CAROTID DOPPLER BY DR NITIN WADHWANI

CARATID DOPPLER

1. Ultrasound evaluation of carotid arteries Dr. Suraj Jaiswal

2. NORMAL ANATOMY

3. DEVELOPMENT OF CAROTID ARTERIES

4. DEVELOPMENT OF CAROTID ARTERIES

5. CCA ascends anterolaterally up the neck medial to the jugular vein and lateral to thyroid. Each artery measures 6-8mm in diameter. CCA dilates in common carotid bulb and bifurcates into ICA and ECA at C3-C4 level. ECA assumes an anteromedial course off the carotid bulb 70% of time. It has branch vessels that supply head and face and measures 3-4mm in diameter. ICA assumes a posterolateral course , supplies brain and measures 5-6mm. Portion of arterial wall between ICA and ECA at their origin is called flow divider. CAROTID ARTERY ANATOMY

6. INTERNAL CAROTID ARTERY There are 7 segments in the Bouthillier classification Cervical segment Petrous segment Lacerum segment Cavernous segment Clinoid segment Ophthalmic ( supraclinoid ) segment Communicating (terminal) segment

7. EXTERNAL CAROTID ARTERY Branches: 1. Superior thyroid artery 2. Lingual artery 3. Facial artery 4. Ascending pharyngeal artery 5. Occipital artery 6. Posterior auricular artery 7. Internal maxillary artery 8. Superficial temporal artery

8. The vertebral artery is the first branch of the subclavian artery, arising from the highest point of the subclavian arch. At the sixth cervical vertebra, the Vertebral artery runs posteriorly to travel upward through the transverse foramen of cervical vertebrae. • Course : can pass through foramen transversarium of C7 (10%) Termination : B/L VA joins to form the basilar artery • VA may terminate in PICA rarely. VERTEBRAL ARTERY

9. MOST IMPORTANT VARIANTS OF THE SUPRA-AORTIC ARTERIES common origin of the innominate artery and left common carotid artery from the aortic arch (13%); persisting communicating trunk arising from the aortic arch and giving off first the left common carotid artery and then the innominate artery (9 %); bilateral innominate artery dividing into the common carotid and subclavian arteries (1 %); situs inversus (very rare).

10. VARIANTS RESULTING FROM ELONGATION OF ICA Variants

11. SONOGRAPHIC ANATOMY

12. INDICATIONS OF CAROTID ULTRASOUND • Evaluation of pts with TIAs • Evaluation of pts with CVA • Evaluation of carotid bruits • Follow up of known disease • Monitor endarterectomy results/stents, bypass • Preoperative screen prior to major vascular surgery • Evaluation of potential source of retinal emboli •Evaluation of pulsatile neck mass • Follow up of carotid dissection

13. Right side of the couch with scanning arm resting on the patient’s upper chest. PROTOCOL Set-up: examiner/patient positioning Patient: Examiner: The patient should lay on the couch in a supine position, head resting on the couch. Their head should be hyper-extended and turned 45 ° away from the side being examined. Option 1: Side Behind the patient’s head with scanning arm resting on the couch. Option 2: Head

14. Set-up: transducer/preset selection Transducer selection : Predominately use a mid/high frequency (6-15 MHz or similar) linear array transducer depending on depth of vessels. Use a low frequency (1-5 MHz or similar) curvilinear array transducer if vessels are deep, short neck or vessel segments near the base of the skull. U/S scanner settings : Select the ‘carotid’ preset on the ultrasound machine as a starting point. The B-mode, colour flow Doppler and pulsed wave Doppler settings will need to be optimised during the examination.

