Application Of Acoustic Radiation Force Impulse In Parotid Focal Lesions

Objective: To evaluate the value of acoustic radiation force impulse-induced virtual touch tissue image(VTI)and virtual touch tissue quantification(VTQ)in the diagnosis of parotid focal lesions.Methods: Fifty-nine patients of oral and maxillofacial surgery due to parotid focal lesions were enrolled in the study.These patients were examined by routine ultrasonography and acoustic radiation force impulse(ARFI)imaging.Two-dimensional ultrasound features and blood flow signal characteristics of the parotid lesions were analyzed.The VTI examination was performed in parotid lesions and surrounding normal tissue.To obtain black and white gray-scale images by VTI six-level scoring method.The shear wave velocity(SWV)of nodules was recorded by the VTQ inspection.To draw receiver operating characteristic curve(ROC)of VTI grade and SWV,to find out the best boundary in the diagnosis parotid of focal lesions by VTI and VTQ.The differential diagnosis value of conventional ultrasound,VTI and VTQ in the parotid focal lesions was compared with the postoperative pathological results.Results: Taking the postoperative pathological results of the parotid gland as gold standard,45 cases were benign and 14 cases were malignant of 59 parotid lesions.(1)The ultrasonography of conventional ultrasound features:the differences of shape,edge,lesion composition,echo structure,echo reflex,with or without calcifictation,rear echo enhancement and blood flow between the benign group and malignant group were not statistically significant;(2)The area under the ROC curve of VTI was 0.813.The sensitivity,specificity and accuracy of VTI in the diagnosis of parotid focal lesions were respectively 78.6%,82.2% and 81.4%.(3)The area under the ROC curve of VTQ was 0.782.The optimal threshold of SWV in the differential diagnosis of parotid focal lesions was 3.89m/s.The sensitivity,specificity and accuracy were respectively 64.3%,86.7% and 81.4%.Conclusion:(1)The difference of VTI grade between benign and malignant parotid lesions was statistically significant,and benign lesions were mostly in grade I ~ III,and malignant lesions were mostly in grade IV ~ VI;(2)The difference of SWV between benign and malignant parotid lesions was statistically significant.The best cutoff point for SWV is 3.89m/s and the SWV values of benign and malignant lesions were partially overlapped,and there was no statistically difference between pleomorphic adenoma and malignant lesions;(3)The SWV values of parotid pleomorphic adenoma was higher than adenocarcinoma,so the hardness of pleomorphic adenoma is greater than what of adenocarcinoma;(4)There was no statistical significance between VTI and VTQ in diagnosing parotid focal lesions.