Duplex criteria for determination of 50% or greater carotid stenosis

Accuracy of the Society of Radiologists in Ultrasound (SRU) Carotid Doppler Velocity Criteria for Grading North American Symptomatic Carotid Endarterectomy Trial (NASCET) Stenosis: A Meta-Analysis

PURPOSE

The Society of Radiologists in Ultrasound (SRU) consensus panel proposed six Doppler velocity cut points for classifying internal carotid artery (ICA) stenosis of 50% and 70% according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method. Their relative accuracies have not been compared.

MATERIALS AND METHODS

Meta-analysis performed following comprehensive literature review and identification of manuscripts with graphs of individual patient NASCET ICA stenosis measured by arteriography versus ICA peak-systolic velocity (PSV), end-diastolic velocity (EDV) and ICA PSV to common carotid artery (CCA) PSV. True positives, true negatives, false positives, and false negatives were calculated and used in two-level mixed effects models. Hierarchical summary receiver operating characteristic (ROC) curves were generated. Areas under the ROC curves were estimated.

RESULTS

Nine studies performed between 1993 and 2016 were identified after review of 337 manuscripts. There were 1738 bifurcation data points extracted for PSV, 1026 for EDV, and 775 for ICA/CCA ratio. The highest sensitivity was 96% (95% CI: 93%, 98%) for PSV of 125 cm/s (50% stenosis) and highest specificity 86% (95% CI: 71%, 93%) for PSV of 230 cm/s (70% stenosis). Areas under the ROC curves ranged from a high of 0.93 (95% CI: 0.92, 0.95) for PSV (50% stenosis) to a low of 0.86 (95% CI: 0.84, 0.88) for EDV (70% stenosis).

CONCLUSIONS

The SRU consensus Doppler cut points vary in their accuracies for predicting ICA stenosis. The PSV cut points have tradeoffs: high sensitivity/low specificity for 50% stenosis and high specificity/moderate sensitivity for 70% stenosis.

Duplex ultrasound for diagnosing symptomatic carotid stenosis in the extracranial segments

BACKGROUND

Carotid artery stenosis is an important cause of stroke and transient ischemic attack. Correctly and rapidly identifying patients with symptomatic carotid artery stenosis is essential for adequate treatment with early cerebral revascularization. Doubts about the diagnostic value regarding the accuracy of duplex ultrasound (DUS) and the possibility of using DUS as the single diagnostic test before carotid revascularization are still debated.

OBJECTIVES

To estimate the accuracy of DUS in individuals with symptomatic carotid stenosis verified by either digital subtraction angiography (DSA), computed tomography angiography (CTA), or magnetic resonance angiography (MRA).

SEARCH METHODS

We searched CRDTAS, CENTRAL, MEDLINE (Ovid), Embase (Ovid), ISI Web of Science, HTA, DARE, and LILACS up to 15 February 2021. We handsearched the reference lists of all included studies and other relevant publications and contacted experts in the field to identify additional studies or unpublished data.

SELECTION CRITERIA

We included studies assessing DUS accuracy against an acceptable reference standard (DSA, MRA, or CTA) in symptomatic patients. We considered the classification of carotid stenosis with DUS defined with validated duplex velocity criteria, and the NASCET criteria for carotid stenosis measures on DSA, MRA, and CTA. We excluded studies that included < 70% of symptomatic patients; the time between the index test and the reference standard was longer than four weeks or not described, or that presented no objective criteria to estimate carotid stenosis.

DATA COLLECTION AND ANALYSIS

The review authors independently screened articles, extracted data, and assessed the risk of bias and applicability concerns using the QUADAS-2 domain list. We extracted data with an effort to complete a 2 × 2 table (true positives, true negatives, false positives, and false negatives) for each of the different categories of carotid stenosis and reference standards. We produced forest plots and summary receiver operating characteristic (ROC) plots to summarize the data. Where meta-analysis was possible, we used a bivariate meta-analysis model.

