 New imaging techniques as dynamic contrast-enhanced CT are being developed to quantify and characterize these unique properties, and may be used as markers of response to angiogenesis inhibitors. Imaging assays of angiogenic status therefore offer the potential to clinically measure anti angiogenic effects of drugs on the tumor vessels themselves, effects that may not be reflected in changing tumor dimensions. These effects may be detectable hours or days from time of treatment initiation, rather than in weeks or months needed typically to detect a change in tumor size. Exploration of local tumor vascular architecture can help to understand mechanism of action of Sunitinib. This vasculature seems to be of poor functionality and tumor vascularization cannot be adequately assessed only by global index such as global tumor blood flow. In addition, exploration of renal tumor vascularization with contrast-enhanced US will be performed to compare blood flow determined by CT and US. 