Research On Diagnosis Of Renal Tumors By Contrast Enhanced Ultrasonography

Renal tumour is the second common urological tumor in our country. Renalangioleiomyolipoma (RAML) accounts for more than90%of renal benign tumors,and renal clear cell carcinoma (RCCC) accounts for more than80%of renalmalignant tumors. So far, diagnosis of renal tumor depends on imaging methodssuch as ultrasound, CT and MRI. Ultrasonography has become the most commonlyused method for the screening of kidney tumour because of its real-time, dynamic,visual and other advantages. But it is still difficult to detect and differentiallydiagnose benign and malignant renal tumors. Contrast enhanced ultrasonography(CEUS) using non-destructive low-acoustic-power ultrasounc scanning withinjection of contrast agent microbubbles, allows to display the blood flow andperfusion of capillary in organs or malignant lesions clearly. In this paper, CEUSwas applied to examine renal tumor and it proved to be a high sensitivity indetection and differential diagnosis of renal tumor.Methods for CEUS performed on kidney according to the Clinical Applicationof norm and guidelines on liver contrast enhanced ultrasound established by theEuropean Federation of Ultrasound Medicine and Biology (EFUMB). Rationalexperimental method was developed based on routine ultrasound andhemodynamics characteristics of renal. Contrast enhanced ultrasound wasperformed on the normal kidney, RAML and RCCC and then contrastographicpictures were analyzed. Based on imaging comparison, data analysis and caseconfirmation, specific qualitative index such as contrast enhanced phase, contrastenhanced degree, perfusion mode, enhancement pattern; quantitative index such asstart time (ST), peak time (PT), peak intensity (PI), ascending slope rate (ASR),descending slope rate (DSR) and area under curve (AUC) were used in this study.Firstly, in order to explore the application standards of CEUS on renal tumors,we applied CEUS in50cases with normal renal cortex and medulla. Phase ofCEUS in normal renal were divided first, then contrastographic pictures of renalcortex and medulla were quantitatively analysed. CEUS proved to be more sensitivethan color and power Doppler ultrasound in displaying renal blood flow, cleared therange of renal cortical and medullary perfusion phase and regression phase. Time-intensity curve showed that perfusion in renal cortex started earlier than that inrenal medulla, perfusion rate in renal cortex was faster than that in renal medulla;however, their PT were close, regression were almost simultaneously; and PI andAUC in renal cortex was higher than those in renal medulla. Secondly, in order to determin the characteristics of benign renal tumordetected by CEUS,86patients of RAML, a benign renal tumor, were performed toCEUS. Phase feature, perfusion mode, enhanced mode and time-intensity curverepresent benign renal tumor was summarized by CEUS images analysis. It showedthat the most common perfusion mode was “gradually enhanced intensity from rimto center”. According to perfusion enhancement modes, it was separated by threetypes: type I was “fast in and slow out”, type II was “slow in and slow out”, type IIIwas “simultaneous in and slow out” which accounts for68.6%(59/86). Time-intensity curve showed that ST, PT, ASR and AUC of RAML was greater than thosein ipsilateral normal renal cortex.Thirdly, we perfomred CEUS on42RCCC and based the experiment onpathology and optical density of blood vessels. The most common perfusion modefor RCCC was“enhanced uneven and diffuse”. Perfusion enhancement mode wasclassified into four types: type I, quick in and quick out; type II, quick in and slowout, type III, simultaneous in and simultaneous out; type IV, slow in and slow out.The most common type was type II. Conclusion from quantitation analysis of time-intensity curve was that ST, PT, PI, ASR and DSR of RCCC were significantlydifferent from those in normal renal cortex.Eventually, according to the differences of phase of CEUS, perfusion modeand enhanced pattern in normal kidney, benign and malignant renal tumor,conclusion as followed was obtained. There qualitative indexes, enhancementhomogenecity, perfusion mode and enhancement pattern were used for renal tumordiagnosis with a sensitivity of80.23%,80.23%and93.02%, respecificity; aspecificity of78.57%,83.33%and71.42%, respectively; an accurate diagnosis rateof79.69%,81.25%and85.93%, respectively; area of ROC curve of0.794,0.818and0.822, respectively. Conclusion from quantitation analysis of time intensitycurve was that ST, PT, ASR, AUC and DSR of RAML were significantly differentfrom RCCC.