoting exhaustion of cerebral collateral flow in ischemic stroke patients affected mid-term functional outcomes following carotid artery stenting (CAS) procedures. In total, 144 consecutive patients with a first episode of ischemic stroke and subsequent CAS procedure conducted between January 2010 and November 2014 at Changhua Christian Hospital, Taiwan were included. Clinical data were obtained by medical record review. Disability was assessed at two time points by utilising the Barthel Index (BI) and modified Rankin Scale (mRS) before CAS and 12 months post-CAS. Among 85 patients presenting without ROAF, 48/85 (56.4%) had improved mRS scores following stenting. The condition remained unchanged (stationary) in 36/85 (43.5%) patients after stenting and one patient exhibited deteriorated condition 1/85(1.1%). In contrast, among the 59 patients presenting with ROAF, 24/59 (40.6%) had improved mRS score following stenting. The condition remained unchanged (stationary) in the remaining 35/59 (59.3%) patients after stenting, and no patient exhibited deteriorated condition 0/59 (0 %). This study provides evidence that CAS is a valid and effective treatment option regardless of whether patients exhibited ROAF or not. Patients without ROAF were significantly more likely to have improved mid-term functional outcomes compared to those with ROAF. In the group without ROAF admission, CRP may play a role in predicting subsequent functional outcomes, whereas admission Barthel Index was a predictor of outcome in the ROAF group.

Accuracy of Carotid Duplex Criteria in Diagnosis of Significant Carotid Stenosis in Asian Patients

BACKGROUND

Extracranial carotid stenosis can be diagnosed by velocity criteria of carotid duplex. Whether they are accurately applied to define severity of internal carotid artery (ICA) stenosis in Asian patients needs to be proved. The purpose of this study was to evaluate the accuracy of 2 carotid duplex velocity criteria in defining significant carotid stenosis.

METHODS

Carotid duplex studies and magnetic resonance angiography were reviewed. Criteria 1 was recommended by the Society of Radiologists in Ultrasound; moderate stenosis (50%-69%): peak systolic velocity (PSV) 125-230 cm/s, diastolic velocity (DV) 40-100 cm/s; severe stenosis (>70%): PSV greater than 230 cm/s, DV greater than 100 cm/s. Criteria 2 used PSV greater than 140 cm/s, DV less than 110 cm/s to define moderate stenosis (50%-75%) and PSV greater than 140 cm/s, DV greater than 110 cm/s for severe stenosis (76%-95%).

RESULTS

A total of 854 ICA segments were reviewed. There was moderate stenosis in 72 ICAs, severe stenosis in 50 ICAs, and occlusion in 78 ICAs. Criteria 2 had slightly lower sensitivity, whereas higher specificity and accuracy than criteria 1 were observed in detecting moderate stenosis (criteria 1: sensitivity 95%, specificity 83%, accuracy 84%; criteria 2: sensitivity 92%, specificity 92%, and accuracy 92%). However, in detection of severe ICA stenosis, no significant difference in sensitivity, specificity, and accuracy was found (criteria 1: sensitivity 82%, specificity 99.57%, accuracy 98%; criteria 2: sensitivity 86%, specificity 99.68%, and accuracy 99%).

CONCLUSIONS

In the subgroup of moderate stenosis, the criteria using ICA PSV greater than 140 cm/s had higher specificity and accuracy than the criteria using ICA PSV 125-230 cm/s. However, there was no significant difference in detection of severe stenosis or occlusion of ICA.

Spontaneous Recanalization After Carotid Artery Dissection: The Case for an Ultrasound-Only Monitoring Strategy

Dissection of the internal carotid artery (ICA) accounts for 5% to 25% of ischemic strokes in young adults. We report a case of spontaneous recanalization of a traumatic ICA dissection in which carotid duplex (CDU) and transcranial color-coded duplex ultrasound (TCCD) were used. A 47-year-old male presented with intermittent episodes of headache, blurry vision, anisocoria, and loss of taste sensation following a whiplash injury while body surfing. Magnetic resonance angiogram (MRA) of the neck revealed absent flow in the cavernous ICA and a clot at the skull base. Carotid duplex, used to further evaluate flow, demonstrated reverberating color Doppler and spectrum signal. A TCCD showed ICA occlusion and smaller-caliber intracranial ICA. The patient reported for follow-up after 1 month on anticoagulation therapy. Upon his return, CDU and TCCD were normal and the ICA showed normal color and spectrum signals. Computed tomography angiogram confirmed ultrasound findings of a dramatic improvement of ICA patency. Additionally, the patient reported that his headaches had resolved. Extracranial CDU and TCCD are useful for monitoring patient progress in cases of spontaneous recanalization following carotid artery dissection. These inexpensive and noninvasive imaging modalities proved to be critical in the initial and follow-up evaluations of the extracranial and intracranial vascular system, providing a strong alternative to expensive magnetic resonance imaging and invasive angiograms and offering more hemodynamic information than "static" MRA.

Vascular imaging in stroke: comparative analysis

Advances in stroke treatment have mirrored advances in vascular imaging. Understanding and advances in reperfusion therapies were made possible by improvements in computed tomographic angiography, magnetic resonance angiography, neurovascular ultrasound, and renewed interest in catheter angiography. As technology allows better noninvasive vascular diagnosis, digital subtraction angiography (the remaining gold standard for vascular imaging) is increasingly used for rescue procedures and elective interventions. This review will examine specific advantages and disadvantages of different vascular imaging modalities as related to stroke diagnosis.