15. The examination sequence: A typical carotid examination takes place as follows : STEP 1 . The best way to do this is to place the transducer in A transverse plane and to sweep the probe slowly upward from the level of the clavicle to the jaw. This can be done In gray-scale mode and, if needed, with color doppler imaging. This scan is used to obtain an overall evaluation of carotid anatomy STEP 2 The transducer position that best displays the carotid vessels in a longitudinal view will typically be from a lateral approach

16. Intima-Media Complex Normal value ≤ 0.8 mm Wall of CCA, bulb, or ICA Best measured on far wall Only intima & media included

17. STEP 3. DOPPLER IMAGING OF THE CCA Start the survey of the CCA low in the neck, moving upward to the bifurcation. Record a velocity spectrum from the CCA low in the neck record a second waveform close to the bifurcation and the following points should be noted: (1) the measurement point should be 2 to 4 cm below the carotid bulb; (2) care should be taken that the sample volume is squarely within the center of the vessel (3) the doppler angle must be low enough (60 degrees or less) to measure the peak systolic velocity accurately

18. STEP 4. BIFURCATION SURVEY The carotid bifurcation is imaged with B-mode and color Doppler imaging in both the longitudinal and transverse planes. The purpose of this survey is to confirm the patency of the arteries, to identify and to localize plaque and associated flow abnormalities, and to define the junction of the ECA and ICA or flow divider in order to help define plaque location.

19. STEP 5. VESSEL IDENTITY Confirm the identity of the ICA and ECA by their Doppler spectral signatures by anatomic features and by performing the temporal tap maneuver The proper identification of the branch vessels is essential because only significant ICA stenoses are treated. Intervention is rare on ECA stenotic lesions and only in cases of complex multiple occlusions of the carotid and vertebral arteries. A color Doppler image of the proximal ECA and ICA should be recorded. As a minimum, a proximal and distal ICA duplex image should be recorded

20. Features That Identify the ECA & ICA Features External Carotid Artery Internal Carotid Artery Size Usually smaller of the two Usually Larger of the two Branches Always Very rarely Position Anteromedial Posterolateral Doppler Characteristics High resistance Low resistance Response to Temporal Tap Well perceived Oscillations Poorly Perceived / absent oscillations

21. Normal doppler waveforms

22. STEP 6 . STENOSIS DETECTION AND DOCUMENTATION When a stenosis is present, properly angle-corrected velocity estimates are made in the stenosis Color Doppler images that document the location and length of the stenosis are also recorded STEP 7. EVALUATION OF THE VERTEBRAL ARTERIES images of each vertebral artery with representative Doppler spectral waveforms, including measurement of the peak systolic and end-diastolic velocities, are recorded. STEP 8. ASSESSMENT OF THE SUBCLAVIAN ARTERIES Additional images of the subclavian arteries are acquired either as part of a fixed protocol or as an option in cases of vertebral artery disease.

23. Protocol for vertebral artery Longitudinal VA between transverse processes - Direction of flow - Waveform configuration - Measure PSV Ultrasound of normal vertebral vessels Vertebral artery Cephalad flow throughout cardiac cycle Low resistance flow pattern Size: variable & asymmetric - Mean diameter 4 mm PSV: 20 - 40 cm/sec - <10 cm/sec potentially abnormal Vertebral vein May occasionally be seen adjacent to VA Flow caudad & non pulsatile

24. Optimal Scanning Techniques and Doppler Settings Doppler Equation US equipment calculates the velocity of blood flow according to the Doppler equation: where f is the Doppler shift frequency, f0 is the transmitted ultrasound frequency, V is the velocity of reflectors (red blood cells), (theta, also referred to as the Doppler angle) is the angle between the transmitted beam and the direction of blood flow within the blood vessel (the reflector path), and C is the speed of sound in the tissue (1540 m/sec)

25. The Doppler angle should not exceed 60°, as measurements are likely to be inaccurate. Our preferred angle of incidence is 45°+/- 4°. The optimal position of the sample volume box in a normal artery is in the mid-lumen parallel to the vessel wall , whereas in a diseased vessel, it should be aligned parallel to the direction of blood flow . In the absence of plaque disease, the sample volume box should not be placed on the sharp curves of a tortuous artery, as this may result in a falsely high-velocity reading. If the sample volume box is located too close to the vessel wall, artificial spectral broadening is inevitable.

