Ewing sarcoma is a highly aggressive small round cell sarcoma primarily affecting children and adolescents. Imaging plays a central role from diagnosis to staging, treatment response assessment, and follow-up. This review synthesizes current evidence across the various imaging modalities involved at each stage of patient management, including conventional radiography, CT, MRI, and nuclear imaging, emphasizing their complementary roles. Radiographs and CT delineate bone destruction patterns, cortical breaches, and periosteal reactions, while MRI provides superior visualization of intramedullary and soft tissue extension, as well as skip lesions. Whole-body MRI and 18F-FDG PET/CT enable sensitive detection of metastatic disease, with PET providing metabolic biomarkers correlated with prognosis and chemotherapy response. Imaging features, including tumor volume, diffusion metrics, and changes in contrast enhancement, increasingly allow non-invasive prediction of histologic response, a key determinant of survival. Lastly, recent quantitative methods, such as radiomics and artificial intelligence, show promise for differentiating Ewing sarcoma from other sarcomas, predicting metastases, and anticipating local recurrence. By reviewing modality-specific findings, staging strategies, and response assessment tools, this article provides a practical, updated, structured framework for radiologists and oncologists to optimize diagnosis, risk stratification, and treatment planning in Ewing sarcoma, ultimately improving patient care.

This review article on atypically displaced meniscal tears serves as a critical reminder for radiologists and orthopedic surgeons. It highlights and details uncommon lesions that may be overlooked during MRI evaluation and/or arthroscopic exploration. The knowledge of their existence can enable radiologists to critically assess any meniscal abnormality, keeping in mind its possible arthroscopic presentation. This is essential for assisting the surgeon in making an accurate preoperative diagnosis. In fact, these atypical lesions pose great challenges to surgeons in terms of the technical aspects of their treatment. Often, they could require additional arthroscopic portals for their identification or the need for special devices or instrumentations for the repair. Knowing these challenges in advance is thus imperative for properly planning a proficient surgery. The correct diagnosis and description of tear patterns, including extent and location, allow optimal pre-operative planning with the choice of the indicated approach. Radiologists should know how to recognize menisci tears, even with atypical dislocation patterns. Particularly, in the case of ‘minus’ detection or thickness reduction in a meniscus, the possible displaced fragment should be carefully searched for, even in atypical sites.

Imaging evaluation for lower extremity infections can be complicated, especially in the setting of underlying conditions and with atypical infections. Predisposing conditions are discussed, including diabetes mellitus, peripheral arterial disease, neuropathic arthropathy, and intravenous drug abuse, as well as differentiating features of infectious versus non-infectious disease. Atypical infections such as viral, mycobacterial, fungal, and parasitic infections and their imaging features are also reviewed. Potential mimics of lower extremity infection including chronic nonbacterial osteomyelitis, foreign body granuloma, gout, inflammatory arthropathies, lymphedema, and Morel-Lavallée lesions, and their differentiating features are also explored.

ObjectiveAnterior cruciate ligament (ACL) injuries are common and lead to significant physical limitations. While MRI is the diagnostic gold standard, its use is restricted in acute trauma cases due to contraindications and longer imaging times. Dual-energy computed tomography (DECT) has emerged as a potential alternative. This meta-analysis evaluates the diagnostic accuracy of DECT for ACL injuries.Materials and methodsFollowing PRISMA guidelines, a comprehensive literature search was conducted using PubMed, Web of Science, Scopus, and Embase for studies published up to June 2024. Studies that provided diagnostic accuracy data for DECT in ACL ruptures were included. Metrics of diagnostic accuracy were aggregated using a bivariate random effects model.ResultsThe meta-analysis, which included five studies with a total of 191 patients, found that DECT had a pooled sensitivity of 88.1% (95% CI, 78.0-93.9%) and a specificity of 82.0% (95% CI, 62.0-92.7%) for diagnosing ACL ruptures, with an AUC of 0.92 (95% CI, 0.72-0.96). For complete ruptures, sensitivity was 83.2% (95% CI, 68.2-92.0%), and specificity was 94.9% (95% CI, 92.2-96.7%), with an AUC of 0.96 (95% CI, 0.81-0.98). In acute/subacute settings, sensitivity was 89.4% (95% CI, 76.8-95.6%), and specificity was 82.1% (95% CI, 56.2-94.2%), with an AUC of 0.93 (95% CI, 0.71-0.97).ConclusionOur findings suggest that DECT is a valuable diagnostic tool for ACL injuries, particularly as an adjunct or alternative when MRI is unavailable or contraindicated, enabling timely and accurate diagnosis.

