The Clinical Application Of Dual Energy CT In Parotid Gland Space Occupied Lesions

Part ?Feasibility study of virtual non-contrast CT with dual source,dual-energy CT in parotid gland space occupied lesionsObjective To evaluate the feasibility of non-contrast CT(TNCT)being replaced by dual-energy virtual non-contrast CT(VNCT)using dual-source CT in patients with parotid gland space.occupied lesions.Data and Methods The clinical manifestations and CT images for 54 patients confirmed by pathological results from surgery were reviewed retrospectively.All of the patients were examined by a pre-contrast scan(ture non contrast;TNC)and then arterial and venous phase enhanced scan.Then enhanced examinations were performed with dual-energy scan mode.The post processing application "Liver VNC" was used to get VNC.images at the arterial and venous phase respectively.Then the diagnostic coincidence,mean CT values,signal-to-noise ratio,contrast noise ratio,subjective image quality,and radiation dose were compared between routine TNC and VNC.Results ?The.TNC and VNC images had the same sensitivity for the detection and high diagnostic consistency of parotid leisions(Kappa were 0.96?0.93?0.73).Sensitivity,specificity,and accuracy from TNC imges for the characterization of benign lesions,malignant lesions and inflammatory masses of parotid gland were 89.5%?81.7%?88.5%,70%?95.2%?90.4%,50%?97.9%?94.2%,from VNC images of arterial phase were 85.7%?86.5%,70%?97.6%?92.3%,75%?95.8%?94.2%.?The subjective score of VNC images were lower than that of TNC images,but the difference was no statistically significant(P>0.05),values were 4.31 ± 0.76?4.19 ±0.82?4.21 ± 0.78.?No significant differences were seen for mean CT values in submaxillary gland and sternocleidomastoid muscle between TNC and VNC images(P>0.05)except the parotid gland lesions,nomal parotid gland and mandible which the difference between TNC and VNG images were statistically significant(P<0.05).The SNR of all two groups in VNC group was greater than that of TNC,and the difference was statistically significant(P<0.05).There was no significant difference between the three groups in contrast noise ratio.?The radiation dose of VNC images was lower than that of TNC(P<0.05),Compared with TNCT,the value of total radiation radiation dose in VNC were significantly reduced by 38.6%.Conclusion The VNC images had the advantages of good image quality,high lesion diagnostic accuracy,and low scanning dose,which may replace the true non-contrast CT in the future.Part ?Analysis of parotid pleomorphic adenoma,adenolymphomas and malignant tumor of parotid gland by dual energy spectrum curveObjective To analyze the spectrum curve characteristic of parotid pleomorphic adenoma,adenolymphomas and malignant tumor of parotid gland.And explore the significance of dual energy CT in differential diagnosis of parotid tumors.Data and Methods Image data of 46 cases with a total of 52 parotid lesions by pathology underwent dual energy enhanced CT scan were retrospectively analyzed.After removal of parotid basal cell tumor and metastatic tumor,there were 44 cases(50 leisions)that included 19 cases of pleomorphic adenoma,14 cases(20 lesions)of lymphoma and 11 cases of malignant tumor.All had pathologically confirmed parotid tumors underwent arterial and venous phase contrast-enhanced dual energy CT scan.Processed images with post processing software called "Mono Energetic" which is in MMWP post-processing workstation,generating spectrum energy curve.Then observed the change trend of the spectrum curve and comparison the different kinds of parotid tumors energy spectrum curve slope.Results In the range from 40 keV to 160 keV,with the increasing of KeV value,the CT value of the three types of parotid tumors decreased gradually.It showed the higher the keV value the less CT value decreased,All the tumors with the energy spectrum curve of "drop type".The arterial phase of parotid adenolymphomas energy spectrum curve slope in the range of 40KeV-160KeV are located at the top,malignant tumor center,pleomorphic adenoma at the bottom,between the three groups in the 40-160KeV CT value difference was statistically significant(P<0.05).The energy curve slope of three different nature of parotid tumors were 1.22 ± 0.99?2.36 ± 1.02 and 1.55 ± 0.83,were statistically significant(P<0.05).There were significant differences in parotid pleomorphic adenoma and adenoma(P<0.05).However,Compared pleomorphic adenoma and lymphoma with malignant tumor,there were no significant difference in the slope.Through removing of overlapping parts of parotid tumors of different nature,we can draw the conclusion:if 1.68>K>0.82,may be pleomorphic adenoma;if 2.87>K>2,may be adenolymphomas.Conclusion Spectrum curve in arterial phase from dual-energy scan has certain reference value for differential diagnosis of three types parotid tumors.Part ?Iodine map and morphology in the diagnosis of the pleomorphic adenoma,adenolymphomas and malignant tumor of parotid glandObjective To explore the value of dual-source,dual-energy CT iodine mapping and morphology in the differential diagnosis of the pleomorphic adenoma,adenolymphomas and malignant tumor.Data and Methods Clinical data and scanning methods were same as the second part.? Analysis the characteristics of three types parotid tumors and the morphology records(including the location,shape,boundary,quadrant,With or without cystic changes,with or without enlarged lymph nodes),by Logistic regression distinguish the main signs and secondary signs.? Iodine concentration,normalized iodine concentration of the three kinds of parotid tumors were measured in Liver VNC software and then compared.Sensitivity,specificity and receiver operating characteristic curve(ROC)was performed for diagnosing the three kinds of tumors.Results The iodine concentration were 10.93 ± 0.79mg/ml?1.94 ± 0.74mg/ml?1.33 ± 0.72mg/ml;and normalized iodine concentration were 0.09 ± 0.09?0.23 ±0.11?0.17±0.11 respectively.The difference was statistically significant(F were 8.755 and 8.648 respectivity,P were<0.05).Further comparison between the two kinds of tumors,the difference was statistically significant between parotid pleomorphic adenoma and adenolymphoma(P<0.05).Compared pleomorphic adenoma and lymphoma with malignant tumor,there were no significant difference(P>0.05).The use of intravenous iodine diagnosis of pleomorphic adenoma,the sensitivity was 63.2%,specificity was 72.7%,AUC(ROC area under the curve is 0.671);using the arterial phase iodine diagnosis of adenolymphoma,sensitivity was 90%,specificity was 68.7%,AUC was 0.795,the arterial phase normalized iodineconcentration when the diagnosis of adenolymphoma,the sensitivity was 95%,specificity was 65.6%,AUC was 0.798;the sensitivity and specificity of iodineconcentration in the diagnosis of malignant tumors are not high.The morphological indexes of the parotid gland were analyzed.It was found that the parotid gland wasaffected by the deep and small lobes of the parotid gland,the boundary was not clear,the shape was irregular,and the enlarged lymph nodes were valuable morphological indexes for the diagnosis of malignant tumors.Conclusion CT spectra of iodine from dual-energy scan has certain reference value for differential diagnosis of three types parotid tumors,but the malignant tumors with pleomorphic adenoma and adenolymphoma between iodine concentration overlapped,combined with morphological characteristics,is helpful to the correct diagnosis and differential diagnosis of three types of tumors.