Optimal carotid duplex velocity criteria for defining the severity of carotid in-stent restenosis

Article Outline

• Abstract
• Material and methods
  • Patient population
  • Statistical analysis
• Results
  • ROC analysis for sensitivity, specificity, PPV, and NPV
    • Peak systolic velocities
    • End diastolic velocities
    • PSV ICA/CCA ratio
• Discussion
• Conclusions
• Author contributions
• Tables (online only). 
• References
• Copyright

Background

The optimal duplex ultrasound (DUS) velocity criteria to determine in-stent carotid restenosis are controversial. We previously reported the optimal DUS velocities for ≥30% in-stent restenosis. This prospective study will further define the optimal velocities in detecting various severities of in-stent restenosis: ≥30%, ≥50%, and 80% to 99%.

Methods

The analysis included 144 patients who underwent carotid artery stenting as a part of clinical trials. All patients had completion arteriograms and underwent postoperative carotid DUS imaging, which was repeated at 1 month and every 6 months thereafter. Patients with peak systolic velocities (PSVs) of the internal carotid artery (ICA) of ≥130 cm/s underwent carotid computed tomography (CT)/angiogram. The PSVs and end-diastolic velocities of the ICA and common carotid artery (CCA) and the PSV of the ICA/CCA ratios were recorded. Receiver operating characteristic curve (ROC) analysis was used to determine the optimal velocity criteria for the diagnosis of ≥30, ≥50, and ≥80% restenosis.

Results

The mean follow-up was 20 months (range, 1-78 months). Available for analysis were 215 pairs of imaging (DUS vs CTA/angiography) studies. The accuracy of CTA vs carotid arteriogram was confirmed in a subset of 22 patients (κ = 0.81). The ROC analysis demonstrated that an ICA PSV of ≥154 cm/s was optimal for ≥30% stenosis with a sensitivity of 99%, specificity of 89%, positive-predictive value (PPV) of 96%, negative-predictive value (NPV) of 97%, and overall accuracy (OA) of 96%. An ICA EDV of 42 cm/s had sensitivity, specificity, PPV, NPV, and OA in detecting ≥30% stenosis of 86%, 62%, 87%, 60%, and 80%, respectively. An ICA PSV of ≥224 cm/s was optimal for >50% stenosis with a sensitivity of 99%, specificity of 90%, PPV of 99%, NPV of 90%, and OA of 98%. An ICA EDV of 88 cm/s had sensitivity, specificity, PPV, NPV, and OA in detecting ≥50% stenosis of 96%, 100%, 100%, 100%, 53%, and 96%. An ICA/CCA ratio of 3.439 had sensitivity, specificity, PPV, NPV, and OA in detecting ≥50% stenosis of 96%, 100%, 100%, 100%, 58%, and 96%, respectively. An ICA PSV of ≥325 cm/s was optimal for >80% stenosis with a sensitivity of 100%, specificity of 99%, PPV of 100%, NPV of 88%, and OA of 99%. An ICA EDV of 119 cm/sec had sensitivity, specificity, PPV, NPV, and OA in detecting ≥80% stenosis of 99%, 100%, 100%, 100%, 75%, and 99%, respectively. The PSV of the stented artery was a better predictor for in-stent restenosis than the end-diastolic velocity or ICA/CCA ratio.

Conclusion

The optimal DUS velocity criteria for in-stent restenosis of ≥30%, ≥50%, and ≥80% were the PSVs of 154, 224, and 325 cm/s, respectively.

Carotid percutaneous transluminal angioplasty and stenting have been proposed as an alternative to carotid endarterectomy (CEA) for significant carotid artery stenosis in high-risk surgical patients.¹, ², ³, ⁴ The incidence of carotid in-stent restenosis has been reported to vary between 1% and 50%.¹, ², ³, ⁴, ⁵ This variation has been attributed to several factors, including the method of stenosis calculation, the definition of severity of stenosis, and the duration of follow-up. Although carotid duplex ultrasound (DUS) imaging has been the procedure of choice to evaluate the incidence of recurrent stenosis after CEA, its role in determining the incidence of carotid in-stent restenosis has been debated.⁵, ⁶, ⁷, ⁸, ⁹

We previously reported a high incidence rate (32%) of ≥50% carotid in-stent restenosis,¹⁰ when applying the standard carotid DUS velocity criteria for native nonstented carotid arteries, as defined by a peak systolic velocity of ≥140 cm/s.¹¹ We also previously reported the optimal DUS velocities for determining ≥30% carotid in-stent restenosis.⁶ This prospective study will further define the optimal velocities in detecting severities of carotid in-stent restenosis of ≥30%, ≥50%, and 80% to 99%.

