carotide doppler

8/9/2019 Carotide Doppler

http://slidepdf.com/reader/full/carotide-doppler 1/10



should also be considered. 6,7 The AsymptomaticCarotid Atherosclerosis Study (ACAS) in patients with asymptomatic high-grade carotid stenosis(≥ 60%) showed a 5.8% risk reduction of stroke at

5 years after endarterectomy and concluded thatCEA was beneficial when performed in centers where morbidity and mortality were 3% orless. 8–10 There is a debate going on about whetherand which subgroups of patients with an asymp-tomatic ICA stenosis should undergo surgery,and risk stratification is necessary to identify these patients. 8,11,12

Because of their superficial location, theextracranial carotid arteries are optimal for colorand duplex Doppler sonography (CDDS). B-modegray scale sonography allows for imaging of atherosclerotic plaques and intima-media thick-ness (IMT). Color Doppler sonography allowssimultaneous real-time visualization of vascularlesions and associated flow abnormalities,guides cursor position on suspected areas of stenosis, and assists in differentiating betweencritical stenosis and occlusion. Examination andrecording of pathologic findings on gray scaleand color Doppler sonography are followed by spectral Doppler hemodynamic analysis.

Doppler sonography is the most commonimaging study performed for the diagnosis of carotid disease. However, a wide range of prac-

tice patterns among vascular laboratories stillexists. Despite technological advances in sono-graphic equipment, improvements in operatorexpertise, and accrediting bodies to increase thequality of carotid sonographic examination,there is still no uniformity in practice and inter-pretation between different centers and evenbetween different operators in the same labora-tory. Therefore, standardized protocols are high-ly recommended for reproducibility andreliability of information provided by carotidsonography. 13

Indications for Carotid SonographicExamination

Candidates for evaluation of carotid artery steno-sis may be divided into 2 groups: symptomaticand asymptomatic. The first group comprisespatients who have had a neurologic event sec-ondary to cerebral ischemia, specifically those who have had amaurosis fugax or a transientischemic attack or a minor stroke, and may ben-efit from CEA. 2–5 Additional indications are sug-

gestive carotid dissection, particularly after trau-ma and in patients after endarterectomy, and astent with neurologic symptoms. The asymp-tomatic group comprised patients with a pul-satile neck mass or cervical bruit and patientsbefore major vascular surgery; some centers fol-low patients having endarterectomy and stentsroutinely and not just when they become symp-tomatic. Regarding carotid sonography forscreening before major cardiovascular surgery, ina recent study by Ascher et al 14 on 3708 patients who underwent open heart surgery and preoper-ative carotid duplex sonography, patient age wasfound to be the most significant risk factor for theprevalence of carotid disease, confirming previ-ous studies. They concluded that carotid screen-ing before open heart surgery (coronary artery bypass graft and valve replacement) should berecommended for all patients older than 60 yearsand for patients younger than 60 years with 2 ormore major risk factors: hypertension, diabetes,and smoking. However, the discussion is stillgoing on about whether asymptomatic patients with combined coronary and carotid artery stenosis should undergo carotid surgery at alland whether staged or synchronous proceduresconfer any overall benefit. 15 Carotid screening may be cost-effective in a patient population in which the prevalence of severe carotid stenosis

exceeds 4.5%.16

Technical Considerations and DataInterpretation

Standard protocols include carotid examination with a high-resolution linear array transducer(7 MHz or broad spectrum 5–12 MHz). Threemodalities must be used: B-mode gray scaleimaging, color flow Doppler, both on transverseand longitudinal planes, and spectral Dopplervelocities on longitudinal planes.

B-Mode Gray Scale ImagingImaging of the entire common carotid artery (CCA), the carotid bifurcation, the ICA as distal aspossible, and the external carotid artery is the firststep in carotid sonographic examination. It is thebest method for measuring IMT and showing atherosclerotic plaques. Mean IMT is calculatedin the CCA between 2 interfaces: blood-intimaand media-adventitia. Intima-media thicknessmeasurement can be performed either manually or by computer software. In the manual method,

