“…Unfortunately, data from these methods are variable, thereby leading to difficulty in diagnosing renal dysfunction. [2][3][4][5][6][7][8] Since sonographic microbubble contrast agents have become available, their efficacy for renal perfusion imaging has been the subject of clinical investigation. Many experimental studies have described how the use of microbubble agents on color and power Doppler sonography can improve the detection and characterization of various renal perfusion abnormalities, including masses [9][10][11][12][13][14][15][16][17][18][19][20] ; however, few studies have dealt with the transplanted kidney.…”