Duplex Ultrasound Velocity Criteria Research Articles

Defining Duplex Ultrasound Criteria for In-Stent Restenosis of the Carotid Artery Using Computed Tomographic Angiography.

IntroductionDuplex ultrasound (DUS) velocity measurement is the preferred method for evaluating carotid artery stenosis. However, velocity criteria based upon native carotid arteries may not apply to internal carotid artery stents. Previously, catheter-based angiography was used to determine DUS velocity criteria for in-stent restenosis (ISR), but conventional angiography is invasive and can be limited. This study sought to define duplex ultrasound velocity criteria for predicting internal carotid artery in-stent restenosis by correlating in-stent velocities with computed tomographic angiography (CTA) measurements of percent stenosis.MethodsA retrospective chart review was conducted on all patients who underwent internal carotid artery (ICA) stenting within our health system between January 2013 and February 2020. Thirty-eight surveillance DUS studies from 32 patients were found to have CTA performed within 30 days. Centerline reconstructions of internal carotid artery stents were created using Aquarius iNtuition software (TeraRecon, Durham, NC, USA). Two independent observers measured percent stenosis by three built-in methods. Stenotic areas were matched to DUS-measured peak systolic velocities (PSV) and end-diastolic velocities (EDV). Internal carotid artery PSV (stent) to common carotid artery (CCA) PSV ratios (ICA/CCA) were calculated, and receiver operating characteristic (ROC) curves were generated. The optimal DUS velocity criteria in the stented ICA were determined by maximizing Youden’s index.ResultsMean vessel diameter measurement of percent stenosis resulted in the most accurate model for all DUS velocity parameters (PSV, EDV, and ICA/CCA ratio) and was used for threshold determinations (area under the receiver operating characteristics (AUROC): 0.99, 0.96, and 0.96, respectively). A PSV cutoff of 240 cm/s for ≥60% ISR resulted in the highest Youden’s index (97%) with 100% sensitivity and 97% specificity. Secondary DUS parameters included an EDV ≥50 cm/s (Youden’s index 84%) and an ICA/CCA ratio ≥ 2.2 (Youden’s index 91%).ConclusionsVelocity criteria to predict internal carotid artery ISR is needed to inform decisions for possible reintervention. Using CTA, we found that a PSV ≥240 cm/s on carotid DUS can predict ≥60% ISR with high sensitivity and specificity. This value can be used as an alternative to current velocity criteria based on native carotid arteries. However, the optimal thresholds for EDV and ICA/CCA ratio were similar to native carotid arteries.

Defining Ultrasound Criteria for In-Stent Restenosis of the Carotid Artery Using Computed Tomography Angiography

Duplex ultrasound (DUS) velocity measurement is the preferred method for evaluating carotid artery stenosis. However, DUS velocity criteria determined from native carotid arteries are not applicable to internal carotid artery (ICA) stents. Previously, catheter-based angiography was used to determine the DUS criteria for in-stent restenosis (ISR), but conventional angiography is invasive and can be limited. This study sought to define DUS velocity criteria for predicting ≥60% internal carotid ISR by correlating the in-stent velocities with the computed tomography angiography (CTA) measurements of the percentage of stenosis.

A Reappraisal of CT Angiography Derived Duplex Ultrasound Velocity Criteria With a Comparison to Digital Subtraction Angiography in Patients With Carotid Artery Stenosis

A Reappraisal of CT Angiography Derived Duplex Ultrasound Velocity Criteria With a Comparison to Digital Subtraction Angiography in Patients With Carotid Artery Stenosis

A Reappraisal of CT Angiography Derived Duplex Ultrasound Velocity Criteria With a Comparison to Digital Subtraction Angiography in Patients With Carotid Artery Stenosis

