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Ultrasound Assessment

Ultrasound Assessment

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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