In modern practice, imaging plays an integral role in the diagnosis, evaluation of extent, and treatment planning for lower extremity infections. This review will illustrate the relevant compartment anatomy of the lower extremities and highlight the role of plain radiographs, CT, US, MRI, and nuclear medicine in the diagnostic workup. The imaging features of cellulitis, abscess and phlegmon, necrotizing soft tissue infection, pyomyositis, infectious tenosynovitis, septic arthritis, and osteomyelitis are reviewed. Differentiating features from noninfectious causes of swelling and edema are discussed.

The purpose of our study was to provide a novel schematized and comprehensive classification of causes and severity grading system for lumbosacral stenosis. The MRI system proposed consisted of a severity grading scale for central and lateral (recess and foramen) stenosis, together with a schematized indication of the main causes of the disease (disc, arthritis, epidural lipomatosis, and their combinations). The system was applied to a cohort of patients from a single Institution in the last 2-years. Two radiologists evaluated all the MRIs to determine intra- and inter-observer reliability according to Cohen Kappa (Kc, for non-ordered categorical variables) and weighted Kappa (Kw, for ordered variables). Two orthopaedic surgeons clinically evaluated all patients and provided a schematic grading system with a central and lateral stenosis clinical score (CS-CS and LS-CS). Associations between ordinals were tested with chi-square test and measured with the Goodman and Kruskal’s gamma index (Gi, with 95

Conventional high-grade osteosarcomas are characterized by aggressive radiologic features, cytologic pleomorphism, and complex genomics. However, rare examples of osteosarcomas remain challenging due to unusual histology, such as sclerosing or osteoblastoma-like features, which may require molecular confirmation of their complex genetic alterations. We have encountered such a case in a 17-year-old man, who presented with a third metatarsal sclerotic bone lesion, found incidentally in the work-up of a foot trauma. The initial imaging revealed a lesion with sclerotic/blastic features proximally and lucent/lytic portion distally, findings interpreted consistent with osteoblastoma. The lesion was managed intra-lesionally with curettings and cryoablation; however, the microscopic findings were non-specific, showing a bland osteoblastic proliferation embedded in a densely sclerotic matrix. Subsequently, the patient developed two rapid recurrences; the first recurrence was treated similarly despite its associated soft tissue extension radiographically, and the histologic findings remained non-specific. The 2nd recurrence showed a large mass, with bone destruction and soft tissue extension and an open biopsy revealed features of osteosarcoma with lace-like osteoid deposition, albeit with uniform cytomorphology. The subsequent below knee amputation showed features compatible with high-grade osteosarcoma, including solid growth of uniform epithelioid cells, with vesicular nuclei and scant cytoplasm, set in a lace-like meshwork of osteoid matrix. There was significant mitotic activity and tumor necrosis. Tumor cells were positive for SATB2. Further molecular work-up was performed showing an unexpected NIPBL::BEND2 fusion, which has been previously reported in two cases of phosphaturic mesenchymal tumor (PMT). FGF23 (ISH) was performed and was negative. By DNA methylation profiling, unsupervised clustering and UMAP dimensionality reduction revealed grouping with high-grade osteosarcomas and not with the PMT group. The patient received chemotherapy post-amputation and is alive without evidence of disease, with 10-month follow-up. We report an aggressive, overtly malignant acral bone-forming tumor, harboring a NIPBL::BEND2 fusion. Further studies are needed to evaluate the recurrent potential of this fusion in osteosarcomas and its relationship with PMT.

Lumbar back pain is one of the main causes of disability around the world. Most patients will complain of back pain at least once in their lifetime. The degenerative spine is considered the main cause and is extremely common in the elderly population. Consequently, treatment-related costs are a major burden to the healthcare system in developed and undeveloped countries. After the failure of conservative treatments or to avoid daily chronic drug intake, invasive treatments should be suggested. In a world where many patients reject surgery and prefer minimally invasive procedures, interventional radiology is pivotal in pain management and could represent a bridge between medical therapy and surgical treatment. We herein report the different image-guided procedures that can be used to manage degenerative spine-related low back pain. Particularly, we will focus on indications, different techniques, and treatment outcomes reported in the literature. This literature review focuses on the different minimally invasive percutaneous treatments currently available, underlining the central role of radiologists having the capability to use high-end imaging technology for diagnosis and subsequent treatment, allowing a global approach, reducing unnecessary surgeries and prolonged pain-reliever drug intake with their consequent related complications, improving patients' quality of life, and reducing the economic burden.

