Artery Peak Systolic Velocity Ratio Research Articles

Common Carotid Artery Peak-Systolic Velocity Ratio Predicts High-Grade Common Carotid Stenosis

Screening for common carotid artery (CCA) stenosis with duplex ultrasound (DUS) velocity criteria alone can be limited due to within-patient and between-patients hemodynamic variability. This study evaluated inter-CCA velocity ratio criteria to predict high-grade CCA stenosis. Retrospective review of consecutive patients who underwent computed tomography angiography (CTA) and DUS peak-systolic velocity (PSV) measurements of bilateral CCA, independently recorded, between 2008 and 2014. Patients with dampened CCA waveforms on DUS, readily indicating high-grade proximal stenosis, consistuted group B. The remainder without dampened waveforms constituted group A. Inter-CCA PSV ratios were calculated by dividing the higher CCA PSV to the lower one of the other side, so the ratios would always be >1. Ratios were subsequently paired with each respective unilateral CCA diameter stenosis (uDS) and differential bilateral CCA diameter stenosis (dDS). A quadratic regression model was fitted to predict uDS and dDS. Receiver operating characteristic curves were used to determine optimal ratios for ≥50% CCA stenosis. The study excluded patients with carotid artery occlusion. From 174 patients, 167 patients were included in group A and seven in group B. In group A, 31 patients had ≥50% uDS and 17 had ≥50% dDS. All stenoses ≥50% were identified on the same side with the higher PSV. Inter-CCA PSV ratio predicted ≥50% uDS (r2 = 0.57; P < .0001) and dDS (r2 = 0.75; P < .0001; Fig). In group B, all patients had ≥60% stenosis that involved the vessel origin. An increasing inter-CCA PSV ratio showed a trend toward contralateral high-grade stenosis (r2 = .54, P = .06). Receiver operating characteristic curves for ≥50% uDS showed an optimal threshold CCA ratio ≥1.96 with 93% accuracy, 75% sensitivity, and 97% specificity (area under curve, 0.857; 95% confidence interval, 0.755-0.958) and for ≥50% a dDS ratio ≥2.62 with 97% accuracy, 82% sensitivity, and 99% specificity (area under curve, 0.938; 95% confidence interval, 0.828-1.0). DUS-based CCA PSV ratio can accurately predict unilateral and differential high-grade CCA stenosis. Also, in patients with dampened waveforms, it implied contralateral severe proximal stenosis. This parameter should be further validated in prospective studies and is a promising adjunct screening tool to detect high-grade common carotid stenosis.

CT Angiography–derived Duplex Ultrasound Velocity Criteria in Patients with Carotid Artery Stenosis

Validation of carotid duplex ultrasound velocity criteria (CDUS VC) to grade the severity of extracranial carotid artery stenosis has traditionally been based on conventional angiography measurements. In the last decade, computed tomographic angiography (CTA) has largely replaced conventional arch and carotid arteriography (CA) for diagnostic purposes. Given the low number of CA being performed, it is impractical to expect noninvasive vascular laboratories to be validated using this modality. CDUS VC have not been developed with the use of CTA-derived measurements. The objective was to determine optimal CDUS VC from CTA-derived measurements with the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method for 50% and 80% stenosis. A retrospective review of all patients who underwent CDUS and CTA from 2000 to 2009 was performed. Vessel diameters were measured on CTA, and corresponding CDUS velocities were recorded. Percent stenosis was calculated using the NASCET method. Receiver operating characteristic (ROC) curves were generated for internal carotid artery (ICA) peak systolic velocity (PSV), ICA end diastolic velocity (EDV), and ICA PSV to common carotid artery PSV ratio (PSVR) for 50% and 80% stenosis. Velocity cut points were determined with equal weighting of sensitivity and specificity. A total of 575 vessels were analyzed to create the ROC curves. A 50% stenosis analysis yielded ideal cut points for PSV, EDV, and PSVR of 130cm/sec, 42cm/sec, and 1.75. An 80% stenosis analysis yielded ideal cut points for PSV, EDV, and PSVR of 297cm/sec, 84cm/sec, and 3.06. CTA-derived CDUS VC appeared to be reliable in defining 50% and 80% stenosis in patients with carotid artery stenosis. Although CDUS VC defined in this study were different from many of the previously published VC for the same percent stenosis, there were many similarities to those reported by the Society of Radiologists in Ultrasound consensus conference. We feel that CTA should be the gold standard imaging technique for validating CDUS VC.

Establishing Common Carotid Artery Peak Systolic Velocity Ratio Criteria to Predict Common Carotid Stenosis

Establishing Common Carotid Artery Peak Systolic Velocity Ratio Criteria to Predict Common Carotid Stenosis

Carotid Stenosis: A Risk Factor for Cerebral White-matter Disease

We sought to study the association between carotid stenosis and white-matter hyperintensity (WMH) among patients without intracranial large-vessel stenosis. This was a prospective study of patients with acute lacunar infarcts without concomitant intracranial large-vessel stenosis having undergone carotid ultrasonography. WMH was quantified using the modified Fazekas scale. Patients were grouped into quartiles based on the degree of carotid stenosis. The association among carotid stenosis, vascular risk factors, and WMH were modeled using logistic regression analysis. In all, 100 patients with a mean age of 56.2± 11.7 years were studied. The quartile with the greatest carotid stenosis had a mean internal/common carotid artery peak systolic velocity ratio of 2.36. Total WMH was 4.64 in the highest quartile and 2.52 in the lowest quartile of carotid stenosis. Periventricular (pv)-WMH was significantly greater between the highest and lowest quartiles (2.80 versus 1.28, P = .025). No significant difference was observed for deep subcortical WMH (1.84 versus 1.24, P = .281). With increasing carotid stenosis, increase in both ipsilateral and contralateral pv-WMH was observed. When patients with significant carotid stenosis were compared to those without significant carotid stenosis, pv-WMH was significantly higher in the group with significant stenosis even after correcting for age and comorbid vascular risk factors (odds ratio 1.24; confidence interval 1.0-1.54). Carotid stenosis is an important risk factor for WMH. Volumes of pv-WMH significantly increase with higher grades of carotid stenosis.

