Carotid Ultrasound: Improving Ultrasound

Carotid Ultrasound: Improving Ultrasound Edward I. Bluth, M.D., F.A.C.R. Chairman Emeritus, Department of Radiology, Ochsner Clinic Foundation, New Orleans, Louisiana Professor, Ochsner Clinical School, The University of Queensland School of Medicine

DUPLEX EVALUATION OF CAROTID ARTERIES 1. Plaque Characterization 2. Evaluation for FlowLimiting Stenosis

PATHOLOGIC TYPES OF PLAQUE Fibrous Plaque With Hemorrhage

Classification Schemes Type 1 Type 2 Matalanis Echolucent & Lusby Gray-Weale Bluth Kelly Heterogeneous Type 3 Type 4 Echogenic Homogeneous

PATHOLOGIC TYPES OF PLAQUE Fibrous Plaque Homogeneous With Hemorrhage Heterogeneous

Homogeneous Plaque Uniform Low level echoes Smooth surface Corresponds to fibrous collagenous plaque < 50% sonolucent

Homogeneous Type 4

Homogeneous Type 3

Heterogeneous Plaque Focal sonolucent areas > 50% sonolucent Smooth or irregular surfaces

Heterogeneous Type 1

SIGNIFICANCE OF PLAQUE CLASSIFICATION The incidence of CT infarction increased with degree of echolucency from 10.5% - 66%. Seen in both symptomatic and asymptomatic patients with a stenosis greater than 50%. Nicolaides, JEMU 1996; 17:404

VULNERABLE PLAQUE Nonatherosclerotic Coronary Vessel Elaborate Atherosclerotic Microvascular Network Intraplaque Hemorrhage Studies involving injection of silicone polymer into atherosclerotic human coronary arteries demonstrated on elaborate microvascular network (the vasa vasorum) extending from the adventitia through the media and into thickened intima. Nonatherosclerotic vessels rarely had vasa vasorum. Kolodgie et al, NEJM 2003;349:2316-24

Origin of Intraplaque Hemorrhage Nonatherosclerotic Coronary Vessel Elaborate Atherosclerotic Microvascular Network Intraplaque Hemorrhage Intraplaque hemorrhage is believed to arise from the disruption of thin-walled microvessels (vasa vasorum) that are lined by discontinuous endothelium without supporting smooth-muscle cells Kolodgie et al, NEJM 2003;349:2316-24.

PATHOLOGIC TYPES OF PLAQUE Fibrous Plaque Homogeneous, Stable With Hemorrhage Heterogeneous, Vulnerable

HINTS TO EFFECTIVELY CHARACTERIZE PLAQUE Plaque must be characterized with grayscale only, not with color or power.

HINTS TO EFFECTIVELY CHARACTERIZE PLAQUE Plaque must be characterized with grayscale only, not with color or power. Homogeneous plaque is most common (80-85%).

HINTS TO EFFECTIVELY CHARACTERIZE PLAQUE Plaque must be characterized with grayscale only, not with color or power. Homogeneous plaque is most common (8085%). Need to evaluate plaque in both transverse and sagittal planes.

Transverse view of heterogeneous plaque C' C' Sagittal view of heterogeneous plaque falsely appearing as homogeneous D' D' Sagittal view of heterogeneous plaque

Transverse view of homogeneous plaque C D C Sagittal view of heterogeneous plaque D Sagittal view of heterogeneous plaque falsely appearing as homogeneous

DUPLEX EVALUATION OF CAROTID ARTERIES 1. Plaque Characterization 2. Evaluation for FlowLimiting Stenosis

Obtain Velocity Measurements ICA CCA

LEFT Peak Systole ICA 444 Peak Systole CCA 79 Systolic Ratio 5.62 Plaque Homogeneous Vertebral Forward flow ICA PSV End Diastole ICA End Diastole CCA Diastolic Ratio Normal < 125 cm/s ICA/CCA PSV ICA EDV ratio < 2.0 < 40 cm/s <50% < 125 cm/s < 2.0 < 40 cm/s 50-69% 125-230 cm/s 2.0-4.0 40 100 cm/s >70 to near occlusion Near occlusion Total occlusion > 230 cm/s > 4.0 > 100 cm/s May be low or undetectable Undetectable Variable Variable Not applicable Not applicable 157 18 8.72 Plaque < 50% diameter reduction > 50% diameter reduction > 50% diameter reduction Significant, detectable lumen Significant, no detectable lumen None