Traditionally, carotid duplex ultrasound (CDUS) velocity criteria have been derived from angiography. Recent studies support a shift toward computed tomography angiography (CTA) derived velocity criteria; however, they lack a comparison to angiography. The purposes of this study are to validate CTA derived measurements with digital subtraction angiography (DSA) and to update our previous CTA-derived velocity criteria for 50% and 80% stenosis. All patients between 2010 and 2019 who underwent CDUS and a neck CTA within 6 months were identified for a retrospective review. Vessel diameter and corresponding CDUS data were recorded. Additional DSA measurements were recorded for a subset of patients. Data from this cohort were added to a previously reported deidentified data set from patients between 2000 and 2009. Receiver operating characteristic (ROC) curves were generated to determine optimal velocity thresholds. Spearman rank correlation was used to correlate measurements obtained by CTA to those obtained by DSA. A total of 1139 vessels from 636 patients were analyzed. ROC analysis to identify ≥ 50% stenosis resulted in optimized thresholds of 143 cm/sec, 46.2 cm/sec, and 2.15 for peak systolic velocity (PSV), end-diastolic velocity (EDV), and PSV to common carotid artery PSV ratio (PSVR), respectively. ROC analysis to identify ≥ 80% stenosis resulted in optimized thresholds of 319 cm/sec, 87.2 cm/sec, and 3.49 for PSV, EDV, and PSVR, respectively. The degree of carotid artery stenosis for a subset of 124 vessels on CTA correlated well with that of DSA (ρ=0.89, P< 0.0001). These data demonstrate a high correlation between measurements obtained on CTA and DSA while forming reliable CTA-derived CDUS velocity criteria.

A Reappraisal Of Ct Angiography Derived Duplex Ultrasound Velocity Criteria With A Comparison To Digital Subtraction Angiography In Patients With Carotid Artery Stenosis

A Reappraisal Of Ct Angiography Derived Duplex Ultrasound Velocity Criteria With A Comparison To Digital Subtraction Angiography In Patients With Carotid Artery Stenosis

Validation of subclavian duplex velocity criteria to grade severity of subclavian artery stenosis

BackgroundValidation of subclavian duplex ultrasound velocity criteria (SDUS VC) to grade the severity of subclavian artery stenosis has not been established or systematically studied. Currently, there is a paucity of published literature and lack of practitioner consensus for how subclavian duplex velocity findings should be interpreted in patients with subclavian artery stenosis. ObjectiveThe objective of the present study was to validate SDUS measurements using subclavian conventional or computed tomography angiogram (subclavian angiogram [SA])-derived measurements. Secondary objectives included measuring the correlation between SDUS peak systolic velocities and SA measurements, and to determine the optimal cutoff value for predicting significant stenosis (>70%). MethodsThis is a retrospective review of all patients with suspected subclavian artery stenosis and a convenience sample of carotid artery patients who underwent SDUS and SA from May 1999 to July 2013. SA reference vessel and intralesion minimal lumen diameters were measured and compared with SDUS velocities obtained within 3 months of the imaging study. Percent stenosis was calculated using the North American Symptomatic Carotid Endarterectomy Trial method for detecting stenosis in a sufficiently large cohort. Receiver operating characteristic curves was generated for SDUS VC to predict >70% stenosis. Velocity cutoff points were determined with equal weighting of sensitivity and specificity. ResultsWe examined 268 arteries for 177 patients. The majority of the arteries were for female patients (52.5%) with a mean age of 66.7 ± 11.1 years. Twenty-three arteries had retrograde vertebral artery flow and excluded from further analysis. For the remaining 245 arteries, the average peak systolic velocity was 212.6 ± 110.7 cm/s, with a range of 45-626 cm/s. Average stenosis was 25.8% ± 28.2%, with a range of 0% to 100%. Following receiver operating characteristic analysis, we found a cutoff value of >240 cm/s to be most predictive of >70%. Area under the curve was 0.94 with 95% confidence intervals of 0.91 to 0.97. The sensitivity and specificity for predicting >70% stenosis was 90.9 and 82.5%, respectively. ConclusionsIn patients with known or suspected disease involving the great vessels, a subclavian artery flow velocity exceeding 240 cm/s seems to be predictive of significant subclavian stenosis. Thus, we propose new SDUS VC, for predicting subclavian artery stenosis. However, because of the use of a convenience sample, it is possible that the current proposed cutoff point might need to be adjusted for other populations.

Renal duplex ultrasound findings in fenestrated endovascular aortic repair for juxtarenal aortic aneurysms

