Patients entering into this protocol will also have a preoperative renal contrast enhanced US for this research study. Renal mass US contrast enhancement results will be compared with surgical pathological findings to determine if contrast enhancement patterns of the renal masses correlate with benign and malignant histopathology, and/or malignant histologic subtype.

Intravenous line will be inserted. After the ultrasound microbubble contrast has been suspended into solution, contrast will be injected intrav via hand bolus with a total activated suspension of 0.2 mL (30 uL octaflouropropane),followed by 10 mL saline flush, with option to rebolus 4 addit time's for tot dose of 150 uL. Post contrast cine images of renal mass will be obtained on commercially available US units primarily using low mechanical index settings & Contrast Pulsed Sequence (CPS®) technique. Images will be acquired at predetermined intervals, for up to 8 min post contrast admin. Manufacturer's guidelines incl immediate post flush image capture, as well as post admin image capture at intervals as 1 min, 2 , 4 & 8 mins. Additional, temporary higher mechanical index imaging of kidney for the purpose of "flash" bubble destruction may be optionally triggered using manufacturer's preset settings & energy w/i FDA guidelines. This will only be performed while imaging the kidney.