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Material and methods 

Patient population 

This study analyzed 144 patients who underwent carotid artery stenting (CAS) between February 6, 2001, and March 29, 2007, as part of carotid clinical trials at our institution. The Institutional Review Board of West Virginia University approved the study. These clinical trials included MAVErIC 1, 2, and 3 (Evaluation of the Medtronic AVE Self-Expanding Carotid Stent System with Distal Protection in the Treatment of Carotid Stenosis), SHELTER (Stenting of High Risk Patients: Extracranial Lesion Trial with Emboli Removal), Parodi (Parodi Anti-Emboli System as an adjuvant cerebral protection device during Carotid Stent-supported angioplasty with the Boston Scientific Carotid Wallstent Monorail Endoprosthesis), CREST (Carotid Revascularization Endarterectomy vs Stent Trial), and CAPTURE (Carotid Rx Acculink/Rx Accunet Post-approval Trial to Uncover Unanticipated or Rare Events).

The indication for CAS included symptomatic ≥50% carotid artery stenosis and asymptomatic ≥80% carotid stenosis. All patients were at high surgical risk except the CREST trial patients. They underwent preoperative DUS imaging with an ATL HDI 5000 Phillips system (Advanced Technology Laboratory, Phillips, Bellevue, Wash) in our vascular laboratory, which is accredited by the Intersocietal Commission of Accreditation of Vascular Laboratories (ICAVL), with or without magnetic resonance angiography/computed tomography angiography (CTA) before carotid arteriograms. They also underwent poststenting carotid DUS imaging that was repeated at 1 month and every 6 months thereafter.

The demographic and risk factors of all patients were tabulated, which included smoking, hypertension, diabetes mellitus, hypercholesterolemia, and the presence of coronary artery disease.

All Doppler spectra were obtained using a Doppler sample volume of 1 to 1.5 mm and a Doppler angle of 60° or less. These ultrasound studies were identical, both preoperatively and postoperatively. The examination also included gray scale B-mode imaging, color images of the common carotid artery (CCA), carotid bifurcation, proximal, middle, and distal portions of the stent, the distal unstented portion of the internal carotid artery (ICA), and the external carotid artery. The peak systolic velocities (PSV) and end diastolic velocities (EDV) of the internal and CCAs, and the internal ICA/CCA PSV ratios were recorded. The PSV velocities were taken as close as possible to the lesion. The highest velocities in the stented segment were used for analysis and comparison to other imaging modalities.

Patients with PSVs of the stented artery of ≥130 cm/s underwent carotid CTA or conventional carotid arteriograms (spin arteriography), or both, to verify the presence of in-stent restenosis. This number was selected from a previous study of a systemic review and meta-analysis of the sensitivity and specificity of color DUS measurements and the estimation of nonstented ICA stenosis.¹² The threshold of PSV of ≥130 cm/s in that study was associated with a sensitivity of 98% and a specificity of 88% in the identification of angiographic stenosis of ≥50%.¹² Conventional carotid angiography was only done in patients with carotid DUS studies or CTAs that suggested ≥80% restenosis.

For practical purposes, and to comply with the standard classification of carotid stenosis, we used a cutoff of <30% stenosis to indicate normal to minimal disease. Accordingly, carotid arteriography that was done at the completion of carotid stenting and carotid arteriography or CTA, or both, that was done at a later date, were reviewed for the presence of <30% stenosis, 30% to 50% stenosis, 50% to 80%, and 80% to 99% stenosis.