1128 J Ultrasound Med 2005; 24:1127–1136

Diagnosing Carotid Stenosis by Doppler Sonography



multiple measurements are made by placing electronic cursors at multiple sites and averag-ing values. In the computerized method, 3 mea-surements are made on the far wall at anterior,lateral, and posterior projections and aver-aged. 17,18 Normal IMT is less than 0.8 mm.Intima-media thickness increases with age; athickness of 0.8 to 1.0 mm is considered inde-terminate. A thickness of 1.1 mm or greater isactually a more accepted abnormal value(Figure 1). Measurement of the IMT can betechnically challenging, and considerable qual-ity assurance measures need to be taken. Thisemphasizes the need to standardize themethod of measuring carotid IMT. Intima-media thickness is considered a marker of early atherosclerosis and is the only sonographicparameter recommended by the AmericanHeart Association to be used routinely whenscreening for cardiovascular risk. 18 Despite theimportance of IMT measurements as an indica-tor of arteriosclerotic changes, IMT is not rou-tinely included in the examination of thesymptomatic patient when looking for stenosis,and testing IMT does not influence the decisionof carotid surgery.

Evaluation of plaque location and characteris-tics is an important part of the standard carotidduplex sonographic examination. Plaque defini-

tion both in the carotid bifurcation and along theICA includes size with its corresponding hemo-dynamic alteration, surface, and echogenicity.

A classification of atherosclerotic plaquesaccording to these parameters was proposed(Table 1). 19 According to hemodynamics, theplaque was classified on a scale from H1 to H5:H1 being mild, less than 50% diameter reduc-tion; H2, moderate, 50% to 69% diameter steno-sis; H3, severe, 70% to near occlusion; H4,critical, near occlusion; and H5, occluding, totalocclusion. According to plaque echogenicity, it was classified into P1, homogeneous; and P2,heterogenous; S1 to S3 indicated surface charac-teristics, from smooth (S1) to irregular with a sur-face defect of less than 2 mm (S2) and ulcerated with a defect of greater than 2 mm (S3). Ulceratedlesions are associated with intraplaque hemor-rhage; 50% to 70% of patients with this type of plaque have hemispheric symptoms. 20 Char-acteristics of the plaque are independent param-eters, unrelated to plaque size and stenosisdiameter percentage, which should be takeninto account for therapeutic planning when thepatient is symptomatic and the diameter of thestenosis does not reach the threshold of 70%. 19,20 It should be noted that Table 1 is anoverall classification of plaques but not one thatis routinely applied clinically or systematically included in the examination report of carotidduplex sonographic examination. A plaqueestimate of diameter percentage reduction is

considered a primary parameter, together withICA peak systolic velocity (PSV) for the diagno-sis of the degree of ICA stenosis (Table 2). 13

J Ultrasound Med 2005; 24:1127–1136 1129

Gaitini and Soudack

Figure 1. Intima-media thickness in the CCA measured between blood-intima and media-adventitia interfaces. A, Normal IMT (0.6–0.8 mm).B, Moderately thickened (1–1.5 mm).

A B



Color Doppler ImagingColor Doppler sonography provides a “road map”for the identification of ICA origin and course andis especially useful for tortuous arteries, highbifurcations, and differentiation between severestenosis and occlusion. Areas of stenosis are seenas a reduced lumen with a red to blue shift due to“aliasing,” a Doppler artifact occurring whenvelocities are higher than the pulse repetition fre-quency. Red represents flow toward the transduc-er, within the range of the pulse repetitionfrequency, whereas blue represents velocitiesbeyond the range of the pulse repetition frequen-cy and not reversed flow. Poststenotic areas may have a mosaic color Doppler pattern due to mul-tiple velocities and flow reversal in a boundary separation zone. 21–23 In the face of a nearly occluded lumen, a narrow hairline string of colorthrough the plaque called the “string sign” may be

seen. Power Doppler sonography may aid in thevisualization of the residual lumen because of itshigher sensitivity to lower velocities. 24,25

Spectral AnalysisFlow velocity is the main parameter for evaluat-ing the severity of carotid stenosis. On the B-mode gray scale image, the cursor is placed in thecenter of the carotid lumen at an angle of 60° or

less for Doppler spectral display of the carotidflow (duplex). Flow velocity must be sampledthrough the whole area of presumed stenosisuntil the distal end of the plaque is seen to ensurethat the site of the highest velocity has beendetected. The data presented by various valida-tion studies relating Doppler sonographic veloc-ity recording to angiographic stenosis percentageshow a considerable spread of values, which ispresent on the so-called scattergrams. Thismeans that for any given degree of angiographicstenosis, a wide range of associated blood flow velocities is recorded. This affects the sensitivity and specificity of the sonographic tests. In addi-tion, it strongly affects the positive and negativepredictive values. Depending on whether thepatients are symptomatic or asymptomatic(related to both the risk of subsequent stroke andthe anticipated benefit from CEA) some authors,

such as Moneta et al,26,27

recommend adjusting the interpretation to reflect these relative risks. Itis recommended that every vascular laboratory should check the results of its different sonogra-phy equipment. Practitioners should be awarethat machines are not necessarily calibrated inthe same way and phantoms are not routinely used to check. 13 Another important recommen-dation to achieve greater reliability in the perfor-


