Skeletal Radiology最新文献

The posterolateral corner (PLC) of the knee comprises a complex arrangement of anatomical and biomechanical structures. Owing to their variability, small size, and the inconsistent terminology found in the literature, these structures have historically been referred to as the "dark side of the knee". This review aims to summarize the relevant anatomy and MR anatomy of the PLC stabilizers, illustrate key MRI findings in acute and chronic injuries, and provide practical considerations for structured diagnosis and reporting. The main stabilizers of this region include the lateral collateral ligament (LCL), the popliteofibular ligament (PFL), and the popliteus myotendinous complex. Together, these elements provide resistance against varus forces and external tibial rotation, with additional compensatory roles in the presence of cruciate ligament insufficiency. Injury mechanisms are diverse, commonly involving direct high-energy trauma, hyperextension, or rotational-varus-hyperextension stress in sports-related activities. Although PLC lesions represent nearly one-third of all ligamentous injuries of the knee, isolated involvement is uncommon, with frequent associations with posterior and anterior cruciate ligament tears. Accurate imaging evaluation, particularly with magnetic resonance imaging (MRI), is fundamental for timely diagnosis, guiding appropriate management, and reducing the risk of chronic posterolateral instability, cruciate graft failure, and progression to osteoarthritis.

Phosphaturic mesenchymal tumours (PMTs) are rare neoplasms that secrete fibroblast growth factor-23 (FGF-23), causing tumour-induced osteomalacia (TIO). Histological overlap with juvenile psammomatoid ossifying fibroma (JPOF) can lead to diagnostic difficulty, particularly outside the craniofacial skeleton. A 4-year-old girl presented with a painful forearm swelling. Radiographs demonstrated a fibro-osseous lesion in the radius and biopsy was initially non-diagnostic, leading to a presumptive diagnosis of fibrous dysplasia. Over the next 6 years, the lesion enlarged, and at age 10, the patient developed genu valgum with biochemical evidence of hypophosphataemic rickets (low phosphate, raised alkaline phosphatase, elevated FGF-23). Medical therapy corrected the rickets, though deformity required guided growth surgery. At age 13, a repeat biopsy of the enlarging lesion revealed a fibro-osseous tumour with spindle stroma and psammomatoid ossicles, negative for GNAS mutation, and consistent with a phosphaturic mesenchymal tumour, connective tissue variant. This case highlights a rare radiologic presentation of PMT involving a long bone, with imaging features closely mimicking fibrous dysplasia and histological overlap with JPOF. The rapid progression of imaging findings, discordant metabolic abnormalities and markedly elevated FGF-23 levels poses a diagnostic challenge. As such, fibrous dysplasia-like lesions of the extremities in the setting of hypophosphataemic rickets should prompt consideration of PMT.

Septic arthritis of the knee is an acute infection that can rapidly destroy articular cartilage if not promptly recognized and treated. Early diagnosis is often difficult because symptoms overlap with crystal or inflammatory arthropathies and post-traumatic effusions, while fever and laboratory markers may be absent or nonspecific. Synovial fluid analysis remains the diagnostic cornerstone, but imaging is essential to confirm effusion, define the extent of synovitis and periarticular involvement, and detect complications such as osteomyelitis or abscess. Radiography provides a rapid baseline, ultrasound is highly sensitive for effusion and guides aspiration, and CT is valuable for cortical destruction and deep soft-tissue mapping. MRI offers the most comprehensive early assessment, revealing synovial enhancement, bone-marrow edema, and occult abscesses. Nuclear medicine studies, including labeled leukocyte scintigraphy and FDG PET/CT, are useful in complex or periprosthetic settings and for monitoring therapy. Staphylococcus aureus remains the leading pathogen, followed by streptococci and Gram-negative bacilli, with atypical and fungal infections mainly in immunocompromised hosts. A stepwise, multimodality imaging strategy enhances diagnostic confidence and guides timely intervention, while advances such as metal-artifact reduction, radiomics, and hybrid imaging hold promise for improving accuracy and standardization in native knee infections.

