Abstract：Objective: To study the diagnostic value of resistance index (RI) in detecting benign and malignant parotid tumors. Methods: Preoperative ultrasound blood flow signal characteristics was analyze and the RI in primary blood supply arteries of surgical pathological confirmed parotid benign pleomorphic adenoma (22 cases), adenolymphoma (14 cases) and malignant lymphoma (17 cases) was measured. Then, the RI threshold value of malignant parotid tumors using the receiver-operating characteristic curve (ROC curve) was detarmined, the qualitative diagnositic sensitivity and specificity for malignant paroted tumors were calculated. Results: ①90% (20/22) of benign pleomorphic adenoma tumor blood flow signals are between I-II level, 79% (11/14) of gland lymphoma tumor blood flow signals was between II-III level, 76% (13/17) of malignancy tumor blood flow signals was between III-IV level. And blood flow signal differences among three groups had statistical significance (P<0.05). ②with RI acuity 0.69 as a diagnostic standard, the diagnostic sensitivity for malignant parotid tumors was 82%, while the specificity was 70%. Conclusion: Benign and malignant parotid tumors blood flow signals are related to its pathological basis. By determining the RI of threshold value it is advantageous in differentiation between benign and malignant parotid tumors, especially for glandular lymphoma and high-grade malignant tumors which have relatively abundant blood supplies, and also for identifying low-grade malignant tumors and benign pleomorphic adenoma.
