Quantification of Carotid Stenosis on CT Angiography
E.S. Bartlett,
T.D. Walters,
S.P. Symons and
A.J. Fox
Department of Neuroradiology, Northwestern University, Chicago, IL
Department of Medical Imaging, Sunnybrook and Women’s College Health Sciences Centre, Ontario, Canada
Department of Medicine, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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Fig 1. CTA showing right severe carotid bulb stenosis with deep plaque ulceration. A, Axial source image. B, Sagittal reformat. C, 3D rendered image (large arrow, stenotic ICA; dashed arrow, bulb plaque ulcer; small arrow, proximal ECA).
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Fig 2. Carotid stenosis measurements were obtained from axial source data at the narrowest portion of the carotid bulb. A, Source image. B, Magnified right carotid portion. C, Submillimeter measuring tool determining 3.2 mm (0.32 cm).
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Fig 3. Oblique artery measure. A, Axial source image with arrow toward ICA. B, Sagittal reformat showing oblique ICA axis of a slightly tortuous ICA. C, Axial measurement, perpendicular to oblique axis. This demonstrates a need for viewing reformats in addition to axial source images.
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Fig 4. Correlation scatter plots. Interobserver agreement between reader measurements. A, Maximum stenosis (mm). B, Distal ICA (mm). C, Derived NASCET-style percent stenosis. (Correlations: 2-tailed significance = 0.01. n values reflect exclusion of pairwise missing data; excludes "near-occlusion" cases).
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Fig 5. Linear regression. Mean percent stenosis to mean millimeter maximum carotid bulb stenosis. (Pearson correlation = –0.95; n = 136; 2-tailed significance = 0.01; R2 linear = 0.895; SE of estimate = 7.63; B value = –21.539).
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Fig 6. Axial source images of left severe ICA stenosis; small residual lumen with vessel wall plaque and thick calcification on the sides. A, Source axial image with "standard" W : L settings for CTA evaluation (W 750 : L 200). B, Magnified left ICA (W 750 : L 200). C, Magnified with wide window for appropriate visualization and measurement of residual carotid lumen (W 900 : L 275). A wider W : L setting allows conspicuity between the different attenuations of contrast in lumen and calcification along the sides.
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