Table 1. Classification of Plaque

Hemodynamic (% Stenosis Diameter) Morphologic By Surface

H1, mild (<50%) P1, homogeneous S1, smoothH2, moderate (50%–69%) P2, heterogeneous S2, irregular (defect <2 mm)

H3, severe (70%–95%) S3, ulcerated (defect >2 mm)H4, critical (95%–99%)H5, occluding (100%)

From Thiele et al. 19

Table 2. Spectral Doppler Velocities and Plaque Estimate Correlated With Degree of ICA Stenosis Diameter

ICA PSV, Plaque ICA/CCA ICA EDV,Stenosis, % cm/s Estimate, % PSV Ratio cm/s

Normal <125 NA <2 <40<50 <125 <50 <2 <4050–69 125–230 >50 2–4 40–10070, near occlusion >230 >50 >4 >100Near occlusion High/low/ Visible Variable Variable

undetectableTotal occlusion NA Visible, NA NA

no detectablelumen

From Grant et al. 13 NA indicates not applicable.

1130 J Ultrasound Med 2005; 24:1127–1136



mance of carotid sonography is to follow a con-sistent protocol, in accordance with the stan-dards of one of the accrediting bodies. 13 Severalclassifications of carotid stenosis degree havebeen proposed, according to PSV and end-dias-tolic velocity (EDV) in the ICA and PSV ICA/CCA ratios. 26–38 It is clear that choosing a velocity threshold affects sensitivity and specificity of thetest; with lowered thresholds, sensitivity increas-es whereas specificity decreases, and vice versa. Achieving high sensitivity comes at the price of lowered specificity. A multidisciplinary panel of experts under the

auspices of the Society of Radiologists inUltrasound (SRU) convened in San Francisco,California, on October 22 and 23, 2002, and drew up a recently published consensus statement onthe performance of Doppler sonography for thediagnosis of ICA stenosis. 13 According to thispanel, stenosis degree in the ICA was classifiedinto 5 categories based on 2 primary parameters,ICA PSV and plaque size, and 2 secondary parameters, ICA/CCA PSV ratio and ICA EDV (Table 2). The ICA/CCA PSV ratio is helpful whenhigh ICA velocities are registered in hyperdy-namic states such as in young patients or whenflow changes are induced by severe bilateralICA stenosis or proximal CCA stenosis or occlu-sion. Probably the most important use for the

carotid ratio is for those patients who have low cardiac output and have proportionally lowersystolic velocities for a given degree of stenosis.Hemodynamically appreciable stenosis startsat greater than a half-diameter reduction. Forclinical applications, identification of 70% to

99% stenosis has the most relevant effect. In arecently published study, Sabeti et al 39 per-formed a comparative analysis of different flow velocity criteria for the quantification of ICA stenosis with duplex sonography. They conclud-ed that exclusion of 70% to 99% angiographicstenosis could be achieved with sensitivity of upto 98%. Obviously, the threshold was put low enough so that this high sensitivity was achievedat the cost of lowered specificity. The SRU thresh-olds were chosen to provide a reasonable bal-ance between sensitivity and specificity.

Each category has its recommended thera-peutic approach according to NASCET and ACAS.2,5,8–10 For stenosis of 50% or less (Figure 2),medical therapy is recommended for symp-tomatic patients. For 50% to 69% stenosis, therecommended treatment is medical therapy andCDDS follow-up every 6 months to detect pro-gression that may warrant surgery. 32 The resultsof the NASCET trial showed that patients withmoderate stenosis may also benefit fromsurgery. 5 For stenosis of 70% or greater (Figure 3)and for near occlusion, 95% or greater diameterreduction, 2 trials, NASCET and ECST, estab-lished the benefit of CEA in symptomaticpatients. A limitation regarding treatment basedon duplex findings may be that no direct valida-tion data have been used to relate the velocity

criteria to patient benefit from CEA. Patients with carotid near occlusion are distinct fromthose with 90% to 95% stenosis and have a lowerrisk of stroke on medical treatment and amarginal benefit from endarterectomy. 6 Withregard to outcome in these patients, actual

J Ultrasound Med 2005; 24:1127–1136 1131

Gaitini and Soudack

Figure 2. Small plaque, lying between the sonographic cursors, homogeneous and with a smooth surface (H1, P1, S1 [Table 1]) in the proximal ICA(A) without signs of hemodynamically appreciable stenosis (PSV, <125 cm/s) ( B).

