The goal of this observational study is to establish a preoperative imaging diagnostic model which highly consistent with the histopathological examinations, as well as a accurate and systematic pathological grading standard of inferior vena cava (IVC) vascular wall invasion in renal cell carcinoma (RCC) with tumor thrombus invading vascular wall.The main questions it aims to answer are: * To establish a preoperative imaging diagnostic model which highly consistent with the histopathological examinations. * To determine what impact does different vascular wall layer invasion make on the long-term prognosis in RCC with IVC tumor thrombus; * To determine which layer invasion according to pathological examination make sense to clinical treatment (can significantly affect prognosis); Participants with IVC vascular wall invasion/ non-invasion are divided into experimental group (invaded group) or control group (non-invaded group) respectively according to pathological examinations, in order to establish a prospective cohort with three-year follow-up. The pathological characteristics of local recurrence and poor prognosis are summarized, and postoperative pathological diagnostic criteria of IVC vascular wall invasion and established. The local recurrence and distant recurrence outcomes are compared between experiment group and control group, in order to analyze the long-term influence of vascular wall invasion. Then the preoperative imaging diagnostic evaluation model will be established.