Duplex scanning of normal or minimally diseased carotid arteries: correlation with arteriography and clinical outcome

This study evaluated the role of duplex scanning in the management of patients with normal or minimally diseases carotid arteries. Carotid duplex scans were interpreted according to previously established criteria and considered normal when pulsed Doppler spectral waveforms showed laminar flow or only minor flow disturbances. Normal flow patterns were noted by duplex scanning in 100 carotid bifurcations of 72 patients who also underwent carotid arteriography. Neurologic symptoms (amaurosis fugax, transient ischemic attack, or stroke) were present in relation to 23 arteries and absent in relation to 77 arteries. On the 23 symptomatic sides arteriography was interpreted as normal in eight, 1% to 15% stenosis in 14, and 16% to 40% stenosis in one. For the 77 asymptomatic sides, arteriography showed normal vessels in 15, 1% to 15% stenosis in 43, and 16% to 40% stenosis in 19. One symptomatic patient was treated by carotid endarterectomy for an irregular 1% to 15% stenosis. None of the asymptomatic lesions were in the range of 80% to 99% stenosis, which would justify endarterectomy for asymptomatic disease. Clinical follow-up for a mean interval of 28 months on 20 of the 22 symptomatic patients not undergoing surgery revealed no strokes and transient recurrent symptoms in two patients. Assuming that the single operation in this study was indicated, duplex scanning correctly identified lesions not requiring carotid endarterectomy in 96% (22/23) of the symptomatic patients. A normal duplex scan also predicted a benign clinical outcome without operation. Duplex scanning can reliably exclude surgically treatable carotid bifurcation lesions in asymptomatic patients, and endarterectomy is rarely indicated in symptomatic patients with normal duplex scan results. This study supports a nonoperative therapeutic approach for most patients with neurologic symptoms and a normal carotid duplex scan on the appropriate side.     

Magnetic resonance angiography is an accurate imaging adjunct to duplex ultrasound scan in patient selection for carotid endarterectomy

PURPOSE: The purpose of this study was to evaluate the accuracy of magnetic resonance angiography (MRA) for categorizing the severity of carotid disease relative to duplex ultrasound scan and cerebral contrast arteriography (CA) to determine if MRA imaging could replace the need for cerebral angiography in cases of indeterminate or inadequate duplex scan imaging. METHODS: Seventy-four carotid bifurcations in 40 patients undergoing 45 carotid endarterectomies from 1996 to 1998 were imaged with duplex ultrasound scan; MRA (two-dimensional neck and three-dimensional intracranial, time-of-flight technique); and biplanar, digital subtraction cerebral arteriography. Studies were blindly reviewed by one reader who used established threshold velocity criteria for the duplex scan and the North American Symptomatic Carotid Endarterectomy Trial method for MRA and CA to determine the percentage of diameter reduction of the internal carotid artery (ICA). Disease severity was grouped into four categories (< 50%, 50%-74%, 75%-99% stenosis and occlusion), and the results of MRA and duplex ultrasound scan were compared with CA. RESULTS: Sensitivity, specificity, positive predictive value, and negative predictive value for detection of > 50% ICA stenosis were 100%, 96%, 98%, and 100% for MRA and 100%, 72%, 88%, and 100% for duplex ultrasound scan, respectively; similarly, for detection of > 75% ICA stenosis values were 100%, 77%, 76%, and 100% for MRA and 90%, 74%, 72%, and 91% for duplex ultrasound scan, respectively. Both MRA and duplex ultrasound scan accurately differentiated all cases of > 95% stenosis (n = 7) from occlusion (n = 4). Short length ICA flow gaps were present on MRA in all cases of 75% to 99% stenosis and one half of cases of CA-defined 50% to 74% stenosis. In patients with 50% to 74% stenosis, the mean angiographic stenosis was significantly greater when a flow gap was present on MRA (64% +/- 6%) versus no flow gap (57% +/- 7%) (P =.04). There was overall agreement among duplex ultrasound scan, MRA, and CA in 73% of carotids imaged. Of the 24% discordant results between MRA and duplex ultrasound scan, MRA correctly predicted disease severity in all cases, and inaccurate duplex ultrasound scan results were due to overestimation in 83% of cases. The operative plan was altered by CA findings in only one patient (2%) after duplex ultrasound scan and MRA. CONCLUSIONS: MRA can accurately categorize the severity of carotid occlusive disease. Duplex ultrasound scan facilitates patient selection for carotid endarterectomy in most cases, but adjunct use of MRA improves diagnostic accuracy for > 75% stenoses and may obviate the need for cerebral arteriography when duplex scan results are inconclusive or demonstrate borderline disease severity.     

