Quantification of carotid stenosis on CT angiography.

PURPOSE Carotid artery stenosis quantification uses percent diameter ratios from conventional angiography. Multidetector high-speed CT angiography (CTA) allows direct millimeter measurement of carotid stenosis. We hypothesize a linear relationship between millimeter stenosis measurements and derived percent, alleviating cumbersome ratio calculations. METHODS Two neuroradiologists separately reviewed CTAs of 268 carotid arteries, blinded to other information. The narrowest portion of each carotid stenosis was measured in millimeters from axial source images. Distal internal carotid arteries (ICAs) were measured beyond the bulb, where walls are parallel. North American Symptomatic Carotid Endarterectomy Trial (NASCET)-style ratios were calculated for each ICA, except for suspected near-occlusions. Interobserver agreement was calculated for all measurements. Correlation coefficients were calculated comparing millimeter and derived percent stenosis, followed by regression analysis. Sensitivity and specificity values tested validity. RESULTS Interobserver agreement correlations were excellent, from 0.78 to 0.89 (2-tailed P </= .01). Excellent reader correlation permitted averaging of millimeter stenosis and distal ICA measurements, which were then used to calculate mean percent stenosis. Stenosis assessment was confidently performed from source images even with calcification. Regression analysis of mean percent as a function of mean millimeter stenosis shows a linear relationship, correlating 1.3 mm to 70% and 2.2 mm to 50% NASCET-style stenosis (Pearson's correlation of -0.95; n = 136). Direct millimeter measurement defining severe stenosis (70% or greater) has sensitivity of 88.2%, specificity of 92.4%, and negative predicted value of 98.2%. CONCLUSION There is a linear relationship between millimeter carotid stenosis diameter and derived percent stenosis. This allows prediction of NASCET-type percent from millimeter stenosis.

[1]  A. Ringer,et al.  Role of Conventional Angiography in Evaluation of Patients With Carotid Artery Stenosis Demonstrated by Doppler Ultrasound in General Practice , 2001, Stroke.

[2]  D. Kallmes,et al.  Frequency and significance of a small distal ICA in carotid artery stenosis. , 1998, AJNR. American journal of neuroradiology.

[3]  R. Limet,et al.  [Analysis of pooled data from the randomized controlled trials of endarterectomy for symptomatic carotid stenosis]. , 2005, Revue medicale de Liege.

[4]  L. Caplan.  Treatment of acute stroke: still struggling. , 2004, JAMA.

[5]  M. Eliasziw,et al.  Analysis of pooled data from the randomised controlled trials of endarterectomy for symptomatic carotid stenosis , 2003, The Lancet.

[6]  X Leclerc,et al.  Computed tomographic angiography for the evaluation of carotid artery stenosis. , 1995, Stroke.

[7]  D. Holdsworth,et al.  Use of a C-arm system to generate true three-dimensional computed rotational angiograms: preliminary in vitro and in vivo results. , 1997, AJNR. American journal of neuroradiology.

[8]  P. Nederkoorn,et al.  Systematic Review of Computed Tomographic Angiography for Assessment of Carotid Artery Disease , 2004, Stroke.

[9]  Tsong-Hai Lee,et al.  Multi-Slice CT Angiography in Diagnosing Total Versus Near Occlusions of the Internal Carotid Artery: Comparison With Catheter Angiography , 2003, Stroke.

[10]  R. F. Smith,et al.  Further Comments on the Measurement of Carotid Stenosis From Angiograms , 1994, Stroke.

[11]  P. Rothwell,et al.  Low risk of ischemic stroke in patients with reduced internal carotid artery lumen diameter distal to severe symptomatic carotid stenosis: cerebral protection due to low poststenotic flow? On behalf of the European Carotid Surgery Trialists' Collaborative Group. , 2000, Stroke.

[12]  Carlo Catalano,et al.  Computed Tomography Angiography: State-of-the-Art Imaging Using Multidetector-Row Technology , 2004, Journal of computer assisted tomography.

[13]  A. Fox,et al.  Clinical events following neuroangiography. A prospective study. , 1986, Acta radiologica. Supplementum.

[14]  J. Grotta,et al.  The risks and benefits of carotid endarterectomy in patients with near occlusion of the carotid artery , 1997, Neurology.

