Objective To explore the diagnostic value of left atrium-pulmonary vein CT characteristics for left atrial appendage thrombosis among patients with non-valvular atrial fibrillation (NVAF). Methods 103 NVAF patients[ 62 male, 41 female; mean age: (67. 17±5. 32)years]between September 2013 and June 2021 were retrospectively divided into thrombosis and non-thrombosis groups by trans-esophageal echocardiography findings. Left atrium-pulmonary vein characteristics on contrast-enhanced CT including the diameter of the opening of each pulmonary vein, angle between the ipsilateral upper and lower pulmonary veins, left atrial width, length and depth, left atrial appendage opening length and depth, CT values of left atrial lumen, CT values and corresponding signal-to-noise ratios (SNR)and contrast-to-noise ratios (CNR)at the opening and deepest part of the left atrial appendage, and D-dimer index were compared using univariate and multivariate logistic regression analysis. Results Compared to the non-thrombosis group, patients in the thrombosis group had significantly smaller left pulmonary vein angle (P=0. 047), larger left atrial width (P=0. 042), length (P=0. 024)and depth (P=0. 001), longer left atrial appendage opening (P<0. 001), higher SNR of the left atrial lumen (P=0. 003), higher left atrial appendage opening and depth CT values (P=0. 053, 0. 006)and SNR (P=0. 01, 0. 044), and lower CNR of the left atrial appendage opening (P=0. 009). There were no significant differences in age (P=0. 747), pulmonary vein opening diameters (P=0. 464. 0. 284, 0. 702, 0. 159), right upper and lower pulmonary vein angles (P=0. 252), depth of left atrial appendage (P=0. 888), and left atrial CT values (P=0. 156). The D-dimer indexes were significantly different (P=0. 014). Multivariate logistic regression analysis of left atrial appendage opening diameter was an independent risk factor for left atrial appendage thrombosis in patients with NVAF (P=0. 003). Using the left atrial appendage opening length of 22. 5 mm as cutoff value, the area under the receiver operating characteristic curve for diagnosing left atrial appendage thrombosis was 0. 838 with 77. 2%sensitivity and 96. 0%specificity. Conclusion NVAF patients have longer left atrial appendage opening, larger left atrial lumen, lower CT values at the left atrial appendage opening, and elevated D-dimer. Left atrial appendage opening length of 22. 5 mm can be used as an independent risk indicator whereas the predictive value of D-dimer is lower than the other variables. [ABSTRACT FROM AUTHOR]