Soft tissue tumor imaging in adults: whole-body staging in sarcoma, non-malignant entities requiring special algorithms, pitfalls and special imaging aspects. Guidelines 2024 from the European Society of Musculoskeletal Radiology (ESSR).

OBJECTIVES: The revised European Society of Musculoskeletal Radiology (ESSR) consensus guidelines on soft tissue tumor imaging represent an update of 2015 after technical advancements, further insights into specific entities, and revised World Health Organization (2020) and AJCC (2017) classifications. This second of three papers covers algorithms once histology is confirmed: (1) standardized whole-body staging, (2) special algorithms for non-malignant entities, and (3) multiplicity, genetic tumor syndromes, and pitfalls. MATERIALS AND METHODS: A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements that had undergone interdisciplinary revision were scored online by the level of agreement (0 to 10) during two iterative rounds, that could result in 'group consensus', 'group agreement', or 'lack of agreement'. RESULTS: The three sections contain 24 statements with comments. Group consensus was reached in 95.8% and group agreement in 4.2%. For whole-body staging, pulmonary MDCT should be performed in all high-grade sarcomas. Whole-body MRI is preferred for staging bone metastasis, with [18F]FDG-PET/CT as an alternative modality in PET-avid tumors. Patients with alveolar soft part sarcoma, clear cell sarcoma, and angiosarcoma should be screened for brain metastases. Special algorithms are recommended for entities such as rhabdomyosarcoma, extraskeletal Ewing sarcoma, myxoid liposarcoma, and neurofibromatosis type 1 associated malignant peripheral nerve sheath tumors. Satisfaction of search should be avoided in potential multiplicity. CONCLUSION: Standardized whole-body staging includes pulmonary MDCT in all high-grade sarcomas; entity-dependent modifications and specific algorithms are recommended for sarcomas and non-malignant soft tissue tumors. CLINICAL RELEVANCE STATEMENT: These updated ESSR soft tissue tumor imaging guidelines aim to provide support in decision-making, helping to avoid common pitfalls, by providing general and entity-specific algorithms, techniques, and reporting recommendations for whole-body staging in sarcoma and non-malignant soft tissue tumors. KEY POINTS: An early, accurate, diagnosis is crucial for the prognosis of patients with soft tissue tumors. These updated guidelines provide best practice expert consensus for standardized imaging algorithms, techniques, and reporting. Standardization can improve the comparability examinations and provide databases for large data analysis.

Long-term outcomes in sacral agenesis.

INTRODUCTION: Sacral agenesis (SA) includes a range of clinical presentations of varying severity, with implications for function and quality of life (QoL). Diagnosis is often made perinatally, and prognostic discussions become an important aspect of parental counselling. This study engaged SA sufferers and their caregivers to obtain objective, long-term patient reported outcome data. METHOD: Patients with radiologically confirmed SA from a single tertiary spinal unit underwent retrospective medical record review. Patients were then contacted by telephone to complete QoL questionnaires including EQ-ED-5L for adults and EQ-ED-Y for < 16-year-olds. Additional information including Renshaw grade, employment, living situation and bladder function was also collected. RESULTS: Twenty-six patients with SA were identified. Mean age is 23.35 years (range 0.92-63.53), 13 M:17F. Renshaw grade ranged from 1 to 4. Sixty-eight percent had associated kyphoscoliotic deformities. The majority (70%) had either impaired or absent bladder control, and 80% need walking aids to mobilise. Twenty patients completed the questionnaire (10 adults and 10 < 16-year-olds). Mean EQ-ED-5L index for adults was +0.474 (range -0.1 to +0.089, 1 = best), with a lower mean value of +0.287 (range -0.54 to +1) for the < 16-year cohort. Those undergoing spinal fusion procedures had significantly lower scores (-0.08 v +0.44, p = 0.022). CONCLUSION: This study provides an objective record of the QoL of individuals with SA, illustrating a wide variety of outcomes, with differences between younger and older individuals which may reflect the results of a long-term adaptive process. The implications for individuals should be carefully tailored to the specific deformity and the likely underlying neurological deficits.

The use of the flow-void sign on MRI: highly sensitive sign in detecting bone metastases from renal cell carcinoma.