CT scanning was performed in the craniocaudal direction using a 64-detector row Philips CT scanner. Data acquisition consisted of 64 × 0.625 mm, with reconstruction of 0.9 mm at increments of 0.45 mm, pitch of 0.89, and rotation time of 1 second. Subsequently, through an 18- or 20-gauge cannula placed in an antecubital vein, 100 mL of nonionic contrast material was injected at a rate of 4.5 mL/s after bolus tracking technique. The reconstructed images were processed with the Philips Brilliance workstation, with source and two- and three-dimensional data sets reviewed using a picture archiving and communication system (PACS). Vessel analysis and lumen calculations obtained using calliper method with the PACS system. Angiographic measurements of stenoses were calculated according to the North American Symptomatic Carotid Endarterectomy Trial,¹³ basically by comparing the narrowest segment of the carotid stent with the diameter of the distal normal ICA where the wall becomes parallel.

The study analyzes patients with concurrent DUS images that were done ≤7 days of the poststenting completion carotid arteriogram, and patients who had carotid DUS studies and CTA or carotid arteriography, or both, at late follow-up, which were done ≤30 days. Six patients with ≥80% stenosis or occlusion of the contralateral carotid artery were excluded from analysis. We also measured the correlation between conventional carotid arteriography and CTA in a subset of 22 patients who underwent both tests for severe carotid artery stenosis based on DUS imaging.

The κ statistic shows the agreement between conventional carotid arteriography and CTA. The Cohen κ coefficient is a statistical measure of inter-rater reliability and, in this case, tells us how often conventional carotid arteriography and CTA agreed. An independent observer who was blinded to the DUS findings was used for the interpretation of the CTA/carotid arteriography.

Statistical analysis 

The velocity data were expressed as a mean ± standard deviation. Analysis of variance was used to compare the means of PSV, EDV, and the velocity ratio with the stenosis. Comparison of the DUS velocity data with the CTA/angiography was done using the Fisher exact method. The accuracy of CTA vs conventional carotid arteriograms was determined using the κ statistics. Receiver operating characteristic curves (ROCs) were used to compare angiographic data and velocity measurements to determine the optimum velocity criteria for in-stent restenosis of ≥30%, ≥50%, and 80% to 99%. Sensitivity, specificity, positive-predictive value (PPV), negative-predictive value (NPV), and overall accuracy were determined for the PSVs, EDVs, and the ICA/CCA ratio of the stented areas.

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Results 

This study included 144 CAS patients. Available for analysis were 215 pairs of imaging (DUS vs CTA/angiogram) studies, including 144 pairs of post-CAS completion arteriograms and carotid DUS studies. The remaining 71 pairs were late CTA/arteriograms and carotid DUS studies, and included 22 patients who had conventional contrast arteriograms. The mean follow-up was 20 months (range, 1-78 months).

The demographic and clinical characteristics are summarized in Table I. The combined perioperative stroke, death, and myocardial infarction rate was 2%, consisting of three minor strokes lasting <7 days in 144 patients.

Table I. Demographics and clinical characteristics

Variable	Value
Patients, No.	144
Age, mean (range) years	70(40-88)
Sex, No. (%)
Male	73(51)
Female	71(49)
Comorbidities, No. (%)
Hypertension	117(81)
Diabetes mellitus	60(42)
Coronary artery disease	97(67)
Congestive heart failure	24(17)
Hypercholesterolemia	70(49)
Current smoking	33(23)
Chronic renal failure	25(17)
Indications, No. (%)
Asymptomatic	83(58)
Transient ischemic attack	51(35)
Stroke	10(7)
Restenosis after CEA	95(66)
Primary stenosis	49(34)

CEA, Carotid endarterectomy.

The mean PSVs for patients with ≥30%, ≥50%, and ≥80% stenosis of the stented carotid arteries according to CTA/angiogram were 178, 278, and 403 cm/s, respectively (Table II). The mean EDVs and the ICA/CCA ratios for patients with ≥30%, ≥50%, and ≥80% stenosis are also noted in Table II. There was a statistically significant difference among the mean values at 30% to 50%, 50% to 80%, and >80% in-stent restenosis.