[15]  George Tomlinson,et al.  Neurologic complications of cerebral angiography: prospective analysis of 2,899 procedures and review of the literature. , 2003, Radiology.

[16]  Glenn B. Anderson,et al.  CT Angiography for the Detection and Characterization of Carotid Artery Bifurcation Disease , 2000, Stroke.

[17]  Rebecca Fahrig,et al.  Characterization of a C-arm-mounted XRII for 3D image reconstruction during interventional neuroradiology , 1996, Medical Imaging.

[18]  Anne L. Martel,et al.  Characterization of Complicated Carotid Plaque With Magnetic Resonance Direct Thrombus Imaging in Patients With Cerebral Ischemia , 2003, Circulation.

[19]  A. Davies,et al.  Endarterectomy for asymptomatic carotid artery stenosis , 1995, BMJ.

[20]  A. Fox,et al.  How to measure carotid stenosis. , 1993, Radiology.

[21]  P. Humphrey,et al.  Variability in measurement of extracranial internal carotid artery stenosis as displayed by both digital subtraction and magnetic resonance angiography: an assessment of three caliper techniques and visual impression of stenosis. , 1996, Stroke.

[22]  D. DeLong,et al.  Variability of Doppler US measurements along the common carotid artery: effects on estimates of internal carotid arterial stenosis in patients with angiographically proved disease. , 2000, Radiology.

[23]  C. Warlow,et al.  MRC European Carotid Surgery Trial: interim results for symptomatic patients with severe (70-99%) or with mild (0-29%) carotid stenosis , 1991, The Lancet.

[24]  A. Buchan.  North American Symptomatic Carotid Endarterectomy Trial (NASCET) Steering Committee. The Benefit of Carotid Endarterectomy in Symptomatic Patients with Moderate and Severe Stenosis. , 1998 .

[25]  D. Sackett,et al.  Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators. , 1998, The New England journal of medicine.

[26]  Lippincott Williams Wilkins,et al.  Clinical alert: benefit of carotid endarterectomy for patients with high-grade stenosis of the internal carotid artery. National Institute of Neurological Disorders and Stroke Stroke and Trauma Division. North American Symptomatic Carotid Endarterectomy Trial (NASCET) investigators. , 1991, Stroke.

[27]  P. Rothwell,et al.  Identification, prognosis, and management of patients with carotid artery near occlusion. , 2005, AJNR. American journal of neuroradiology.

[28]  Raymond Limet,et al.  A propos d'une analyse rétrospective parue dans lancet sur les bénéfices de la chirurgie des sténoses carotidiennes symptomatiques : L'importance de définir ce dont on parle , 2005 .

[29]  C Marsault,et al.  Carotid artery stenosis: prospective comparison of CT, three-dimensional gadolinium-enhanced MR, and conventional angiography. , 2001, Radiology.

[30]  T. Jensen,et al.  MRC European Carotid Surgery Trial: interim results for symptomatic patients with severe (70-99%) or with mild (0-29%) carotid stenosis. European Carotid Surgery Trialists' Collaborative Group , 1991 .

[31]  J. Kirkpatrick,et al.  Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. , 1998, Journal of insurance medicine.

[32]  G. Schroth,et al.  Contrast-enhanced 3D MR angiography of the carotid artery: comparison with conventional digital subtraction angiography. , 2002, AJNR. American journal of neuroradiology.

[33]  J. Seeger,et al.  The nearly occluded internal carotid artery: a diagnostic trap. , 1981, Radiology.

[34]  D. Sackett,et al.  Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. , 1991, The New England journal of medicine.

[35]  D. Kallmes,et al.  Accuracy and precision of CT angiography in a model of carotid artery bifurcation stenosis. , 1997, AJNR. American journal of neuroradiology.

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

[37]  S. Gutnikov,et al.  Analysis of pooled data from the randomised controlled trials of endarterectomy for symptomatic carotid stenosis , 2003, The Lancet.

[38]  D. Birchall,et al.  Evaluation of Cross-Sectional Luminal Morphology in Carotid Atherosclerotic Disease by Use of Spiral CT Angiography , 2001, Stroke.