Background:Quantifying inflammatory cells in the aortic root of Type A aortic dissection using computed tomography angiography (CTA) can be useful for assessing disease severity and prognosis in patients with Type A aortic dissection. However, this approach has not yet been validated against quantitative histologic results.Materials and Methods:This study included patients who underwent CTA prior to modified Cabrol surgery for TAAD between April 2023 and April 2024.On CTA, Inflammatory cell composition in the aortic root was quantified using a Gaussian mixture model on cytokine density.Aortic specimens were stained and quantitatively analyzed by a pathologist for histologic evaluation. Correlation analysis was conducted with Spearman's rank correlation coefficient, and intermodal and interobserver variability were assessed using intraclass correlation coefficients (ICC) and Bland-Altman plots.