This study characterized duplex ultrasound (DUS) findings and clinical outcomes associated with covered stent placement in renal arteries during fenestrated endovascular aortic repair (FEVAR) to determine if velocity criteria for native renal artery stenosis can be applied. Data from a prospectively maintained database of patients who underwent FEVAR between January 2010 and August 2014 were obtained before FEVAR (preoperative or baseline) and at follow-up assessments at 30days, 6months, and 1, 2, and 3years. The established DUS threshold criteria for ≥60% stenosis in native renal arteries were applied at baseline and all follow-up intervals: renal artery peak systolic velocity (PSV) ≥200cm/s or renal-aortic velocity ratio (RAR) ≥3.5. Forty-nine patients underwent placement of 88 covered renal artery stents during FEVAR. At least 30-day follow-up was available for 43 patients with 80 stents. A ≥60% stenosis was identified in seven renal arteries of six patients on baseline DUS, and these patients were analyzed separately. The remaining 73 renal arteries were classified as normal or<60% stenosis at baseline, with a median PSV of 121cm/s (interquartile range, 96-143) and median RAR of 1.4 (interquartile range, 1.1-1.7). No significant differences were found between the baseline and follow-up PSV measurements at any time point. The RAR differed significantly at some time points, although median values remained below the ≥60% stenosis threshold. Some increased RAR values were attributed to low aortic velocities after repair. In the 13 patients with 17 covered renal artery stents found to have PSV or RAR exceeding a DUS threshold for ≥60% native renal artery stenosis, there was no evidence of stenosis by computed tomography angiography, of renal dysfunction by estimated glomerular filtration rate, or of renal volume decrease by three-dimensional analysis. None of the seven renal arteries with ≥60% stenosis atbaseline showed evidence of restenosis at 1, 2, or 3years. Covered stent placement in nonstenotic renal arteries during FEVAR is safe and durable, with PSV and RAR remaining in the normal or<60% stenosis range in most patients. Increases in PSV or RAR that occur are not associated with clinically significant sequelae or in-stent stenosis on computed tomography angiography. DUS velocity criteria for stenosis in native renal arteries appear to overestimate the severity of stenosis in covered stents after FEVAR.

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.

Invited commentary

Invited commentary

Application of duplex ultrasound imaging in determining in-stent stenosis during surveillance after mesenteric artery revascularization

Currently, there are no well-established duplex ultrasound (DUS) criteria for the evaluation of the mesenteric arteries after stenting for occlusive disease. Previous studies suggested DUS velocity criteria in the native superior mesenteric artery (SMA) overestimate stenosis in stented arteries, but most studies have not evaluated DUS imaging after SMA stenting longitudinally. This study was undertaken to determine the accuracy of DUS after mesenteric artery revascularization and, in particular, to evaluate the utility of DUS imaging for the detection of in-stent stenosis (ISS) of the SMA. A retrospective record review was performed for all patients who underwent SMA stenting for chronic mesenteric ischemia at a single institution from January 2004 to May 2011. Mesenteric artery occlusive disease resulted in 24 patients undergoing mesenteric stenting of the SMA alone (n = 20) or the SMA and celiac artery simultaneously (n = 3). The mean ± standard deviation peak systolic velocity (PSV) in 13 prestent DUS images of the SMA was 464 ± 130 cm/s. Prestenting angiography revealed an average SMA stenosis of 79% ± 14%. After stenting, completion angiography in each case revealed <20% residual stenosis. No significant correlation was identified between SMA PSV and angiographic stenosis before and after stenting (P > .05). Follow-up SMA DUS imaging showed an average PSV of 335 ± 138 cm/s at 0.9 ± 1.5 months, 360 ± 143 cm/s at 4.8 ±2.6 months, and 389 ± 95 cm/s at 14.4 ± 5.1 months. A significant difference existed between the prestent and the first poststent mean SMA PSV (P < .05), but no significant difference existed between each poststenting interval. Eight reinterventions for SMA ISS were performed, with a mean elevated in-stent SMA PSV of 505 ± 74 vs 341 ± 145 cm/s in patients who did not undergo reintervention. Angiography before the eight reinterventions demonstrated an average SMA ISS of 53% ± 25%. In-stent SMA PSV decreased from 505 ± 74 to 398 ± 108 cm/s after the reintervention (P < .05). Consistent with other reports, our data demonstrate the PSV in successfully stented SMAs remains higher than the PSV threshold of 275 cm/s used for the diagnosis of high-grade native SMA stenosis. In addition, in-stent SMA PSVs did not significantly change over DUS surveillance for patients who did not undergo reintervention. Thus, obtaining a baseline DUS early after mesenteric stenting should be considered to compare future surveillance DUS. An increase above this baseline or an in-stent SMA PSV approaching 500 cm/s should be considered suspicious for ISS, but larger prospective studies will be required to validate these preliminary findings.