Changing trends in the use of preoperative carotid arteriography: the community experience

Between 1 January 1991 and 31 December 1994, 215 carotid endarterectomies were performed at the authors' institution, which utilized a clinical pathway. Prior to May 1992, arteriography was performed routinely. A near perfect correlation was found between the arteriograms and duplex scans when they were compared as part of the Intersocietal Commission for the Accreditation of Vascular Laboratories (ICAVL) vascular laboratory accreditation process. A policy of selective arteriography was instituted in May 1992. Only 11 arteriograms were performed on the next 148 patients (7%) who underwent carotid endarterectomies. Arteriography was performed on two patients with extremely high bifurcations, and five patients when an exact degree of stenosis could not be determined. Two patients with simultaneous mid common carotid and bifurcation stenoses had arteriography to confirm the duplex findings. Arteriography confirmed a long, high-grade internal carotid artery stenosis, which was felt to be operable by duplex, and a simultaneous bifurcation and suspected left common carotid orificial stenosis in one patient each. Arteriograms were performed on three non-operated patients felt to have occluded internal carotid artery on duplex scanning. Two had string-like internal carotid arteries that extended intracranially from the bifurcation, and one patient had an internal carotid artery dissection. Duplex results were grossly confirmed at operation and pathologically. There were no neurological complications in those patients undergoing carotid endarterectomies based on the results of duplex scanning alone. Carotid endarterectomies can be safely performed based on the results of a duplex scan performed in an accredited vascular laboratory. This approach eliminates the risk and cost of arteriography. Approximately 10% of patients will require arteriography if the duplex scan is equivocal or shows disease at other areas than the carotid bifurcation.     

Can carotid duplex scanning supplant arteriography in patients with focal carotid territory symptoms?

Previous reports have suggested that duplex ultrasonography might supplant arteriography as a guide to operative decision making in selected patients with cerebrovascular disease. This study was undertaken to test that tenet in patients with focal carotid territory symptoms. Seventy-two patients having independently interpreted arch and selective carotid arteriography and duplex scanning underwent 78 carotid endarterectomies. Operative specimens were analyzed in all cases and used as the standard in evaluating the accuracy of the preoperative studies. All patients had disease found at the time of operation. The sensitivity of duplex scanning was 99% vs. 91% for arteriography (p = 0.06). In seven cases the scan accurately predicted disease in patients with normal arteriograms and in a single case the scan was read as normal in a patient with a smooth minimally stenotic plaque read as an irregular 30% stenosis on arteriography. The accuracy of duplex scanning was markedly superior to arteriography in detecting intimal surface abnormalities (92% vs. 64%, p less than 0.001) and ulceration (90% vs. 54%, p less than 0.001). There was no difference between duplex scan and arteriography (p = 1.0) in predicting a greater or less than 50% stenosis (accuracy, 94% for arteriogram; 92% for duplex scanning). Of the patients with preoperative potentially reversible symptoms, 97% were free of symptoms at a mean follow-up of 9 months after operation. Eighty-nine percent (17 of 19 patients) of patients with concomitant, ipsilateral, intracranial, or intrathoracic cerebrovascular disease were free of symptoms after carotid endarterectomy.     

