Radiographic Analysis of Bone Tumors: A Systematic Approach

Diagnostic performance and inter-reader reliability of bone reporting and data system (Bone-RADS) on computed tomography

OBJECTIVE

To evaluate the diagnostic performance and inter-reader reliability of the Bone Reporting and Data System (Bone-RADS) for solitary bone lesions on CT.

MATERIALS AND METHODS

This retrospective analysis included 179 patients (mean age, 56 ± 18 years; 94 men) who underwent bone biopsies between March 2005 and September 2021. Patients with solitary bone lesions on CT and sufficient histopathology results were included. Two radiologists categorized the bone lesions using the Bone-RADS (1, benign; 4, malignant). The diagnostic performance of the Bone-RADS was calculated using histopathology results as a standard reference. Inter-reader reliability was calculated.

RESULTS

Bone lesions were categorized into two groups: 103 lucent (pathology: 34 benign, 12 intermediate, 54 malignant, and 3 osteomyelitis) and 76 sclerotic/mixed (pathology: 46 benign, 2 intermediate, 26 malignant, and 2 osteomyelitis) lesions. The Bone-RADS for lucent lesions had sensitivities of 95% and 82%, specificities of 11% and 11%, and accuracies of 57% and 50% for readers 1 and 2, respectively. The Bone-RADS for sclerotic/mixed lesions had sensitivities of 75% and 68%, specificities of 27% and 27%, and accuracies of 45% and 42% for readers 1 and 2, respectively. Inter-reader reliability was moderate to very good (κ = 0.744, overall; 0.565, lucent lesions; and 0.851, sclerotic/mixed lesions).

CONCLUSION

Bone-RADS has a high sensitivity for evaluating malignancy in lucent bone lesions and good inter-reader reliability. However, it has poor specificity and accuracy for both lucent and sclerotic/mixed lesions. A possible explanation is that proposed algorithms heavily depend on clinical features such as pain and history of malignancy.

Validation of American College of Radiology Bone Reporting and Data System (Bone-RADS) Version 2023 for diagnosis of malignant tumors of appendicular bone on conventional radiographs

PURPOSE

To evaluate the diagnostic performance of the American College of Radiology(ACR) Bone Reporting and Data System (Bone-RADS) in diagnosis of malignant tumors of the appendicular bone on conventional radiographs.

METHODS

Primary and secondary tumors of appendicular bone in patients who underwent radiographic and MRI examinations were classified into benign, intermediate, and malignant using a reference standard of histopathology, imaging follow-up, or clinical-radiologic consensus. Two radiologists assessed five radiographic features (margin, periosteal reaction, endosteal erosion, pathologic fracture, and extra-osseous mass), scored point total (points from radiographic features and a history of cancer), and assigned Bone-RADS categories. The diagnostic performance of Bone-RADS and interreader agreements were calculated.

RESULTS

A total of 778 patients (507 benign, 45 intermediate, and 226 malignant tumors) were included. Bone-RADS showed high discrimination performance, with areas under the receiver-operating characteristics curve of 0.940-0.957 for point total and 0.895-0.900 for categorization. Bone-RADS had high sensitivity (95.2 %-99.1 %) and negative predictive value (NPV) (96.4 %-99.5 %), but relatively low specificity (65.0 %-68.6 %) and positive predictive value (PPV) (53.7 %-61.9 %). Interreader agreements were good to excellent for Bone-RADS point total (ICC = 0.850), categorization (k = 0.739), and most of the radiographic features (k = 0.621-0.822), except for endosteal erosion (k = 0.537) and extra-osseous mass (k = 0.234).

CONCLUSION

In diagnosis of malignant bone tumors, ACR Bone-RADS showed high discrimination performance, with high sensitivity and NPV, but relatively low specificity and PPV. Nevertheless, relatively low interobserver agreement in some radiographic features and the consensus-based points system in Bone-RADS warrant further research and possible updates.

Performance and reliability comparison: original vs. revised bone reporting and data system (Bone-RADS)

OBJECTIVE

To propose a revised bone reporting and data system (Bone-RADS) and evaluate its diagnostic performance and inter-reader reliability compared to the original Bone-RADS for solitary bone lesions on CT.

MATERIALS AND METHODS

This retrospective study included 159 adult patients (mean age: 56 ± 19 years; 88 men) who underwent bone biopsy for solitary bone lesions between March 2005 and September 2021. Two radiologists (R1/2) independently categorized the lesions twice, once using the original Bone-RADS and once using the revised version. Lesions were classified as follows: (1, benign; 2, incompletely assessed; 3, indeterminate; 4, malignancy or requiring treatment). The revised Bone-RADS excluded the original criteria for lesion related pain and history of malignancy. Diagnostic performance was assessed using histopathology as the reference standard, and inter-reader reliability was analyzed.