We study the design of transfer functions for volumetric rendering of magnetic resonance imaging (MRI) datasets of human hands. Human hands are anatomically complex, containing various organs within a limited space, which presents challenges for volumetric rendering. We focus on hand musculoskeletal organs because they are volumetrically the largest inside the hand, and most important for the hand's main function, namely manipulation of objects. While volumetric rendering is a mature field, the choice of the transfer function for the different organs is arguably just as important as the choice of the specific volume rendering algorithm; we demonstrate that it significantly influences the clarity and interpretability of the resulting images. We assume that the hand MRI scans have already been segmented into the different organs (bones, muscles, tendons, ligaments, subcutaneous fat, etc.). Our method uses the hand MRI volume data, and the geometry of its inner organs and their known segmentation, to produce high-quality volume rendering images of the hand, and permits fine control over the appearance of each tissue. We contribute two families of transfer functions to emphasize different hand tissues of interest, while preserving the visual context of the hand. We also discuss and reduce artifacts present in standard volume ray-casting of human hands. We evaluate our volumetric rendering on five challenging hand motion sequences. Our experimental results demonstrate that our method improves hand anatomy visualization, compared to standard surface and volume rendering techniques.

Recent advancements in artificial intelligence (AI) and machine learning offer numerous opportunities in musculoskeletal radiology to potentially bolster diagnostic accuracy, workflow efficiency, and predictive modeling. AI tools have the capability to assist radiologists in many tasks ranging from image segmentation, lesion detection, and more. In bone and soft tissue tumor imaging, radiomics and deep learning show promise for malignancy stratification, grading, prognostication, and treatment planning. However, challenges such as standardization, data integration, and ethical concerns regarding patient data need to be addressed ahead of clinical translation. In the realm of musculoskeletal oncology, AI also faces obstacles in robust algorithm development due to limited disease incidence. While many initiatives aim to develop multitasking AI systems, multidisciplinary collaboration is crucial for successful AI integration into clinical practice. Robust approaches addressing challenges and embodying ethical practices are warranted to fully realize AI's potential for enhancing diagnostic accuracy and advancing patient care.

Spondylodiscitis is defined by infectious conditions involving the vertebral column. The incidence of the disease has constantly increased over the last decades. Imaging plays a key role in each phase of the disease. Indeed, radiological tools are fundamental in (i) the initial diagnostic recognition of spondylodiscitis, (ii) the differentiation against inflammatory, degenerative, or calcific etiologies, (iii) the disease staging, as well as (iv) to provide clues to orient towards the microorganisms involved. This latter aim can be achieved with a mini-invasive procedure (e.g., CT-guided biopsy) or can be non-invasively supposed by the analysis of the CT, positron emission tomography (PET) CT, or MRI features displayed. Hence, this comprehensive review aims to summarize all the multimodality imaging features of spondylodiscitis. This, with the goal of serving as a reference for Physicians (infectious disease specialists, spine surgeons, radiologists) involved in the care of these patients. Nonetheless, this review article may offer starting points for future research articles.

Spectral CT represents a novel imaging approach that can noninvasively visualize, quantify, and characterize many musculoskeletal pathologies. This modality has revolutionized the field of radiology by capturing CT attenuation data across multiple energy levels and offering superior tissue characterization while potentially minimizing radiation exposure compared to traditional enhanced CT scans. Despite MRI being the preferred imaging method for many musculoskeletal conditions, it is not viable for some patients. Moreover, this technique is time-consuming, costly, and has limited availability in many healthcare settings. Thus, spectral CT has a considerable role in improving the diagnosis, characterization, and treatment of gout, inflammatory arthropathies, degenerative disc disease, osteoporosis, occult fractures, malignancies, ligamentous injuries, and other bone-marrow pathologies. This comprehensive review will delve into the diverse capabilities of dual-energy CT, a subset of spectral CT, in addressing these musculoskeletal conditions and explore potential future avenues for its integration into clinical practice.

Bone lesions of the appendicular skeleton can be caused by primary benign or malignant tumors, metastases, osteomyelitis, or pseudotumors. Conventional radiography plays a crucial role in the initial assessment of osseous lesions and should not be underestimated even in this era of modern complex and advanced imaging technologies. Combined with patient age, clinical symptoms and biology, and lesion features including location, solitary versus multiplicity, density, margin (transitional zone evaluated with Lodwick-Madewell grading score), and, if present, the type of periosteal reaction and matrix mineralization can narrow the differential diagnosis or offer a likely diagnosis. These radiographic features help guide further follow-up or management.