Tenosynovial giant cell tumour (TSGCT) of the head and neck is exceedingly rare. We report a case of a TSGCT at a novel anatomical site, the nasal dorsum. This case also contributes to the expanding genetic landscape of TSGCT through the identification of a gene fusion that has not previously been described in the literature, to the best of our knowledge. A 20-year-old male presented with progressive changes in the shape of his nasal dorsum, without prior history of trauma or surgery. Clinical examination revealed a firm, mobile, non-tender swelling over the middle third of the nose. Imaging identified a well-defined soft tissue mass, closely related to the nasal cartilage. The mass was completely excised via an external septorhinoplasty approach, enabling removal with reconstruction of the nasal contour. Histopathological analysis demonstrated a giant cell-rich neoplasm with mononuclear cells, foamy histiocytes, and haemosiderin deposition. The unusual location of the mass prompted molecular analysis by next-generation sequencing, RNA analysis of which identified a novel CSF1::AKNAD1 gene fusion. A localised TSGCT was diagnosed. Whilst TSGCT typically arises at sites where synovium is present, its presence at the nasal dorsum introduced uncertainty regarding the tumour's pathogenesis. This case demonstrates the importance of integrating clinical, radiological, histopathological, and molecular findings in diagnosing rare presentations of soft tissue tumours and expands the anatomical locations at which TSGCT may arise.

Objective: Clinical adoption of T2 mapping is limited by poor reproducibility, lengthy examination times, and cumbersome image analysis. This study aimed to develop an accelerated deep learning (DL)-enhanced cartilage T2 mapping sequence (DL CartiGram), demonstrate its repeatability and reproducibility, and evaluate its accuracy compared to conventional T2 mapping using a semi-automatic pipeline.

Methods: DL CartiGram was implemented using a modified 2D Multi-Echo Spin-Echo sequence at 3 T, incorporating parallel imaging and DL-based image reconstruction. Phantom tests were performed at two sites to obtain test-retest T2 maps, using single-echo spin-echo (SE) measurements as reference values. At one site, DL CartiGram and conventional T2 mapping were performed on 43 patients. T2 values were extracted from 52 patellar and femoral compartments using DL knee segmentation and the DOSMA framework. Repeatability and reproducibility were assessed using coefficients of variation (CV), Bland-Altman analysis, and concordance correlation coefficients (CCC). T2 differences were evaluated with Wilcoxon signed-rank tests, paired t tests, and accuracy CV.

Results: Phantom tests showed intra-site repeatability with CVs ≤ 2.52% and T2 precision ≤ 1 ms. Inter-site reproducibility showed a CV of 2.74% and a CCC of 99% (CI 92-100%). Bland-Altman analysis showed a bias of 1.56 ms between sites (p = 0.03), likely due to temperature effects. In vivo, DL CartiGram reduced scan time by 40%, yielding accurate cartilage T2 measurements (CV = 0.97%) with no significant differences compared to conventional T2 mapping (p = 0.1).

Conclusions: DL CartiGram significantly accelerates T2 mapping, while still assuring excellent repeatability and reproducibility. Combined with the semi-automatic post-processing pipeline, it emerges as a promising tool for quantitative T2 cartilage biomarker assessment in clinical settings.

Vertebrogenic back pain (VBP) has emerged as a potentially undiagnosed subtype of chronic low back pain that is thought to arise from structural damage and subsequent inflammatory changes in the vertebral endplates and bone marrow. Modic changes (MCs) found on MRI have been proposed to be a potential indicator for VBP. However, the pathophysiology and clinical basis for MCs are still being investigated. This literature review aims to comprehensively synthesize the available evidence on the pathogenesis, etiologies, and therapeutic outcomes associated with MCs. MCs are classified into three types based on MRI characteristics, with the potential to present with mixed types or to interconvert over time. Risk factors and hypotheses include mechanical disruption, inflammation, bacterial, and autoimmune etiologies increasingly linked to nociceptive signaling from the basivertebral nerve (BVN), causing VBP. Diagnostic and criteria standardization is a major gap for further research to produce more consistent therapeutic outcomes. Future directions with biomarkers, advanced emerging imaging techniques, and clinical translation are required to refine the clinical role of MCs in diagnosing and managing VBP.

Objectives: To review the MRI, histological, and clinical features of extraskeletal myxoid chondrosarcoma (EMC).

Methods: Retrospective review of pre-treatment MRIs in 44 patients with pathologically proven EMC. Patient demographics, tumor MR-imaging features, histology and gene rearrangements, clinical management, and follow-up were reviewed. MRI features assessed included lesion size, location, morphology, signal characteristics, and relation to adjacent structures. Correlative analysis was performed to assess associations between demographic, clinical, molecular, and MRI variables with metastatic disease.