Carotid endarterectomy for symptomatic carotid artery disease demonstrated by duplex ultrasound with minimal arteriographic findings

Ulcerated or irregular heterogeneous carotid plaque as seen by duplex ultrasound can cause hemispheric transient ischemic attacks (TIAs) and/or a cerebrovascular accident, even if only associated with nonsignificant carotid stenosis on arteriography. The purpose of this study was to review our experience in patients who underwent a carotid endarterectomy after medical treatment had failed, based on pathologic findings detected by carotid duplex ultrasound with minimal disease on arteriography. The medical records of 14 patients who underwent cartoid endarterectomy for TIA symptoms related to ulcerated or irregular heterogeneous plaques were analyzed. All had had preoperative carotid duplex ultrasound, arteriography, and cardiac and neurologic workups to rule out other causes for their TIAs. Medical treatment had failed in all of them. There were 10 men and four women whose median age was 68 years. Carotid duplex ultrasound showed irregular heterogeneous carotid plaque in all patients associated with 20% to 50% stenosis in 12 and approximately 50% to 60% stenosis in two. All had normal to <20% stenosis on arteriograms. The duplex ultrasound findings were all confirmed at operation. All had an uneventful postoperative course with relief of symptoms. Carotid duplex ultrasound is superior to carotid arteriography in detecting irregular or ulcerative heterogeneous plaque associated with nonsignificant stenosis. Carotid duplex ultrasound can be used to determine the desirability of carotid endarterectomy after failed medical treatment in patients with classical and persistent TIA symptoms despite normal or minimal disease on arteriograms. A successful endarterectomy appears to predict an asymptomatic postoperative course.     

The role of carotid duplex scanning in surgical decision making

Eighty-one patients suspected of having cerebrovascular disease had 157 carotid arterial systems studied by both duplex ultrasonography and contrast arteriography to better define the role of carotid duplex scanning in the surgical decision-making process. These studies were reviewed in a blinded fashion in conjunction with history and physical examination data by two surgeons, one operating on only symptomatic lesions, the other operating on both symptomatic and asymptomatic lesions. Results were analyzed to ascertain if there was agreement regarding decisions for carotid endarterectomy based on scan findings compared with decisions based on arteriographic findings. Scans were also compared with arteriograms and data were analyzed by decision matrix analysis. The accuracy of duplex scanning in relation to arteriography was 81% for detection of disease, 90% for the detection of ulceration, 83% for the detection of a critical stenosis, and 99% for the detection of total arterial occlusion. There was agreement between the two studies regarding the need for carotid surgery in 91% and 89% of carotid arteries, according to surgeons A and B, respectively. Regardless of the surgeons' indications for carotid endarterectomy, duplex ultrasonography provides sufficient information for proper surgical decision making in a high percentage of patients. The accuracy of duplex scanning and the risks of contrast arteriography suggest a possible future role for the routine use of duplex ultrasonography with selective utilization of arteriography in the surgical decision-making process in patients being evaluated for cerebrovascular occlusive disease.     

Vascular surgery without arteriography: use of Duplex ultrasound

Although contrast arteriography has served as the historical 'gold standard' for diagnosis of arterial disease, recent improvements in noninvasive diagnostic methods have made it possible to plan surgical treatment without subjecting patients to this invasive procedure. This approach avoids both the risks and costs associated with arteriography. Duplex scanning has become the standard noninvasive test for extracranial carotid artery disease, and it can also be used to directly evaluate the lower extremity arteries. In addition to the standard duplex criteria for classification of carotid stenosis, new criteria are available that reflect the stenosis thresholds identified in randomized clinical trials. Clinical experience has clearly shown that carotid endarterectomy can be performed safely based on the duplex scan alone in the majority of patients: however, arteriography is still indicated in selected cases. The evaluation of lower extremity arterial disease requires examination of multiple arterial segments, and most vascular surgeons still rely on the anatomic detail provided by arteriography for preoperative planning. Still, it may be possible to avoid formal preoperative arteriography in selected patients by using a combination of lower extremity duplex scanning and intraoperative arteriography. Further developments in noninvasive testing will continue to reduce the need for diagnostic arteriography prior to direct arterial surgery.     