OBJECTIVE: To evaluate a range of pathologically proven malignant bone tumours, including primary bone sarcoma and metastatic bone lesions, referred to a tertiary referral centre for the presence of the flow-void sign on MR imaging. MATERIALS AND METHODS: A retrospective search was performed using the radiology information system and oncology database in our institution to identify patients over the age of 40 years referred with a solitary bone lesion. Patients with a range of pathologically proven malignant bone tumours, including primary bone tumours and metastatic bone lesions, were included in the study. MRI images were reviewed for the presence of the flow-void sign. The presence and type of the flow-void sign were correlated with lesion size. RESULTS: Two hundred and sixty-six cases were included in the study. Overall, the flow-void sign was identified in 40.9% of cases. The flow-void sign was most frequently seen in renal cell carcinoma metastasis (90.0%). The sign is highly sensitive (90%) for renal cell carcinoma metastases with a high negative predictive value (98.09%). When the flow-void sign is identified, the lesion is almost three times more likely to represent a renal cell carcinoma metastasis than any other malignant tumour in patients over the age of 40 years with a solitary bone lesion. CONCLUSION: The flow-void sign is highly sensitive for renal cell carcinoma bone metastases and could negate the need for biopsy in patients with a known history of renal cell carcinoma or in whom an occult renal cell carcinoma is subsequently identified.

An unusual case of nodular fasciitis presenting as an intra-tendinous mass.

Nodular fasciitis is a benign soft tissue pseudotumour typically occurring in the upper extremities, head and neck, thigh and trunk. It is most commonly seen in subcutaneous locations but also can be present in intramuscular and intermuscular (fascial) locations. Its occurrence in the hand is rare, and while it can occur in close proximity to tendons, its presentation as an intra-tendinous mass has not been previously described. We present a unique and rare case of nodular fasciitis arising within the flexor digitorum profundus (FDP) tendon of the hand in a 16-year-old female. The patient presented with a painful swelling in the volar aspect of the base of her left middle finger, with progressive flexion deformity of the finger. Ultrasound and magnetic resonance imaging revealed a mass within the FDP tendon of the middle finger. An ultrasound-guided biopsy revealed a diagnosis of nodular fasciitis. Given the self-limiting nature of the condition, she was managed conservatively with close clinical and imaging follow-up. This case highlights the importance of considering nodular fasciitis in the differential diagnosis of an intra-tendinous lesion in the hand, even though it is a rare occurrence in this location. The clinical presentation, diagnostic workup, and management of this unique case are discussed, emphasising the potential for its misdiagnosis as a malignancy which can have important implications in management.

Bone metastases from chondroblastoma: a rare pattern of metastatic disease in an adult.

Chondroblastoma is a rare benign tumor, typically presenting in the first two decades. Systemic metastases in chondroblastoma are extremely rare and it is the rarity of these metastases which lead the World Health Organisation to re-classify this lesion from "intermediate" to "benign" in its updated classification of bone tumors in 2020. We present an unusual case of a 55 year-old male patient who presented with multiple FDG-avid bone lesions on a background of conventional chondroblastoma of the rib excised at another institution 11-years previously. Two of these lesions were also histologically-proven as conventional chondroblastoma at biopsy. This case highlights that, although rare, metastases can be seen in patients with chondroblastoma. To our knowledge, this is the only case with an unusual pattern of metastases limited to bone.

An unusual cystic presentation of pelvic skeletal Ewing sarcoma: a case series.

Ewing sarcoma (ES) is the second most common primary malignant bone tumour in children and adolescents. About 14.5% of primary malignancies develop in pelvic bones, where they typically have worse prognoses than extremity or acral sarcomas. It usually presents with aggressive features on radiology scans, but may also present with different radiological characteristics. In this series, we describe rare appearances of pelvic skeletal Ewing sarcoma, with large extraosseous cystic component on imaging, defined by the presence of fluid-filled spaces in the extraosseous tumour lesion, which distinguishes it from the solid nature of conventional ES. We report 3 cases of cystic presentation of ES, with imaging features supporting diagnosis of a primary malignant bone tumour arising from the superior pubic ramus with associated massive intrapelvic solid and cystic mass. CT-guided biopsy provided diagnosis of ES, with large intrapelvic soft tissue and cystic component. These patients underwent neo-adjuvant chemotherapy and proton beam therapy with significant reduction in size of the solid components, while the cystic components remained relatively unchanged. Two patients underwent surgical resection of the tumour (navigated P3 internal hemipelvectomy and hemipelvis P2/P3 resection, respectively), and one patient died while on treatment. In both who underwent surgery, histology showed ES with margins clear and more than 99% of treatment-induced necrosis. To the authors' knowledge, this unusual presentation of pelvic ES is described for the first time in the literature as a case series, with particular reference to atypical extraosseous cystic changes, along with the clinical and radiological characteristics, and their treatment.

Cubital tunnel syndrome: anatomy, pathology, and imaging.

Cubital tunnel syndrome (CuTS) is the second most common peripheral neuropathy in the upper limb. It occurs due to ulnar nerve compression within the fibro-osseous cubital tunnel at the elbow joint. Although CuTS is typically diagnosed clinically and with electrodiagnostic studies, the importance of imaging in evaluating the condition is growing. Knowing the typical imaging findings of ulnar nerve entrapment is necessary for precise diagnosis and proper treatment. In this article, we focus on the clinical features, workup and complex imaging of the "anatomic" cubital tunnel and relevant pathological entities.