Velocity Parameters for Carotid Stenosis % Stenosis > 60% > 70% > 80% Peak Systolic End Systolic Diastolic Velocity Diastolic Velocity Ratio Velocity Ratio Reference (cm/sec) Velocity (VICA/VCCA) (VICA/VCCA) Bluth et al > 130 Carpenter et al > 170 Moneta et al > 260 Filinger et al > 200 Jackson et al > 245 Moneta et al > 325 Carpenter et al > 210 Neale et al > 270 Hunink et al > 230 Bluth et al > 250 > 40 > 40 > 70 > 65 > 110 > 100 VICA = peak velocity at point of maximum stenosis in internal carotid artery VICA = peak velocity in unobstructed common carotid artery > 1.8 > 2.0 > 3.5 > 3.3 > 4.0 > 3.0 > 3.7 > 2.4 > 2.4 > 5.5

ICA ECA Measurement Methodology ECST = B - A x 100 B NASCAT = 1 - A x 100 C ACAS CCA

Criteria Comparison ICA ECA ECST = 66% CCA NASCET = 0% ACAS = 0%

Which velocity values are correct?

COMMON PITFALLS Mistaking ICA for ECA or ECA for ICA Improper plaque characterization Confusion over carotid grading criteria and which table or cut-off value to use Measuring CCA velocities at incorrect location Relying on systolic velocity parameters only Forgetting to integrate all information (internal consistency) In patients with arrhythmias, measuring velocities of compensatory beat

Differences in Internal Carotid Artery and External Carotid Artery ICA ECA Size Larger Smaller Location Posterior/lateral Anterior/medial Branches No Yes Waveform Low resistance High resistance Temporal tap No pulsations Pulsations

ICA: PSV 166 cm/sec EDV 79 cm/sec Stenosis: 50-69%??

CCA: ICA: PSV 166 cm/sec EDV 79 cm/sec CCA: PSV 96 cm/sec EDV 36 cm/sec Ratios: SVR 1.7 DVR 2.2 Stenosis = < 50% PATIENT IS HYPERTENSIVE

Normal Velocities Peak Systole ICA Peak Systole CCA 67 23 End Diastole ICA End Diastole CCA 23 8

ABNORMAL RATIOS Peak Systole ICA 67 End Diastole ICA 23 Peak Systole CCA 23 End Diastole CCA 8 Systolic Ratio 2.91 (Diastolic Ratio Stenosis 50 69% Poor Cardiac Output Cardiomyopathy 2.88)

Rt ICA 69/0 Rt CCA 27/0 SVR 2.6

RT BULB

500 Velocity 6 5 400 Volume Flow 300 3 200 2 100 Fo = 3 MHZ = 60 Vessel Dia. = 5 mm 4 1 96 84 64 Percent Stenosis Doppler Frequency (KHz) (ml/min) and (cm/sec) THE EFFECT OF STENOSIS ON BLOOD FLOW 36 From Spencer & Reid, Cerebrovascular Evaluation with Doppler Ultrasound. 1981

COMMON PITFALLS (continued) Incorrect angle position Inconsistent angle-cursor adjustment Ignoring symmetry of CCA Ignoring dampening of CCA Ignoring dampening of ICA Contralateral stenosis causing an ipsilateral velocity elevation Occlusion versus tight stenosis Unusual velocity measurements with post-op venous grafts

