Color-coded duplex ultrasound compared to CT angiography for detection and quantification of carotid artery stenosis

A Comparative Analysis and Results of Carotid Interventions Based on Duplex Ultrasound as a Single Exam Versus Multiple Diagnose Exams

BACKGROUND

To determine the results, safety, and clinical outcomes of carotid interventions performed with duplex ultrasound (DUS) as a single preoperative image for internal carotid artery (ICA) assessment, compared to computed tomography angiography (CTA) and magnetic resonance angiography (MRA).

METHODS

Prospective, consecutive cohort study of 2 groups of patients submitted to carotid interventions, 1 group of patients with DUS as a sole exam (group DUS) compared to patients with DUS plus CTA or MRA for ICA stenosis diagnosis (group CTA/MRA) regarding clinical outcomes such as major stroke, minor stroke, transient ischemic attack and perioperative mortality.

RESULTS

Two groups of patients were identified: group DUS with 47 patients and group CTA/MRA plus DUS with 68 patients. The mean age of the patients was 71.67 years in total cohort, and most of them were male (66.1%). Group DUS had higher prevalence of male, dyslipidemia, ischemic heart disease, peripheral artery disease and chronic kidney disease than group CTA/MRA (83% vs. 54.4%, P = 0.001; 93.6% vs. 51.5%, P < 0.001; 36.2% vs. 16.2%, P = 0.009; 29.8% vs. 13.2%, P = 0.019; 14.9% vs. 5.9%, P = 0.007, respectively). We have performed a Kaplan-Meier regarding survival rates: Group DUS had 93.5%% and Group CTA/MRA had 90.3%% at 720 days. P = 0.15, standard error < 10 at 720 days. a Kaplan-Meier analysis regarding primary patency rates showed Group DUS with 92.7% and Group CTA/MRA with 94.7% at 720 days. P = 0.78, standard error < 10 at 720 days. Furthermore, the incidence of postoperative stroke was 2.6% (asymptomatic 1.7%, symptomatic 2.9%), with no differences among DUS and CTA/MRA groups (2.1% vs. 2.9%, P = 0.78, respectively).

CONCLUSIONS

Independently of the type of carotid intervention (carotid endarterectomy and carotid stenting (CAS)), DUS as an only preoperative carotid image has similar results regarding postoperative outcomes when compared to CTA/MRA for preoperative carotid evaluation.

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.

Neurovascular disease, diagnosis, and therapy: Cervical and intracranial atherosclerosis, vasculitis, and vasculopathy

Stroke is a leading cause of death, disability, and financial burden in the United States. Perhaps more than any other disease process, the rapidity with which the diagnosis and treatment of stroke are successfully achieved is paramount to the reduction of its associated morbidity and mortality. Steno-occlusive intracranial vascular disease, the most notorious culprit of cerebral ischemia and/or hemorrhage, traces its etiology to native and embolic atherosclerosis as well as various forms of vascular inflammation, insult, and dysfunction. Distinguishing between these causes is a critical first step in the diagnosis and treatment of a patient presenting with cerebrovascular compromise. In this chapter, we delineate the clinical and imaging features of cervical and intracranial atherosclerosis, vasculitis, and vasculopathy, along with the evidence behind the treatments which comprise their current-day standard of care. The modern imaging armamentarium is diverse and complex, with contrast-enhanced and non-contrast MR angiography, CT angiography, digital subtraction angiography, and ultrasound; each playing an important role in providing rapid insight into the patient's disease process. Understanding these imaging techniques and their application in the acute setting is critical for the provider caring for stroke patients.

Systematic review of preoperative carotid duplex ultrasound compared with computed tomography carotid angiography for carotid endarterectomy

INTRODUCTION

We reviewed the literature for preoperative computed tomography carotid angiography and/or carotid duplex to determine their respective sensitivity and specificity in assessing the degree of carotid stenosis. We aimed to identify whether one imaging modality can accurately identify critical stenosis in patients presenting with transient ischaemic attack or symptoms of a cerebrovascular accident requiring carotid endarterectomy.

METHODS

Systematic search of MEDLINE, Embase, Cochrane database of systematic reviews, all Evidence-Based Medicine Reviews (Cochrane Database of Systematic Reviews, ACP Journal club, Database of Abstracts of Reviews of Effects, Cochrane Clinical Answers, Cochrane Controlled Trials Register, Cochrane Methodology Register, Health Technology Assessment and NHS Economic Evaluation Database) for primary studies relating to computed tomography carotid angiography (CTA) and/or carotid duplex ultrasound (CDU). Studies included were published between 1990 and 2018 and focused on practice in the UK, Europe and North America.