Table II. Mean peak systolic and end diastolic velocities and ratios for severity of in-stent restenosis

EDV, End diastolic velocity; PSV, peak systolic velocity; SE, standard error.

A subset analysis of 22 patients who underwent both conventional carotid arteriography and CTA showed very good correlation of the degree of stenosis as measured by both modalities (κ = 0.81, 95% confidence interval [CI], 0.555-1.0).

There were 19 patients with ≥50% in-stent restenosis, 8 at 12 months, 7 at 24 months, 2 at 36 months, and 2 at 48 months. The mean carotid stenosis before CAS was 84%, and no correlation existed between preoperative stenosis and late in-stent restenosis, which may be because seven patients had preoperative stenosis of <70%.

ROC analysis for sensitivity, specificity, PPV, and NPV 

As noted in Table III (online only), ROC analysis demonstrated that an ICA PSV of ≥154 cm/s was optimal for ≥30% in-stent restenosis, with a sensitivity of 99%, specificity of 89%, PPV of 96%, NPV of 97% and an overall accuracy of 96%. An ICA PSV ≥224 cm/s was optimal for ≥50% in-stent restenosis with a sensitivity of 99%, specificity of 90%, PPV of 99%, NPV of 90%, and an overall accuracy of 98%. An ICA PSV of ≥325 cm/s was optimal for ≥80% in-stent restenosis with a sensitivity of 100%, specificity of 99%, PPV of 100%, NPV of 88%, and overall accuracy of 99%.

As noted in Table IV (online only), ROC analysis demonstrated that an ICA EDV of ≥42 cm/s was optimal for ≥30% in-stent restenosis with a sensitivity of 86%, specificity of 62%, PPV of 87%, NPV of 60%, and an overall accuracy of 80%. An ICA EDV ≥88 cm/s was optimal for ≥50% in-stent restenosis with a sensitivity of 96%, specificity of 100%, PPV of 100%, NPV of 53%, and overall accuracy of 96%. An ICA EDV of ≥119 cm/s was optimal for ≥80% in-stent restenosis with a sensitivity of 99%, specificity of 100%, PPV of 100%, NPV of 75%, and overall accuracy of 99%.

As noted in Table V (online only), ROC analysis demonstrated that an ICA/CCA ratio of ≥1.53 was optimal for ≥30% in-stent restenosis with a sensitivity of 92%, specificity of 54%, PPV of 75%, NPV of 83%, and an overall accuracy of 77%. An ICA/CCA ratio ≥3.43 cm/s was optimal for ≥50% in-stent restenosis with a sensitivity of 96%, specificity of 100%, PPV of 100%, NPV of 58%, and overall accuracy of 96%. An ICA/CCA ratio of ≥4.5 cm/s was optimal for ≥80% in-stent restenosis with a sensitivity of 99%, specificity of 86%, PPV of 100%, NPV of 75%, and overall accuracy of 99%.

Fig 1 shows the ROC curve for the sensitivity and specificity for the PSV, EDV, and ICA/CCA ratio values for ≥30% in-stent restenosis. As noted, a cutoff of 154 cm/s for PSV, 42 cm/s for EDV, and 1.53 ratio, resulted in an area under the ROC curve (AUROC) of 0.97 for the PSV value, 0.76 for the EDV, and 0.83 for the ICA/CCA ratio. A larger AUROC is a measure of improved discrimination. PSV was statistically significantly superior to the EDV (P < .0001) and was also superior to the ICA/CCA ratio (P < .0001). There was no statistical significance between the EDV values vs the ratio (P = .0693).

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• Fig 1. 

  Receiver operating characteristic (ROC) curve for ≥30% in-stent restenosis shows peak systolic velocity (PSV, black line), end diastolic velocity (EDV, red line), and velocity ratio area under the curve (AUC, green line).

Fig 2 shows the ROC curve for ≥50% restenosis comparing the sensitivity and specificity of the PSV, EDV, and the ICA/CCA ratio. As noted on this curve, the AUROC was 0.95 for the PSV value, 0.82 for the EDV, and 0.88 for ICA/CCA ratio (PSV vs EDV, P = .058; PSV vs ICA/CCA ratio, P = .0279; EDV vs ICA/CCA ratio, P = .344).

