Computerized tomography in the diagnosis of transitional cell carcinoma of the kidney.

We present 8 patients with transitional cell carcinoma of the kidney who underwent preoperative computerized tomographic examination of the lesions. The computerized tomographic findings are discussed and are correlated with the conventional radiographic appearance. The tumor presents on computerized tomographic examination as a solid mass in the renal pelvis and/or in a ballooned calix, with displacement and compression of the renal sinus fat. It shows attenuation values of 8 to 20H and enhances minimally after intravenous injection of iodinated contrast material. Trapping of contrast material in curvilinear caliceal spaces or in compressed collecting ducts around the periphery of the tumor results in crust-like rims of contrast density tightly and persistently encircling portions of the tumor. Retention of contrast material in obstructed tubules results in accentuated delayed enhancement of the renal parenchyma surrounding the larger lesions. A striated parenchymal pattern, secondary to uneven collecting duct obstruction, also may be seen on delayed views. The reniform contour of the kidney usually is preserved even in the presence of larger neoplasms.