Can Carotid Angiography Be Performed by Vascular Surgeons? A Critical Evaluation of Indications, Technique, and Results

The purpose of this report is to examine the contemporary indications for diagnostic carotid arteriography and evaluate its utility and safety when performed by vascular surgeons. The records of all patients having selective carotid arteriography from September 2000 through March 2002 at our institution were reviewed. One hundred sixty-four consecutive patients had selective arteriography of the extracranial carotid arteries for the following indications: hemispheric symptoms with stenosis <80% by duplex ultrasound (20.6%), suspected brachiocephalic trunk stenosis (15.8%), unclear anatomy by duplex (10.3%), recurrent carotid stenosis (10.3%), symptomatic high-grade (>80% by duplex) internal carotid stenosis (9.8%), ipsilateral internal carotid artery occlusion (7.1%), bilateral high-grade internal carotid artery stenoses (7.1%), vertebral-basilar ischemia (7.0%), contralateral internal carotid occlusion (5.4%), duplex ultrasound from a nonaccredited vascular laboratory (3.3%), and evaluation of nonatherosclerotic carotid disease (3.3%). There were no transient ischemic attacks, strokes, or deaths related to the index procedure. Selective angiography of the extracranial carotid arteries remains an important adjunct in the evaluation of patients with carotid disease. This procedure can be performed safely by vascular surgeons.     

Which asymptomatic patients should undergo routine screening carotid duplex scan?

The benefits of obtaining a routine screening carotid duplex scan have not been established for patients with peripheral vascular disease but no signs or symptoms of carotid artery disease. We retrospectively reviewed all carotid duplex scans (4,000) performed at our institution between 1985 through 1989 and found for analysis 91 scans in 78 patients who underwent a screening duplex scan because of the presence of peripheral vascular disease. Patients with carotid bruits, abnormal carotid pulses, and focal or nonspecific neurologic symptoms were excluded. Thirty-three percent of these patients had carotid stenosis of 16% to 50%, 14% had carotid stenosis greater than or equal to 50%, and 5% had stenosis greater than or equal to 75%. Individual risk factors for atherosclerosis, including elderly age, coronary artery disease, hypertension, diabetes, smoking, and a recent or past history of cardiac or vascular surgery, did not predict the detection of high-grade carotid stenosis. However, all 11 of the patients with carotid stenosis greater than or equal to 50% were 68 years of age and older, and this age range, in combination with the various risk factors, increased the incidence of significant carotid artery stenosis (greater than or equal to 50%) to as high as 45%. We conclude that routine screening carotid duplex scan is indicated in elderly patients (age greater than or equal to 68 years) with peripheral vascular disease, even in the absence of any signs or symptoms of carotid artery disease, when other atherosclerotic risk factors are present.     

Magnetic resonance angiography minimizes need for arteriography after inadequate carotid duplex ultrasound scanning

PURPOSE: We prospectively evaluated whether magnetic resonance angiography (MRA) enabled definition of cerebrovascular anatomy after indeterminate or inadequate results at duplex ultrasound scanning to facilitate patient selection for carotid endarterectomy (CEA) and for technical planning. METHODS: After implementation of a protocol in October 1998 to minimize use of cerebral arteriography, MRA (arch/cervical two-dimensional and cranial three-dimensional time of flight technique) was performed in 138 consecutive patients with cerebrovascular occlusive disease and inconclusive duplex scans obtained by an ICAVL-approved laboratory. The ability of MRA to define anatomic features unresolved at duplex scanning was compared between categories of duplex scan inadequacies. Operative outcome was compared between patients requiring MRA before CEA (n = 66) and a concurrent cohort undergoing CEA on the basis of duplex scan results only (n = 69). RESULTS: Incomplete imaging of the carotid bifurcation, because of high bifurcation, long (>3 cm) internal carotid artery (ICA) plaque, or calcific shadows, was the most common reason for inadequate duplex scans (n = 74, 53%), followed by borderline severe ICA disease (23.17%), suspected extracervical disease (supra-aortic trunk, vertebral, or intracranial, 22, 16%), ICA near- occlusion (12.9%), and diffuse recurrent stenosis (7.5%). MRA enabled resolution of duplex scan inadequacies in 95% of patients with disease confined to the carotid bifurcation, and 90% of all patients, but was least accurate for delineation of extracervical lesions (77%) and near-occlusions (75%). In 5 of 8 patients (6%) arteriography was performed to determine operability of ICA near-occlusion or extracervical lesions. Combined stroke and death rates after CEA were not statistically different (P =.3) between patients requiring MRA (3 of 66, 4.6%) and the concurrent group in whom MRA was performed solely on the basis of duplex results (1 of 69, 1.5%). However, intraoperative technical adjustments (anatomy that precluded shunt use, extended endarterectomy length, ICA shortening due to tortuosity) were planned in 71% of patients (12 of 17) with MRA-defined anatomy, but only 36% of patients (4 of 11) with long CEA on the basis of duplex results only (P =.08). CONCLUSION: MRA replaces the need for cerebral arteriography in most patients after inadequate carotid duplex scanning. Delineation of cerebrovascular anatomy at MRA assists in determination of CEA candidacy and operative planning.     

