Fundamentals of Vascular Ultrasound. Looking at the basics of carotid, lower extremity arterial, renal, celiac, SMA studies, as well as touching on venous insufficiency. Part I of series.

1. steve henao md
new mexico heart institute

2. Carotid

3. •Carotid disease accounts
for 25% of all strokes
•detection by physical exam
is poor
•stroke is the result of
embolization
•lesions are typically at the
posterolateral wall of the
internal carotid
artery

4. CAROTID ULTRASOUND
• The most common clinical application is for the
detection of proximal ICA atherosclerotic plaque
and estimation of stenosis severity.
• The extent of ICA bifurcation diameter
reduction predicts the risk for stroke and thus
assists clinicians in identifying patients who
may benefit from carotid intervention
(endarterectomy, stent angioplasty) based on
clinical trial results

5. Scanning the ICA
grayscale, color Doppler and Pulse-wave
Doppler
proximal, middle, and distal portions
>50% stenosis of the proximal ICA renders
flow turbulent in the distal ICA
severe stenosis yields parvus et tardus
waveforms

6. proxmial ICA stenosis severity is
established on the baisis of :
GRAYSCALE APPEARANCE
PEAK SYSTOLIC VELOCITY OF THE ICA
END DIASTOLIC VELOCITY OF THE ICA
PEAK SYSTOLIC VELOCITY OF THE
COMMON CAROTID ARTERY
velocity ratios

7. Grayscale imaging is
performed to localize
and characterize plaque
severity as:
•less than 50%
•greater than or equal to 50%
•occlusion

8. Color Doppler
flow mapping is
useful
to define the lumenbecause hypoechoic plaque
and restenosis material may
be inapparent by regular
grayscale

9. assessment of stenosis
• angiography is the traditional gold
standard
• ultrasound has developed steadily with
sufficiently reliable preoperative results

10. assessment of stenosis
• there are MANY differences in the
carotid reference standard to establish
percent stenosis

11. stenosis ‘standards’

12. doppler ultrasound criteria for
diagnosis of internal carotid artery
stenosis
(2003)

13. validating the consensus document
(2011)

14. characteristic”
characteristic
”
The ROC curve was first developed by
electrical engineers and radar engineers
during World War II for detecting enemy objects in
battlefields and was soon introduced to
psychology to account for perceptual detection
of stimuli.
ROC analysis since then has been used in
medicine, radiology, biometrics, and other
areas for many decades and is increasingly
used in machine learning and data mining
research.

15. Fig 1
Source: Journal of Vascular Surgery 2011; 53:53-60 (DOI:10.1016/j.jvs.2010.07.045 )
Copyright © 2011 Society for Vascular Surgery Terms and Conditions

16. Fig 2
Source: Journal of Vascular Surgery 2011; 53:53-60 (DOI:10.1016/j.jvs.2010.07.045 )
Copyright © 2011 Society for Vascular Surgery Terms and Conditions

17. Fig 3
Source: Journal of Vascular Surgery 2011; 53:53-60 (DOI:10.1016/j.jvs.2010.07.045 )
Copyright © 2011 Society for Vascular Surgery Terms and Conditions

18. analysis
the parameter with the highest Pearson
correlate to angiography was the PSV (0.813),
in contrast to both EDV (0.7) and ICA/CCA
PSV ratios (0.57, P < .0001)
A PSV of >230 cm/s was the most sensitive in
the diagnosis of 70% to 99% stenosis, and
adding other parameters (EDV or ratios) did
not improve the overall accuracy

19. analysis
Using a PSV of >230 cm/s with an
EDV of >100 cm/s or a systolic
ratio of >4 would improve the PPV
to 99% and the specificity to 97%

20. analysis
the ICA/CCA PSV ratio and the ICA EDV are
useful parameters when the ICA PSV may not
be representative of the extent of carotid
disease because of technical or clinical factors:
•
presence of contralateral high-grade stenosis or occlusion
•
discrepancy between visual assessment of the carotid plaque and
the ICA PSV
•
elevated CCA velocity, low cardiac output, or hyperdynamic
cardiac state

21. analysis
patients with low cardiac output would have a
low ICA PSV, which is disproportionate when
compared with the ICA/CCA PSV ratio.
In these situations, the clinician must rely on
the presence of the plaque and perhaps the
ICA/CCA ratio rather than the absolute ICA
PSV