RESULTS

The bone lesions included 96 lucent and 63 sclerotic/mixed lesions. Sensitivity showed no significant difference between the original and revised Bone-RADS for both readers across lucent and sclerotic/mixed lesions (all P ≥ .05). However, the specificity of the revised Bone-RADS was significantly higher than that of the original (lucent: 11% vs. 50% [R1], 11% vs. 46% [R2]; sclerotic/mixed: 32% vs. 92% [R1], 32% vs. 86% [R2]). Other performance metrics, including positive/negative predictive value and accuracy, were also higher in the revised Bone-RADS. Inter-reader reliability was higher for the revised Bone-RADS compared to the original (κ = .744 vs .854).

CONCLUSION

The revised Bone-RADS significantly improved specificity while maintaining sensitivity compared to the original version.

Inter-observer and intra-observer agreement of bone reporting and data system (Bone-RADS) in the interpretation of bone tumors on computed tomography

OBJECTIVE

To assess inter-observer & intra-observer agreement of the American College of Radiology (ACR) bone reporting and data system (Bone-RADS) in the interpretation of bone tumors on computed tomography (CT).

METHODS

This retrospective study included 273 bone tumors 184 (67.4 %) benign and 89 (32.6 %) malignant. Two blinded radiologists independently reviewed the CT images to assess the defined CT features of bone lesions and assign a bone-RADS category. A third observer reviewed the CT images twice with one month interval and reported the specified CT features and final bone-RADS category for bone lesions. Inter-observer and intra-observer agreement of bone-RADS were analyzed.

RESULTS

There was almost perfect inter-observer agreement between the two reviewers for all defined variables as well as bone-RADS categories (Kappa = 92.2 %). Overall intra-observer agreement was also perfect for all defined CT features and bone RADS categories with higher percentage than inter-observer one (κ = 98.3 %).

CONCLUSION

Bone-RADS is an effective clinical tool for practicing radiologists in the risk assessment and management of bone tumors with perfect agreement among observers. To our knowledge, no studies have been conducted for assessing reliability or validity of the recent ACR Bone-RADS using CT. Hence, this study could serve as a cornerstone for further upcoming studies to assess the reproducibility and validity of the ACR Bone-RADS.

Implementation of a new classification and stratification system for solitary bone tumour: osseous tumour radiological and interpretation and management system

OBJECTIVES

To propose a histological-grades-based Osseous Tumor Radiological and Interpretation and Management System (OT-RIMS) that would simplify the radiological evaluation of bone tumours, 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 tumours confirmed by pathology and imaging follow-up received 2 or 3 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 tumours 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 3 readers was considered excellent (Kendall's W = 0.924, P < .001) with a kappa value of reproducibility in categories 1&2, 3, and 4 of 0.764, 0.528, and 0.930, respectively.

CONCLUSIONS

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

ADVANCES IN KNOWLEDGE

The OT-RIMS category reliably stratifies bone tumours into 4 categories corresponding to histological grades and standardized patient management.

Living with a tumor: A case of osteosarcoma involving the medullary region in Phrynops cf. P. geoffroanus (Testudines: Chelidae)

The individual Geoffroy's side-necked turtle, Phrynops cf. P. geoffroanus, was diagnosed postmortem with osteosarcoma associated with the forelimb through morphological and histological analysis. Osteosarcoma stands as the most prevalent primary malignant bone tumor in tetrapods. The tumor presents itself as a large mass in the distal epiphysis, characterized by spicular outgrowths and a rugose external texture. Histologically, the afflicted humerus displayed a high degree of vascularity and exhibited an extensive bone resorption process involving the medullary and endosteal regions. Notably, a clear transition between the bone marrow and cortical bone was absent, indicative of a remodeling process featuring Haversian bone system apposition. Additionally, the diaphyseal region displayed the progression of neoplastic bone tissue along the bone. For comparative purposes, we describe a humeral thin section from a healthy specimen revealing compact primary bone interrupted by cyclical growth marks which differs from the continuous growth observed in the neoplastic humerus. To assess the neoplastic bone growth rate at the mid-diaphysis level, phylogenetic eigenvector maps (PEM) were employed, utilizing osteocyte density and vascular density as explanatory variables. The findings indicated that the osteosarcoma exhibited a slow-growing nature, suggesting that the turtle had to live with this condition for years. As the neoplasia continued to expand, it likely led to disadvantages for the pathological Phrynops individual due to humeral deformity. Furthermore, malignancy was associated with angiogenesis and the invasion of the medullary region by neoplastic bone tissue, raising the likelihood of metastasis as an additional factor contributing to the individual's sickness. The presence of numerous vascular canals in the diaphyseal thin section suggested a low-grade central osteosarcoma. It is worth noting that osseous neoplasms are rarely documented in Testudines, making this case of osteosarcoma in a South American freshwater chelid specimen a unique and rare occurrence.

