RADS classification systems for bone tumors: current status and where do we go from here?

The assessment and management of bone tumors can be challenging as there are numerous neoplastic and non-neoplastic lesions. It can be difficult to understand which lesions can be ignored and which lesions require treatment. To standardize the reporting and management of bone tumors, four bone-lesion related reporting and data systems (RADS) have been published since 2021. The Bone Tumor Imaging Reporting and Data System (BTI-RADS), Oncologic Tumor Reporting and Data System (OT-RADS), Society of Skeletal Radiology Bone Reporting and Data System (SSR Bone-RADS), and American College of Radiology Bone Reporting and Data System (ACR Bone-RADS) are based in part on Breast Imaging Reporting & Data System (BI-RADS). These bone-lesion related RADS aim to improve communication, simplify management, and improve diagnostic consistency by linking imaging features to specific risks and evidence-based action recommendations. Although these systems show high sensitivity for determination of malignancy and moderate consistency for intra-observer readings, their coexistence leads to fragmentation and a lack of a unifying system. This review will discuss the main features of these 4 RADS systems and discuss future directions.