22. carotid endarterectomy
the PSV threshold of 230 cm/s for detecting
≥70% stenosis can be used before CEA for
symptomatic patients since surgery has been
proven to be beneficial, even for ≥50%
symptomatic stenosis
A higher PSV (eg, ≥280 cm/s), which has a
PPV of 97%, or a PSV of >230 cm/s with an
EDV of >100 cm/s, or a systolic ratio of >4
(PPV of 99%) may be considered in
asymptomatic patients

23. POST-CAROTID STENTING
CRITERIA
Interpretation of high-grade (>75% to 80%) in-stent
stenosis should be based on elevation of EDV
beyond 125 to 140 cm/second

24. SUMMARY(2014)
The variability in carotid stenosis interpretation across accredited facilities
undermines the usefulness of this important diagnostic modality.
The IAC Vascular Testing Board of Directors feels that more standardization of
carotid duplex ultrasound diagnostic criteria will address these concerns and will
enhance the accuracy, reproducibility, portability and value of duplex
sonography for the diagnosis of carotid disease.

25. lower extremity
arterial
arterial

26. Indications for
Duplex Arterial Testing
Duplex Arterial Testing
•
Acute limb ischemia as a result of arterial thrombosis caused by
atherosclerosis, thromboembolism, trauma, or peripheral aneurysm
•
Chronic arterial occlusion/stenosis with intermittent claudication or an
abnormal (<0.9) ankle-brachial index (ABI)
•
Chronic arterial occlusion and threatened limb loss caused by rest
pain, ischemia, ulceration, or gangrene (i.e., critical limb ischemia)
ischemia
•
Aneurysmal disease, including false aneurysm after catheter-based
disease
interventions, or screening for abdominal aortic aneurysm (AAA) in
“selected,” high-risk patients
•
Surveillance for hemodynamic failure of arterial interventions
(percutaneous transluminal angioplasty [PTA], stent-grafts, bypass
grafting, dialysis access procedures)

27. criteria for classifying
peripheral artery lesions
peripheral artery lesions
triphasic
waveform
no spectral
broadening

28. criteria for classifying
peripheral artery lesions
peripheral artery lesions
triphasic with
minimal spectral
broadening
PSV increased
<30% relative to
adjacent proximal
segment (<150 cm/s)
proximal and distal
waveforms remain
normal

29. criteria for classifying
peripheral artery lesions
peripheral artery lesions
Triphasic wave usually
maintained
reverse flow component may
be diminished
spectral broadening
prominent
filling in of clear area
under the systolic peak
PSV increased 30 - 100%
relative to the adjacent
proximal segment (150-200cm/s)
proximal and distal
waveforms remain normal

30. criteria for classifying
peripheral artery lesions
peripheral artery lesions
monophasic wave with loss of
reverse flow component and
forward flow throughout
cardiac cycle
extensive spectral broadening
PSV >100% relative to proximal
segment (>200-300cm/s)
distal wave monophasic with
reduced systolic velocity

31. criteria for classifying
peripheral artery lesions
peripheral artery lesions
• no flow
detected
• distal
waveforms
monophasic
with reduced
systemic
velocities

32. Vein Bypass Evaluation

33. vein
vein
graft stenosis
graft stenosis
Graft Stenosis: Less Than 20%
•
Velocity ratio less than 2
•
Mild turbulence in systole
•
PSV less than 200 cm/sec

34. vein
vein
graft stenosis
graft stenosis
Graft Stenosis: 20% to 50%
• Velocity ratio greater than 2
• Turbulence throughout
• PSV less than 200 cm/sec

35. vein
vein
graft stenosis
graft stenosis
Graft Stenosis: 50% to 75%
•
Velocity ratio greater than 2.5
•
Severe turbulence with reversed flow
components
•
PSV greater than 200 cm/sec

36. vein
vein
graft stenosis
graft stenosis
Graft Stenosis: 75% to 99%
Velocity ratio greater than 3.5
End-diastolic velocity in flow jet greater than 100
cm/sec
PSV greater than 300 cm/sec

37. vein
vein
graft stenosis
graft stenosis
Impending Graft Thrombosis
•
Velocity ratio greater than 3.5
•
PSV less than 50 cm/sec

38. Risk Stratification for graft thrombosis based on
vascular lab testing data
approximately 20% of infrainguinal vein
bypasses will have a category I or II
stenosis identified within the first year
after grafting

39. AORTA

40. Aorta
Normal Infrarenal abdominal aorta 2cm
(range, 1.4 to 3 cm)
‘dilated’ = AP diameter 3 to 3.5 cm
‘aneurysm’ = > 3.5 cm, especially if mural
thrombus is imaged