Incorrect Angle PSV = 61 cm/sec Angle = 60 PSV = 132 cm/sec Angle = 70

Dampening of CCA

Elevated Velocities PSV = 563 cm/sec, EDV = 325 cm/sec

Asymmetry of the CCA

Normal Velocity Measurements in ICA

Normal Velocities: Tardus Parvus

Innominate Stenosis

RECOMMENDATIONS FOR FOLLOW-UP RECOMMENDATIONS FOR FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT RECOMMENDATIONS FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT BASEDFORON ULTRASOUND ASSESSMENT ASYMPTOMATIC 1-39%** (1-50%)*** SYMPTOMATIC HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE HETEROGENEOUS PLAQUE 3 months 2 Then 6 months Then yearly 2-5 years depending the degree of plaque and other risk factors 1-3 years depending the degree of plaque Then yearly and other risk factors Medical therapy* Refer for evaluation for other sources such as cardioembolic disease or neurovascular sources of symptoms 3 months 2 6 months 2 Then every 6 months Then yearly until converted to homogeneous or degree of stenosis increases 3 months 2 ASYMPTOMATIC Then 6 months HETEROGENEOUS PLAQUE 1-39%** (1-50%)*** 3 months 2 Then 6 months Then yearly 3 months 2 Yearly Then every 6Medical months Medical Rx* Rx* until converted to HOMOGENEOUS PLAQUE HOMOGENEOUS PLAQUE SYMPTOMATIC HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE 2-5 years depending 3 months 2 the degree of plaque Then 6 months and other risk factors Then yearly Medical therapy* 1-3 years depending the degree of plaque and other risk factors 40-59%** Refer for evaluation homogeneous or for other sources degree of stenosis increases such as cardioembolic 60-79%** Refer to vascular 6-month follow-up 2 Refer to vascular Refer to vascular (50-70%)*** specialist** for stability, then specialist ** specialist** disease or annually (Alternatively, if no (Alternatively, if no neurovascular intervention, followintervention, followup every 3 months to up every 3 months to sources of assess stability) assess stability) 80-99%** Refer to vascular specialist** symptoms (>70%)*** *Medical Rx includes antiplatelet Rx, statin Rx, smoking good blood pressure control. 40-59%** 3 months 2 cessation, andyearly 3 months 2 6 months 2 **Bluth et al. Criteria ***SRU Criteria Then every 6 months Then every 6 months Then yearly **Vascular specialist could be a vascular surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon, depending on the skill set of providers given area. Treatment. converted to untilin anyconverted to recommended by these specialists could be endovascular until stent, endarterectomy, or intensive Medical Rx homogeneous or homogeneous or degree of stenosis degree of stenosis increases increases 45 122 60-79%** (50-70%)*** Refer to vascular specialist** 6-month follow-up 2 Refer to vascular for stability, then specialist ** Refer to vascular specialist** 1

RECOMMENDATIONS FOR FOLLOW-UP ASYMPTOMATIC SYMPTOMATIC BASED ON ULTRASOUND ASSESSMENT RECOMMENDATIONS FOR FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT HETEROGENEOUS FOR HOMOGENEOUS HETEROGENEOUS HOMOGENEOUS RECOMMENDATIONS FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT PLAQUE 1-39%** (1-50%)*** 1-39%** (1-50%)*** 40-59%** 60-79%** 40-59%** (50-70%)*** 80-99%** (>70%)*** PLAQUE PLAQUE PLAQUE 3 months 2 2-5 years depending 3 months 2 1-3 years depending Then 6 months the degree of plaque Then 6 months the degree of plaque ASYMPTOMATIC SYMPTOMATIC Then yearly and other risk factors Then yearly and other risk factors HETEROGENEOUS HOMOGENEOUS HETEROGENEOUS HOMOGENEOUS Medical Rx* Medical therapy* Refer for evaluation PLAQUE PLAQUE PLAQUE for other sources PLAQUE such2as 3 months 2 2-5 years depending 3 months 1-3 years depending cardioembolic Then 6 months the degree of plaque Then 6 months the degree of plaque disease or Then yearly and other risk factors Then yearly and other risk factors neurovascular Medicalsources therapy* Refer for evaluation of symptoms for other sources 3 months 2 Yearly 3 months 2 6 months 2 such as Then every 6 months Then every 6 months Then yearly cardioembolic until converted to until converted to disease or homogeneous or homogeneous or degree of stenosis degree of stenosis neurovascular increases increases sources of Refer to vascular 6-month follow-up 2 Refer to vascular Refer to vascular 3 months 2 for stability,yearly 3 months 2 specialist** then specialist ** specialist** Medical Rx* every 6 months annually Then every Medical Rx* Then 6 months (Alternatively, if no Medical Rx* (Alternatively, if no converted to until converted to until intervention, follow intervention, follow homogeneous homogeneous or up every 3 months to or up every 3 months to degree of stenosis degree of stenosis assess stability) assess stability) Refer to vascular specialist** increases increases symptoms 6 months 2 Then yearly *Medical Rx includes antiplatelet Rx, smoking6-month cessationfollow-up, and good blood pressure control. 60-79%** ReferRx, to statin vascular 2 Refer to vascular Refer to vascular **Bluth et al. Criteria45 (50-70%)*** specialist** for stability, then specialist ** specialist** 122 ***SRU Criteria annually Medical Rx* **Vascular specialist could bemedical a vascularrx* surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon, depending on the skill set of(alternatively, providers in any given specialists could be endovascular Treatment Rx* recommended by these. if no area. Medical (Alternatively, if no stent, endarterectomy, or intensive Medical Rx intervention, followup every 3 months to assess stability) 80-99%** (>70%)*** intervention, followup every 3 months to assess stability) Refer to vascular specialist** *Medical Rx includes antiplatelet Rx, statin Rx, smoking cessation, and good blood pressure control. **Bluth et al. Criteria45 ***SRU Criteria122 **Vascular specialist could be a vascular surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon,