Imaging of Osteosarcoma: Presenting Findings, Metastatic Patterns, and Features Related to Prognosis

Background: Osteosarcomas are rare malignancies (<1% of all cancers) that produce an osteoid matrix. Osteosarcomas are the second most frequent type of primary bone tumor after multiple myeloma and the most prevalent primary bone tumor in children. The spectrum of imaging findings of these malignancies varies significantly, reflecting different histological subtypes. For instance, conventional osteosarcoma typically presents with a mixed radiological pattern (lytic and bone mineralization) or with a completely eburneous one; aggressive periosteal reactions such as sunburst, Codman triangle, and soft-tissue components are frequently displayed. On the other hand, telangiectatic osteosarcoma usually presents as a purely lytic lesion with multiple fluid-fluid levels on MRI fluid-sensitive sequences. Other typical and atypical radiological patterns of presentation in other subtypes of osteosarcomas are described in this review. In addition to the characteristics associated with osteosarcoma subtyping, this review article also focuses on imaging features that have been associated with patient outcomes, namely response to chemotherapy and event-free and overall survivals. This includes simple semantic radiological features (such as tumor dimensions, anatomical location with difficulty of radical surgery, occurrence of pathological fractures, and presence of distant metastases), but also quantitative imaging parameters from diffusion-weighted imaging, dynamic contrast-enhanced MRI, and 18F-FDG positron emission tomography and radiomics approaches. Other particular features are described in the text. Overall, this comprehensive literature review aims to be a practical tool for oncologists, pathologists, surgeons, and radiologists involved in these patients' care.

Bone tumors: state-of-the-art imaging

Imaging plays a central role in the management of patients with bone tumors. A number of imaging modalities are available, with different techniques having unique applications that render their use advantageous for various clinical purposes. Coupled with detailed clinical assessment, radiological imaging can assist clinicians in reaching a proper diagnosis, determining appropriate management, evaluating response to treatment, and monitoring for tumor recurrence. Although radiography is still the initial imaging test of choice for a patient presenting with a suspected bone tumor, technological innovations in the last decades have advanced the role of other imaging modalities for assessing bone tumors, including advances in computed tomography, magnetic resonance imaging, scintigraphy, and hybrid imaging techniques that combine two existing modalities, providing clinicians with diverse tools for bone tumor imaging applications. Determining the most suitable modality to use for a particular application requires familiarity with the modality in question, its advancements, and its limitations. This review highlights the various imaging techniques currently available and emphasizes the latest developments in imaging, offering a framework that can help guide the imaging of patients with bone tumors.

Solitary bone tumor imaging reporting and data system (BTI-RADS): initial assessment of a systematic imaging evaluation and comprehensive reporting method

OBJECTIVES

Identify the most pertinent imaging features for solitary bone tumor characterization using a multimodality approach and propose a systematic evaluation system.

METHODS

Data from a prospective trial, including 230 participants with histologically confirmed bone tumors, typical "do not touch" lesions, and stable chondral lesions, were retrospectively evaluated. Clinical data, CT, and MR imaging features were analyzed by a musculoskeletal radiologist blinded to the diagnosis using a structured report. The benign-malignant distribution of lesions bearing each image feature evaluated was compared to the benign-malignant distribution in the study sample. Benign and malignant indicators were identified. Two additional readers with different expertise levels independently evaluated the study sample.

RESULTS

The sample included 140 men and 90 women (mean age 40.7 ± 18.3 years). The global benign-malignant distribution was 67-33%. Seven imaging features reached the criteria for benign indicators with a mean frequency of benignancy of 94%. Six minor malignant indicators were identified with a mean frequency of malignancy of 60.5%. Finally, three major malignant indicators were identified (Lodwick-Madewell grade III, aggressive periosteal reaction, and suspected metastatic disease) with a mean frequency of malignancy of 82.4%. A bone tumor imaging reporting and data system (BTI-RADS) was proposed. The reproducibility of the BTI-RADS was considered fair (kappa = 0.67) with a mean frequency of malignancy in classes I, II, III, and IV of 0%, 2.2%, 20.1%, and 71%, respectively.