41. AORTA
Reporting should include:
• morphology (saccular, fusiform)
• extent
• presence of mural thrombus or
dissection
• outside wall-to-wall diameter

42. AORTA
• typical growth rate for AAA= 3 to 4
mm/year

43. RENAL
artery
artery

44. Renal Artery Duplex
HTN and sudden deterioration in renal function
are the most common indications
•
atherosclerosis 95%
•
1 to 6% of HTN patients, but most common
cause of HTN in pts >50
•
men affected 2x women
arterial fibrodysplasia 5%

45. RAR
• interpretation of renal artery stenosis is based
on the maximum PSV obtained from the aorta
above the renal arteries (at the level of the SMA)
and the renal artery itself

46. renal interpretation
& reporting
& reporting
Normal Study:
•
PSV: 80 ± 20 cm/second
•
Renal-to-aortic PSV ratio (RAR): less than
RAR
3.5
•
Normal waveform: biphasic
•
No focal velocity increase
•
Low resistance waveform (RI <0.8)
•
- similar to internal carotid

47. renal interpretation
& reporting
& reporting
Less Than 60% Diameter Reduction
•
Low resistance waveform
•
RAR: less than 3.5
RAR
•
PSV: less than 180 cm/sec
•
Focal velocity increase

48. renal interpretation
& reporting
& reporting
Greater Than 60% Diameter Reduction
• RAR: greater than 3.5
RAR
• True post-stenotic turbulence
• Focal PSV increase greater than 180 cm/sec

49. NORMAL KIDNEY
• LENGTH: 9 TO 13 CM
• WIDTH: 4 TO 6 CM
• REASONABLE DIFFERENCE IN LENGTH
BETWEEN KIDNEYS: 1 CM
• length difference greater than 1 cm suggests
that the smaller kidney is abnormal

50. • biphasic: normal (similar to internal carotid
artery)
• triphasic: highly abnormal
• monophasic: highly abnormal, consistent with
distal occlusion or significant renal
malfunction

51. renovascular resistance
RI: measured in the body of the kidney
vasculature to assess renal resistance and
suggest perfusion
• RI < 0.7 NORMAL
• RI 0.7 to 0.8 questionably elevated
• RI >0.8 ABNORMAL

52. CELIAC
SMA
IMA
IMA

53. Celiac
NORMAL
• PSV = 90 to 110 cm/second
• low-resistance flow pattern
• no plaque visualized
• laminar and forward flow throughout
diastole

54. celiac
< 70% Stenosis
• PSV: < 200 cm/second
• EDV: < 55 cm/ second
• resistive index similar to that of the
ICA

55. celiac
> 70% stenosis
• PSV > 200 cm/second
• EDV > 55 cm/ second with
retrograde hepatic artery flow

56. SMA
NORMAL
• PSV: 95 to 150 cm/second
• high-resistance flow pattern in fasting
state
• EDV > 0 after a meal
• no plaque visualized
• laminar and forward flow throughout
diastole

57. SMA
< 70% Stenosis
• PSV <300 cm/second
• EDV < 45 cm/ second with diastolic
flow reversal in the distal SMA
• plaque visualized
• color doppler evidence of focal and
post-stenotic turbulence

58. SMA
> 70% Stenosis
• PSV > 300 cm/second
• EDV > 45 cm/ second with loss of diastolic
flow reversal
• mesenteric - aorta ratio > 3
• velocity spectra change with test meal
• increase in PSV at sites of stenosis with
damping of the distal waveform

59. LOWER EXTREMITY
VENOUS
VENOUS

60. VENOUS REFLUX
• a prospective study has demonstrated that the
acceptable physiologic flow reversal is
different for different veins
Jeanneret C, Labs KH, Aschwanden M, et al: Physiological reflux and venous diameter
change in the proximal lower limb veins during a standardised Valsalva manoeuvre. Eur J
Vasc Endovasc Surg 1999; 17:398-403.

61. VENUS REFLUX
the theory supporting this concept is
that larger veins have fewer valves
• the expected time for the valve
leaflets to come together is longer
than that for smaller, shorter veins

62. venous reflux
REFLUX = 1000 milliseconds
• common femoral
• femoral
• popliteal

63. venous reflux
REFLUX = 500 milliseconds
• superficial
• deep femoral
• deep calf axial
• muscular veins

64. venous reflux
REFLUX = 350 milliseconds
• perforating veins

65. steve henao md
new mexico heart institute