26. SAMPLE VOLUME BOX AND ANGLE CORRECTION

27. SPECTRAL BROADENING Spectral broadening occurs when there is a wide range of velocities in the Doppler sample volume. There is filling in of the spectral window or area under the spectral line This finding is typically seen with stenosis; however, spectral broadening may be related to technical factors and other causes of turbulent flow. These include the following: A large Doppler sample volume that includes all or most of the artery lumen High gain settings Increased vessel wall motion High velocities contralateral to a severely diseased or occluded ICA Tortuous vessels

28. SPECTRAL BROADENING

29. COLOR DOPPLER SAMPLING WINDOW ADJUSTMENT

30. Color scale adjustment

31. ADJUSTMENT OF THE COLOR SCALE IN A NEAR OCCLUSION.

32. Color gain adjustment

33. Plaque imaging

34. Grading of plaque Type Description 1 Dominantly echolucent with thin echogenic cap 2 Substantially echolucent plaque with small areas of echogenicity 3 Dominantly echogenic lesions with small area(s) of echolucency (<25%) 4 Uniformly echogenic lesions (equivalent to homogeneous)

35. Plaque morphology HOMOGENOUS HETEROGENOUS

36. PLAQUE ULCERATION Ultrasound Features of plaque ulceration Focal depression or break in plaque surface Anechoic region within plaque extending to vessel lumen Eddies of color within plaque

37. INTRAPLAQUE HEMORRHAGE

38. Common sites of extracranial arterial disease Most common site at carotid bifurcation with plaque extending into ICA

39. Primary Parameters Additional Parameters Degree of Stenosis% ICA PSV(cm/sec) Degree of plaque(%) ICA/CCA PSV Ratio ICA EDV(cm/sec) Normal <125 None <2.0 <40 <50 <125 <50 <2.0 <40 50-69 125-230 ≥50 2.0-4.0 40-100 ≥70 but less than near occlusion >230 ≥50 >4.0 >100 Near occlusion High, low, or undetectable Visible Variable Variable Total occlusion Undetectable Visible, no detectable lumen NA NA Criteria for Diagnosis of ICA Stenosis with Gray-Scale and Doppler US

40. Estimation of carotid stenosis Diameter Reduction Surface Reduction

41. Vertebral artery & subclavian steal IDENTIFICATION OF THE VERTEBRAL ARTERY IS ACHIEVED BY LOCATING THE CCA IN A SAGITTAL VIEW AND SWEEPING THE TRANSDUCER LATERALLY TO THE TRANSVERSE PROCESSES OF THE CERVICAL SPINE ON THE BASIS OF THE HEMODYNAMIC CHANGES IN THE VERTEBRAL ARTERY, THERE ARE THREE TYPES OF SUBCLAVIAN STEALS. IN OCCULT STEAL (MINIMAL HEMODYNAMIC CHANGES), PW DOPPLER IMAGING MAY SHOW ANTEGRADE FLOW WITH MIDSYSTOLIC DECELERATION, WHICH MAY TEMPORARILY CONVERT TO A MORE ABNORMAL WAVEFORM PARTIAL SUBCLAVIAN STEAL CORRESPONDS TO MODERATE HEMODYNAMIC CHANGES. THE PW DOPPLER SPECTRUM SHOWS PARTIALLY REVERSED FLOW. THE PW DOPPLER SPECTRUM IN OCCULT AND PARTIAL SUBCLAVIAN STEAL MAY RESEMBLE THE PROFILE IMAGE OF A RABBIT (THE “ BUNNY RABBIT” SIGN) IN COMPLETE (FULL) SUBCLAVIAN STEAL , FLOW IN THE VERTEBRAL ARTERY IS COMPLETELY REVERSED . THIS MAY BE ASSOCIATED WITH ISCHEMIC SYMPTOMS IN THE IPSILATERAL ARM.

42. LIMITATIONS OF CAROTID US EXAMINATION Short muscular neck High carotid bifurcation Tortuous vessels Calcified shadowing plaques Surgical sutures, postoperative hematoma, Central line Inability to lie flat in respiratory or cardiac disease Inability to rotate head in patients with arthritis Uncooperative patient

43. NON ARTERIOSCLEROTIC CAROTID DISEASES Fibromuscular dysplasia Dissection Vasospasm Aneurysm & pseudoaneurysm Takayasu Arteritis Carotid Body Tumour

44. FIBROMUSCULAR DYSPLASIA Middle age women- Renal arteries- String of beads pattern Alternating zones of vasoconstriction & vasodilation for 3 - 5 cm ICA frequently- VA less frequently Usually bilateral