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• Fig 2. 

  Receiver operating characteristic (ROC) curve for ≥50% in-stent restenosis shows peak systolic velocity (PSV, black line), end diastolic velocity (EDV, red line), and velocity ratio area under the curve (AUC, green line).

Fig 3 shows the ROC curve for ≥80% in-stent restenosis, comparing the sensitivity and specificity of the PSV, EDV, and ICA/CCA ratio values. As noted in this figure, the AUROC was 0.88 for the PSV, 0.90 for the EDV, and 0.86 for the ICA/CCA ratio (PSV vs EDV, P = .3236; PSV vs ICA/CCA ratio, P = .3114; EDV vs ICA/CCA ratio, P = .1857). Table VI summarizes the optimal values of PSVs, EDVs, and ICA/CCA ratios in determining ≥30%, ≥50%, and ≥80% in-stent restenosis. The PSV of the stented artery was a better predictor for ≥30% and ≥50% in-stent restenosis than the EDV or the ICA/CCA ratio, as noted in Fig 1 and Fig 2.

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• Fig 3. 

  Receiver operating characteristic (ROC) curve for ≥80% in-stent restenosis shows peak systolic velocity (PSV, black line), end diastolic velocity (EDV, red line), and velocity ratio area under the curve (AUC, green line).

Table VI. The optimal cutoff values for peak systolic velocity, end diastolic velocity, and internal carotid artery/common carotid artery ratios

Stenosis	Peak systolic velocity			End diastolic velocity			ICA/CCA ratio
	Cutoff	AUC (95% CI)	SE	Cutoff	AUC (95% CI)	SE	Cutoff	AUC (95% CI)	SE
≥30%	>154	.97(.93-1)	0.02	>42	.76(.68-.84)	0.04	>1.533	.83(.77-.90)	0.03
≥50%	>224	.95(.84-1)	0.05	>88	.82(.69-.96)	0.07	>3.439	.88(.77-.99)	0.06
≥80%	>325	.88(.63-1)	0.12	>119	.90(.72-1)	0.09	>4.533	.86(.62-1)	0.12

AUC, Area under the curve; CI, confidence interval; ICA/CCA, internal carotid artery/common carotid artery; SE, standard error.

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Discussion 

Carotid DUS imaging has been used for the diagnosis of carotid artery stenosis for more than two decades. The appropriate threshold velocities defining various degrees of stenoses have been analyzed, leading to the use of specific PSVs, EDVs, or PSV/EDV ratios, or both, to define various categories of carotid artery stenosis. DUS can also be used to examine stented carotid arteries. Although the stent material is highly reflective, it does not produce any significant artifact to limit DUS visualization of the stent. It can provide image details of the stent, vessel wall characteristics, and any abnormalities.

It has been speculated that stents may decrease the compliance of the carotid artery, therefore causing elevated PSVs, even in stenting with normal lumen.⁶, ⁹ In addition, because the plaque is not removed with CAS, this may also add to a decreased compliance and elevated velocities. Although B-mode image data are generally useful, the primary ultrasound parameters used in most vascular laboratories to diagnose the severity of carotid artery disease have been the hemodynamic parameters of PSV, EDV, and ICA/CCA ratio, alone or combined.¹¹

At the present time, DUS criteria have not been standardized for patients undergoing CAS. In an earlier study, Robbin et al⁷ concluded that the use of DUS in the follow-up of stented carotid arteries was unreliable in detecting in-stent restenosis based on variable velocity measurements. Similarly, Ringer et al⁸ also reviewed their experience after CAS and concluded that strict velocity criteria for restenosis were unreliable. In a previously published study, and when we initially applied our ICAVL-accredited vascular laboratory duplex velocity cutoff PSV of ≥140 cm/s criteria, which was developed for native nonstented carotid arteries to distinguish between <50% vs ≥50% stenosis, 32% of our patients were considered to have ≥50% in-stent restenosis (a PSV of ≥140 cm/s).⁶ When the same duplex velocity criteria for nonstented carotid arteries were applied, 54% of our stented patients were considered to have ≥30% restenosis. However, when we used new duplex velocity criteria for stented arteries (PSV >155 cm/s to define ≥30% restenosis), only 33% were considered to have ≥30% in-stent restenosis at a mean follow-up of 18 months.⁶ The same observations were noted when we applied our new criteria in this study. These new defined PSVs of stented carotid arteries were very comparable with carotid arteriography or CTA, or both, with a sensitivity of 100%, a specificity of 90%, PPV of 74%, and a NPV of 100%.⁶