A B



results are mixed but, importantly, typically notas good as with lesser degrees of stenosis. The ACAS study used 60% diameter stenosis or lessfor the surgical threshold and recommendedsurgery for asymptomatic patients with 60%stenosis or greater in centers where the morbidi-ty and mortality of CEA do not exceed 3%. 10 In

total occlusion, the arterial lumen is filled by theplaque, and flow is undetectable. Other featuresof ICA occlusion are increased pulsatility of theCCA with decreased or absent diastolic flow,“internalization” of the external carotid artery due to high diastolic flow, and higher velocities inthe contralateral carotid arteries. 38,40 For totalocclusion, no surgical options remain.

It should be pointed out that there is more than1 technique for determining the degree of angio-graphic stenosis. Specifically, there is theNASCET definition, using the high cervical ICA as the standard, 2 comparing the narrowest por-tion of the vascular lumen with the normalizedlumen distally, as opposed to the University of Washington criteria, 30 the ECST, 3,4 and olderNorth American studies trials, using the antici-pated diameter of the carotid bulb as the stan-dard, comparing the narrowest lumen with anestimate of the original lumen in the same area.The method used has implications with regard toselection of thresholds, affecting the referencestandard and recommendations for CEA. TheNASCET angiographic method of carotid steno-

sis measurement should be used as the referencestandard for comparison with sonographic find-ings. 13

Another issue that should be addressed regard-ing reference standards for velocity criteria is thelack of validation data that directly relate duplex carotid velocities to patient benefits from CEA.

Further investigations on this topic may increasethe sensitivity and specificity of the Dopplersonographic test.

The differentiation between near and totalocclusion is critical for treatment decisions.Because velocity rates may decrease beforeocclusion, velocity indices are useless for differ-entiation. After the instrument sensitivity israised, color and power Doppler sonography may show even minimal residual flow as a few intraluminal color pixels and may allow reliabledifferentiation. Hetzel et al 41 reported sensitivity of 88% and specificity of 99% for detection of nearly occluded ICA stenosis. This limitation is apromising challenge for sonographic echo-enhancing agents. Furst et al 42 reported sensitiv-ity and specificity of echo-enhanced powerDoppler sonography for detection of residualflow of 94% and 100%, respectively, compared with 85% and 92% for the unenhanced test.

Several important unanswered questions thatmerit future research were identified by the SRUpanel. One of them is the need to define themethod or the report of duplex sonography in

1132 J Ultrasound Med 2005; 24:1127–1136


Figure 3. Large plaque causing high-grade (>70%) ICA stenosis. A, Aliasing phenomenon on color Doppler sonography due to high velocities in thecenter of the stenotic lumen and poststenotic flow disturbances. B, On spectral display, high systolic and diastolic velocities are shown (PSV, 284 cm/s;EDV, 114 cm/s).

A B



and more effective than nearly all other strate-gies, including DSA. The combination strategy of CDDS and MRA has a slight benefit in clinicaloutcome but at extremely high additional costs,in which DSA is inferior for the associated com-plications. 51–53

The main drawback of CDDS is the high depen-dence on technological factors in both perfor-mance and interpretation. For the operator to befamiliar with the baseline, about 200 examina-tions are needed, and a considerable larger num-ber are needed for reliable grading of ICA stenosis and knowledge of pitfalls and limita-tions of the examination. 54

Conclusions

Color and duplex Doppler sonography is the firstimaging examination performed for the diagno-sis of carotid stenosis. Because of its dual ability toevaluate both morphologic and hemodynamicabnormalities and its cost-effectiveness, CDDS isusually the only test applied before a therapeuticdecision. A standardized protocol of examina-tion, knowledge, and experience among opera-tors and imaging specialists and continuousquality control are necessary to ensure reliableresults. The choice of a therapeutic approach isbased on the degree of stenosis diameter.