CONCLUSION

BTI-RADS is an evidence-based systematic approach to solitary bone tumor characterization with a fair reproducibility, allowing lesion stratification in classes of increasing malignancy frequency.

TRIAL REGISTRATION

Clinical trial number NCT02895633 .

KEY POINTS

• The most pertinent CT and MRI criteria allowing bone tumor characterization were defined and presented. • Lodwick-Madewell grade III, aggressive periosteal reaction, and suspected metastatic disease should be considered major malignant indicators associated with a frequency of malignancy over 75%. • The proposed evidence-based multimodality reporting system stratifies solitary bone tumors in classes with increasing frequencies of malignancy.

Using Machine Learning to Unravel the Value of Radiographic Features for the Classification of Bone Tumors

Objectives

To build and validate random forest (RF) models for the classification of bone tumors based on the conventional radiographic features of the lesion and patients' clinical characteristics, and identify the most essential features for the classification of bone tumors.

Materials and Methods

In this retrospective study, 796 patients (benign bone tumors: 412 cases, malignant bone tumors: 215 cases, intermediate bone tumors: 169 cases) with pathologically confirmed bone tumors from Nanfang Hospital of Southern Medical University, Foshan Hospital of TCM, and University of Hong Kong-Shenzhen Hospital were enrolled. RF models were built to classify tumors as benign, malignant, or intermediate based on conventional radiographic features and potentially relevant clinical characteristics extracted by three musculoskeletal radiologists with ten years of experience. SHapley Additive exPlanations (SHAP) was used to identify the most essential features for the classification of bone tumors. The diagnostic performance of the RF models was quantified using receiver operating characteristic (ROC) curves.

Results

The features extracted by the three radiologists had a satisfactory agreement and the minimum intraclass correlation coefficient (ICC) was 0.761 (CI: 0.686-0.824, P < .001). The binary and tertiary models were built to classify tumors as benign, malignant, or intermediate based on the imaging and clinical features from 627 and 796 patients. The AUC of the binary (19 variables) and tertiary (22 variables) models were 0.97 and 0.94, respectively. The accuracy of binary and tertiary models were 94.71% and 82.77%, respectively. In descending order, the most important features influencing classification in the binary model were margin, cortex involvement, and the pattern of bone destruction, and the most important features in the tertiary model were margin, high-density components, and cortex involvement.

Conclusions

This study developed interpretable models to classify bone tumors with great performance. These should allow radiographers to identify imaging features that are important for the classification of bone tumors in the clinical setting.

A systematic approach to describing fractures

Clinicians, including practitioners in primary care and across numerous specialties, are essential to the interpretation of imaging for correlating clinical presentation with fracture identification on plain radiographs. A comprehensive review of radiographs lets clinicians document findings accurately and communicate these findings to colleagues, specialists, and patients. This article reviews fracture terminology that clinicians need to provide better understanding of the injury and direct appropriate management.

Cognitive map to support the diagnosis of solitary bone tumors in pediatric patients

Abstract

Role of Ultrasound in the Diagnosis Approach of Malignant Solitary Fibrous Tumor

This is a case study of solitary fibrous tumor (SFT), which is a rare neoplasm of mesenchymal origin that comprises less than 2% of all soft tissue tumors. SFT located in the extremities, especially in the legs, has a high possibility of developing malignancy. The case study presented demonstrates a sonogram which identified an inhomogenous hypoechoic solid lesion located in the subcutaneous layer of the femoral region. The use of Doppler showed hypervascular activity in the hyperechoic area. This finding was consistent with malignant SFT and confirmed by histopathologic exam. The possibility of an SFT should be a diagnostic consideration with any large soft tissue mass in extremities. This is a further consideration with the diagnostic medical sonography findings demonstrating a hypoechoic, well-defined mass that has a large collateral feeding vessel and displaces the adjacent structures.

A case of enchondroma from Carolingian necropolis of St. Pere De Terrassa (Spain): An insight into the archaeological record

Enchondromas occur with an estimated modern incidence rate of 27.7% of benign bone tumors (Hauben and Hogendoorn, 2010), but few are represented in the paleopathological record. The medieval site of St. Pere in Spain has produced a convincing case. The diagnosis was confirmed by X-Ray, CT-scan and μ-CT scan. Therefore UF 755 from St. Pere - a male of more than 60 years old - can be confirmed as a femoral case of enchondroma, supported by evidence, in the paleopathological record.