Carotid arteriography impacts carotid stenosis management

Recent literature advocates carotid endarterectomy on duplex alone. The authors hypothesized that carotid angiography adds information that alters clinical management in a substantial number of patients compared to the use of carotid duplex examination alone. The records of 182 consecutive patients who underwent carotid artery duplex and subsequent carotid/cerebral angiography for suspected carotid artery stenosis between January 1998 and April 1999 were reviewed retrospectively. Carotid artery duplex examinations were stratified based on stenosis: < or =39%, 40% to 59%, 60% to 79% (moderate), 80% to 99% (severe), 100%. Carotid stenosis on angiograms was determined by NASCET criteria. New information found at angiography included vertebral, subclavian, or arch atherosclerosis, intracranial pathosis, or a change in duplex stenosis category to a degree of stenosis not requiring surgery. Clinical importance was attributed to angiograms that altered the patients' management plan. Angiography provided additional information in 53% (97/182) of patients. Vertebral disease was found in 25.1%, subclavian disease in 16.4%, intracranial disease in 15.3%, aortic arch disease in 3.3%. Patient treatment was altered in 30% (55/182). Angiographic findings downgraded the stenosis to medical therapy in 20.9% (38/182). The surgical plan was influenced in 5.5% (10/182). Nine intracranial aneurysms were discovered. Carotid angiography was essential for vascular bypass surgery planning in 3.3% (6/182). Angioplasty was performed in 2.2% (4/182). The accurate determination of stenosis is critical in determining optimal treatment of patients with carotid artery stenosis. Routine carotid angiography remains valuable in the clinical treatment of these patients.     

Accuracy of duplex scanning in the detection of stenosis after carotid endarterectomy

The results of duplex ultrasonography in grading stenosis after carotid endarterectomy (78 sites) were compared with those of contrast angiography in 71 patients studied for recurrent or contralateral occlusive disease of the carotid bifurcation. Duplex and angiographic studies were performed within one month of each other at a mean postoperative interval of 44 months (range 3 to 122 months). Stenosis of the common carotid (CCA) and internal carotid artery (ICA) was classified into five disease categories (normal or less than 15% diameter reduction [DR], 16% to 49% DR, 50% to 75% DR, greater than 75% DR, and occlusion). The overall accuracy of duplex scanning compared with angiography in predicting recurrent carotid bifurcation disease was 83%, a level of agreement similar to classification of disease involving the nonoperated, contralateral bifurcation (overall accuracy 87%). Recurrent stenosis (greater than 50% DR) or occlusion of the CCA or ICA after endarterectomy was identified with an accuracy of 97%. Overestimation of severity of recurrent stenosis accounted for 11 of 13 duplex classification errors (85%). Presence of moderate (30% to 50% DR) recurrent stenosis of the CCA, tortuosity of the ICA, and severe contralateral carotid bifurcation disease were associated with velocity spectra that predicted a more severe recurrent stenosis at the endarterectomy site compared with angiographic grading. The level of agreement between duplex scanning and angiography was comparable to the interobserver variability in angiographic interpretation. The accuracy reported justifies the use of duplex scanning to grade the severity of carotid bifurcation recurrent stenosis and to follow these lesions for disease progression.     