Although duplex sonography cannot precisely define the stenosis diameter percentage, a rangeof stenosis diameters may be achieved withdefined diagnostic strata. Additional proceduressuch as computed tomographic angiography,MRA, and DSA have selected indications. Thesemore expensive or invasive tests are required fordefinitive diagnosis and therapy management ina small number of patients such as those with dis-crepant clinical and duplex sonographic findings.

Cost-effectiveness analysis is mandatory fordeciding which test strategy is the best for sus-pected carotid artery stenosis. Duplex sonogra-phy as a single examination strategy is optimal fora final diagnosis and a treatment plan for patients with symptomatic carotid artery stenosis; at pre-sent, many centers perform surgery solely on thebasis of duplex sonographic information. 52

Several important topics merit future research,such as the role of plaque characterization andintima-media thickness measurements, criteriafor assessment of patients after endarterectomy or stent placement, and screening for carotid dis-ease in selected patient populations. 13

References

1. Landwehr P, Schulte O, Voshage G. Ultrasoundexamination of carotid and vertebral arteries. EurRadiol 2001; 11:1521–1534.

2. North American Symptomatic Carotid Endart-erectomy Trial Collaborators. Beneficial effect ofcarotid endarterectomy in symptomatic patientswith high-grade carotid stenosis. N Engl J Med1991; 325:445–453.

3. European Carotid Surgery Trialists CollaborativeGroup. MRC European Carotid Surgery Trial: interimresults for symptomatic patients with severe(70–99%) or with mild (0–29%) carotid stenosis.Lancet 1991; 337:1235–1243.

4. European Carotid Surgery Trialists CollaborativeGroup. Randomized trial of endarterectomy forrecently symptomatic carotid stenosis: final results ofthe MRC European Carotid Surgery Trial (ECST).Lancet 1998; 351:1379–1387.

5. Barnett HJ, Taylor DW, Eliasziw M, et al. Benefit ofcarotid endarterectomy in patients with symp-tomatic moderate or severe stenosis. NorthAmerican Symptomatic Carotid EndarterectomyTrial Collaborators. N Engl J Med 1998; 339:1415–1425.

6. Rothwell PM, Eliasziw M, Gutnikov SA, et al.Analysis of pooled data from the randomized con-trolled trials of endarterectomy for symptomaticcarotid stenosis. Lancet 2003; 361:107–116.

7. Rothwell PM, Eliasziw M, Gutnikov SA, et al.Endarterectomy for symptomatic carotid stenosis inrelation to clinical subgroups and timing of surgery.Lancet 2004; 363:915–924.

8. Executive committee for the Asymptomatic CarotidAtherosclerosis Study. Endarterectomy for asymptomat-ic carotid artery stenosis. JAMA 1995; 273:1421–1428.

9. Mayo SW, Eldrup-Jorgensen J, Lucas FL, WennbergDE, Bredenberg CE. Carotid Endarterectomy afterNASCET and ACAS: a statewide study. NorthAmerican Symptomatic Carotid EndarterectomyTrial, Asymptomatic Carotid Artery Stenosis Study.J Vasc Surg 1998; 27:1017–1022.

10. Young B, Moore WS, Robertson JT, et al. An analysisof perioperative surgical mortality and morbidity inthe asymptomatic carotid atherosclerosis study. ACASInvestigators Asymptomatic Carotid ArteriosclerosisStudy. Stroke 1996; 27:2216–2224.

1134 J Ultrasound Med 2005; 24:1127–1136




11. Mohammed N, Anand SS. Prevention of disablingand fatal strokes by successful carotid endarterecto-my in patients without recent neurological symptoms:randomized controlled trial. MRC AsymptomaticCarotid Surgery Trial (ASCT) Collaborative Group.Lancet 2004; 363:1491–1502.

12. Rothewell PM. ACST: which subgroups will benefitmost from carotid endarterectomy? Lancet 2004;364:1122–1123.

13. Grant EG, Benson CB, Moneta GL et al. CarotidArtery Stenosis: Gray-scale and Doppler US diagno-sis—Society of Radiologists in Ultrasound ConsensusConference. Radiology 2003; 229:340– 346.

14. Ascher E, Hingorani A, Yorkovich W, Ramsey PJ,Salles-Cunha S. Routine preoperative carotid duplex

scanning in patients undergoing open heart surgery:is it worthwhile? Ann Vasc Surg 2001; 15:669–678.