RECOMMENDATIONS FOR FOLLOW-UP BASED ON ULTRASOUND ASSESSMENT RECOMMENDATIONS FOR FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT ASYMPTOMATIC 1-39%** (1-50%)*** SYMPTOMATIC HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE 3 months 2 Then 6 months Then yearly 2-5 years depending the degree of plaque and other risk factors 3 months 2 Then 6 months Then yearly Medical therapy* 1-3 years depending the degree of plaque and other risk factors Refer for evaluation for other sources such as cardioembolic disease or neurovascular sources of symptoms 6 months 2 Then yearly RECOMMENDATIONS FOR FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT ASYMPTOMATIC 1-39%** (1-50%)*** 40-59%** 40-59%** SYMPTOMATIC HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE HETEROGENEOUS PLAQUE 3 months 2 Then 6 months Then yearly 2-5 years depending the degree of plaque and other risk factors 3 months 2 Then 6 months Then yearly Medical therapy* HOMOGENEOUS PLAQUE 1-3 years depending the degree of plaque and other risk factors Refer for evaluation for other sources such as 3 months 2 Yearly cardioembolic disease orrx* Then every 6 months Medical neurovascular until converted to sources of symptoms homogeneous or 3 months 2 Yearly 3 months 2 6 months 2 degree of stenosis Then every 6 months Then every 6 months Then yearly until converted to increases until converted to homogeneous or homogeneous or degree of stenosis degree of stenosis increases increases Refer to vascular 6-month follow-up 3 months 2 Then every 6 months until converted to homogeneous or degree of stenosis increases 60-79%** 2 Refer to vascular 60-79%** Refer to vascular 6-month follow-up 2 Refer to vascular Refer to vascular (50-70%)*** specialist** for stability, then specialist ** (50-70%)*** specialist** for stability, then specialist ** specialist** annually Medical Rx* annually (Alternatively, if no (Alternatively, if no no (Alternatively, if no intervention, follow-(alternatively, if intervention, followup every 3 months to up every-3 months to intervention, follow intervention, follow assess stability) assess stability) up every months to up every 3 months to 80-99%** Refer3 to vascular specialist** (>70%)*** assess stability) assess stability) 80-99%** *Medical Rx includes antiplatelet Rx, statin Rx, smoking cessation, and good blood pressure control. Refer to vascular specialist** **Bluth et al. Criteria45 (>70%)*** ***SRU Criteria122 Refer to vascular specialist** **Vascular specialist could be a vascular surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon, depending on the skill set of providers in any given area. Treatment recommended by these specialists could be endovascular. *Medical Rxorincludes Rx, statin Rx, smoking cessation, and good blood pressure control. stent, endarterectomy, intensive Medicalantiplatelet Rx **Bluth et al. Criteria45 122 ***SRU Criteria **Vascular specialist could be a vascular surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon, depending on the skill set of providers in any given area. Treatment recommended by these specialists could be endovascular. stent, endarterectomy, or intensive Medical Rx 1

