Imaging of solid renal masses.

: Detection of renal cell carcinoma is still a major task for the radiologist. Ultrasonography has replaced excretory urography as the most cost-effective means of detecting early renal cell carcinoma. Detection of small tumors confined to the renal parenchyma has made partial nephrectomy a safe therapeutic alternative, but a longer life expectancy has not been proved. Doppler ultrasonography and MR imaging are used to help distinguish between benign and malignant renal tumors with initial equivocal results. However, accurate diagnostic criteria for CT have been developed and CT remains the standard diagnostic method for characterizing and staging renal tumors. MR imaging has one major advantage: it depicts the degree of tumor involvement of the renal vein and inferior vena cava. Percutaneous fine-needle aspiration biopsy is still important for discriminating between benign and malignant tumors as well as enlarged lymph nodes.