MAIN RESULTS

We identified 25,087 unique studies, of which 22 were deemed eligible for inclusion (4957 carotid arteries). The risk of bias varied considerably across the studies, and studies were generally of moderate to low quality. We narratively described the results without meta-analysis in seven studies in which the criteria used to determine stenosis were too different from the duplex velocity criteria proposed in our protocol or studies that provided insufficient data to complete a 2 × 2 table for at least in one category of stenosis. Nine studies (2770 carotid arteries) presented DUS versus DSA results for 70% to 99% carotid artery stenosis, and two (685 carotid arteries) presented results from DUS versus CTA in this category. Seven studies presented results for occlusion with DSA as the reference standard and three with CTA as the reference standard. Five studies compared DUS versus DSA for 50% to 99% carotid artery stenosis. Only one study presented results from 50% to 69% carotid artery stenosis. For DUS versus DSA, for < 50% carotid artery stenosis, the summary sensitivity was 0.63 (95% confidence interval [CI] 0.48 to 0.76) and the summary specificity was 0.99 (95% CI 0.96 to 0.99); for the 50% to 69% range, only one study was included and meta-analysis not performed; for the 50% to 99% range, the summary sensitivity was 0.97 (95% CI 0.95 to 0.98) and the summary specificity was 0.70 (95% CI 0.67 to 0.73); for the 70% to 99% range, the summary sensitivity was 0.85 (95% CI 0.77 to 0.91) and the summary specificity was 0.98 (95% CI 0.74 to 0.90); for occlusion, the summary sensitivity was 0.91 (95% CI 0.81 to 0.97) and the summary specificity was 0.95 (95% CI 0.76 to 0.99). For sensitivity analyses, excluding studies in which participants were selected based on the presence of occlusion on DUS had an impact on specificity: 0.98 (95% CI 0.97 to 0.99). For DUS versus CTA, we found two studies in the range of 70% to 99%; the sensitivity varied from 0.57 to 0.94 and the specificity varied from 0.87 to 0.98. For occlusion, the summary sensitivity was 0.95 (95% CI 0.80 to 0.99) and the summary specificity was 0.91 (95% CI 0.09 to 0.99). For DUS versus MRA, there was one study with results for 50% to 99% carotid artery stenosis, with a sensitivity of 0.88 (95% CI 0.70 to 0.98) and specificity of 0.60 (95% CI 0.15 to 0.95); in the 70% to 99% range, two studies were included, with sensitivity that varied from 0.54 to 0.99 and specificity that varied from 0.78 to 0.89. We could perform only a few of the proposed sensitivity analyses because of the small number of studies included.

AUTHORS' CONCLUSIONS

This review provides evidence that the diagnostic accuracy of DUS is high, especially at discriminating between the presence or absence of significant carotid artery stenosis (< 50% or 50% to 99%). This evidence, plus its less invasive nature, supports the early use of DUS for the detection of carotid artery stenosis. The accuracy for 70% to 99% carotid artery stenosis and occlusion is high. Clinicians should exercise caution when using DUS as the single preoperative diagnostic method, and the limitations should be considered. There was little evidence of the accuracy of DUS when compared with CTA or MRA. The results of this review should be interpreted with caution because they are based on studies of low methodological quality, mainly due to the patient selection method. Methodological problems in participant inclusion criteria from the studies discussed above apparently influenced an overestimated estimate of prevalence values. Most of the studies included failed to precisely describe inclusion criteria and previous testing. Future diagnostic accuracy studies should include direct comparisons of the various modalities of diagnostic tests (mainly DUS, CTA, and MRA) for carotid artery stenosis since DSA is no longer considered to be the best method for diagnosing carotid stenosis and less invasive tests are now used as reference standards in clinical practice. Also, for future studies, the participant inclusion criteria require careful attention.

