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Doppler Indices and Clinical Implications

Doppler Indices and Clinical Implications. Doppler Indices and Clinical Interpretation. Hsu Hung Yi. Doppler Indices and Clinical Implications. Doppler Indices and Clinical Interpretation. Hsu Hung Yi. Doppler Indices. PI: pulsatility index RI: resistance index

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Doppler Indices and Clinical Implications

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  1. Doppler Indices and Clinical Implications Doppler Indices and Clinical Interpretation Hsu Hung Yi

  2. Doppler Indices and Clinical Implications Doppler Indices and Clinical Interpretation Hsu Hung Yi

  3. Doppler Indices • PI: pulsatility index • RI: resistance index • PTI: pulsatility transmission index • S/D ratio: A/B ratio, systolic to diastolic ratio • FA: flow acceleration, systolic upstroke, • AT: acceleration time • VMCA/VICA: hemispheric index • VMCA/VACA: • D-MCA: velocity difference between MCAs • ACAVR: ACAs velocities ratio

  4. Pulsatility Index “PI, Gosling Pulsatility Index”

  5. Resistance Index“RI, Pourcelout Pulsatility index”

  6. Systolic to Diastolic Ratio

  7. Systolic Upstroke (Flow acceleration; Acceleration time)

  8. PI & RI & A/B ratio RI(r)= (A-B)/A => rA= A-B => B= A-rA=(1-r)A (1) => 1/(1-r)= A/B PI(p)= (A-B)/mean V = (A-B) / [(A+2B)/3] => p = 3x [ A-(1-r)A] / [ A+2(1-r)A] => p= 3rA / 3A-2rA => 3pA-2prA= 3rA => 3p-2pr = p(3-2r)= 3r => p = 3r / (3-2r) => PI= 3x RI/ ( 3- 2 x RI)

  9. Pulsatility Index “PI, Gosling Pulsatility Index”

  10. Pulsatility Index • Low resistance vascular bed had higher diastolic flow • An estimated of downstream vascular resistance • Not dependent on the angle of incidence

  11. Age Gender Vessel diameter Blood pressure Cardiac output Heart rate Examiner variability Hematocruit Fibrinogen Carbon Dioxide Medication Insonation angle Cerebral blood volume Physiologic Determinants of Flow Velocity and Indices

  12. Pulsatility Index Normal PI: 0.5~1.1 (0.7~1.02) --pooled data PI for MCA, ACA and PCA : 0.690.11~0.710.13 EC-ICA:0.74 0.13 --J Ultrasound Med,1990

  13. Pulsatility Index Side to side difference: <20% for MCA; 24% for PCA; <30% for ACA Day to day difference <28% for MCA; <34% for ACA; <30% for PCA

  14. Conditions of Increased PI • Increased distal vascualar resistance • Hydrocephalus • Increased intracranial pressure • Brain death (not 100% specific) • Arterial stenosis: upstream to stenosis • Slow heart rate • Hypoplastic vertebral artery • Aortic valve incompetence

  15. Conditions of Decreased PI • Decreased distal vascular resistance • Feeding artery of AVM • Vasospasm after SAH • Arterial stenosis: downstream to stenosis and collateral branches • Hyperemia • Headache free period of migraine

  16. Hemispheric Index “VMCA/VICA” • Discriminating vasospasm from hyperemia • Normal: 1.7~1.8 ( 1.1~3.0 ) • Mild to moderate vasospasm: >3 & <6 • Severe vasospasm: >6 • ICA flow velocity must be measured from the neck, below the angle of mandible

  17. Clinical Implications of Pulsatility Indices • Arterial occlusive disease • Primary, Secondary and Tertiary effects • Vasospasm • Brain death • Arteriovenous Malformation • Cerebral perfusion pressure; intracranial pressure ( indirectly) • Intraoperative Monitoring

  18. Manifestations of Carotid Artery Stenosis-Primary • in < 50% stenosis; spectral broadening • in > 50% stenosis; increased velocity

  19. Manifestations of Carotid Artery Stenosis-Secondary • Downstream • turbulence • decreased velocity • delayed systolic upstroke • decreased pulsatility • Upstream • decreased velocity • increased pulsatility

  20. Manifestations of Carotid Artery Stenosis-Tertiary • Adjacent Branches • increased velocity • decreased pulsatility • Distant interconnecting branches • reversed flow direction • decreased pulsatility • increased velocity • turbulence

  21. TCD Criteria of Abnormal Waveform • Dampedsignal • Blunted signal • Minimal signal • Absent signal

  22. Damped Signal • Pulsatile flow • Normal flow acceleration • Decreased mean flow velocity(>30% difference between hemispheres)

  23. Blunted Signal • delayed flow acceleration, maximum velocity during mid to late systole • focal decreased mean flow velocity • positive end diastolic flow • low PI <1.19

  24. Blunted Signal • Delayed flow acceleration, maximum velocity during mid to late systole • focal decreased mean flow velocity • positive end diastolic flow • low PI <1.19

  25. Minimal Signal • Flow signal • No end diastolic flow • High PI ( >1.7 )

  26. Absent Signal • No detectable flow at appropriate depths of insonation • Adequate acoustic window

  27. Pulsatility and velocity changes of ICA occlusion???

  28. V,p V,T,R,p or v,p,AT v,p V,T,R,p V,p V,p V,p P,v

  29. The physical law of Laplace T R P = P = pressure in the vessel T = tension in the wall R = radius of the vessel

  30. MCA occlusion -- increased ACA flow & decreased MCA flow

  31. From Transcranial Doppler, ed. II DW Newell, R Aaslid

  32. From Transcranial Doppler, ed. II DW Newell, R Aaslid

  33. Thanks for your attention !!! 許弘毅 台中榮總

  34. “Fluttering”

  35. Turbulence“ Doppler Bruit”

  36. Harmonic Bruit“Seagull sound”

  37. Estimation of Carotis Stenosis

  38. Normal Carotid Bifurcation

  39. Arterial to arterial embolization

  40. Cervical ICA occlusion -- OA increased flow & decreased pulsatility

  41. Flapping Thrombus in MCA

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