The present prospective study was designed to further classify the severity of in-stent restenosis of ≥30%, ≥50%, and 80% to 99%. For practical purposes, and to comply with the standard classification of carotid stenosis, we used the cutoff for <30% stenosis to signify normal to minimal disease.⁶, ¹¹ Furthermore, stenosis of ≥50% is generally the accepted definition of in-stent restenosis in most CAS studies.⁹, ¹⁴, ¹⁵ In addition, reintervention is generally recommended for symptomatic in-stent ≥50% restenosis and for ≥80% asymptomatic in-stent restenosis.¹⁴, ¹⁵, ¹⁶

Our present study suggests that carotid DUS imaging after CAS using our new described velocity criteria can detect hemodynamically significant carotid in-stent restenosis with very good accuracy. ROC analysis found that an ICA PSV of ≥224 cm/s was optimal for the diagnosis of ≥50% in-stent restenosis with a sensitivity of 99% and specificity of 90%, and similarly, an ICA PSV of ≥325 cm/s was optimal for ≥80% in-stent restenosis with a sensitivity of 100% and specificity of 88%.

A few recent studies have reported on the optimal duplex velocity criteria in the diagnosis of ≥50% in-stent restenosis. Bae Ju Kwon et al¹⁷ reported that a PSV of 200 cm/s and an ICA/CCA ratio of 2.5 were optimal in the diagnosis of ≥50% in-stent restenosis with a sensitivity of 90%, specificity of 97%, PPV of 86%, and NPV of 86%. Stanziale et al¹⁸ analyzed 118 pairs of DUS velocities and carotid arteriography measurements and reported that a PSV of ≥350 cm/s and an ICA/CCA ratio of ≥4.75 were optimal in the diagnosis of ≥70% stenosis. They also concluded that a PSV of ≥225 cm/s and ICA/CCA ratio of ≥2.5 were compatible with carotid in-stent restenosis of ≥50%.¹⁸

Unlike our present study, these previous reports⁷, ⁸, ¹⁷, ¹⁸ lack a reliable ROC analysis of their velocities. In addition, only patients with high velocities underwent carotid arteriography for comparison, which may lead to potential bias towards higher velocity thresholds and may impact the rate of false-negative and false-positive values. Clinicians who examine our ROC analysis data can select thresholds with high NPV and sensitivity, which will ensure that fewer patients with in-stent restenosis will be missed using carotid DUS imaging, which is usually used as a screening modality before further imaging is done before any intervention.

Recently, Lal et al¹⁹ reported their DUS criteria for stented carotid arteries, with findings somewhat similar to our study. Of the 255 CAS procedures that they reviewed, 39 patients had contralateral ICA stenosis and were excluded from the study, 23 died, and 64 were lost to follow-up. The remaining tests and procedures available for analysis included 189 pairs of DUS and procedural carotid angiogram measurements, 99 pairs of DUS and CTA measurements during routine follow-up, and 29 pairs of DUS and carotid angiogram measurements during follow-up for suspected high-grade ≥80% in-stent restenosis (310 pairs of observations, DUS vs carotid angiograms/CTA). The ROC analysis demonstrated the following optimal threshold criteria: ≥20% stenosis (PSV ≥150 cm/s and ICA/CCA ratio ≥2.15), in-stent restenosis ≥50% (PSV ≥220 cm/s and ICA/CCA ratio ≥2.7), and in-stent restenosis ≥80% (PSV 340 cm/s and ICA/CCA ratio ≥4.15). Our present study confirms their values of PSVs in detecting ≥30%, ≥50%, and ≥80% in-stent restenosis; however, adding the ICA/CCA ratio to the PSV value did not significantly change our ability to detect in-stent restenosis.

