Contrast Enhanced Ultrasonography to Detect Human Renal Transplant Rejection

This study will be divided into two stages. In the first stage the investigators will assess the transplant kidney with ultrasound after contrast injection (Sonazoid) to determine if contrast in the kidney is detectable by ultrasound and to determine if the amount of perfusion can be quantified directly or qualitatively. The investigators aim to have one to two subjects in this stage. If perfusion of the kidney can be assessed, then the investigators will move to stage two of the study. In stage 2, the investigators will look to determine the ability of the contrast enhanced ultrasonography method to detect renal transplant rejection using Sonazoid. For this stage the investigators will recruit subjects with biopsy confirmed renal transplant rejection. Once subjects are consented, they will undergo contrast enhanced ultrasonography with Sonazoid and have images taken. These images will be compared to images of renal transplant patients that have displayed no rejection or clinical issues. These clinically normal subjects will have previously consented to a medical record review so that the investigators may use their images.