Characterizing solid renal neoplasms with MRI in adults

Until recently, most solid renal neoplasms without macroscopic fat were presumed to represent renal cell carcinoma and were indiscriminately treated with nephrectomy. Expanding surgical options and ablative technologies, a growing acceptance of renal mass biopsy, the advent of targeted molecular agents, and advances in our understanding of tumor biology have challenged the wisdom of this approach and are ushering in a potential new era in which therapy is linked to histologic subtype and cytogenetics. This approach mandates evolution of our diagnostic algorithm beyond the distinction between solid and cystic and enhancing and nonenhancing. Computed tomography (CT) has traditionally been the imaging technique of choice for evaluating potential solid renal tumors, in large part due to its widespread availability, high spatial resolution, calcium discrimination, and multiphase, enhanced imaging capabilities. For the most part, however, CT is limited to characterization based upon the attenuation and enhancement characteristics of a lesion and necessitates exposure of patients to ionizing radiation. For these latter reasons, multiparametric magnetic resonance imaging (MRI) is being increasingly used to characterize solid renal masses. The purpose of this manuscript is to review our imaging approach to solid renal masses in adults utilizing MRI with an emphasis on a multiparametric approach augmented by clinical data.