03-02-2025 | Scientific Article
Validation of the American College of Radiology Bone Reporting and Data System™ (ACR Bone-RADS™) for classifying osteolytic bone tumors
Published in: Skeletal Radiology
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Objective
To validate the performance of the American College of Radiology (ACR) Bone-RADS™ in identifying malignant osteolytic bone tumors and to evaluate the inter-observer agreement between musculoskeletal radiologists performing ACR Bone-RADS™ assessments.
Methods
This single-center, retrospective study included patients who visited our orthopedic oncology department on January 2019–December 2020 for bone tumors. Three radiologists evaluated the initial radiographs and assessed whether the tumor was eligible for ACR Bone-RADS™ assessment considering its transverse location and radiodensity. For eligible tumors, the radiologists rated the descriptors of ACR Bone-RADS™ and calculated the Bone-RADS™ categories. Using multi-reader, multi-case analysis, the performance in identifying malignant bone tumors was assessed in terms of sensitivity and area under the receiver-operating-characteristic curve (AUC), while dichotomizing the Bone-RADS™ categories into potentially benign (categories 1–2) and potentially malignant (categories 3–4). Gwet’s AC1 was calculated to evaluate inter-observer agreement on the categories. The proportion of malignancy in each Bone-RADS™ category was calculated.
Results
In total, 278 patients (mean age ± standard deviation, 40 ± 22 years; 161 men; and 93 with malignant tumors) were eligible for assessment. The sensitivity and AUC for discriminating malignancy using ACR Bone-RADS™ were 95.0% and 0.915, respectively. There was moderate inter-observer agreement on the ACR Bone-RADS™ category, with a Gwet’s AC1 of 0.594 (95% confidence interval, 0.536–0.652). The proportions of malignancy were 0.0–1.2% in Bone-RADS™ category 1; 4.0–9.0% in category 2; 18.2–30.3% in category 3; and 77.7–83.3% in category 4.
Conclusion
The ACR Bone-RADS™ showed high diagnostic performance in detecting malignant osteolytic bone tumors, with moderate inter-observer agreement.