Evaluating Renal Masses Using Ultrasound Intravenous Microbubble Contrast

The purpose of this study is to evaluate the blood flow in kidney masses by using ultrasound microbubble contrast material, and to see if results from ultrasound contrast studies can predict if a kidney mass is benign or malignant. Patterns of blood flow in the kidney mass will be examined to see if: 1. benign kidney masses can be distinguished from kidney cancers and 2. if slow growing, lower risk cancers have different blood flow compared to clear cell cancer which is the most common type of kidney cancer.