RR12. CT Angiography-Derived Duplex Ultrasound Velocity Criteria in Patients with Carotid Artery Stenosis

RR12. CT Angiography-Derived Duplex Ultrasound Velocity Criteria in Patients with Carotid Artery Stenosis

Proposed duplex velocity criteria for carotid restenosis following carotid endarterectomy with patch closure

Duplex ultrasound velocity criteria have been used to evaluate the severity of carotid stenosis, however, these standard velocities may not be applicable to carotid restenosis after carotid endarterectomy (CEA) with patch angioplasty. The purpose of this study is to determine if patch angioplasty closure alters velocities just distal to CEA and to define the optimal velocities for detecting >or=30%, >or=50%, and >or=70% restenosis. This study includes 200 CEAs randomized into 100 with polytetrafluoroethylene (PTFE) ACUSEAL patch and 100 with Hemashield Finesse patch. All patients underwent immediate postoperative duplex ultrasounds, which were repeated at 1 month and every 6 months thereafter. Patients with a peak systolic velocity (PSV) of the internal carotid artery ([ICA], just distal to the patch) of >or=130 c/s underwent computed tomography angiogram (CTA). PSVs, end diastolic velocities (EDV), and internal carotid artery/common carotid artery (ICA/CCA) ratios were correlated to completion arteriograms/CTAs. Receiver operator characteristic curves analyses were used to determine optimal velocity criteria in detecting >or=30%, >or=50%, and >or=70% restenosis. One hundred ninety-five pairs of imagings (duplex ultrasound vs CTA/angiogram) were available for analysis. When standard velocity criteria for nonoperated arteries were applied, 37% and 10% of patients were believed to have >or=50% to <70% and >or=70% to 99% restenosis vs 11.3% and 11.3% on CTA/angiography, respectively (P < .001). The mean PSV for >or=30%, >or=50%, and >or=70% restenosis were 172, 249, and 389 c/s, respectively (P < .001). An ICA PSV of >or=155c/s was optimal for >or=30% restenosis with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy (OA) of 98%, 98%, 98%, 98%, and 98%, respectively. A PSV of >or=213 c/s was optimal for >or=50% restenosis with sensitivity, specificity, PPV, NPV, and OA of 99%, 100%, 100%, 98%, and 99%, respectively. An ICA PSV of 274 c/s was optimal for >or=70% restenosis with sensitivity, specificity, PPV, NPV, and OA of 99%, 91%, 99%, 91%, and 98%, respectively. ROC analysis showed that the PSVs were significantly better than EDVs and ICA/CCA ratios in detecting >or=30% and >or=50% restenosis. The mean PSVs of a normal ICA distal to CEA patching were higher than normal nonoperated ICAs, therefore, standard duplex velocities criteria should be revised after CEA with patch closure.

RR27. Visceral Artery Duplex Ultrasound Velocity Criteria for Instent Stenosis Following Mesenteric Artery Stenting: Validated with Arteriography

RR27. Visceral Artery Duplex Ultrasound Velocity Criteria for Instent Stenosis Following Mesenteric Artery Stenting: Validated with Arteriography

Duplex ultrasound velocity criteria for the stented carotid artery

Duplex ultrasound velocity criteria for the stented carotid artery

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

The optimal duplex ultrasound (DUS) velocity criteria to determine in-stent carotid restenosis are controversial. We previously reported the optimal DUS velocities for >or=30% in-stent restenosis. This prospective study will further define the optimal velocities in detecting various severities of in-stent restenosis: >or=30%, >or=50%, and 80% to 99%. 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 >or=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 >or=30, >or=50, and >or=80% restenosis. 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 (kappa = 0.81). The ROC analysis demonstrated that an ICA PSV of >or=154 cm/s was optimal for >or=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 >or=30% stenosis of 86%, 62%, 87%, 60%, and 80%, respectively. An ICA PSV of >or=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 >or=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 >or=50% stenosis of 96%, 100%, 100%, 100%, 58%, and 96%, respectively. An ICA PSV of >or=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 >or=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. The optimal DUS velocity criteria for in-stent restenosis of >or=30%, >or=50%, and >or=80% were the PSVs of 154, 224, and 325 cm/s, respectively.

