Accuracy of digital subtraction angiography, computed tomography angiography, and magnetic resonance angiography in grading of carotid artery stenosis in comparison with actual measurement in an in vitro model

Background: The aim of this study was to investigate the accuracy of digital subtraction angiography (DSA), computed tomography angiography (CTA), and magnetic resonance angiography (MRA) in grading of carotid stenosis compared with actual measurement in an in vitro model. Methods: Various grades of stenosis were created by adhering different amounts of silicone rubber sealant onto the inner wall of clear, radiolucent tubes. After DSA, CTA, and MRA, the tubes were transected with 1-mm interval through the plaques. The cross-sectional areas were digitally photographed, and the percentage of area reduction of every single slide was measured with ImageJ planimetric software. The maximum actual area reduction (AAR) stenosis of each tube was recorded. The differences among DSA, CTA, MRA, and AAR were compared statistically using paired Student t test. Results: Overall, CTA and MRA significantly underestimated the degrees of stenosis compared with AAR (P = 0.001 and P = 0.0009, respectively), and no significant difference was found between DSA and AAR (P = 0.40). In the subgroup with stenosis of <70%, there was no significant difference between DSA, CTA, and MRA versus AAR (P = 0.18, P = 0.16, and P = 0.08, respectively). In the subgroup with severe stenosis of >70%, CTA and MRA significantly underestimated the stenosis versus AAR (P = 0.004, and P = 0.007 respectively), and DSA significantly overestimated the stenosis (P = 0.0007). Conclusions: This in vitro model study demonstrated that CTA and MRA underestimate the lesions in severe stenosis of >70%. DSA tends to overestimate the disease. The accuracy of DSA is affected by plaque morphology, such as mountain-shaped lesions.