Renal Oncocytoma And Common Renal Cell Carcinoma Subtypes MSCT Differential Diagnosis

ObjectiveAnalysis the image characteristics of MSCT plain scanning and enhanced triple-phase scanning of renal oncocytoma(RO)and common renal cell carcinoma subtypes(clear cell renal cell carcinoma CCRCC,papillary renal cell carcinoma PRCC and chromophobe renal cell carcinoma CRCC).Investigate the value of multiphase MSCT scanning on the differential diagnosis of renal oncocytoma and common renal cell subtype to improve the preoperative diagnostic accuracy of renal oncocytoma and reduce clinical overtreatment.Materials and MethodsCollect the clinical and image data of 19 cases of RO and common RCC subtypes in 98 cases(CCRCC 68 cases,PRCC 17 cases and CRCC 13 cases),which were confirmed by pathology and underwent MSCT scanning and enhanced scanning before treatment from Jan.2013 to Nov.2016,for retrospective analysis and investigation.SIEMENS SOMATOM Definition AS(made in Germany)was used for MSCT scanning.Volume scanning was achieved with high pressure injector(Medtron Accutron CT-D,Germany)and through intravenous injection before the elbow.Plain scanning and enhanced triple phase dynamic scanning were performed for all of the patients and the images of plain scanning and those in corticomedullary,parenchymal and excretory phases were obtained respectively.Scanning range was from the superior margin of the adrenal glands to the bottom of the double renal,and it was expanded appropriately for those with larger lesions according to the images of plain scanning.The CT images of all the cases were analyzed on SIEMENS Syngo via workstation by two senior imaging diagnosis doctors without knowing the pathological results before and an agreement was reached finally after the diagnosis.The contents of analysis and measurement included:the location of the tumor(left kidney,right kidney),tumor size(diameter),necrotic and cystic changes within the tumor,tumor calcification,tumor scar,tumor CT value(plain scanning,corticomedullary,parenchymal and excretory phases)and the tumor enhancement model.SPSS 22.0 software was used for data processing and analysis.The single factor variance analysis and LSD-t test were used to compare the tumors size,onset ages and CT values in different phases of various patients.Chi-squared test was used for the comparison of gender,tumors location,cystic and necrotic changes,calcification,abnormal blood supply and tumor enhancement model.The difference was statistical significance with P<0.05.ResultsFour groups of tumor cases confirmed by pathology include 19 cases of RO,68 cases of CCRCC,17 cased of PRCC and 13 cases of CRCC.The ratio of male to female in the four groups are 12:7,41:27,12:5 and 7:6 respectively.All of the tumor cases affect more men than women with a ratio close to 2:1,but without obvious statistical significance between each other(P=0.806).No obvious statistical significance was observed for ages(P=0.953),the risk of left or right kidney(0.868),calcification(P=0.267)and abnormal blood supply(P=0.401).The average tumor diameter of the four groups are:3.92±2.38cm for RO,5.89±3.36cm for CCRCC,3.01±1.67cm for PRCC and 6.78±4.67cm for CRCC respectively.Significant statistical difference can be observed between RO and CRCC(P=0.022),CCRCC and PRCC(P=0.004),PRCC and CRCC(P=0.002).P>0.5 for all of the other two groups,without statistical difference.Cystic and necrotic change was not detected in RO,but it was detected in CCRCC(53 cases out of 68,77.94%),PRCC(5 cases out of 17,29.41%)and CRCC(3 cases out of 13,23.07%).Significant statistical difference was observed between the four groups of cases(P<0.001).Stellate scar was detected in RO(9 cases out of 19,47.36%)and CRCC(3 cases out of 13,23.07%),not in CCRCC and PRCC.The Chi-squared test result shown that there is significant statistical difference between RO and CCRCC(P<0.001),RO and PRCC(P<0.001),but not between RO and CRCC(P=0.163).The CT value of RO(36.31±6.53Hu)obtained from MSCT plain scanning is significantly higher than those of CCRCC(P=0.011)and PRCC(P=0.007),but without significant statistical difference with that of CRCC.The CT value of RO(113.57±10.78Hu)in corticomedullary phase is significantly higher than those of PRCC and CRCC(P<0.001),but without significant statistical difference with that of CCRCC.In parenchymal phase,the CT value of RO decreases slightly,the CT value of CCRCC decreases obviously but those of PRCC and CRCC increase slightly.Significant difference was observed between the CT value of RO and those of all the common RCC subtypes,but not significant between those of CCRCC and CRCC.The CT values of the four groups cases decrease slightly or moderately in excretory phase with the same statistical difference to parenchymal phase.According to the enhancement difference of the four kinds tumors in different phases,PRCC and CRCC show slightly enhancement delay in excretory phase.So only the enhancement of RO and CCRCC in CMP-NP phases are examined with T-test and the result is P<0.001.Among the 19 cases of RO,11 cases are homogeneous enhancement,8 cases heterogeneous enhancement.Among the 68 cases of CCRCC,15 cases are homogeneous enhancement,47 cases heterogeneous enhancement and 6 cases edge enhancement.Among the 17 cases of PRCC,12 cases are homogeneous enhancement,4 cases heterogeneous enhancement and 1 case edge enhancement.Among the 13 cases of CRCC,7 cases are homogeneous enhancement,6 cases heterogeneous enhancement.Significant statistical difference was observed between RO and CCRCC(P=0.012),no significant difference was observed between RO and PRCC(P=0.254),RO and CRCC(P=0.949).ConclusionAccording to the MSCT multiphase scanning results of RO and common RCC subtypes,the enhancement degree of tumor(or CT value)in CMP phase from high to low is CCRCC>RO>CRCC>PRCC.In NP phase,the internal contrast medium of CCRCC retreats faster than RO,which shows "fast in and slow out" highly enhancement,and CCRCC shows“fast in and fast out" type highly enhancement,while PRCC and CRCC show slightly enhancement delay.In combination with the characteristics,like high rate of cystic and necrotic changes in CCRCC,high incidence rate of stellate scar in RO,high incidence rate of calcification in CRCC and lower CT value of PRCC in tetra phase scanning,will benefit the differential diagnosis of RO and common RCC subtypes and provide accurate basis for clinic diagnosis.For the minority of undetermined RCC,we should avoid overtreatment based on clinical analysis and do percutaneous renal biopsy when necessary.