A Comparison Study of Vector Velocity, Spectral Doppler and Magnetic Resonance of Blood Flow in the Common Carotid Artery

Magnetic resonance phase contrast angiography (MRA) is the gold standard for blood flow evaluation. Spectral Doppler ultrasound (SDU) is the first clinical choice, although the method is angle dependent. Vector flow imaging (VFI) is an angle-independent ultrasound method. The aim of the study was to compare VFI- and SDU-estimated peak systolic velocities (PSV) of the common carotid artery (CCA) with PSV obtained by MRA. Furthermore, intra- and inter-observer agreement was determined. MRA estimates were significantly different from SDU estimates (left CCA: p < 0.001, right CCA: p < 0.001), but not from VFI estimates (left CCA: p = 0.28, right CCA: p = 0.18). VFI measured lower PSV in both CCAs compared with SDU (p < 0.001) with improved precision (VFI: left: 24%, right: 18%; SDU: left 38%, right: 23%). Intra- and inter-observer agreement was almost perfect for VFI and SDU (inter-observer correlation coefficient: VFI 0.88, SDU 0.91; intra-observer correlation coefficient: VFI 0.96, SDU 0.97). VFI is more accurate than SDU in evaluating PSV compared with MRA.

Carotid endarterectomy should not be based on consensus statement duplex velocity criteria

OBJECTIVE

Randomized trials support carotid endarterectomy (CEA) in asymptomatic patients with ≥60% internal carotid artery (ICA) stenosis. The widely referenced Society for Radiologists in Ultrasound Consensus Statement on carotid duplex ultrasound (CDUS) imaging indicates that an ICA peak systolic velocity (PSV) ≥230 cm/s corresponds to a ≥70% ICA stenosis, leading to the potential conclusion that asymptomatic patients with an ICA PSV ≥230 cm/s would benefit from CEA. Our goal was to determine the natural history stroke risk of asymptomatic patients who might have undergone CEA based on consensus statement PSV of ≥230 cm/s but instead were treated medically based on more conservative CDUS imaging criteria.

METHODS

All patients who underwent CDUS imaging at our institution during 2009 were retrospectively reviewed. The year 2009 was chosen to ensure extended follow-up. Asymptomatic patients were included if their ICA PSV was ≥230 cm/s but less than what our laboratory considers a ≥80% stenosis by CDUS imaging (PSV ≥430 cm/s, end-diastolic velocity ≥151 cm/s, or ICA/common carotid artery PSV ratio ≥7.5). Study end points included freedom from transient ischemic attack (TIA), freedom from any stroke, freedom from carotid-etiology stroke, and freedom from revascularization.

RESULTS

Criteria for review were met by 327 patients. Mean follow-up was 4.3 years, with 85% of patients having >3-year follow-up. Four unheralded strokes occurred during follow-up at <1, 17, 25, and 30 months that were potentially attributable to the index carotid artery. Ipsilateral TIA occurred in 17 patients. An additional 12 strokes occurred that appeared unrelated to ipsilateral carotid disease, including hemorrhagic events, contralateral, and cerebellar strokes. Revascularization was undertaken in 59 patients, 1 for stroke, 12 for TIA, and 46 for asymptomatic disease. Actuarial freedom from carotid-etiology stroke was 99.7%, 98.4%, and 98.4% at 1, 3, and 5 years, respectively. Freedom from TIA was 98%, 96%, and 95%, freedom from any stroke was 99%, 96%, and 93%, and freedom from revascularization was 95%, 86%, and 81% at 1, 3, and 5 years, respectively.

CONCLUSIONS

Patients with intermediate asymptomatic carotid stenosis (ICA PSV 230-429 cm/s) do well with medical therapy when carefully monitored and intervened upon using conservative CDUS criteria. Furthermore, a substantial number of patients would undergo unnecessary CEA if consensus statement CDUS thresholds are used to recommend surgery. Current velocity threshold recommendations should be re-evaluated, with potentially important implications for upcoming clinical trials.

Multi-parametric ultrasound criteria for internal carotid artery disease-comparison with CT angiography

INTRODUCTION

The German Society of Ultrasound in Medicine (known by its acronym DEGUM) recently proposed a novel multi-parametric ultrasound approach for comprehensive and accurate assessment of extracranial internal carotid artery (ICA) steno-occlusive disease. We determined the agreement between duplex ultrasonography (DUS) interpreted by the DEGUM criteria and CT angiography (CTA) for grading of extracranial ICA steno-occlusive disease.

