Objective To probe the difference of MSCT features between clear cell renal cell carcinoma (ccRCC)and renal oncocytoma (RO),to improve the diagnostic accuracy.Methods 31 cases of ccRCC and 16 cases of RO which were confirmed by pathology were analyzed retrospectively,and the difference in some CT features including the morphology and CT value of plain scanning and three phases of enhancement scanning were analyzed.Results The diameter of the tumor of the ccRCC group was (5.04 ± 1.9 1 4)cm,meanwhile that of the RO group was (3.5 9±2.1 6)cm,exhibiting statistically significant difference in the diameter which was bigger in ccRCC group than that in RO group (P＝0.023).There were 90.32% (28/31)of cases with cystic necrosis in the ccRCC group and 18.75%(3/16)in the RO group,which was statistically significant that the patients with cystic deterioration in the ccRCC group were more than those in the RO group (P＜0.001).35.48% (11/31)of cases with peritumoral or intratumoral neovascularization in the ccRCC group and no cases in the RO group were found,and there was a statistically significant difference (P＝0.009).The enhancement degree in the ccRCC group was greater than that in the RO group in cortical phase and excretory phase,but lower in parenchy phase.However, there was no significant difference in the enhancement degree and the enhancement index in three phases of enhancement scanning (P＞0.05). Conclusion MSCT can demonstrate the renal tumor with or without cystic necrosis and neovascularization around or inside the tumor,which is helpful to differentiate ccRCC from RO.

Objective:To explore the feasibility of quantitative evaluation of extracellular volume (ECV) fraction in acute ST-segment elevation myocardial infarction (STEMI) by dual-layer spectral detector CT.Methods:The clinical and imaging data of 20 patients with STEMI who underwent cardiac contrast-enhanced CT and MRI from January to October 2019 in Renji Hospital affiliated to Shanghai Jiaotong University School of Medicine were retrospectively analyzed.The dual spectral detector was used in the enhanced CT scan of the coronary artery with retrospectively gate and the late iodine enhancement with prospective gate. Conventional image and holographic spectral image were obtained by iterative and spectral reconstruction. The short axis image of the heart matched with MR image was obtained by multiplanar reconstruction. Based on the data of spectral based image, the IDD map was reconstructed for the calculation of myocardial CT-ECV during the late iodine enhancement. ECV of infarcted myocardium, salvageable myocardium and remote myocardium based on CT and MRI were calculated respectively. Bland-Altman consistency test and intra group correlation coefficient analysis (ICC) were used to compare the consistency of two measurements and different methods. The correlation between CT-ECV and MRI-ECV was compared by Spearman method.Results:The CT-ECV values of infarcted, salvageable, and remote myocardium were 51.21 (49.27, 53)%, 38.64 (36.17, 40)%, and 51.21 (49.27, 53)%, respectively. The difference was statistically significant ( H= 43.17, P<0.01). The CT-ECV value of infarcted myocardium was significantly higher than that of salvageable myocardium and remote myocardium ( Z=-24.60, 35.40, P<0.01), but there was no significant difference between salvageable myocardium and remote myocardium ( Z= 10.80, P=0.15). The T 1 values of infarcted myocardium, salvageable myocardium and remote myocardium were (1 554.85±70.94), (1 443.85±67.28) and (1 307.05±91.73) ms respectively, the difference was statistically significant ( F=51.35, P<0.01). The T 1 value of infarcted myocardium was higher than that of salvageable myocardium and remote myocardium ( t=-5.07, 9.55, P<0.01), and salvageable myocardium was significantly higher than that of remote myocardium ( t=5.38, P<0.01). The MRI-ECV values of infarcted myocardium, salvageable myocardium and remote myocardium were 55.00 (49.27, 57.75)%, 33.50 (29.00, 35.00)%,and 27.00 (26.00, 29.00)%, respectively. The difference was statistically significant ( Z= 47.12, P<0.01). MRI-ECV of infarcted myocardium was significantly higher than that of salvageable myocardium and remote myocardium ( Z=37.45, -20.30, P< 0.01), and salvageable myocardium was significantly higher than that of remote myocardium ( Z = 17.15, P<0.05). The difference between CT-ECV and MRI-ECV measured by two physicians was good. The bias of Bland-Altman analysis was -0.1% (95% CI:-5.5%-5.2%), 0.8% (95% CI:-9.8%-8.2%), and the ICC values were 0.92 and 0.94, respectively. The bias of Bland-Altman analysis in CT-ECV and MRI-ECV consistency test was 4.00% (95% CI:-9.0%-16.9%) and ICC value was 0.88, which had a good correlation ( r=0.75, P=0.001). Conclusions:The iodine density based ECV fromdual-layer spectral detector CT can be used to quantitatively evaluate the changes of extracellular space after acute STEMI, which is helpful to quantitatively evaluate the histological changes after myocardial ischemia.