15. Naylor AR, Cuffe RL, Rothwell PM, Bell PR. A sys-tematic review of outcomes following staged andsynchronous carotid endarterectomy and coronaryartery bypass. Eur J Vasc Endovasc Surg 2003; 25:380–389.

16. Yin D, Carpenter JP. Cost-effectiveness of screeningfor asymptomatic carotid stenosis. J Vasc Surg 1998;27:245–255.

17. Simon A, Gariepy J, Chironi G, Megnien JL,

Levenson J. Intima-media thickness: a new tool fordiagnosis and treatment of cardiovascular risk.J Hypertens 2002; 20:159–169.

18. O’Leary DH, Polak JF. Intima-media thickness: a toolfor atherosclerosis imaging and event prediction.Am J Cardiol 2002; 90(suppl):18L–21L.

19. Thiele BL, Jones AM, Hobson RW, et al. Standards innoninvasive cerebrovascular testing. Report from theCommittee on Standards for Noninvasive VascularTesting of the Joint Council of the Society forVascular Surgery and the North American Chapterof the International Society for CardiovascularSurgery. J Vasc Surg 1992; 15:495–503.

20. Calliada F, Verga L, Pozza S, Bottinelli O, Campani R.Selection of patients for carotid endarterectomy: therole of ultrasound. J Comput Assist Tomogr 1999;23(suppl 1):S75–S81.

21. Middleton WD, Foley WD, Lawson TL. Color-flowDoppler imaging of carotid artery abnormalities. AJRAm J Roentgenol 1988; 150:419–425.

22. Hallam MJ, Reid JM, Cooperberg PL. Color-flow

Doppler and conventional duplex scanning of thecarotid bifurcation: prospective, double blind, correl-ative study. AJR Am J Roentgenol 1989; 152:1101–1105.

23. Steinke W, Kloetzsch C, Hennerici M. Carotid arterydisease assessed by color Doppler flow imaging: cor-relation with standard Doppler sonography andangiography. AJR Am J Roentgenol 1990; 154:1061–1068.

24. Steinke W, Ries S, Artemis N, Schwartz A, HennericiM. Power Doppler imaging of carotid artery steno-sis: comparison with color Doppler flow imagingand angiography. Stroke 1997; 10:1981–1987.

25. Koga M, Kimura K, Minematsu K, Yamaguchi T.Diagnosis of internal carotid artery stenosis greater

than 70% with power Doppler duplex sonography.AJNR Am J Neuroradiol 2001; 22:413–417.

26. Moneta GL, Edwards JM, Chitwood RW, et al.Correlation of North American Symptomatic CarotidEndarterectomy Trial (NASCET) angiographic defini-tion of 70% to 99% internal carotid artery stenosiswith duplex scanning. J Vasc Surg 1993; 17:152–159.

27. Moneta GL, Edwards JM, Papanicolaou G, et al.Screening for asymptomatic carotid internal arterystenosis: duplex criteria for discriminating 60% to99% stenosis. J Vasc Surg 1995; 21:989–994.

28. Nicolaides AN, Shifrin E, Bradbury A, et al.Angiographic and duplex grading of internal carotidstenosis: can we overcome the confusion?J Endovasc Surg 1996; 3:158–165.

29. Elgersma OE, van Leersum M, Buijs PC, et al.Changes over time in optimal duplex threshold forthe identification of patients eligible for carotidendarterectomy. Stroke 1998; 29:2352–2356.

30. AbuRahma AF, Robinson PA, Strickler DL, Alberts S,Young L. Proposed new duplex classification forthreshold stenoses used in various symptomatic andasymptomatic endarterectomy trials. Ann Vasc Surg1998; 12:349–358.

31. Nederkoorn PJ, Mali W, Eikelboom BC, et al.Preoperative diagnosis of carotid artery stenosis:accuracy of noninvasive testing. Stroke 2002;33:2003–2008.

32. Filis KA, Arko FR, Johnson BL, et al. Duplex ultra-sound criteria for defining the severity of carotidstenosis. Ann Vasc Surg 2002; 16:413–421.

J Ultrasound Med 2005; 24:1127–1136 1135

Gaitini and Soudack



33. Zwiebel WJ, Knighton R. Duplex examination of thecarotid arteries. Semin Ultrasound CT MR 1990;11:97–135.

34. Staikov IN, Nedeltchev K, Arnold M, et al. Duplex

sonographic criteria for measuring carotid stenoses.J Clin Ultrasound 2002; 30:275–281.

