Objective:To investigate whether the existence of thoracic artery blood supply in peripheral pulmonary lesions is the key factor affecting the accuracy of contrast-enhanced ultrasound in differentiating benign and malignant lesions.Methods:From June 2020 to December 2021, a total of 170 patients with peripheral pulmonary lesions were consecutively enrolled in Xi′an Chest Hospital, and all patients underwent conventional ultrasound and contrast-enhanced ultrasound(CEUS). Taking ΔAT(lesion-lung arrival time difference ) of 2.5 seconds as the cut-off point for differentiating benign and malignant lesions(ΔAT<2.5 s for benign, ΔAT≥2.5 s for malignant), and the final pathological results as the gold standard, these patiens were divided into correct classification group and wrong classification group, and the main influencing factors of wrong classification were analyzed.Results:Compared with the correct classification group, the proportion of thoracic artery blood supply in the wrong classification group was significantly higher ( P<0.001). After adjusting the dendritic venous reflux, thoracic artery blood supply was an independent influencing factor for CEUS misclassification ( OR=3.531, 95% CI=1.805-6.908, P<0.001). In the patients with thoracic artery blood supply, the sensitivity of the absence of dendritic venous reflux in judging malignant peripulmonary lesions was 75.0%, the specificity was 91.3%, and the area under the ROC curve (AUC) was 0.832 (95% CI=0.715-0.915, P<0.001), while the sensitivity, specificity and AUC of CEUS in judging malignant peripulmonary lesions were 68.7%, 67.4% and 0.659 (95% CI=0.528-0.775, P=0.006), and there was significant statistical difference in the AUC between them( P<0.001). In the group of patients without thoracic arterial blood supply, the sensitivity of the absence of dendritic venous reflux in judging malignant peripulmonary lesions was 82.8%, the specificity was 63.3%, and the AUC was 0.730 (95% CI=0.636-0.811, P<0.001), while the sensitivity, specificity and AUC of CEUS in judging malignant peripulmonary lesions were 62.1%, 81.0% and 0.684 (95% CI=0.587-0.770, P=0.003), and there was no significant difference in the AUC between them ( P=0.425). Conclusions:The presence of thoracic artery blood supply significantly decrease the diagnostic efficiency of CEUS in differentiating benign and malignant of peripheral pulmonary lesions. For peripheral pulmonary lesions with thoracic arterial blood supply, the diagnostic efficiency of dendritic venous reflux is better than CEUS, while for lesions without thoracic artery supply, the diagnostic efficiency of dendritic venous reflux is equivalent to CEUS.