Figure 11a. Transitional cell carcinoma of the renal pelvis in a 65-year-old man with a 1-month history of left flank pain and intermittent gross hematuria. (a) Axial contrast-enhanced CT scan obtained during the nephrographic phase shows an ill-defined low-attenuation mass (arrow) in the central portion of the left kidney. (b) Coronal maximum intensity projection CT scan obtained during the excretory phase shows a large filling defect with an irregular margin (arrows) in the pelvicalices of the left kidney, thus clearly demonstrating the extent of the tumor.