Correlations Between the Gradient of Contrast Density, Evaluated by Cardio CT, and Functional Significance of Coronary Artery Stenosis

Background: Assessment of the hemodynamic significance of a coronary artery stenosis is a challenging task, being extremely important for the establishment of indication for revascularization in atherosclerotic coronary artery stenosis. The aim of this study was to evaluate the role of a new marker reflecting the functional significance of a coronary artery stenosis, represented by the attenuation degree of contrast density along the stenosis by Coronary CT.
Material and Method: We evaluated retrospectively 30 patients with angina and coronary luminal narrowing, who underwent 64-slice Coronary Computed Tomography Angiography. We measured the stenosis degree, intraluminal contrast density (Hounsfield units [HU]) at two levels, proximal and distal to stenosis, and the attenuation gradient was calculated on this basis.
Results: The average contrast density was 77,96 UH proximal to the stenosis and 67,6 UH distal to the stenosis. The average transluminal gradient was 10,36. The average length of the coronary lesions was 16,93 mm. In those lesions with significant stenosis, expressed by >70% luminal narrowing, we recorded a significantly higher transluminal attenuation gradient as compared to those with <70% luminal narrowing (6.16 +/-3.7, 95%CI 4.3-80 vs 16.6 +/- 8.4, 95% CI 11.3 – 21.9). The degree of luminal narrowing significantly correlated with the contrast attenuation gradient (r=0.71, p<0.001).
Conclusions: The assessment of intraluminal contrast density by Coronary Computed Tomography Angiography may represent a new noninvasive tool to obtain relevant information about the clinical significance of a coronary stenosis. Larger studies are requested to emphasize the benefits brought by CCTA in evaluating coronary lesions.