Radiological &Imaging . I Approaches Towards Renal . Cysts

Abstract

Renal cysts, cystic disease, and cystic masses are the most common abnormalities encountered in uroradiology. In some cases, the renal cysts are part of a systemic process that also involves the kidneys. In most patients, however, one or several cystic masses are detected, and the question is whether the lesion is benign or malignant. In the vast majority of cases, the radiographic findings are sufficiently characteristic that surgery is not required. However, use of various radiographic modalities may be necessary before a confident diagnosis can be reached.

The accuracy of the radiographic diagnosis of a renal cyst depends un how well it is seen with each modality. When all the criteria of a benign simple cyst are present, it is highly unlikely to be anything else and further evaluation is not warranted.

In a pl::!in abdominal film, calcified cyst wall or an expansion of a portion of the kidney shadow can usually be seen. The axis of the kidney may be abnormal because of rotation due to the weight or position of the cysts.

Excretory urograms establish the presumptive diagnosis of cyst. On a film taken 1-2 minutes after infusion ofthe contrast media, the vascularized parenchyma becomes white while the space-occupying cyst does not because it is avascular. The radiographic series shows changes compatible with the cyst. One or more calyces or the renal pelvis usually are indented or bent around the cyst; these are often broadened and flattened or even obliterated. If the cyst occupies the lower pole of the kidney, the upper part of the ureter may be displaced towards the spine. The kidney itself may be rotated. The psoas muscle may be seen through the radiolucent cystic fluid. •