METHODS

Consecutive patients with acute cerebral ischemia underwent DUS and CTA. Internal carotid artery stenosis was graded according to the DEGUM-recommended criteria for DUS. Independent readers manually performed North American Symptomatic Carotid Endarterectomy Trial-type measurements on axial CTA source images. Both modalities were compared using Spearman's correlation and Bland-Altman analyses.

RESULTS

A total of 303 acute cerebral ischemia patients (mean age, 72 ± 12 years; 58 % men; median baseline National Institutes of Health Stroke Scale score, 4 [interquartile range 7]) provided 593 DUS and CTA vessel pairs for comparison. There was a positive correlation between DUS and CTA (r s  = 0.783, p < 0.001) with mean difference in degree of stenosis measurement of 3.57 %. Bland-Altman analysis further revealed widely varying differences (95 % limits of agreement -29.26 to 22.84) between the two modalities.

CONCLUSION

Although the novel DEGUM criteria showed overall good agreement between DUS and CTA across all stenosis ranges, potential for wide incongruence with CTA underscores the need for local laboratory validation to avoid false screening results.

Effects of carotid endarterectomy and carotid artery stenting on high-risk carotid stenosis patients

OBJECTIVE

To analyze the clinical effects and safety of carotid endarterectomy (CEA) and carotid artery stenting (CAS) in the treatment of high-risk carotid stenosis patients.

METHODS

Total 63 patients who underwent CEA or CAS in our hospitals from January 2007 to December 2012 were selected in this study, and were randomly divided into an observation group and a control group. The patients in the observation group were subjected to CAS and those in the control group were subjected to CEA to compare the primary and secondary endpoints of the treatment.

RESULTS

The arrival rates of the primary and secondary endpoints were 7.14% and 10.71% respectively in the observation group, while those were 11.43% and 11.43% respectively in the control group. There were no significant differences in the arrival rates of primary and secondary endpoints between the two groups (P>0.05).

CONCLUSION

The efficacies and safety of CAS and CEA are similar in treating high-risk carotid stenosis patients.

Carotid Doppler velocity measurements and anatomic stenosis: correlation is futile

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Grading carotid stenosis using ultrasonic methods

The controversy as to whether Doppler ultrasonic methods should play a role in clinical decision-making in the prevention of stroke is attributable to reported disagreement between angiographic and ultrasonic results and the lack of internationally accepted ultrasound criteria for describing the degree of stenosis. Foremost among the explanations for both is the broad scatter of peak systolic velocities in the stenosis, the criterion that has so far received most attention. Grading based on a set of main and additional criteria can overcome diagnostic errors. Morphological measurements (B-mode images and color flow imaging) are the main criteria for low and moderate degrees of stenosis. Increased velocities in the stenosis indicate narrowing, but the appearance of collateral flow and decreased poststenotic flow velocity prove a high degree stenosis (≥70%), additionally allowing the estimation of the hemodynamic effect in the category of high-degree stenosis. Additional criteria refer to the effect of a stenosis on prestenotic flow (common carotid artery), the extent of poststenotic flow disturbances, and derived velocity criteria (diastolic peak velocity and the carotid ratio). This multiparametric approach is intended to increase the reliability and the standard of reporting of ultrasonic results for arteriosclerotic disease of the carotid artery.

The frequency of symptoms in transient ischaemic attack: analysis of Nanjing Stroke Register Program data

The clinical characteristics of 172 patients experiencing single or multiple (two or more) transient ischaemic attacks (TIAs) were investigated. Risk factors, clinical manifestations and vascular examinations were compared. Intracranial and extra-cranial large-artery disease (stenosis > or = 50%) occurred more frequently in multiple-TIA patients than in single-TIA patients, and weakness and atrial fibrillation were observed more frequently in single TIA than in multiple TIA patients. The type of aetiological examination performed in TIA patients should depend on the frequency of attacks.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Clinicians need to be aware of the limitations of duplex ultrasound scanning when making management decisions.

Duplex ultrasound and magnetic resonance angiography compared with digital subtraction angiography in carotid artery stenosis: a systematic review

BACKGROUND AND PURPOSE

The purpose of this work was to review and compare published data on the diagnostic value of duplex ultrasonography (DUS), MR angiography (MRA), and conventional digital subtraction angiography (DSA) for the diagnosis of carotid artery stenosis.