The Fate of a Patent Carotid Artery Contralateral to an Occlusion

The finding of carotid stenosis contralateral to a carotid occlusion is becoming more frequent. While the neurologic outcomes in this patient population have been described, the rate of disease progression measured by duplex examination and the eventual need for carotid endarterectomy has not been described. In this study, a computerized database of carotid duplex examinations was reviewed and clinical data were obtained from clinic records. From 9124 studies 117 patients were identified. Thirty patients had previous carotid surgery on the patent side and were excluded. Of 87 patients 33 required carotid endarterectomy on the patent side. The rate of disease progression and/or the performance of a carotid endarterectomy by life-table analysis was 85.9% over 8 years. There were 10 neurologic events during the follow-up period. Patients with carotid stenosis and contralateral occlusion are at significant risk for disease progression. Follow-up should be more frequent and of longer duration in this patient population. A significant number of patients with carotid artery occlusion will require a carotid endarterectomy of the patent contralateral carotid.     

The relative contributions of carotid duplex scanning,magnetic resonance angiography,and cerebral arteriography to clinical decisionmaking: A prospective study in patients with carotid occlusive disease

Purpose: Recent reports suggest that 80% to 90% of patients can safely undergo carotid endarterectomy on the basis of duplex scanning alone without cerebral angiography. Other investigators have recommended that a complementary imaging study such as magnetic resonance angiography (MRA) also be obtained.Methods: We prospectively evaluated 103 consecutive patients with carotid occlusive disease. Eighty percent of patients were symptomatic. All 103 patients underwent duplex scanning and arteriography. Additional noninvasive tests included computed tomography, magnetic resonance imaging, and MRA in 50%, 56%, and 48% of patients, respectively. At a multispecialty conference all studies except angiograms were reviewed, and a treatment decision was made by a panel of attending vascular surgeons, neurosurgeons, and neurologists. The cerebral angiograms then were reviewed and changes made to final treatment plans were noted.Results: After review of noninvasive studies, 30 of 103 of patients (29%) were believed to require arteriography because of diagnostic uncertainty of carotid occlusion in three patients, suggestion of nonatherosclerotic disease in four, suggestion of proximal disease in two, suboptimal noninvasive studies in one, and uncertainty of therapy despite good-quality noninvasive studies in 20 patients primarily with borderline stenoses and unclear symptoms. In 10 of these 30 patients (33%) management decisions were changed on the basis of angiogram results. Of the remaining 73 patients (71%) in whom the panel felt comfortable proceeding with operative or medical therapy without angiography, only one patient (1.4%) would have had management altered by results of angiography. MRA results concurred with duplex findings in 92% of studies, but did not alter management in any patient.Conclusions: In patients with good-quality duplex images, focal atherosclerotic bifurcation disease, and clear clinical presentation, treatment decisions can be made without arteriography. In 30% of patients angiography is useful in clarifying decisionmaking. MRA is unlikely to influence management decisions and is thus rarely indicated. (J Vasc Surg 1996;23:950-6.)     

Duplex ultrasound criteria for defining the severity of carotid stenosis

Duplex ultrasound scan (DUS) criteria for grading >50% carotid artery stenosis is typically divided into broad categories such as 50-79% stenosis, 80-99% stenosis, and occlusion. The purpose of this study is to validate DUS criteria for stratifying 50 to 100% carotid stenosis into 10% intervals using digital substraction cerebral angiography (DSCA) as the standard of comparison. Between 1996 and 2001, 163 patients were evaluated with duplex ultrasound and angiography. A total of 326 carotid arteries were studied using DUS in an accredited ICAVL vascular laboratory. Threshold velocity criteria for determining the degree of carotid stenosis was defined according to seven categories: <50%, 50-59%, 60-69%, 70-79%, 80-89%, 90-99%, and occlusion. Treatment decisions were based on the angiographic findings. In cases where the degree of stenosis as defined by duplex velocity criteria did not correlate with angiographically defined stenosis, each record was reviewed to determine whether the angiographic findings altered the surgeon's treatment decision. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for DUS-defined degree of stenosis as compared to angiographically defined stenosis were determined. There was a high correlation (R = 0.96) between duplex scan and angiography in 93% (302/326) of the cases. Clinical management was altered in only 3% (10/326) of the cases because of the results of angiography. The DUS velocity criteria to grade the severity of carotid disease in 10% intervals is reliable and accurate. Clinical management of patients with carotid stenosis can be based solely on carotid DUS in 97% of patients considered for treatment of carotid artery disease.     

