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Ultrasound Assessment

Ultrasound Assessment Lower Extremity Arteries Ultrasound Assessment When Adjunct to physiologic testing Determine stenosis vs. occlusion Determine level and extent of occlusion May assist in determination of treatment Angioplasty vs. surgical

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Ultrasound Assessment

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  1. Ultrasound Assessment Lower Extremity Arteries

  2. Ultrasound Assessment • When • Adjunct to physiologic testing • Determine stenosis vs. occlusion • Determine level and extent of occlusion • May assist in determination of treatment • Angioplasty vs. surgical • Patients with renal failure who cannot have arteriography or MRA • Trauma

  3. Ultrasound Imaging • Modalities • B-mode • Spectral Doppler • Color Doppler • Power Doppler

  4. Ultrasound Imaging • B-mode • Evaluate vessel walls for: • Stenosis due to: • Calcification (medial calcinosis) • Plaque formation • Thrombus • Aneurysmal dilatation, measure • Longitudinal diameter • Make vessel as wide as possible • Transverse diameter • Make vessel as narrow as possible

  5. Ultrasound Imaging • Spectral Doppler • Determine peak systolic & end diastolic velocities • Use PSV’s to calculate systolic velocity ratios • > 2.0 = > 50% stenosis • > 4.0 = > 75% stenosis • Some labs determine volume flow • No validation or normals determined

  6. Ultrasound Imaging • Color Doppler Flow Imaging • Assists in determining the presence of flow • Must set appropriate scale (PRF) • Low PRF for question of occlusion • Assists in determining laminar vs. turbulent flow • Must set appropriate scale (PRF) • Assists in placement of spectral Doppler sample volume at point of greatest velocity • Assists in the detection of collaterals

  7. Ultrasound Imaging • Power Doppler • Assists in determining the presence of flow • More sensitive in detecting low flow than color Doppler • Can use simultaneous spectral Doppler • May assist in the detection of collaterals • No directional information

  8. Mean Arterial Diameters

  9. Peak Systolic Flow Velocities

  10. Classifying Peripheral Artery Lesions • Normal • Triphasic waveform • No spectral broadening

  11. Classifying Peripheral Artery Lesions • 1 – 19% diameter reduction • Triphasic waveform • Minimal spectral broadening • PSV increased <30% relative to the adjacent proximal segment • Proximal & distal waveforms remain normal

  12. Classifying Peripheral Artery Lesions • 20 – 49% diameter reduction • Triphasic waveform usually maintained; reverse flow component may be diminished • Prominent spectral broadening • PSV increased 30 – 100% relative to the adjacent proximal segment • Proximal & distal waveforms remain normal

  13. Classifying Peripheral Artery Lesions • 50 – 99% diameter reduction • Monophasic waveform with loss of reverse flow component • Extensive spectral broadening • PSV increased >100% relative to the adjacent proximal segment • Distal waveform is monophasic with reduced systolic velocities

  14. Classifying Peripheral Artery Lesions • Occlusion • No flow detected within imaged arterial segment • Preocclusive “thump” may be heard just proximal to site of occlusion • Distal waveforms are monophasic with reduced systolic velocities

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