Application Study Of Magnetic Resonance Imaging In Diagnosis Of Parotid Gland Tumors

Objective:To compare the conventional MRI and DWI features that may improve differential diagnosis between benign and malignant parotid tumors.To defined some typical MR findings for some frequently encountered parotid tumors.Methods: MR of 87 cases with parotid gland tumors confirmed by histopathology were analyzed retrospectively.These 87 cases were divided into 2 groups including benign tumors and malignant tumors.The following parameters were analyzed:patient’s gender,age,tumor location,shape,margins,signal intensity,enhancement pattern,grwoth patten,extension.An unpaired 2-tailed student t test was used for comparison of the different of the patient’s age,and the chi-square analysis and Fisher exact test were used for comparison the different of the MRI features between benign and malignant parotid tumors,P<.05 was considered to indicate statistical significance.Analysis the DWI and ADC values of benign and malignant parotid gland tumors,an unpaired 2-tailed student t test was used for comparison of the different of the ADC value between benign and malignant parotid tumors,P<.05 was considered to indicate statistical significance.Using ROC curve to find out the cutoff ADC value for differentiating malignant parotid tumors from benign tumors,and the specificity and sensitivity of differential diagnosis for both.Results:The significant difference between benign and malignant tumors including:tumor sharp,location,margin,signal intensity on T2 WI,enhancement pattern,grwoth patten and extension.The following features have no significant difference between benign and malignant tumors:patient’s ages,scx,tumor homogeneity,signal intensity on T1 WI.The mean ADC value were significantly different between benign tumors(1.32±0.27×10-3mm2/s)and malignant tumors(1.05±0.14×10-3mm2/s).The mean ADC value of malignant tumors was significantly higher than that in pleomorphic adenomas,and lower than that in warthin tumors.Conclusion:MRI and ADC value have a potential value in differential diagnosis of benign and malignant parotid tumors.Objective:To evaluation the diagnostic efficacy of an MRI algorithm characteristic of pleomorphic adenoma(PA).Methods: MR of 87 cases with parotid gland tumors confirmed by histopathology were analyzed retrospectively.These 87 cases were divided into 2 groups including PA(n=37)and other parotid gland tumor(n=50).Six of the MR imaging features characteristic for PA(lobulated contours,sharp margins,bright T2-signal,T2-dark rim,heterogeneous nodular enhancement,ADC value)of these 2 groups were compared and analyzed.MRI scores of each patient were acquired using a revised MRI algorithm system,which was based on initial scoring system of five “high probability” criteria,and added the scores of the ADC value.We then identified MRI images to test the diagnostic accuracy of the proposed algorithm.Results:There were statistical differences in these MR imaging features characteristic between the two groups.Twenty-four of 27 cases that met all six “high probability”MRI criteria were consistent with PA on final histopathology.MRI had a specificity of94.00% and sensitivity of 64.86% for PA.The positive predictive value was 88.89% and the negative predictive value was 78.33%.The overall diagnostic accuracy was 81.64%.Conclusion: The revised MRI algorithm characteristic of PA is about 94% specific for pleomorphic adenoma.A subset of patients with MRI imaging that is highly suggestive of PA may reliably avoid further workup.A significant proportion of PAs,however,have indeterminate imaging features that overlap considerably with other benign and malignant lesions.