Preliminary Study Of Gemstone Spectral Imaging In The Differential Diagnosis Of Parotid Gland Tumor

Objectives: Parotid gland tumor was one of the most common tumor of oral and maxillofacial region,and the pathological type was relatively complex.Different types of tumor in manifestation,treatment and prognosis were not the same.How to improve the preoperative diagnosis is a problem demanding prompt solution to the Maxillofacial surgeon.With the quickly development of spectral CT,Gemstone Spectral Imaging(GSI)have the advantages of high sensitivity and low radioactive dose imaging features.Some preliminary researches of GSI had obtained in organizational specificity,benign and malignant tumors identification,the tumor quality and grading as a new functional imaging method.It would provide a new approach for diagnosis and differential diagnosis in parotid gland tumors.The purpose of this study is to explore the value of spectral CT imaging in differential diagnosis of parotid gland tumor,and to provide more reference for diagnosis and clinical treatment.Method: 64 cases of parotid gland tumors from 2015.1 to 2016.12 in Department of Oral and Maxillofacial Surgery,The First Affiliated Hospital of Zhengzhou University were selected.All cases were confirmed by postoperative pathology.These cases included 24 cases of pleomorphic adenoma,15 cases of Warthin tumor,7 cases of basal cell adenoma and 18 cases of malignant tumor.All patients underwent plain CT scan and two phases of enhanced spectral CT imaging by GE Discovery 750 HD to obtain a single image energy.Image data of plain spiral and enhanced CT was analyzed to get single-energy image of ROI(region of interest),every single level of CT value(HU)of arterial and venous phase.CT spectral curves were obtained and the spectral curve of the slope was calculated.ROI iodine concentration of arterial and venous phase and internal carotid arteries and veins were measured to calculate the standard iodine concentration and iodine concentration difference of arterial and venous phase.Application of receiver operating characteristics curve(ROC)to comparison of diagnostic efficacy of different energy spectrum parameters in benign and malignant parotid gland tumors.All data was statistical analyzed using SPSS21.0 statistical analysis software.Results with P < 0.05 showed statistically significant difference.Results: 1.The parotid pleomorphic adenoma group had the lowest level of CT value(54.15±25.12HU)in arterial phase,and increased to 123.44±48.46 HU in venous phase significantly.The CT value of Warthin tumor group in arterial phase was 143.01±27.39 HU,while decreased to 110.95±47.65 HU in venous phase.The CT value of basal cell adenoma group was 125.89±35.43 HU in arterial phase,and had a slight increase to 178.52±67.62 HU in venous phase.The malignant tumor group had a significantly higher CT value in venous phase(171.76±59.33HU)than arterial phase(92.25±24.00HU).The difference was statistically significant(P < 0.01).2.In the arterial period,the slope of the spectrum of the parotid pleomorphic adenoma 40-70 kev was the lowest,at 0.53±0.51,and the highest in Warthin tumor,2.11±0.58.In the venous phase of basal cell adenoma of the slope top,3.24±0.52, Warthin tumor slope,1.49±1.17 is markedly reduced arterial,the differences were statistically significant(P < 0.01).3.Iodine concentration of each group in the arterial phase,parotid pleomorphic adenoma was the lowest(2.14±4.18 mg/ml),Warthin tumor was 9.83±4.19mg/ml,basal cell adenoma was 9.19±5.25mg/ml,while malignant tumor was the highest(13.69±7.57 mg/ml).In venous phase,iodine concentration of pleomorphic adenoma increased to10.99±5.93 mg/ml,Warthin tumor decreased to 7.86±6.24mg/ml,basal cell adenoma increased significantly to 16.45±7.49mg/ml,and malignant tumor increased mildly to 17.09±7.50mg/ml.All the differences were statistically significant(P < 0.01).4.The comparative results of standard iodine concentration had consistency with the iodine concentration after excluding individual differences.5.Parotid benign and malignant tumor different diagnosis efficiency of the energy spectrum parameters comparison: In arterial,Iodine concentration area under ROC curve(area under the curve,AUC)is 0.801,standard of iodine concentration AUC is 0.792.In the venous phase,The AUC of iodine concentration is 0.732,and the standard iodine concentration AUC is 0.784.The highest diagnostic performance in the diagnosis of arterial iodine concentration in the parotid gland was 66.7%,and 87.0%,when the threshold was 11.89.Conclusion: 1.CT Spectral imaging could provide more diagnostic information and had good prospect in future clinical practice.2.Different kind of parotid gland tumor had its special CT value,spectral curve and iodine concentration indexes.3.CT Spectral imaging was valuable to identify the property of different parotid tumors.