45. CAROTID AND VERTEBRAL ARTERY DISSECTION • Spontaneous dissection Bleeding from vasa vasorum Most common ICA & VA (atlas loop) Intramural hematoma Pain - Stenosis - Horner • Vascular injury Iatrogenic: puncture - surgery CCA Intramural hematoma +/-intimal tear • Stanford A dissection Intimal rupture in ascending aorta &CCA

46. DISSECTION OF AORTA & CERVICAL ARTERIES External intramural hematoma Lumen constriction Rare intimal rupture Patho-anatomy Cervical Aorta Intimal rupture with false lumen Open or secondarily thrombosed

47. SPONTANEOUS DISSECTION OF ICA Asymmetric wall hematoma- Lumen stenosis-Expansion to outside Diagnostic criteria (one sufficient) Intramural hematoma Intimal rupture/double lumen Distal stenosis or occlusion Symptoms: acute pain, Horner, Course: recanalization in few weeks

48. SPONTANEOUS DISSECTION OF VA Wall hematoma in V1 Diagnostic criteria (one sufficient) Intramural hematoma(asymmetric, not concentric) Intimal rupture/double lumen (rare) Double lumen in V2

49. DISSECTION OF COMMON CAROTID ARTERY Transverse view Detection of two lumina & dissection membrane Longitudinal view

50. DISSECTION OF CCA / STENOSIS Doppler of true lumen Doppler of false lumen

51. VASOSPASM Causes Migraine, eclampsia, vasculitis, drug abuse, idiopathic Incidence Rarely identified (short duration) Occur frequently & remain undetected Symptoms Cerebral or ocular ischemia USG Direct &/or indirect signs of severe stenosis Far above bifurcation - Sometimes bilateral Complete regression in hours to days – Relapse Dd Dissection: wall hematoma - regression in weeks Treatment Calcium antagonists

52. VASOSPASM Severe narrowing of ICA No stenosis Detected 4 days later

53. ICA ANEURYSM

54. CCA ANEURYSM / RUPTURE

55. CCA PSEUDOANEURYSM / RARE Color Doppler USG CE Multidetector CT CCA PSEUDOANEURYSM LARGE CONNECTING NECK

56. TAKAYASUS ARTERITIS Young female- SCA ('pulseless’ disease] - CCA ‘Macaroni sign’ in the right common carotid artery detected by carotid ultrasound. Long, homogeneous, isoechoic, circumferential wall thickening of the common carotid arteries is demonstrated

57. CAROTID BODY TUMOUR HIGHLR VASCULAR MASS IN CAROTID BIFURCATION

58. EFFECTS OF EXTRA-CAROTID DISEASES Idiopathic dilated cardiomyopathy Aortic regurgitation Aortic stenosis Stenosis of right innominate artery or origin of LCCA High & low PSV in CCA Stenosis of intra-cranial ICA

59. IDIOPATHIC DILATED CARDIOMYOPATHY PSV oscillate between two levels on sequential beats C ardiac rhythm remains regular throughout. Pulsus Alternans

60. AORTIC REGURGITATION Two systolic peaks with a mid- systolic dip. Also found in HOCM Pulsus Bisferiens

61. SEVERE AORTIC REGURGITATION Normal or elevated PSV with precipitous deceleration of flow in late systole, sustained reversal of flow through diastole. Water-Hammer spectral Appearance

62. AORTIC STENOSIS A delayed systolic upstroke (prolonged acceleration time) with blunted amplitude and rounded waveform appearance Pulsus Tardus et Parvus

63. Intracranial ICA Stenosis High-grade stenosis distally (intracranial ICA) Major occlusive lesions of cerebral arteries (MCA, ACA) Massive spasm of cerebral arteries from intracranial haemorrhage High Resistance Waveform

64. Normal PSV in CCA (45 - 125 cm/sec) High flow > 125 cm/sec in both CCAs High cardiac output: Hypertensive patients Young athletes Low flow < 45 cm/sec in both CCAs Poor cardiac output: Cardiomyopathies Valvular heart disease Extensive myocardial infarction

65. STANDARD REPORTING FORMAT