35. Robinson ML, Sacks D, Perlmutter GS, Marinelli DL.Diagnostic criteria for carotid duplex sonography.AJR Am J Roentgenol 1988; 151:1045–1049.

36. Thomas N, Taylor P, Padayachee S. The impact oftheoretical errors on velocity estimation and accura-cy of duplex grading of carotid stenosis. UltrasoundMed Biol 2002; 28:191–196.

37. Hwang CS, Shau WY, Tegeler CH. Doppler velocitycriteria based on receiver operating characteristic

analysis for the detection of threshold carotidstenoses. J Neuroimaging 2002; 12:124–130.

38. Strandness DE Jr. Duplex Scanning in VascularDisorders. New York, NY: Raven Press; 1993.

39. Sabeti S, Schillinger M, Mlekusch W, et al.Quantification of internal carotid artery stenosis withduplex US: comparative analysis of different flowvelocity criteria. Radiology 2004; 232:431–439.

40. Arger PH, DeBari Iyoob S. Cerebrovascular system.In: The Complete Guide to Vascular Ultrasound.Philadelphia, PA: Lippincott Williams & Wilkins;2004.

41. Hetzel A, Eckenweber B, Trummer B, Wernz M,Schumacher M, von Reutern G. Colour-codedduplex sonography of preocclusive carotid stenoses.Eur J Ultrasound 1998; 8:183–191.

42. Furst G, Saleg A, Wenserski F, et al. Reliability andvalidity of noninvasive imaging of internal carotidartery pseudo-occlusion. Stroke 1999; 30:1444–1449.

43. Norris JW, Morriello F, Rowed DW, Maggisano R.Vascular imaging before carotid endarterectomy [let-ter]. Stroke 2003; 34:e16.

44. AbuRahma AF, Richmond BK, Robinson PA, Khan S,Pollack JA, Alberts S. Effect of contralateral severestenosis or carotid occlusion on duplex criteria ofipsilateral stenoses: comparative study of variousduplex parameters. J Vasc Surg 1995; 22:751–762.

45. Chen JC, Salvian AJ, Taylor DC, Teal PA, Marotta TR,Hsiang YN. Predictive ability of duplex ultrasonogra-phy for internal carotid artery stenosis of

70%–90%: a comparative study. Ann Vasc Surg1998; 12:244–247.

46. Alexandrov AV, Brodie DS, McLean A, Hamilton P,Murphy J, Burns PN. Correlation of peak systolic

velocity and angiographic measurement of carotidstenosis. Stroke 1997; 28:339–342.

47. Moore WS, Barnett HJ, Beebe HG, et al. Guidelinesfor carotid endarterectomy: a multidisciplinary con-sensus statement from the ad hoc Committee,American Heart Association. Stroke 1995; 26:188–201.

48. Gronholt ML. B-mode ultrasound and spiral CT for theassessment of carotid atherosclerosis. NeuroimagingClin North Am 2002; 12:421–435.

49. Johnston DCC, Eastwood JD, Nguyen T, Goldstein

LB. Contrast-enhanced magnetic resonance angiog-raphy of carotid arteries. Stroke 2002; 33:2834–2838.

50. Pan XM, Saloner D, Reilly LM, et al. Assessment ofcarotid artery stenosis by ultrasonography, conven-tional angiography, and magnetic resonanceangiography: correlation with ex vivo measurementof plaque stenosis. J Vasc Surg 1995; 21:82–88.

51. Kent KC, Kuntz KM, Patel MR, et al. Perioperativeimaging strategies for carotid endarterectomy: ananalysis of morbidity and cost-effectiveness in symp-

tomatic patients. JAMA 1995; 274:888–893.52. Buskens E, Nederkoorn PJ, Buijs-Van Der Woude T,

et al. Imaging of carotid arteries in symptomaticpatients: cost effectiveness of diagnostic strategies.Radiology 2004; 233:101–112.

53. Moore WS. For severe carotid stenosis found onultrasound, further arterial evaluation prior tocarotid endarterectomy is unnecessary. Stroke 2003;34:1816–1817.

54. Gahn G, von Kummer R. Ultrasound in acute stroke:a review. Neuroradiology 2001; 43:702–711.

1136 J Ultrasound Med 2005; 24:1127–1136


carotide doppler

Documents