RESULTS

The sensitivity and specificity of CTA and CDU are comparable. CDU is safe and readily available in the clinical environment hence its use in the initial preoperative assessment of carotid stenosis. CDU is an adequate imaging modality for determining stenosis greater than 70%; sensitivity and specificity are improved when the criteria for determining greater than 70% stenosis are adjusted. Vascular laboratories opting to use duplex as their sole imaging modality should assess the sensitivity and specificity of their own duplex procedure before altering practice to preoperative single imaging for patients.

CONCLUSIONS

The sensitivity and specificity of CTA (90.6% and 93%, respectively) and CDU (92.3% and 89%, respectively) are comparable. Both are dependent on criteria used in vascular laboratories. CDU sensitivity and specificity was improved to 98.7% and 94.1%, respectively, where peak systolic velocity and end diastolic velocity were assessed. Either modality can be used to determine greater than 70% stenosis, although a secondary imaging modality may be required for cases of greater than 50% stenosis.

Comparison of Measurement and Grading of Carotid Stenosis with Computed Tomography Angiography and Doppler Ultrasound

BACKGROUND

Doppler ultrasound (DUS) and computed tomography angiography (CTA) are the most commonly used imaging modalities for carotid disease. The aim of this study was to test the accuracy and reproducibility of CTA-derived measurements of carotid stenosis and compare them with those obtained by DUS.

METHODS

Images of 100 carotid arteries of patients who underwent carotid DUS at our unit and CTA of the carotids within a 28-day period were identified retrospectively from multidisciplinary team meeting records. CTAs were assessed by 2 investigators, each using a manual and a semi-automated method. With both methods, the degree of stenosis was calculated using the North American Symptomatic Carotid Endarterectomy Trial equation and graded as mild (0-49%), moderate (50-69%), or severe (70-99%). Cohen's kappa and specificity and sensitivity for ≥50% stenosis were calculated.

RESULTS

The interobserver agreement was moderate (κ 0.407, weighted-κ 0.517) for the manual method and good (κ 0.786, weighted-κ 0.842) for the semi-automated method. Using DUS as the gold standard, the semi-automated method had greater sensitivity (75%) and specificity (91%) in detecting clinically significant carotid artery stenosis (≥50%) than the manual one (63% and 86%, respectively). Agreement between DUS and the semi-automated method of CTA reporting was moderate (κ 0.453, 95% confidence interval [CI]: 0.320-0.586, weighted-κ 0.598, 95% CI: 0.486-0.710), whereas DUS and the manual method of CTA reporting had only fair agreement (κ 0.344, 95% CI: 0.209-0.478, weighted-κ 0.446, 95% CI: 0.315-0.577).

CONCLUSIONS

CTA tends to underestimate the degree of stenosis when compared with DUS. The semi-automated method of CTA reporting has greater reproducibility and greater agreement with DUS. These findings have practical implications when CTA is used to measure the degree of carotid stenosis in clinical practice.

Management of extracranial carotid artery disease

Stroke is the third leading cause of death in developed nations. Up to 88% of strokes are ischemic in nature. Extracranial carotid artery atherosclerotic disease is the third leading cause of ischemic stroke in the general population and the second most common nontraumatic cause among adults younger than 45 years. This article provides comprehensive, evidence-based recommendations for the management of extracranial atherosclerotic disease, including imaging for screening and diagnosis, medical management, and interventional management.

Color duplex sonography in the detection of internal carotid artery restenosis after carotid endarterectomy: comparison with computed tomographic angiography

OBJECTIVES

Internal carotid artery restenosis after carotid endarterectomy is a major postoperative event, but the clinically best suited means for diagnosis of restenosis are still debated. The objective of this study was to evaluate the sensitivity and specificity of color duplex sonography for detection of substantial internal carotid artery restenosis, verified by computed tomographic (CT) angiography.

METHODS

The study group consisted of 210 consecutive patients with internal carotid artery restenosis, defined as restenosis of 50% or greater, verified by color duplex sonography. The degree of restenosis was calculated according to the European Carotid Surgery Trial guidelines. All patients underwent CT angiography. The specificity, sensitivity, positive predictive value, and negative predictive value of color duplex sonography were calculated.

RESULTS

In 85 patients, internal carotid artery restenosis on color duplex sonography was 50% to 69%, whereas in 125 patients it was 70% or greater. When color duplex sonography was compared with CT angiography, only 2 patients in the group with restenosis of 50% to 69% were misclassified by color duplex sonography, in whom CT angiography showed stenosis of 70% or greater. No patient with stenosis of 70% or greater on color duplex sonography was shown to have a lesser degree of restenosis on CT angiography. When compared with CT angiography, color duplex sonography had specificity of 97.7%, sensitivity of 100%, a positive predictive value of 98.4%, and a negative predictive value of 100% for the detection of internal carotid artery restenosis.