Improvement in accuracy of diagnosis of carotid artery stenosis with duplex ultrasound scanning with combined use of linear array 7.5 MHz and convex array 3.5 MHz probes: validation versus 489 arteriographic procedures

OBJECTIVE: Validity of a method to improve the accuracy of carotid artery duplex scanning was tested in comparison with arteriography. Study Design: In 489 patients who had not previously undergone arteriography, 978 carotid arteries were examined with duplex ultrasound scanning. In method A, a linear array 7.5 MHz transducer with pulsed-wave 4.7 MHz Doppler scanning was used. For the diagnosis and grading of carotid stenosis, peak systolic and end-diastolic velocity of the Doppler waves were recorded. Method B consisted of complete ultrasound imaging and color-flow mapping with a convex array 3.5 MHz transducer with pulsed-wave 2.8 MHz Doppler scanning in all patients who had previously undergone method A. Further velocity measurements were performed at the sites of stenosis. The results of methods A and B were compared with data from neurologic assessment and arteriographic studies. RESULTS: Method B showed significantly higher diagnostic agreement with arteriography than did method A (K 95% confidence interval [CI], 0.87-0.93 vs 0.79-0.85; P <.05), and the number of mistakes in grading stenosis was significantly lower (primarily because of decreased overestimation) in patients with internal carotid kinking (>60 degrees of angulation) (P <.05), distal stenosis (>20 mm from bifurcation) (P <.01), or wide acoustic shadowing (>1 cm) (P <.01) and in those without these conditions (P <.05). Compared with arteriography, diagnostic accuracy with the new method proved higher for carotid stenoses 50% or greater, 60% or greater, 70% or greater, and 80% or greater; no statistically significant difference was found for carotid stenosis 96% or greater or for carotid occlusion. Compared with data from neurologic assessment and arteriography, method B proved more accurate than method A in designating patients for carotid endarterectomy (P =.014). CONCLUSIONS: The new method significantly improved diagnostic reliability of duplex ultrasound scanning, especially in carotid arteries with kinking, distal stenosis, or wide acoustic shadowing (32.2% of all arteries studied). In clinical practice, we suggest additional use of a lower frequency transducer in cases in which these three conditions are found or suspected at first scanning.     

Is routine CT scanning necessary in the preoperative evaluation of patients undergoing carotid endarterectomy?

To evaluate the usefulness of CT scanning before carotid endarterectomy, a prospective study was performed on 469 consecutive patients considered for carotid endarterectomy during a 5-year period. All patients underwent carotid duplex scanning and CT scanning before carotid arteriography. Two hundred thirty-seven patients (51%) had transient ischemic attacks, 109 (23%) had a prior stroke, and 122 (26%) were asymptomatic. Results of the CT scan were abnormal in 68 (62%) of the 109 patients with stroke. Fifty-one of the 360 patients (14%) without a clinical history of stroke had an abnormal CT scan outcome. Of patients with a stroke documented by CT scanning, 27 had lacunar infarcts, and 92 had cortical infarcts; these findings did not change surgical management in any patient. CT scanning did not reveal any unsuspected infarcts or tumors. Two hundred thirty carotid endarterectomies were performed on 206 patients. Forty-seven patients (23%) in the operative group had abnormal CT scan findings, but the scan did not influence operative decisions or timing in any case. Seventy-two patients (27%) in the nonoperative group had abnormal CT scan results, but CT scan findings did not exclude any patient from arteriography or surgery. Three perioperative strokes (1.3%) occurred. CT scan findings did not correlate with postoperative neurologic complications. Cost of CT scanning was one-half million dollars in our study alone. Routine CT scanning is unnecessary before carotid endarterectomy and is not cost-effective.     