Carotid Doppler Velocity Measurements and Anatomic Stenosis

Duplex ultrasound with Doppler velocimetry is widely used to evaluate the presence and severity of internal carotid artery stenosis; however, a variety of velocity criteria are currently being applied to classify stenosis severity. The purpose of this study is to compare published Doppler velocity measurements to the severity of internal carotid artery stenosis as assessed by x-ray angiography in order to clarify the relationship between these 2 widely used approaches to assess carotid artery disease. Scatter diagrams or "scattergrams" of correlations between Doppler velocity measurements and stenosis severity as assessed by x-ray contrast angiography were obtained from published articles for native and stented internal carotid arteries. The scattergrams were graphically digitized, combined, and segmented into categories bounded by 50% and 70% diameter reduction. These data were combined and divided into 3 sets representing different velocity parameters: (1) peak systolic velocity, (2) end-diastolic velocity, and (3) the internal carotid artery to common carotid artery peak systolic velocity ratio. The horizontal axis of each scattergram was transformed to form a cumulative distribution function, and thresholds were established for the stenosis categories to assess data variability. Nineteen publications with 22 data sets were identified and included in this analysis. Wide variability was apparent between all 3 velocity parameters and angiographic percent stenosis. The optimal peak systolic velocity thresholds for stenosis in stented carotid arteries were higher than those for native carotid arteries. Within each category of stenosis, the variability of all 3 velocity parameters was significantly lower in stented arteries than in native arteries. Although Doppler velocity criteria have been successfully used to classify the severity of stenosis in both native and stented carotid arteries, the relationship to angiographic stenosis contains significant variability. This analysis of published studies suggests that further refinements in Doppler velocity criteria will not lead to improved correlation with carotid stenosis as demonstrated by angiography.

Effect of Doppler Angle in Diagnosis of Internal Carotid Artery Stenosis

The purpose of this study was to compare velocity measurements obtained with 2 fixed insonation angles and to investigate whether there is a difference in their ability in determining internal carotid artery (ICA) stenosis. Eighty-seven patients with ICA stenosis were examined with color duplex ultrasonography. Velocity measurements were made at 60 degrees and 45 degrees insonation angles, and they were compared with Bland-Altman and receiver operating characteristic curve analysis. Peak systolic velocity (PSV) and end-diastolic velocity measurements obtained at the 60 degrees insonation angle were higher compared with those obtained at the 45 degrees insonation angle (24.2% and 24.7%, respectively). The ICA-to-common carotid artery PSV ratio, conversely, was slightly higher (3.9%). Although the threshold values for the same velocity parameters obtained at 2 different insonation angles were different, the accuracy ratios (sensitivity and specificity) were not. With application of the Society of Radiologists in Ultrasound consensus criteria to the data obtained at either of the 2 insonation angles, the accuracy ratios of PSV and end-diastolic velocity were found to be statistically different. In the ICA-to-common carotid artery PSV ratio, however, there were no statistically significant differences in the accuracy ratios. Doppler velocity measurements made at different fixed insonation angles show considerable differences. In determining ICA stenosis, although optimal thresholds are different, the diagnostic performance is not different. In determining ICA stenosis with color duplex ultrasonography, angle-specific thresholds must be determined, and examinations must be made at a fixed angle.

Sensitivity and specificity of color duplex ultrasound measurement in the estimation of internal carotid artery stenosis: A systematic review and meta-analysis

Duplex ultrasound is widely used for the diagnosis of internal carotid artery stenosis. Standard duplex ultrasound criteria for the grading of internal carotid artery stenosis do not exist; thus, we conducted a systematic review and meta-analysis of the relation between the degree of internal carotid artery stenosis by duplex ultrasound criteria and degree of stenosis by angiography. Data were gathered from Medline from January 1966 to January 2003, the Cochrane Central Register of Controlled Trials and Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, ACP Journal Club, UpToDate, reference lists, and authors' files. Inclusion criteria were the comparison of color duplex ultrasound results with angiography by the North American Symptomatic Carotid Endarterectomy Trial method; peer-reviewed publications, and >/=10 adults. Variables extracted included internal carotid artery peak systolic velocity, internal carotid artery end diastolic velocity, internal carotid artery/common carotid artery peak systolic velocity ratio, sensitivity and specificity of duplex ultrasound scanning for internal carotid artery stenosis by angiography. The Standards for Reporting of Diagnostic Accuracy (STARD) criteria were used to assess study quality. Sensitivity and specificity for duplex ultrasound criteria were combined as weighted means by using a random effects model. The threshold of peak systolic velocity >/=130 cm/s is associated with sensitivity of 98% (95% confidence intervals [CI], 97% to 100%) and specificity of 88% (95% CI, 76% to 100%) in the identification of angiographic stenosis of >/=50%. For the diagnosis of angiographic stenosis of >/=70%, a peak systolic velocity >/=200 cm/s has a sensitivity of 90% (95% CI, 84% to 94%) and a specificity of 94% (95% CI, 88% to 97%). For each duplex ultrasound threshold, measurement properties vary widely between laboratories, and the magnitude of the variation is clinically important. The heterogeneity observed in the measurement properties of duplex ultrasound may be caused by differences in patients, study design, equipment, techniques or training. Clinicians need to be aware of the limitations of duplex ultrasound scanning when making management decisions.