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Knowledge of lymph node metastases in patients with urologic tumors is important for clinical management and may help the urologic surgeon in choosing the best treatment for these patients. Accurate nodal staging helps to predict prognosis. Conventional magnetic resonance imaging (MRI) often fails to differentiate between benign and malignant changes in lymph nodes because this technique is reliant on nonspecific features such as size and morphologic criteria. Therefore, there is a need for more accurate non-invasive diagnostic technique to improve nodal assessment. Diffusion-weightedmagnetic resonance imaging (DW-MRI) is a non-invasive functional imaging technique that provides unique information related to tumor cellularity and the integrity of the cellular membrane. DW imaging has the potential to differentiate malignant from benign lymph nodes based on the mean ADC value. Metastatic nodes show, as most primary malignant tumors, lower ADC values due to their impeded diffusion caused by high cellularity. Improved diagnostic of lymph node metastases might guide the surgeon to remove positive nodes only. Although initial results are promising, larger-scale studies will be needed to improve detection and localization of lymph node metastases. Standardizing the technical parameters and improving the image analysis represent major challenges to the widespread adoption of DW imaging. [ABSTRACT FROM AUTHOR]

Introduction and objectives. The aim of this paper is to systematize and illustrate distinct imaging patterns and lesions distribution seen in renal lymphomas and to discuss the differential diagnosis with other renal tumors. Materials and methods. We realized a retrospective study over a period of 12 years from the cases investigated by CT or MRI in our hospital and diagnosed with a lymphoproliferative disease. Of the 3290 patients found, a total of 48 showed renal lymphoma. There was pathological confirmation for all patients, either node biopsy or after nephrectomy. All patients had at least two CT / MRI examinations. Indications for CT examination were: disease staging, follow-up at 6 or 12 months, clinical suspicion of recurrence and evaluation of renal or other organs lesions. Follow-up interval varied from four months to four years. MRI examination was performed only in two patients with iodinated contrast material allergy. Results. The most common imaging appearance of renal lymphomas is that of homogeneous, isodense (non-enhanced CT) and hypoattenuated (contrast-enhanced CT) masses compared with normal parenchyma. We found a wide variety of manifestation: multiple bilateral (52%) or unilateral masses (13%), a solitary nodular lesion (8%) or infiltrative lesions (13%), contiguous retroperitoneal extension (6%) or masses in the perirenal space (8%). Conclusions. Contrast enhanced CT is useful in: detection and characterization of renal involvements in patients with lymphoma, disease staging, follow-up and response after therapy and differential diagnosis with other renal masses. Histological confirmation of disease and the presence of bilateral renal nodular lesions associated with other extra-nodal involvements can establish the diagnosis of renal lymphoma. Otherwise renal biopsy is necessary. [ABSTRACT FROM AUTHOR]