Comparison of duplex Doppler scanning with contrast angiography in carotid artery disease

The results of ultrasonic pulsed Doppler duplex scanning with spectral analysis were compared with the results of contrast arteriography in 37 patients screened for extracranial carotid artery disease. The kappa value for this comparison was 0.476 +/- 0.149. The overall diagnostic accuracy of duplex scanning was 91% (67/74 vessels) for agreement within one category of true assessment of stenosis. All 5 occluded internal carotid arteries were identified correctly by duplex scanning. Duplex scanning of the internal carotid artery is one of the few noninvasive tests that has the capability of discriminating normal arteries from minimal disease, minimal disease from severe disease, and severe disease from occlusion. Duplex scanning should be used as the initial test in patients with non-hemispheric symptoms and complete stroke. The intra-operative and postoperative routine assessment of the endarterectomised segment has become mandatory. Duplex scanning is invaluable in the management of the patient with an asymptomatic carotid bruit.     

Helical CT angiography in the preoperative evaluation of carotid artery stenosis

Purpose: To determine the utility and accuracy of helical CT angiography (CTA) in the evaluation of carotid artery stenosis. Methods: A comparison of CTA and conventional arteriogram was performed in 53 patients undergoing evaluation for carotid artery stenosis. Ninety-six carotid systems were evaluable. CTA stenosis was determined by the percent of area reduction seen on axial images through the level of greatest narrowing. MIP images were used to identify the point of maximal stenosis and to visualize overall vascular anatomy. The percent diameter stenosis was measured on conventional arteriograms using strict North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) criteria. Results: Significant correlation was found between CTA and arteriography (NASCET method R = 0.87, ECST method R = 0.87, p < 0.001). Using NASCET >60% as an indicator for disease, CTA had a sensitivity of 87%, specificity of 90%, accuracy of 89%, negative predictive value of 88%, and positive predictive value of 89%. CTA identified plaque characteristics such as ulcerations (8), occlusion (10), fatty plaques (22), calcifications (48), and fibrosis (2). CTA underestimated 2 cases of short segment stenoses because of volume averaging, but this discrepancy was detected by duplex scan. No complications or renal dysfunction occurred with CTA; 1 patient became symptomatic during arteriography, necessitating termination of the procedure. Conclusion: CTA is a safe, non-invasive technique that precisely measures carotid artery area reduction and highly correlates to conventional arteriography. With this new technology, the current standards for carotid artery imaging may need to be reevaluated, and the precise role for helical CTA more clearly defined. (J Vasc Surg 1998;28:290-300.)     

Why do some patients with > 80% stenosis of the internal carotid artery not undergo surgery? A retrospective review

Background: Carotid endarterectomy is known to benefit both symptomatic and asymptomatic patients with high‐grade internal carotid artery stenosis. Duplex scanning is the ‘gold standard’ for non‐invasive preoperative investigation of carotid artery stenosis. The aim of the present study was to analyse the indications for duplex scanning and to identify other factors that influenced the management of patients with high‐grade stenosis who did not undergo carotid endarterectomy. Methods: A total of 271 patients was observed to have > 80% stenosis of the internal carotid artery on duplex scanning during the period of review. Of these patients, 85 did not undergo carotid endarterectomy. The vascular laboratory database and hospital records of these patients were retrospectively reviewed. Results: The indications for requesting a carotid duplex scan in the 85 patients were transient ischaemic attack (22%), stroke (25%), symptomatic bruit (7%), asymptomatic bruit (12%), and stroke and symptomatic bruit combined (7%). Falls and preoperative carotid assessment prior to coronary surgery were the commonest indications in the remaining patients. The main risk factors were cardiac (68%), hypertension (60%), respiratory (21%), diabetes (25%), peripheral vascular disease (19%), neoplasm (16%) and renal disease (16%). Twenty‐five per cent of the patients were over 80 years of age. Conclusion: In the present study risk factors associated with increased perioperative morbidity and mortality were the commonest explanation for patients with high‐grade stenosis of the internal carotid artery not undergoing surgery. These patients would generally not meet the inclusion criteria for the major carotid endarterectomy trials.