Comparative analysis of RADS classification systems for solitary bone lesions: malignancy risk stratification performance and clinical utility.

Abstract

To compare the malignancy risk stratification performance and inter-reader reliability of four Reporting and Data System (RADS) algorithms for solitary bone lesions: CT Bone-RADS, MRI Bone-RADS, Osseous Tumor (OT)-RADS, and Bone Tumor Imaging (BTI)-RADS. This retrospective analysis included patients with solitary bone lesions who underwent both CT and MRI between March 2005 and September 2021. Three radiologists independently categorized each lesion using CT Bone-RADS (1-4), MRI Bone-RADS (1-4), OT-RADS (2-5), and BTI-RADS (1-4). Categories were dichotomized into high- versus low-risk for malignancy. Diagnostic performance metrics and area under the receiver operating characteristic curve (AUC) were calculated for each reader as well as for a consensus interpretation generated using a majority-vote method. The reference standard was either histopathologic confirmation or imaging surveillance. Inter-reader reliability was assessed using Gwet's AC1 statistic. A total of 207 patients (mean age, 49 ± 18 years; 111 men and 96 women) were included. Consensus malignancy risk stratification performance (AUC; sensitivity/specificity/positive predictive value/negative predictive value/accuracy, %) was as follows: CT Bone-RADS (0.52; 95/9/43/73/44), MRI Bone-RADS (0.60; 98/12/44/88/47), OT-RADS (0.91; 93/71/69/94/80), and BTI-RADS (0.89; 98/39/53/96/63). Inter-reader reliability (AC1) was excellent for CT Bone-RADS (0.978), MRI Bone-RADS (0.931), and BTI-RADS (0.822), and moderate for OT-RADS (0.585). Among the evaluated bone tumor-RADS, OT-RADS demonstrated the most balanced diagnostic performance with moderate inter-reader reliability. CT Bone-RADS, MRI Bone-RADS, and BTI-RADS showed excellent inter-reader reliability. Question Evaluation of solitary bone lesions is important but often challenging. This study compared four bone tumor-RADS algorithms to determine which provides the best malignancy risk stratification. Findings Among the four RADS algorithms, OT-RADS demonstrated the most balanced overall diagnostic performance in consensus analysis, while CT Bone-RADS, MRI Bone-RADS, and BTI-RADS showed excellent inter-reader reliability. Clinical relevance Knowledge of each RADS system's performance characteristics helps clinicians apply these algorithms appropriately to optimize the assessment of solitary bone lesions.