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. 2018 Aug;9(4):527-534.
doi: 10.1007/s13244-018-0622-5. Epub 2018 May 24.

Grading of carotid artery stenosis with computed tomography angiography: whether to use the narrowest diameter or the cross-sectional area

Kristina Samarzija  1 , Petar Milosevic  2 , Zoran Jurjevic  3 , Emilija Erdeljac  4
Affiliations

Grading of carotid artery stenosis with computed tomography angiography: whether to use the narrowest diameter or the cross-sectional area

Kristina Samarzija et al. Insights Imaging. 2018 Aug.

Abstract

Objectives: To compare the estimation of carotid artery stenosis by computed tomography angiography (CTA) based on cross-sectional area versus the smallest diameter measurement, and test the accuracy of both CTA measurements using color Doppler ultrasonography (CDUS) as a reference method.

Methods: For 113 carotid arteries with stenosis ≥50% we analysed the differences in the estimated stenosis level between both CTA methods and CDUS using the Bland-Altman approach. Further, we calculated sensitivity, specificity and plotted receiver operating characteristic (ROC) curves for both CTA methods.

Results: The mean difference between CDUS and CTA (area) measurements was -0.4% (p = 0.68); between CDUS and CTA (diameter), 20.7% (p < 0.001); and between CTA (area) and CTA (diameter), 21.2% (p < 0.001). Sensitivity and specificity for the CTA (area) method were 81% and 77%, and for CTA (diameter) were 23% and 100%. The area under the curve (AUC) for CTA (diameter) was 0.62 (0.57, 0.66), and for CTA (area) 0.79 (0.71-0.87). The equality test for the two AUCs was <0.0001.

Conclusions: CTA (diameter)-based measurements significantly underestimated the degree of carotid stenosis. We recommend the CTA (area) method because of its higher predictive power for a correct stenosis classification and a lack of significant difference in the estimated stenosis level, compared to CDUS.

Main messages: • Cross-sectional area measurement considers asymmetric shape of the residual vessel lumen. • CTA (diameter) method on average significantly underestimates the true level of stenosis. • CTA (area) method correctly classifies vessels needing surgical intervention.

Keywords: Atherosclerosis; CT angiography; Carotid artery stenosis; Color Doppler ultrasonography; Medical imaging.

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Figures

Fig. 1
Fig. 1
Automated quantification of an eccentric right carotid artery stenosis on CTA. Percentage of stenosis is calculated by electronically outlining the residual and the normal vessel lumen in a plane perpendicular to the longitudinal axis of the vessel. In this example, the area of the residual lumen is 9.7 mm2, the area of the normal lumen is 38.8 mm2, resulting in 75% stenosis. The residual lumen diameter is 3.5 mm, the normal lumen diameter is 7.0 mm, resulting in 50% stenosis
Fig. 2
Fig. 2
Empirical distributions of differences in stenosis measurements from three pairs of methods
Fig. 3
Fig. 3
Bland-Altman plot of the difference between CDUS- and CTA (area)-based measurements
Fig. 4
Fig. 4
Bland-Altman plot of the difference between CDUS- and CTA (diameter)-based measurements
Fig. 5
Fig. 5
ROC curves demonstrating the specificity and sensitivity of both CTA (area) and CTA (diameter) methods in identifying surgical stenosis
See this image and copyright information in PMC

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