CONCLUSIONS

Color duplex sonography can be effectively used as a primary diagnostic tool for evaluation of patients with suspected internal carotid artery restenosis after carotid endarterectomy.

Concordance rates of Doppler ultrasound and CT angiography in the grading of carotid artery stenosis: a systematic literature review

Physicians have been increasingly relying on noninvasive imaging methods to grade carotid stenosis. The accuracy of Doppler ultrasound (DUS) and CT angiography (CTA) versus intra-arterial angiography (IA) has been assessed in many studies and at least two meta-analyses. Here, we performed a systematic review of studies that compared DUS to CTA. In a PubMed review of the literature from 2000 to 2009, we found 12 studies that compared DUS and CTA-based grading of carotid stenosis. Only 4 of them included at least 20 patients and provided data to classify the diseased arteries into the following categories: mild, moderate or severe NASCET stenosis or occlusion. We extracted 431 arteries from 244 patients (range per study: 48-164). It was not possible to distinguish symptomatic from asymptomatic stenoses. Nearly half arteries had severe stenosis (46% based on DUS and 43% based on CTA). The weighted kappa was 0.85 (95% CI 0.76-0.94), and the accuracy was 0.78. When the arteries were classified into medical and potentially surgical groups, the kappa was 0.76 (95% CI 0.70-0.83), and the accuracy was 0.89. Overall, 17% of the stenoses classified as medical based on DUS were reclassified as surgical based on CTA and 14% of the stenoses classified as medical based on CTA were reclassified as surgical based on DUS. The sparse available data comparing DUS and CTA suggest that the grading of a carotid stenosis as medical or potentially surgical remains uncertain in a relatively high proportion of patients.

Comparison of carotid Doppler ultrasound and computerised tomographic angiography in the evaluation of carotid artery stenosis

PURPOSE

To compare results of carotid Doppler ultrasound (CDUS) and spiral computerised tomographic angiography (CTA) in patients with suspected carotid artery stenosis and to evaluate their combined effect on decision making for carotid endarterectomy (CEA).

METHODS

A total of 107 patients were studied. All of the patients had CDUS followed by CTA as a standard method of investigation. Data included the indications for investigation, stenosis degree measured in both modalities, in addition to difficulties and limitations faced while doing them.

RESULTS

Out of the 214 carotid scans performed, 187 scans were included in the comparison, while 27 scans were excluded due to inadequate data or imaging difficulties. The overall concordance between both CDUS and CTA was 79.1% (148/187) (95% CI 0.72-0.83). CDUS under-estimated and over-estimated the degree of stenosis in 26/187 (14%, 95% CI 0.09-0.19) and 13/187 (7%, 95% CI 0.04-0.12), respectively. When CTA was considered in conjunction with CDUS, the decision regarding operative treatment was changed in 29/187 cases (16%) (95% CI 0.11-0.21).

CONCLUSIONS

CDUS remains the first line non-invasive imaging for carotid artery stenosis. However, in cases where it is inconclusive, CTA is an excellent, reliable, minimally invasive, and outpatient alternative for patient selection for CEA.

Spiral computed tomography angiography (SCTA) and color coded duplex ultrasound (CCDUS): two complementary diagnostic techniques for assessment of extracranial cerebral artery stenosis

Atherosclerotic lesions of the extracranial cerebral arteries account for ischemic stroke in over half of all cases. The risk of stroke associated with symptomatic carotid artery disease is related to the severity of the stenosis. Results of the two major clinical trials, North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST), showed that patients with symptomatic carotid artery disease may benefit from carotid endarterectomy. Therefore, detection and quantification of stenosis are essential. Discrepancies in the angiographic criteria used in both NASCET and ECST trials resulted in continued controversy about the most accurate method of measuring carotid artery stenosis. Moreover, to avoid complications related to the angiography procedure, a good evaluation of vessel wall and plaque composition need to be considered. Both SCTA and CCDUS are non invasive techniques that could overcome angiographic complications and give detailed information on stenosis grading and plaque characteristics. They have been used to evaluate carotid stenosis as a single or combined methods.

Parameters affecting bolus geometry in CTA: a review

CT angiography (CTA) is based on acquisition of data during the arterial phase of contrast material passage. CTA needs timing of the contrast bolus, which should be based on accurate knowledge of bolus geometry. Experimental and human studies on bolus geometry and bolus timing in CTA were reviewed. Important parameters of bolus geometry and methods of bolus timing (test bolus and bolus tracking) are described. Recommendations are given for an optimal CTA protocol.