Magnetic resonance imaging of renal masses

Renal cancer is diagnosed in 27,000 Americans and accounts for 12,000 deaths per year. Fortunately, improvements in imaging technology have resulted in earlier detection and longer survival. Although computed tomography (CT) and ultrasound (US) have accounted for much of this success, magnetic resonance (MR) imaging can offer several improvements in renal cancer imaging. MR imaging has demonstrated increased detection of tumor thrombus in the renal vein and IVC with better delineation of the superior extent of the tumor thrombus in the IVC, especially in the region of the right atrium. This information potentially impacts the surgical approach in cases where CT or US is equivocal. Visualization of tumor extension to the liver, spleen, and psoas muscle is also improved with MR imaging, increasing staging accuracy in selected cases. In addition, because of the relatively low nephrotoxicity and allergic potential of gadolinium chelates, contrast-enhanced MR imaging remains the study of choice for patients who cannot tolerate iodinated contrast agents. Although the current role of MR in renal cancer imaging is complementary to that of CT and US, its future role has not yet been completely defined. Recent developments in rapid MR imaging techniques have suggested the possibility of improved detection and characterization of renal masses relative to CT. In addition, as MR spectroscopic imaging of the kidney evolves, the possibility of future identification and characterization of renal masses on a biochemical basis may provide completely new insight into our understanding of renal cancer.