[Image diagnosis of small renal carcinoma--a report of 7 cases].

Seven cases (8 tumors) of small renal carcinoma (less than 3 cm in diameter) proven by pathology were reviewed. It accounted for 7% of patients with renal cell carcinoma during the same period. Sonogram was hypoechogenic in 3 tumors, isoechogenic in 2 and slightly hyperechogenic in 3. Heteroechogenicity was shown in 3 cases and homoechogenicity in 5. None of the margins was sharp. CT scan showed 4 isodense, 1 hypodense and 1 slightly hyperdense masses. After contrast enhancement, increased attenuation to different degrees but still lower than the normal renal parenchyma was observed. The sensitivity of IVP was low because of the small size of the tumor, peripheral location and rare involvement of the renal calyces and pelvis. MRI is helpful in differential diagnosis of hilar adenopathy and small vessels for tumor staging. Yet, the value of MRI for renal masses should be further studied. On cost benefit, sonography and CT are more practical in the diagnosis of renal carcinoma.