Duplex ultrasound velocity criteria for the stented carotid artery

Ultrasound velocity criteria for the diagnosis of in-stent restenosis in patients undergoing carotid artery stenting (CAS) are not well established. In the present study, we test whether ultrasound velocity measurements correlate with increasing degrees of in-stent restenosis in patients undergoing CAS and develop customized velocity criteria to identify residual stenosis > or =20%, in-stent restenosis > or =50%, and high-grade in-stent restenosis > or =80%. Carotid angiograms performed at the completion of CAS were compared with duplex ultrasound (DUS) imaging performed immediately after the procedure. Patients were followed up with annual DUS imaging and underwent both ultrasound scans and computed tomography angiography (CTA) at their most recent follow-up visit. Patients with suspected high-grade in-stent restenosis on DUS imaging underwent diagnostic carotid angiograms. DUS findings were therefore available for comparison with luminal stenosis measured by carotid angiograms or CTA in all these patients. The DUS protocol included peak-systolic (PSV) and end-diastolic velocity (EDV) measurements in the native common carotid artery (CCA), proximal stent, mid stent, distal stent, and distal internal carotid artery (ICA). Of 255 CAS procedures that were reviewed, 39 had contralateral ICA stenosis and were excluded from the study. During a mean follow-up of 4.6 years (range, 1 to 10 years), 23 patients died and 64 were lost. Available for analysis were 189 pairs of ultrasound and procedural carotid angiogram measurements; 99 pairs of ultrasound and CTA measurements during routine follow-up; and 29 pairs of ultrasound and carotid angiograms measurements during follow-up for suspected high-grade in-stent restenosis > or =80% (n = 310 pairs of observations, ultrasound vs carotid angiograms/CTA). The accuracy of CTA vs carotid angiograms was confirmed (r(2) = 0.88) in a subset of 19 patients. Post-CAS PSV (r(2) = .85) and ICA/CCA ratios (r(2) = 0.76) correlated most with the degree of stenosis. Receiver operating characteristic analysis demonstrated the following optimal threshold criteria: residual stenosis > or =20% (PSV >or =150 cm/s and ICA/CCA ratio > or =2.15), in-stent restenosis > or =50% (PSV > or =220 cm/s and ICA/CCA ratio > or =2.7), and in-stent restenosis > or =80% (PSV 340 cm/s and ICA/CCA ratio > or =4.15). Progressively increasing PSV and ICA/CCA ratios correlate with evolving restenosis within the stented carotid artery. Ultrasound velocity criteria developed for native arteries overestimate the degree of in-stent restenosis encountered. These changes persist during long-term follow-up and across all grades of in-stent restenosis after CAS. The proposed new velocity criteria accurately define residual stenosis >or =20%, in-stent restenosis >or =50%, and high-grade in-stent restenosis > or =80% in the stented carotid artery.

Carotid Duplex Velocity Criteria Revisited for the Diagnosis of Carotid In-Stent Restenosis

Carotid percutaneous transluminal angioplasty/stenting has become an accepted treatment modality for carotid artery stenosis in high-risk patients. There has been an ongoing debate regarding which duplex ultrasound (DUS) criteria to use to determine the rate of in-stent restenosis. This prospective study revisits DUS criteria for determining the rate of in-stent restenosis. In analyzing a subset of 12 patients (pilot study) who had both completion carotid angiography and DUS within 30 days, 10 patients with normal post-stenting carotid angiography (< 30% residual stenosis) had peak systolic velocities (PSVs) of the stented internal carotid artery (ICA) of < or = 155 cm/s and two patients with > or = 30% residual stenosis had internal carotid artery (ICA) PSVs of > 155 cm/s. Eighty-three patients who underwent carotid stenting as part of clinical trials were analyzed. All patients underwent post-stenting carotid DUS that was done at 1 month and every 6 months thereafter. PSVs and end-diastolic velocities of the ICA and common carotid artery were recorded. Patients with PSVs of the ICA of > 140 cm/s underwent carotid computed tomographic (CT) angiography. The perioperative stroke rate was 1.2%. When the old DUS velocity criteria for nonstented carotid arteries were applied, 54% of patients had > or = 30% restenosis (PSV of > 120 cm/s), but when our new proposed DUS velocity criteria for stented arteries were applied (PSV of > 155 cm/s), 33% had > or = 30% restenosis at a mean follow-up of 18 months (p = .007). The mean PSVs for patients with normal stented carotid arteries based on CT angiography, were 122 cm/s versus 243 cm/s for > or = 30% restenosis and 113 cm/s versus 230 cm/s for > or = 30% restenosis based on our new criteria. The mean PSVs of in-stent restenosis of 30 to < 50%, 50 to < 70%, and 70 to 99%, based on CT angiography, were 205 cm/s, 264 cm/s, and 435 cm/s, respectively. Receiver operating curve analysis demonstrated that an ICA PSV of > 155 cm/s was optimal for detecting > or = 30% in-stent restenosis, with a sensitivity of 100%, a specificity of 90%, a positive predictive value of 74%, and a negative predictive value of 100%. The currently used carotid DUS velocity criteria overestimated the incidence of in-stent restenosis. We propose new velocity criteria for the ICA PSV of > 155 cm/s to define > or = 30% in-stent restenosis.