Implementation of a New Classification and Stratification System for Solitary Bone Tumor: Osseous Tumor Radiological and Interpretation and Management System (OT-RIMS)

Abstract

Objectives: To propose a histological-grades-based Osseous Tumor Radiological Interpretation and Management System (OT-RIMS) that would simplify the radiological evaluation of bone tumors, categorize key radiological features into severity levels, and inform corresponding patient management actions.

Methods: This retrospective study between January 2015 and August 2022 evaluated patients with solitary bone tumors confirmed by pathology and imaging follow-up received two or three imaging modalities of radiographs, CT, or MRI. Three radiologists independently assessed radiological features, categorized bone lesions based on OT-RIMS criteria, and reached a consensus. Kappa statistics and observed agreement were calculated.

Results: A total of 341 patients (mean age, 26.0 years; 159 women) were included, with 102 malignant, 177 benign, and 62 intermediate or low-grade malignant bone lesions. Sensitivity and specificity of readers 1, 2, and 3, respectively, in the identification of malignant tumors into OT-RIMS 4 were 93.1% (95 of 102) and 93.3% (223 of 239), 96.1% (98 of 102) and 91.6% (219 of 239), 92.2% (94 of 102) and 89.5% (214 of 239). Inter-reader agreement of OT-RIMS category for three readers was considered excellent (Kendall's W = 0.924, p < 0.001) with a kappa value of reproducibility in categories 1&2, 3, and 4 of 0.764, 0.528, and 0.930, respectively.

Conclusion: The OT-RIMS category demonstrated excellent reproducibility despite the reader's expertise level in categorizing the risk stratification of bone tumors and informing patient management, with histological grades used as the reference standard.

Advances in knowledge: The OT-RIMS category reliably stratifies bone tumors into four categories corresponding to histological grades and standardized patient management.

Keywords: Bone Tumor; New Classification; OT-RIMS.