RECOMMENDATIONS FOR FOLLOW-UP BASED ON ULTRASOUND ASSESSMENT RECOMMENDATIONS FOR FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT ASYMPTOMATIC 1-39%** (1-50%)*** SYMPTOMATIC HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE 3 months 2 Then 6 months Then yearly 2-5 years depending the degree of plaque and other risk factors 3 months 2 Then 6 months Then yearly Medical therapy* 1-3 years depending the degree of plaque and other risk factors Refer for evaluation for other sources such as cardioembolic disease or neurovascular sources of symptoms 6 months 2 Then yearly RECOMMENDATIONS FOR FOLLOW -UP BASED ON ULTRASOUND ASSESSMENT ASYMPTOMATIC 1-39%** (1-50%)*** 40-59%** 40-59%** SYMPTOMATIC HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE HETEROGENEOUS PLAQUE HOMOGENEOUS PLAQUE 3 months 2 Then 6 months Then yearly 2-5 years depending the degree of plaque and other risk factors 3 months 2 Then 6 months Then yearly Medical therapy* 1-3 years depending the degree of plaque and other risk factors Refer for evaluation for other sources such Rx*as cardioembolic disease or neurovascular sources of symptoms 6 months 2 Then yearly 3 months 2 Yearly Then every 6 months Medical until converted to homogeneous or degree of stenosis 3 months 2 Yearly 3 months 2 increases Then every 6 months Then every 6 months until converted to until converted to 3 months 2 Then every 6 months until converted to homogeneous or degree of stenosis increases or homogeneous or 60-79%** homogeneous follow-up 2 Refer to vascular degree of stenosisrefer to vascular degree of 6-month stenosis increases increases for stability, then (50-70%)*** specialist** specialist ** annually 60-79%** Refer to vascular 6-month follow-up 2 Refer to vascular Refer to vascular (Alternatively, Rx* (Alternatively, if no (50-70%)*** specialist** for stability, then if no specialist Medical ** specialist** annually Medical Rx* intervention, follow intervention, follow (Alternatively, if no if no up every 3 months(alternatively, to up every 3 months to intervention, followintervention, followup every 3 monthsassess to stability) up every 3 months to assess stability) assess stability) 80-99%** assess stability) Refer to vascular specialist** 80-99%** Refer to vascular specialist** (>70%)*** (>70%)*** *Medical Rx includes antiplatelet Rx, statin Rx, smoking cessation, and good blood pressure control. 45 *Medical Rx includes antiplatelet Rx, statin Rx, smoking cessation, and **Bluth et al. Criteria 45 ***SRU Criteria122 **Bluth et al. Criteria **Vascular specialist could be a 122 vascular surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon, depending on thecriteria skill set of providers in any given area. Treatment recommended by these specialists could be endovascular ***SRU. stent, endarterectomy, or intensive Medical Rx Refer to vascular specialist** good blood pressure control. **Vascular specialist could be a vascular surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon, depending on the skill set of providers in any given area. Treatment recommended by these specialists could be endovascular. stent, endarterectomy, or intensive Medical Rx 1

Summary 1. The carotid evaluation study involves plaque characterization and stenosis grading 2. Either heterogeneous/homogeneous or the 1-4 International Classification System should be used 3. Careful attention must be directed to technique, similar to the attention needed to evaluate flow limiting stenosis

PLAQUE CONCLUSIONS Heterogeneous plaque histologically correlates with intraplaque hemorrhage. Heterogeneous plaque appears to be an unstable plaque The presence of significant stenosis and heterogeneous plaque appear to be independent risk factors.

CONCLUSION The key factor to identifying heterogeneous plaque is a focal sonolucent area greater than 50% of the plaque volume. Examination of the plaque must be made in both the sagittal and transverse planes.

Summary 4. Duplex US is an accurate method to assess flowlimiting stenosis 5. The SRU consensus group has recommended a new table, but if you have a tested verified system in your laboratory, you can continue to use it. 6. Integrate all anatomic and physiologic (hemodynamic) date to make an accurate interpretation and to insure internal consistency.

Summary 7. By careful attention to detail, you can avoid pitfalls and improve accuracy in duplex carotid interpretation