Imaging in Renal Cancer

Imaging modalities (ultrasonography, computed tomography and magnetic resonance imaging) are essential for the detection, characterization and staging of parenchymal renal masses. More recently, computed tomography (CT) and/or magnetic resonance imaging (MRI) were used also to define anatomical and topographic characteristics of renal tumors suitable for partial nephrectomy with the aim to estimate the different risk of postoperative complications. Ultrasound is usually performed as the first line imaging modality and its diagnostic potential can be significantly improved through the injection of intravenous contrast medium (CEUS). However, CT scan is currently considered the gold standard due to the wide availability, the fast scan times, and the comprehensive evaluation. Moreover, dual-energy CT can add important information in terms of iodine highlighting and quantification. Finally, MRI can be successfully employed in this field, allowing the assessment of structure, enhancement and cellular density of renal masses. According to imaging investigations, renal lesions are usually distinguished on the basis of their cystic or solid structure. Complex cystic lesions (Bosniak categories III and IV) are considered as malignant tumors. Solid tumors can present imaging characteristics able to identify benign from malignant tumors. Controversies still exist about the ability of CT scan and MRI to define appropriately the different histologic subtypes in the context of malignant tumors. Technological advancement in this field is not over yet and other novelties are expected to further improve accuracy in radiological diagnosis within the next future. In this scenario, radiomics seems to be particularly interesting to increase the ability of traditional imaging investigations.