Study population
Patients with histologically proven bone lesion of the extremities were retrospectively enrolled. The reference standard was post-surgical pathology for surgically-treated lesions and biopsy for non-operated lesions.
All biopsies and surgical procedures were performed between January 2015 and December 2022 in a tertiary bone sarcoma center.
All included patients had undergone a radiograph of the involved bone segment within three months prior to biopsy or surgery.
Radiologists' evaluation
All x-rays were reviewed following the ACR Bone-RADS score by three radiologists with different experience in musculoskeletal radiology and particularly in bone tumors imaging: two musculoskeletal radiologists (Reader 1 and 2) with 10 and 3 years of experience in bone tumors radiology, respectively, and one general junior radiologist (Reader 3).
Statistical analysis
Interobserver agreement was assessed using percent agreement and Cohen’s kappa coefficient, with 95% confidence intervals. Agreement was calculated for all the assessment categories of the ACR-Bone RADS and for the final score value.
The diagnostic performance of the score was assessed according to the expert radiologist’s diagnosis: ROC curve, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated (cut-off: Bone-RADS score ≥ 3).
The histological results were used as reference standard: histology was classified as positive for malignant tumors and intermediate tumors (e.g. atypical cartilaginous tumor, osteoblastoma and giant cell tumor of the bone), according to the 2020 WHO classification of soft tissue and bone tumors (5th edition) [5].
A p-value < 0.05 was considered as statistically significant.
Data were analyzed using IBM SPSS Statistics (New York, NY) software version 29.0.1.