Primary Study O F The Value Of Spectral CT Imaging For Distinguishing Renal Cell Carcinoma And Renal Angiomyolipoma With Minimal Fat

Objective Through comparison of renal cell carcinoma and renal angiomyolipoma with minimal fat underwent CT scan and energy spectrum imaging of each parameter analysis, to investigate the value of spectral CT imaging in differential diagnosis of renal cell carcinoma and renal angiomyolipomMethods 79 patients with renal tumor between 2011.11~2014.9 in Anhui Provincial Hospital were retrospectively analyzed, including 57 cases of RCC and 22 cases of RAML with minimal fat were scanned in gemstone spectral imaging( GSI) mode by using dual energy CT.The spectral analysis were used to calculate the differences of CT spectral imaging parameters,such as 70 ke V single energy ratio,spectral curves,iodine concentration ratio, water concentration ratio,and then standardize them. Comparison of standard spectral characteristic parameter and the difference between the intensive way, results were compared with pathology.The classification of data between the two groups was compared using the chi square test; the measurement data expressed by the mean±standard deviation,and than using independent t test.To assess the diagnostic efficacy of different parameters with the ROC curve, and calculated the diagnostic sensitivity and specificity.Results ①The regular feature of tumor: There were statistically significant betweengender proportion of cancer patients, P<0.05; Age structure, tumor location(left or right) was not statistically significant, P>0.05. ②Spectral characteristic of tumor: In 57 cases of renal cell carcinoma group " fast in fast out" enhancement in 45 cases(78.95%), delayed enhancement in 12 cases(21.05%). In 22 cases of renal angiomyolipoma with minimal fat group " fast in fast out" enhancement in 3 cases(13.64%), delayed enhancement in 19 cases(86.36%), There is significant difference between the enhancement mode(P<0.05). The 70 ke V single energy ratio were a valuable predictor for differentiating RCC from RAML(P<0.05) both in the cortical phase and in the medulla phase. In the cortical phase, the 70 ke V single energy ratio were 0.85±0.25、0.44±0.12(t=7.394 P<0.05) in the RCC and in the RAML,and were 0.41±0.10、0.62±0.15(t=6.088 P<0.05) when they were in the medulla phase. The iodine concentration ratio in the cortical phase and in the medulla phase were 0.67±0.36、0.40±0.12(t=5.076 P<0.05);0.45±0.23、0.50±0.11(t= 7.577 P<0.05),there was significant different(p<0.05). There were no difference between RCC and RAML with minimal fat both in the cortical phase and in the medulla phase of the water concentration ratio(p>0.05).There was significant difference in the mean slope of HU curve between RCC and RAML with minimal fat(P<0.05) both in the cortical phase and in the medulla phase, the mean slope of HU curve in the cortical phase and in the medulla phase were 3.58±1.52、2.18±0.83(t=5.207 P<0.05);2.32±1.13、3.41±0.95(t=3.994 P<0.05). The 70 ke V single energy ratio in the cortical phase provided high sensitivity in differentiating RCC from RAML with minimal fat(87.7% and 95.5%,respectively),and the area under the ROC curve was 0. 952.Conclusion Combined with the application of the CT spectral imaging GSI technology such as spectrum curve slope, single energy CT value, iodine value, energy spectrum curve slope have certain reference value to the differential diagnosis of RCC from RAML with minimal fat. Is expected to provide a basis for the choice of treatment of renal tumor.