Purpose To investigate the value of MRI multi-sequence-based radiomic nomogram in identifying clear cell renal cell carcinoma from fat-poor renal angiomyolipoma in small renal masses(≤4 cm).Materials and Methods A retrospective analysis was performed for 78 renal masses in 75 patients with pathologically confirmed cases in the First Affiliated Hospital of Nanjing Medical University from July 2017 to December 2022,including 56 cases of renal clear cell carcinoma and 22 cases of fat-deficient angiomyolipoma,and all participants were divided into a training set(n=55)and a validation set(n=23)in a ratio of 7∶3.Radiomics features were extracted from T2WI and diffusion-weighted imaging sequences,and the t-test and minimum absolute shrinkage and selection algorithm were used for feature selection,the radiomics model was constructed,and the radiomics score was calculated.The clinical characteristics and subjective characteristics of MRI were evaluated to establish a clinical model,and the radiomics nomogram was constructed based on the radiomics score and clinical features,and the calibration,discrimination and clinical practicability of the nomogram were evaluated.Results A total of2 632 radiomics features were extracted from each patient,and 4 features were used to construct a radiomics model.The radiomics model had good discrimination ability in the training set[area under the curve(AUC)=0.979,95％CI 0.937-1.000)]and the validation set(AUC=0.833,95％CI 0.626-1.000).The radiomics nomogram had good calibration and discrimination ability in the training set(AUC=0.988,95％CI 0.963-1.000)and validation set(AUC=0.867,95％CI 0.698-1.000),which was better than the clinical model(AUC=0.725,95％CI 0.478-0.972)and radiomics model(AUC=0.833,95％CI 0.626-1.000)in the test set.Decision curve analysis showed that the clinical utility of nomogram was better than that of clinical factor model and radiomics features.Conclusion MRI-based radiomics nomogram combined with radiomics scores and clinical factors can be used to non-invasively distinguish clear cell renal cell carcinoma from alipid-deficient angiomyolipoma before surgery.

Objective To investigate the correlation between preoperative MR imaging features and the incidence of tumor metastasis in clear cell renal cell carcinoma.Methods The clinical and preoperative MR imaging data of 64 patients with clear cell renal cell carcinoma were analyzed retrospectively.According to the occurrence of metastasis,the patients were divided into non-metastasis group(n=42)and metastasis group(n=22).The clinical and imaging features of the two groups were analyzed with univariate analysis and multivariate logistic regression.Results The results of the univariate analysis showed that among the clinical and preoperative MR imaging data,there was no significant difference between the two groups in gender,tumor location and intra-tumoral cystic changes(P>0.05),but the patient's ages,clinical symptoms,tumor sizes,necrosis,capsule breakthrough,low signal nodules in T2WI,venous thrombosis,TNM stages,and Fuhrman grades were significantly different between two groups(P<0.05).Multivariate logistic regression analysis showed that low signal nodules in T2WI was an independent predictor of metastasis of clear cell renal cell carcinoma(P=0.028).Combined with diffusion weighted imaging(DWI)sequence,the average apparent diffusion coefficient(ADC)in related areas was measured.The ADC value of low signal nodules area was(0.541±0.101)×10-3 mm2/s in the metastasis group,and the ADC value of non-low signal nodules area was(0.972±0.113)×10-3 mm2/s(P<0.001).Conclusion The metastasis of clear cell renal cell carcinoma is often accompanied by low signal nodules in T2WI in tumors.Combined with the lower ADC value,they can be used as the characteristic imaging features to effectively evaluate the risk of metastasis of clear cell renal cell carcinoma.

Objective To establish and evaluate a morning check system for linac based on electronic portal image device (EPID).Methods Delivered fluence maps of open and wedge fields at 10 cm×10 cm field size of Synergy Linac were measured by EPID.Figure features from these two images were extracted with matlab codes and analyzed to realize a quick morning check.The repeatability of dose response and mechanical setup,relationship between gray value and machine unit (MU),accuracy of output and field size test were investigated with both EPID and DailyQA3.The status of Synergy linac was monitored both by DailyQA3 and EPID for two months.Results EPID was able to test the linac consistently with a testing error of 0.50 mm,1.00 mm for field size and center,respectively.Both of the test accuracy for flatness and symmetry was 0.17％.The mechanical accuracy test and dosimetric repeatability test were also consistent.The dose response of EPID was linearly related to the linac output (R2＞0.999).EPID was highly sensitive to the change of output and radiation field size.The measurement deviations between EPID and DailyQA3 were consistent and within clinical acceptable tolerance.Conclusions EPID showed great accuracy and stability on monitoring the performance of linac.The established daily check tool based-on EPID is accurate and reliable for clinical usage.