CEUS Bosniak Classification—Time for Differentiation and Change in Renal Cyst Surveillance

SIMPLE SUMMARY: The present work deals with the different imaging procedures in the surveillance of renal cysts. The accuracy, interobserver variability, strengths and weaknesses of CT, MRI and CEUS in the classification of renal cysts are compared. The analysis refers to the original classification by MA Bosniak 1986, the update by GM Israel and MA Bosniak 2005, the version by SG Silverman et al. 2019, and the EFSUMB CEUS proposal by V Cantisani et al. 2021. The authors come to the conclusion that benign renal cysts, which are subject to surveillance, can and should be examined with contrast-enhanced ultrasound. CEUS is equivalent in the evaluation of renal cysts requiring surveillance compared with CE-CT and MRI. Appropriate qualification of the investigators is an unconditional requirement. MRI and CT can be used to investigate specific questions or for staging in case of surgery. ABSTRACT: It is time for a change. CEUS is an established method that should be much more actively included in renal cyst monitoring strategies. This review compares the accuracies, strengths, and weaknesses of CEUS, CECT, and MRI in the classification of renal cysts. In order to avoid overstaging by CEUS, a further differentiation of classes IIF, III, and IV is required. A further development in the refinement of the CEUS-Bosniak classification aims to integrate CEUS more closely into the monitoring of renal cysts and to develop new and complex monitoring algorithms.