The importance of Doppler angle of insonation on differentiation between 50-69% and 70-99% carotid artery stenosis.

AIM to investigate the importance of Doppler angle differentiating between 50-69% and >/=70% internal carotid artery (ICA) stenosis. MATERIAL AND METHODS fifty-one patients with a previous diagnosis of 50-69% ICA stenosis (n =53) were re-evaluated by duplex scanning. Spectral Doppler velocity waveforms were obtained from common carotid (CCA), ICA and external (ECA) carotid arteries with the same Doppler angle of insonation as used at the initial duplex scanning, followed by repeated measurements with a fixed 60 degrees angle of insonation. RESULTS the peak systolic velocity (PSV) in the ICA was 181+/-55 cm/s (mean+/-SD) at the second duplex scanning when the same angle of insonation (mean 46 degrees +/-9) was used as during the initial investigation. When the examination was done with a 60 degrees angle of insonation, PSV ICA was 261+/-96 cm/s (mean+/-SD). In fifteen arteries the estimated degree of ICA stenosis changed from 50-69% to 70-99% due to the application of a fixed Doppler angle of insonation at 60 degrees. CONCLUSION the Doppler angle of insonation has a significant effect on spectral Doppler velocity measurements. It is crucial that duplex criteria are standardised with a fixed angle of insonation and that this angle is consistently used during velocity estimations.

[1]  D. Sumner,et al.  Carotid endarterectomy without angiography: is color-flow duplex scanning sufficient? , 1994, Surgery.

[2]  Frederick W. Kremkau.  Doppler Ultrasound Principles and Instruments , 1990 .

[3]  N. Bornstein,et al.  Carotid endarterectomy without angiography , 1996, The British journal of surgery.

[4]  S Byrd,et al.  Carotid duplex ultrasonography: importance of standardisation. Asymptomatic Carotid Surgery Trial Collaborators and Vascular Laboratories. , 1998, International angiology : a journal of the International Union of Angiology.

[5]  D S Sumner,et al.  Color-flow duplex scanning of carotid arteries: new velocity criteria based on receiver operator characteristic analysis for threshold stenoses used in the symptomatic and asymptomatic carotid trials. , 1994, Journal of vascular surgery.

[6]  D. Bandyk,et al.  Carotid Endarterectomy Based on Duplex Ultrasonography: A Safe Approach Associated with Long-term Stroke Prevention , 2000 .

[7]  G. Moneta,et al.  Correlation of North American Symptomatic Carotid Endarterectomy Trial (NASCET) angiographic definition of 70% to 99% internal carotid artery stenosis with duplex scanning. , 1993, Journal of vascular surgery.

[8]  H Becker,et al.  Standardization of Carotid Ultrasound: A Hemodynamic Method to Normalize for Interindividual and Interequipment Variability , 1999, Stroke.

[9]  M. Fillinger,et al.  Carotid duplex criteria for a 60% or greater angiographic stenosis: variation according to equipment. , 1996, Journal of vascular surgery.

[10]  D S Sumner,et al.  Prospective evaluation of new duplex criteria to identify 70% internal carotid artery stenosis. , 1996, Journal of vascular surgery.

[11]  D. Dawson,et al.  The role of duplex scanning and arteriography before carotid endarterectomy: a prospective study. , 1993, Journal of vascular surgery.

[12]  A. Whittemore.  Presidential address: a team for the 21st century: the vascular center. , 2000, Journal of vascular surgery.

[13]  W H Baker,et al.  An approach for the use of Doppler ultrasound as a screening tool for hemodynamically significant stenosis (despite heterogeneity of Doppler performance). A multicenter experience. Asymptomatic Carotid Atherosclerosis Study Investigators. , 1996, Stroke.

[14]  R. Zwolak.  Carotid Endarterectomy Without Angiography: Are We Ready? , 1997 .

[15]  H. Trappe,et al.  Blood flow velocity measurements for carotid stenosis estimation: interobserver variation and interequipment variability. , 1997, VASA. Zeitschrift fur Gefasskrankheiten.

[16]  M G Hunink,et al.  Detection and quantification of carotid artery stenosis: efficacy of various Doppler velocity parameters. , 1993, AJR. American journal of roentgenology.

[17]  J. Marek,et al.  Evaluating institutional variability of duplex scanning in the detection of carotid artery stenosis. , 1998, American journal of surgery.

[18]  F. Lexa,et al.  Determination of duplex Doppler ultrasound criteria appropriate to the North American Symptomatic Carotid Endarterectomy Trial. , 1996, Stroke.