Results: EMCs were predominantly located in the lower extremity (38/44, 86%) and deep-to-fascia (36/44, 82%). All lesions (44/44) demonstrated well-circumscribed margins. Mean maximal dimension was 8.8 cm (range 1.7-36 cm); 93% (41/44) of lesions were hyperintense on fat-suppressed T2-weighted/ STIR imaging. Post-contrast enhancement was "solid" (> 80% enhancement) in 18%, "mixed" (20-80% enhancement) in 53%, and "sparse" (< 20% enhancement) in 29%. Nodal metastases were detected on preoperative imaging in four patients (9%), and pulmonary metastases in three cases preoperatively, and five cases postoperatively (range 14-128 months). EWSR1::NR4A3 fusion rearrangements were documented in 25 tumors (57%), and non-EWSR1 NR4A3 fusions in six cases (14%). The only variable demonstrating a significant correlation with metastatic disease was "solid" pattern of lesional enhancement (p = 0.035).

Conclusions: EMC is most commonly a deep lesion of the extremities demonstrating hyperintense T2-weighted signal, internal septations, and variable patterns of enhancement on MRI. Nodal disease is relatively frequent, and prolonged surveillance is recommended as metastases may develop years after diagnosis. Although analysis is limited by small case numbers, a "solid" (> 80%) pattern of enhancement was significantly associated with metastatic disease.

Objectives: To systematically assess whether MRI-based measurements of glenoid bone loss (GBL) are comparable to CT in patients with shoulder instability.

Methods: We searched PubMed, Cochrane Library, Web of Science, and Embase for studies comparing GBL measurements between CT and MRI through May 16, 2024. We performed subgroup analyses based on 2D versus 3D imaging and linear versus area measurement methods. We conducted statistical analysis using Review Manager (RevMan) version 5.4.1, applying a random-effects model to calculate the mean difference.

Results: Eleven studies were included, totaling 492 shoulders. Of these, 119 shoulders were evaluated using 3D MRI versus 3D CT, 126 using 2D MRI versus 2D CT, 292 using the linear method, and 149 using the area method. The pooled analysis showed no significant difference in GBL measurements between MRI and CT (mean difference -0.05; 95% CI: -0.26 to 0.15; p = 0.61). Subgroup analyses also showed no significant differences (p = 0.94 for 3D, p = 0.14 for 2D, p = 0.67 for linear, p = 0.46 for area, and p = 0.51 comparing linear vs area methods).

Conclusions: MRI provides GBL measurements comparable to CT across various imaging protocols including 2D and 3D approaches and the linear and area methods. MRI may be sufficient as the sole imaging modality for comprehensive preoperative evaluation in patients with shoulder instability.

Objectives: To determine whether MRI can differentiate hips with nonspecific inflammatory conditions from controls based on measurements of the capsule and to identify the most significant measurements.

Methods: In this retrospective and case-control study, we reviewed hip MRIs containing the term "capsulitis" in the reports. Cases with other known diagnoses or confounding joint pathologies were excluded. Controls were asymptomatic hips with normal laboratory results. Three musculoskeletal radiologists independently reviewed the studies, assessing for qualitative (edema, enhancement, effusion, synovitis, and subjective thickening) and quantitative (capsular thickness in standardized planes) parameters. Interobserver agreement, group comparisons, and optimal cutoffs were analyzed.

Results: The final study group comprised 38 cases, and the control group included 51 matched subjects. Inter-reader agreement was moderate to excellent. For capsular thickness, ICC ranged from 0.49 (posterior sagittal) to 0.87 (anterior sagittal). For qualitative findings, kappa ranged from 0.59 (capsular enhancement) to 0.84 (joint effusion), the greatest being capsular thickening and effusion. All planes showed significantly larger capsular thickness in cases vs. controls (p < 0.05). Sensitivity reached 85.2% for anterior sagittal measurement (mean, 6.27 vs. 4.58 mm), and specificity reached 84% for lateral coronal (6.53 vs. 4.13 mm). Among cases, capsular signal abnormality was observed in 89.2% of cases, pericapsular edema in 91.9%, capsular enhancement in 97.3%, pericapsular enhancement in 94.6%, joint effusion in 81.1%, synovitis in 89.2%, and capsular thickening in 100% of cases.

Conclusions: Our study reveals increased hip capsular thickness in nonspecific inflammatory conditions of the hip (capsulitis), both for qualitative and quantitative assessments.