Obtaining an immediate postoperative DUS study after CAS is critical. Peterson et al,²⁰ in analyzing DUS velocity criteria obtained in 158 patients who were treated with CAS, demonstrated the importance of obtaining a carotid DUS study in the immediate postoperative period to serve as a reference for future follow-up, thus insuring early detection of in-stent restenosis. Similar observations were made by Ringer et al⁸ and in our present series.

The present study has a few limitations, including the use of CTA instead of conventional arteriography in some of our patients; however, several studies found that CTA and conventional arteriography have comparable accuracies.²¹, ²² Similar findings were also noted in our present study, with close agreement between the two modalities (κ = 0.81). Another limitation of the study is the small number of 19 patients with severe carotid stenosis.

Until new proposed revised DUS criteria for CAS are standardized in each vascular laboratory, it is mandatory for follow-up DUS velocities to be compared with earlier velocities after stenting. Persistent elevation of PSVs may be the clue for progressive in-stent carotid restenosis and should be clinically managed accordingly.

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Conclusions 

This study indicates that the optimal DUS velocity criteria for in-stent restenosis of ≥30%, ≥50%, and ≥80% were PSVs of 154, 224, and 325 cm/s, respectively. Early registration of baseline velocities to compare with subsequent follow-up velocities of the stented carotid artery is ideal. Elevation in PSVs, EDVs, or ICA/CCA ratios, or both, may be indicative of developing in-stent restenosis, which may then undergo angiographic evaluation and management, if clinically indicated.

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Author contributions 

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Tables (online only) 

Table III (online only). Sensitivity and specificity of peak systolic velocities for ≥30%, ≥50%, and ≥80% in-stent restenosis

CI, Confidence interval; NPV, negative-predictive value; OA, overall accuracy; PPV, positive-predictive value; PSV, peak systolic velocities.

Table IV (online only). Sensitivity and specificity of end diastolic velocities for ≥30%, ≥50%, and ≥80% in-stent restenosis

CI, Confidence interval; EDV, end diastolic velocity; NPV, negative-predictive value; OA, overall accuracy; PPV, positive-predictive value.

Table V (online only). Sensitivity and specificity of internal carotid artery/common carotid artery ratios for ≥30%, ≥50%, and ≥80% in-stent restenosis

CI, Confidence interval; ICA/CCA, internal carotid artery/common carotid artery; NPV, negative-predictive value; OA, overall accuracy; PPV, positive-predictive value.

