IN RECENT years, computed tomography (CT) has been found extremely useful in the diagnosis and management of renal masses. Computed tomography provides an accurate morphological picture of the renal mass, and its precise contrast resolution allows identification of characteristic attenuation values as well. Often, the CT diagnosis is conclusive enough to obviate further diagnostic or preoperative radiological studies.
Computed tomography is highly accurate in the diagnosis of the simple renal cyst and, therefore, is reliable in the differentiation between a cyst and a renal neoplasm. Renal cysts may be cortical, intrarenal, or parapelvic and can be diagnosed confidently when the mass fulfills the following CT criteria: (1) uniform, near-water density attenuation values, (2) imperceptible thickness of wall if a portion of the cyst projects beyond the surface of the kidney, (3) sharp separation from normal renal parenchyma, and (4) lack of enhancement after intravenous (IV) administration of contrast (Fig