The sacroiliac joints (SIJ) play a pivotal role in pelvic stability and load transmission. SIJ-related disorders can pose a diagnostic challenge because of complex anatomy, non-specific imaging findings, and overlapping symptomatology with other lower back conditions. Broadly, SIJ pathology can be divided into the following categories: infectious, inflammatory, degenerative, mechanical, traumatic, and neoplastic. On the spectrum of mechanical disorders is the entity of SIJ dysfunction, defined as pain localized to the SIJ due to non-inflammatory causes. This paper aims to enhance the understanding of SIJ dysfunction by exploring SIJ anatomy, pathophysiology, and differential diagnosis for SIJ pain. Etiologies, associations, and diagnostic physical examination maneuvers for SIJ dysfunction are reviewed. We will discuss the role of diagnostic imaging in SIJ dysfunction and propose imaging findings which may indicate the diagnosis. Finally, we will discuss therapeutic strategies to treat SIJ dysfunction. By delving into the complexities of SIJ anatomy and pathophysiology, this paper provides valuable discernment for the diagnosis and management of SIJ-related disorders.

To evaluate the performance of machine learning–augmented MRI-based radiomics models for predicting response to neoadjuvant chemotherapy (NAC) in soft tissue sarcomas. Forty-four subjects were identified retrospectively from patients who received NAC at our institution for pathologically proven soft tissue sarcomas. Only subjects who had both a baseline MRI prior to initiating chemotherapy and a post-treatment scan at least 2 months after initiating chemotherapy and prior to surgical resection were included. 3D ROIs were used to delineate whole-tumor volumes on pre- and post-treatment scans, from which 1708 radiomics features were extracted. Delta-radiomics features were calculated by subtraction of baseline from post-treatment values and used to distinguish treatment response through univariate analyses as well as machine learning–augmented radiomics analyses. Though only 4.74

Back pain is a common health complaint that contributes globally to medical burden and costs, particularly in elderly populations. Nuclear medicine techniques using PET tracers offer diagnostic information about various spine disorders, including malignant, degenerative, inflammatory, and infectious diseases. Herein, the authors briefly review applications of PET in the evaluation of spine disorders in elderly patients.

Nuclear medicine and the array of different radiotracers have an important role in the diagnosis and evaluation of a variety of musculoskeletal diseases. Conventional radiography has long been considered the first-line diagnostic for suspected traumatic fracture. Broadly speaking, stress fractures fall into one of two categories: fractures that arise from normal loading on abnormal bone, termed “insufficiency fractures,” and fractures that arise from abnormal loading on normal bone, termed “fatigue fractures”. Rheumatoid arthritis is an inflammatory disorder with a main target for the synovial membrane of joints, bursae, and tendon sheaths. Radiography is the mainstay in the preliminary evaluation of rheumatoid arthritis. Diabetic patients are at risk for foot infections due to underlying diabetic neuropathy, which leads to a loss of protective sensation and development of anatomic deformities and altered weight-bearing, and peripheral vascular disease, which limits access of phagocytic cells and antibiotics to infected sites due to impaired circulation.

Ultrasound fusion is an established technique that pairs real time B-scan ultrasound (US) with other forms of cross-sectional imaging, including computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). Each of these imaging modalities has distinct advantages. CT provides superior anatomic resolution, with improved imaging of bone and calcified structures; MRI has superior contrast resolution; and PET provides physiologic information, identifying processes that are metabolically active (i.e., tumor, inflammatory conditions). However, these modalities are static. A key highlight of ultrasound is its capability of dynamic, real-time scanning. The ability to pair CT, MRI or PET with ultrasound can have significant advantages, both in diagnostic evaluation and when performing difficult or challenging image-guided interventions. Percutaneous interventions using ultrasound fusion have been described in the abdominal imaging literature; however, there have been very few musculoskeletal applications detailed in the literature. The purpose of this article is to review the basic concepts of real-time ultrasound fusion, and to detail, through the use of multiple case examples, its potential use as a safe and effective method for performing image-guided musculoskeletal interventions.

To date, studies investigating radiomics-based predictive models have tended to err on the side of data-driven or exploratory analysis of many thousands of extracted features. In particular, spatial assessments of texture have proven to be especially adept at assessing for features of intratumoral heterogeneity in oncologic imaging, which likewise may correspond with tumor biology and behavior. These spatial assessments can be generally classified as spatial filters, which detect areas of rapid change within the grayscale in order to enhance edges and/or textures within an image, or neighborhood-based methods, which quantify gray-level differences of neighboring pixels/voxels within a set distance. Given the high dimensionality of radiomics datasets, data dimensionality reduction methods have been proposed in an attempt to optimize model performance in machine learning studies; however, it should be noted that these approaches should only be applied to training data in order to avoid information leakage and model overfitting. While area under the curve of the receiver operating characteristic is perhaps the most commonly reported assessment of model performance, it is prone to overestimation when output classifications are unbalanced. In such cases, confusion matrices may be additionally reported, whereby diagnostic cut points for model predicted probability may hold more clinical significance to clinical colleagues with respect to related forms of diagnostic testing.