Comparative Study And Clinical Application Of Ultrasonography And MRI In Differential Diagnosis Of Benign And Malignant Parotid Tumors

Objective:To evaluate the value of ultrasonography and magnetic resonance imaging in the diagnosis of benign and malignant parotid tumors.Method:Ultrasound and MRI were also performed on 47 patients with parotid tumors from April 2014 to August 2015.All cases were confirmed by surgery and pathology.Ultrasound: use feifan color doppler ultrasonic diagnostic instrument,linear array probe,frequency 3-9MHz.The size,border,shape and internal echo of the tumor were recorded.,then the blood flow distribution in the tumor was observed by color doppler,and the blood flow classification was recorded.The index of resistance and systolic peak velocity were measured by spectral Doppler measurements in the thickest blood vessels and the most luminous blood flow signals.MRI:all patients received rotine MRI and DCE-MRI examinations with Siemens Aera 1.5T MRI scanner.The diagnosis were according to ultrasound and MRI imaging,and ultrasound and MRI combined diagnosis by a parallel mode,follow the malignant diagnosis,namely two kinds of examination results are malignant was diagnosed as malignant,any examination results were diagnosed as benign as benign.The best diagnostic thresholds of PSV and RI for parotid benign and malignant tumors were calculated by using ROC curve.To compare the clinical value of ultrasonography and MRI examination and ultrasonography combined with MRI in the diagnosis of common benign and malignant tumors of parotid gland.All the data were analyzed by SPSS13.0 statistical software,and the chi square test was used to count the data.The difference was statistically significant,according to P<0.05.Result:(1)Ultrasound: there were significant differences in morphology and borders between 47 cases of parotid benign and malignant tumors(P < 0.05),and there was no significant difference in internal echo and blood flow grading(P > 0.05).Warthin tumor removed from the benign tumor group,the difference of blood flow between benign and malignant tumors was statistically significant(P < 0.05),PSV=24.4cm/s and RI=0.707 could be used as the diagnostic threshold of parotid benign and malignant tumors.(2)MRI: 47 cases of benign and malignant parotid tumors were statistically significant differences in the boundary(P < 0.05).There was no significant difference in T1 WI signal,T2 WI signal,location,envelope,cystic change,time intensity curve(TIC)between groups(P > 0.05).(3)The coincidence rate of ultrasonography and MRI in the diagnosis of parotid tumors was 74.47%(35/47)and(37/47),respectively.There was no significant difference between the two groups(P > 0.05).The diagnostic coincidence rate of the two methods was 89.36%(42/47),and the sensitivity and specificity of the two methods were significantly increased compared with that of the single method.Conclusion:(1)Boundary and morphology are very important indexes for qualitative diagnosis of parotid tumors.In combination with color doppler examination,the specificity of Warthin tumor should be considered,and the influence of Warthin tumor should be excluded.PSV=24.4cm/s and RI=0.707 have higher diagnostic value in differentiating the critical value of parotid benign and malignant tumors.(2)The routine MRI examination of parotid tumor has many disadvantages,such as low sensitivity,low specificity and overlap of multiple signs.The type of time intensity curve had certain overlap in the different pathological types of parotid tumors.(3)The clinical value of ultrasonography and MRI in diagnosis of parotid tumors were high,both in the diagnosis rate of no significant difference,but both combined the accuracy of diagnosis of parotid tumors was better than either alone,significantly improve the preoperative qualitative diagnosis coincidence rate of parotid gland tumor.