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Transcranial Doppler Up Stroke Time Fraction (USTF) and Severe Carotid Stenosis

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Transcranial Doppler Up Stroke Time Fraction (USTF) and Severe Carotid Stenosis

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Transcranial Doppler criteria for decision making in treatment of Carotid Stenosis

Transcranial Doppler criteria for decision making in treatment of Carotid Stenosis

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Transcranial Doppler Up Stroke Time Fraction (USTF) and Severe Carotid Stenosis

  1. 1. Combination Of Carotid Duplex And Transcranial Doppler For The Assessment Of Carotid Stenosis Roberto Hirsch*, Donald H. Lee**, Milberto Scaff* *Department of Neurology of the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil **Department of Neuroradiology of the University Hospital of the University of Western Ontario, London, Canada
  2. 2. Background NASCET published data from the severe stenosis randomization phase 70% ICA stenosis arbitrary cutoff “Poor results” achieved by ultrasound in correlating with angio measurements Why should this threshold represent a greater risk for stroke if not corrected by endarterectomy Can TCD and DCU address this question?
  3. 3. Background Is there a physiological phenomenon at this boundary that might be detected by physiological approach? Is there room for non invasive approach for the assessment of ICA stenosis?
  4. 4. Background Can TCD provide additional information in order to optimize DCU results in determining ICA degree of stenosis? Is the combination TCD/DCU more reliable than carotid ultrasound alone in determining severe stenosis?
  5. 5. NASCET angiographic criteria Bulbo de ACI Diâmetro da luz Diâmetro distal Método NASCET angiográfico %= 1- luz/luz distal The NASCET angio measurement technique brought clear standards reducing interobserver variation, unlike ultrasound at the beggining
  6. 6. Methods 67 out of 72 (42 NASCET and 8 ACAS) consecutive patients were studied by CA, TCD and DCU performed closest possible to concurrent. We estimated the degree of proximal ICA stenosis with CA according to NASCET criteria Best images were selected for study, 3 TCD “no shows” ruled out
  7. 7. Methods 134 arteries were randomized according to angio degree of ICA stenosis into below and over 70% stenosis and ICA occlusion, and had their TCD and DCU readings compared Multivariate and univariate analysis with logistic regression and chi-square and T- student test performed for each and total of TCD and DCU parameters having angiogram as gold standard
  8. 8. Methods TCD parameters: MCA velocities, presence of collateral circulation, pulsatility index, flow acceleration DCU parameters: ICA peak systolic velocity, ICA/CCA ratio, turbulence, ultrasound stenosis, CCA asymmetry or CCA damping
  9. 9. Upstroke time fraction x y UST-F = x/y ACI Normal B MCA reading distal and ipsilateral to normal ICA. Note the flow acceleration showing steep elevation of systolic flow velocity reaching its peak early in the cardiac cycle
  10. 10. Upstroke time fraction x y UST-F = x/y cas o de s ub-oclus ão A MCA reading distal and ipsilateral to a near-occluded ICA bulb. Note that peak systolic flow velocity is reached later in the cardiac cycle.
  11. 11. Upstroke time fraction x y UST-F = x/y cas o de s ub-oclus ão A UST-f was taken measuring the linear distance (time) for systolic velocity to be first achieved (x) and dividing it by the linear distance that represents one cardiac cycle.
  12. 12. Reproducibility of UST-f Patient presenting ICA near-occlusion, being the only conflictive result among the two readings (D.Lee = 7,82 ; RH = 15,92)
  13. 13. Reproducibility of UST-f By shifting background colour one can identify 2 spectra
  14. 14. Reproducibility of UST-f Superimposed retrograde ACA showing quicker flow acceleration time and underlying MCA affected by proximal ICA near-occlusion
  15. 15. Univariate analysis of TCD and DCU parameters - under 70% angio Mean SD p MCA mfv 48.5 10.62 0.0014 MCA UST-f 8.7 1.37 0.0001 ECICA psv 158.2 97.68 0.0000 ICA/CCA ratio 2.05 1.38 0.0001 CCA damp/asym 79.81 19.03 0.0000
  16. 16. Univariate analysis of TCD and DCU parameters - over 70% angio, excluding ICA occlusion Mean SD p MCA mfv 41.32 11.1 0.0014 MCA UST-f 19.8 3.42 0.0001 ECICA psv 338.89 125.43 0.0000 ICA/CCA ratio 6.63 4.16 0.0001 CCA damp/asym 57.52 19.92 0.0000
  17. 17. Most important TCD parameters - UST-f Upstroke time fraction could not be predictive in multivariate analysis because of the wide SD, but in univariate analysis was predictive with 100% of both specificity and sensitivity, provided there were no proximal ICA occlusion Ust-f <70% Ust-f >70% Occl < 70% 103 0 0 >70% 0 31 0 Occl 0 0 10
  18. 18. Most important TCD parameters - presence of collateral circulation Presence of collaterals in all patients with severe stenosis except when more severe stenosis or occlusion was present in contralateral side (p=0.000) Yes no total < 70% 98 95.15% 5 4.85% 103 > 70% 4 12.90% 27 87.10% 31 total 102 32 134
  19. 19. Multivariate analysis Logistic regression, with analysis of maximum likelihood estimates, shows that CCA damp/asymmetry has 101.686 odds ratio and 95% confidence limits. This parameter was arbitrarily defined as a more than 14 cm/s velocity reduction below the stenotic site or spectral damping. It may be jeopardized when contralateral to an ICA severe stenosis or occlusion
  20. 20. Probability of peak systolic extra-cranial ICA velocity to determine severe ICA stenosis 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 0 100 200 300 400 500 EC_ICA Probability CCADAMP=N CCADAMP=S
  21. 21. Sensitivity and specificity for CCA asymmetry to determine severe ICA stenosis 0 20 40 60 80 100 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 PROBABILITY SENSIBILIDADE ESPECIFICIDADE This model gives 90% of both sensitivity and specificity for CCA asymmetry presence to indicate severe stenosis
  22. 22. Conclusion Combined TCD and DCU parameters can reliably predict ICA proximal stenosis greater than 70% according to NASCET angiographic criteria. If indication of endarterectomy in a symptomatic patient is to be based only upon degree of stenosis, it can safely be done solely on non-invasive combined transcranial and cervical ultrasound approach
  23. 23. Conclusion These findings may bring us to the point that hemodynamic features, detectable by physiological methods, may play an important additional role in the genesys of ischemic events in symptomatic patients suffering from ICA stenosis along with embolic risk of a given plaque.

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