Current role and future perspective of MRI for diagnosis and characterization of renal cell carcinoma.

During the past years, magnetic resonance imaging (MRI) has been established as a reliable method for examination of the kidneys. Modern MRI systems enable to visualize renal masses with a high spatial resolution. This enables not only to differentiate between benign lesions and renal cancer but also to define the tumor stage with high accuracy. The impact of a precise preoperative staging has increased significantly due to stage adapted therapy approaches such as nephron sparing surgery or local ablative techniques (e.g. radiofrequency ablation). Tumor-related infiltration of the renal pelvis, infiltration of the perinephric fat or a tumor thrombus within the inferior caval vein has to be diagnosed with high accuracy to enable these stage adapted treatment regimens. This article introduces into clinically established "morphologic" MRI techniques for diagnosis and staging of renal cell carcinoma (RCC). Besides detection and staging of kidney cancer, the recent development of molecularly targeted therapies in patients with metastatic or non-operable tumors has led to novel diagnostic demands. To evaluate treatment efficiency, more information than just tumor morphology should be provided. Functional imaging techniques including dynamic contrast enhanced (DCE) MRI, diffusion weighted imaging (DWI), arterial spin labeling (ASL) and MR-spectroscopy are being investigated in preclinical and clinical trials. While some new techniques have shown promising results for a broad clinical application, others seem to be suited for dedicated questions only.