Magnetic resonance imaging of the renal mass.

To compare the effectiveness of magnetic resonance imaging with that of excretory urography, retrograde pyelography, ultrasound, computerized tomography, angiography and venography 34 patients with renal masses, including 25 renal cell carcinomas, were examined on a 0.15 Tesla Picker 1100 magnetic resonance imager with multiple pulse sequences. Pathological proof was available for all cases except renal cysts, for which ultrasound or computerized tomographic findings were accepted. Differentiation of solid from cystic lesions was seen with magnetic resonance imaging, ultrasound and computerized tomography but not excretory urography. Tumor invasion of the renal vein and inferior vena cava was visualized in 7 patients by magnetic resonance imaging, ultrasound, computerized tomography and venography but not by excretory urography. Magnetic resonance T1 contrast scans best characterized renal masses, with good resolution of metastatic lymphadenopathy and renal cysts. Scans showing T2 contrast were best for identification of pseudocapsules in renal carcinoma, venous invasion by tumors and papillary adenocarcinoma. Advantages of magnetic resonance imaging include differentiation of solid masses from benign cystic lesions, and identification of major blood vessels and vascular invasion without administration of contrast medium. Disadvantages of magnetic resonance imaging are long imaging times and motion artifacts. Advances by the manufacturer in solving these problems will strengthen the role of magnetic resonance imaging in renal evaluation.