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References 

1. Ferguson RD, Ferguson JG. Carotid angioplasty (In search of a worthy alternative to endarterectomy). Arch Neurol. 1996;53:696–698
   • View In Article
   • MEDLINE
2. New G, Roubin GS, Iyer SS, Vitek JJ, Wholey MH, Diethrich EB, et al. Safety, efficacy and durability of carotid artery stenting for restenosis following carotid endarterectomy: a multicenter study. J Endovasc Ther. 2000;7:345–352
   • View In Article
   • MEDLINE
   • CrossRef
3. Yadav J SAPPHIRE Investigators. Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy: the SAPPHIRE study. Circulation. 2002;106:2986–2989
   • View In Article
   • CrossRef
4. Hobson RW, Lal BK, Chakhtoura E, Goldstein J, Haser PB, Kubicka R, et al. Carotid artery stenting: analysis of data for 105 patients at high risk. J Vasc Surg. 2003;37:1234–1239
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (138 KB)
   • CrossRef
5. Lal BK, Hobson RW, Goldstein J, Geohagan M, Chakhtoura E, Pappas PJ, et al. In-stent recurrent stenosis after carotid artery stenting: Life table analysis and clinical relevance. J Vasc Surg. 2003;381162–381168discussion 9
   • View In Article
6. AbuRahma AF, Maxwell D, Eads K, Flaherty SK, Stutler T. Carotid duplex velocity criteria revisited for the diagnosis of carotid in-stent restenosis. Vascular. 2007;15:119–125
   • View In Article
   • MEDLINE
   • CrossRef
7. Robbin ML, Lockhart ME, Weber TM, Vitek JJ, Smith JK, Yadav J, et al. Carotid artery stents: Early and intermediate follow-up with Doppler US. Radiology. 1997;205:749–756
   • View In Article
   • MEDLINE
8. Ringer AJ, German JW, Guterman LR, Hopkins LN. Follow-up of stented carotid arteries by Doppler ultrasound. Neurosurgery. 2002;51:639–643
   • View In Article
   • MEDLINE
   • CrossRef
9. Lal BK, Hobson RW, Goldstein J, Chakhtoura EY, Duran WN. Carotid artery stenting: Is there a need to revise ultrasound velocity criteria?. J Vasc Surg. 2004;39:58–66
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (156 KB)
   • CrossRef
10. AbuRahma AF, Bates MC, Stone PA, Wulu JT. Comparative study of operative treatment and PTA/stenting for recurrent carotid disease. J Vasc Surg. 2001;34:831–838
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (73 KB)
    • CrossRef
11. AbuRahma AF, Robinson PA, Stickler DL, Pollack JA, Richmond BK, Alberts S, et al. Proposed new duplex classification for threshold stenoses used in various symptomatic and asymptomatic carotid endarterectomy trials. Ann Vasc Surg. 1998;12:349–358
    • View In Article
    • Abstract
    • Full-Text PDF (646 KB)
    • CrossRef
12. Jahromi AS, Cina CS, Liu Y, Clase CM. Sensitivity and specificity of color duplex ultrasound measurement in the estimation of internal carotid artery stenosis: a systematic review and meta-analysis. J Vasc Surg. 2005;41:962–972
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (759 KB)
    • CrossRef
13. North American Symptomatic Carotid Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high grade carotid stenosis. N Engl J Med. 1991;325:445–453
    • View In Article
    • MEDLINE
    • CrossRef
14. Hobson RW. CREST (carotid revascularization endarterectomy versus stent trial): Background, design, and current status. Semin Vasc Surg. 2000;13:139–143
    • View In Article
    • MEDLINE
15. Yadav JS, Wholey MH, Kuntz RE, Fayad P, Katzen BT, Mishkel GJ, et al. Protected carotid artery stenting versus endarterectomy in high-risk patients. N Engl J Med. 2004;351:1493–51
    • View In Article
16. Gray WA, Hopkins LN, Yadav S, Davis T, Wholey M, Atkinson R, et al. Protected carotid stenting in high-surgical-risk patients: the ARCHeR results. J Vasc Surg. 2006;44:258–268
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (158 KB)
    • CrossRef
17. Kwon BJ, Jung C, Sheen SH, Cho JH, Han MH. CT angiography of stented carotid arteries: Comparison with Doppler ultrasonography. J Endovasc Ther. 2007;14:489–497
    • View In Article
    • CrossRef
18. Stanziale SF, Wholey MH, Boules TN, Selzer F, Makaroun MS. Determining in-stent stenosis of carotid arteries by duplex ultrasound criteria. J Endovasc Ther. 2005;12:346–353
    • View In Article
    • MEDLINE
    • CrossRef
19. Lal BK, Hobson RW, Tofighi B, Kapadia I, Cuadra S, Jamil Z. Duplex ultrasound velocity criteria for the stented carotid artery. J Vasc Surg. 2008;47:63–73
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (879 KB)
    • CrossRef
20. Peterson BG, Longo GM, Kibbe MR, Matsumura JS, Blackburn D, Astleford P, et al. Duplex ultrasound remains a reliable test even after carotid stenting. Ann Vasc Surg. 2005;19:793–797
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (471 KB)
    • CrossRef
21. Cinat M, Lane CT, Pham H, Lee A, Wilson SE, Gordon I. Helical CT angiography in the preoperative evaluation of carotid artery stenosis. J Vasc Surg. 1998;28:290–300
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (150 KB)
    • CrossRef
22. Cinat M, Casalme C, Wilson SE, Pham H, Anderson P. Computed tomography angiography validates duplex sonographic evaluation of carotid artery stenosis. Am Surg. 2003;69:842–847
    • View In Article
    • MEDLINE