METHODS

We performed a systematic review of published studies retrieved through PUBMED, from bibliographies of review papers, and from experts. The English-language medical literature was searched for studies that met the selection criteria: (1) The study was published between 1994 and 2001; (2) MRA and/or DUS was performed to estimate the severity of carotid artery stenosis; (3) DSA was used as the standard of reference; and (4) the absolute numbers of true positives, false negatives, true negatives, and false positives were available or derivable for at least one definition of disease (degree of stenosis).

RESULTS

Sixty-three publications on duplex, MRA, or both were included in the analysis, yielding the test results of 64 different patient series on DUS and 21 on MRA. For the diagnosis of 70% to 99% versus <70% stenosis, MRA had a pooled sensitivity of 95% (95% CI, 92 to 97) and a pooled specificity of 90% (95% CI, 86 to 93). These numbers were 86% (95% CI, 84 to 89) and 87% (95% CI, 84 to 90) for DUS, respectively. For recognizing occlusion, MRA yielded a sensitivity of 98% (95% CI, 94 to 100) and a specificity of 100% (95% CI, 99 to 100), and DUS had a sensitivity of 96% (95% CI, 94 to 98) and a specificity of 100% (95% CI, 99 to 100). A multivariable summary receiver-operating characteristic curve (ROC) analysis for diagnosing 70% to 99% stenosis demonstrated that the type of MR scanner predicted the performance of MRA, whereas the presence of verification bias predicted the performance of DUS. For diagnosing occlusion, no significant heterogeneity was found for MRA; for DUS, the presence of verification bias and type of DUS scanner were explanatory variables. MRA had a significantly better discriminatory power than DUS in diagnosing 70% to 99% stenosis (regression coefficient, 1.6; 95% CI, 0.37 to 2.77). No significant difference was found in detecting occlusion (regression coefficient, 0.73; 95% CI, -2.06 to 3.51).

CONCLUSIONS

These results suggest that MRA has a better discriminatory power compared with DUS in diagnosing 70% to 99% stenosis and is a sensitive and specific test compared with DSA in the evaluation of carotid artery stenosis. For detecting occlusion, both DUS and MRA are very accurate.

Carotid artery stenting in the first 100 consecutive patients: results and follow up

BACKGROUND

Carotid artery stenting is now used as an alternative to surgical endarterectomy. The availability of cerebral protection systems has expanded the area of application of this procedure.

OBJECTIVE

To assess the feasibility, safety, and immediate and late clinical outcome in patients undergoing percutaneous carotid interventions.

METHODS

Between January 1999 and December 2000, 100 consecutive patients with 102 carotid artery stenoses were treated (71 men, 29 women, mean (SD) age 67 (8) years): 49 had coronary artery disease, 28 had previous stroke or transient ischaemic attack (TIA). On the basis of the Mayo Clinic carotid endarterectomy risk scale, 73 patients were grade III-IV and 13 grade VI.

RESULTS

Baseline diameter stenosis was 78.8 (10)%, with a mean lesion length of 12.6 (5.8) mm. Angiographic success was obtained in 99 lesions (97.0%) with a final diameter stenosis of 2.4 (3.5)%. Procedural success was obtained in 96 patients (96%). Selective cannulation of three carotid arteries was impossible owing to severe vessel tortuosity. Carotid stenting was performed in 97 of the treated lesions, and protection devices were used in 67 lesions. In-hospital complications occurred in seven patients (six TIA, one (category 1) minor stroke). No major stroke or death occurred. All patients were discharged from the hospital after an average of 2.5 days. At 12 (6.2) months of follow up restenosis occurred in three patients (3.4%) (one patient with carotid occlusion had TIA). Six patients had died: two from cerebrovascular events (5 and 11 months after the procedure) and four from cardiovascular causes.

CONCLUSIONS

Carotid stenting appears feasible and safe, with few major complications. Long term follow up is affected by a high incidence of cardiovascular mortality.