Effectiveness of AI-powered Chatbots in responding to orthopaedic postgraduate exam questions-an observational study.

PURPOSE: This study analyses the performance and proficiency of the three Artificial Intelligence (AI) generative chatbots (ChatGPT-3.5, ChatGPT-4.0, Bard Google AI®) and in answering the Multiple Choice Questions (MCQs) of postgraduate (PG) level orthopaedic qualifying examinations. METHODS: A series of 120 mock Single Best Answer' (SBA) MCQs with four possible options named A, B, C and D as answers on various musculoskeletal (MSK) conditions covering Trauma and Orthopaedic curricula were compiled. A standardised text prompt was used to generate and feed ChatGPT (both 3.5 and 4.0 versions) and Google Bard programs, which were then statistically analysed. RESULTS: Significant differences were found between responses from Chat GPT 3.5 with Chat GPT 4.0 (Chi square = 27.2, P < 0.001) and on comparing both Chat GPT 3.5 (Chi square = 63.852, P < 0.001) with Chat GPT 4.0 (Chi square = 44.246, P < 0.001) with. Bard Google AI® had 100% efficiency and was significantly more efficient than both Chat GPT 3.5 with Chat GPT 4.0 (p < 0.0001). CONCLUSION: The results demonstrate the variable potential of the different AI generative chatbots (Chat GPT 3.5, Chat GPT 4.0 and Bard Google) in their ability to answer the MCQ of PG-level orthopaedic qualifying examinations. Bard Google AI® has shown superior performance than both ChatGPT versions, underlining the potential of such large language processing models in processing and applying orthopaedic subspecialty knowledge at a PG level.

Soft tissue tumor imaging in adults: European Society of Musculoskeletal Radiology-Guidelines 2023-overview, and primary local imaging: how and where?

OBJECTIVES: Early, accurate diagnosis is crucial for the prognosis of patients with soft tissue sarcomas. To this end, standardization of imaging algorithms, technical requirements, and reporting is therefore a prerequisite. Since the first European Society of Musculoskeletal Radiology (ESSR) consensus in 2015, technical achievements, further insights into specific entities, and the revised WHO-classification (2020) and AJCC staging system (2017) made an update necessary. The guidelines are intended to support radiologists in their decision-making and contribute to interdisciplinary tumor board discussions. MATERIALS AND METHODS: A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements were scored online by level of agreement (0 to 10) during two iterative rounds. Either "group consensus," "group agreement," or "lack of agreement" was achieved. RESULTS: Eight sections were defined that finally contained 145 statements with comments. Overall, group consensus was reached in 95.9%, and group agreement in 4.1%. This communication contains the first part consisting of the imaging algorithm for suspected soft tissue tumors, methods for local imaging, and the role of tumor centers. CONCLUSION: Ultrasound represents the initial triage imaging modality for accessible and small tumors. MRI is the modality of choice for the characterization and local staging of most soft tissue tumors. CT is indicated in special situations. In suspicious or likely malignant tumors, a specialist tumor center should be contacted for referral or teleradiologic second opinion. This should be done before performing a biopsy, without exception. CLINICAL RELEVANCE: The updated ESSR soft tissue tumor imaging guidelines aim to provide best practice expert consensus for standardized imaging, to support radiologists in their decision-making, and to improve examination comparability both in individual patients and in future studies on individualized strategies. KEY POINTS: • Ultrasound remains the best initial triage imaging modality for accessible and small suspected soft tissue tumors. • MRI is the modality of choice for the characterization and local staging of soft tissue tumors in most cases; CT is indicated in special situations. Suspicious or likely malignant tumors should undergo biopsy. • In patients with large, indeterminate or suspicious tumors, a tumor reference center should be contacted for referral or teleradiologic second opinion; this must be done before a biopsy.

Angle of BRINK - a new way to measure Haglund's deformity.

INTRODUCTION: Haglund's deformity, an abnormality of the postero-superior corner of the calcaneum, is a common, critically debated cause of posterior heel pain. Several radiological indices such as Fowler-Philip angle, Ruch pitch, Chauveaux-Liet angle, calcaneal pitch angle, parallel pitch lines, and X-Y ratio have been described to measure this deformity. However, most of these lack specificity and have variable intra- and inter-observer reliability. PURPOSE: The study aims to describe a new radiological "angle of BRINK" (Botchu-Reilly-Iyengar-Nischal-Kakarala) to measure Haglund's deformity. PATIENT AND METHODS: We performed a retrospective cohort analysis, assessing 20 weight-bearing lateral ankle radiographs of patients with Haglund's deformity (Haglund's cohort) and 100 radiographs without the deformity (normal cohort). Demographic details and angle of BRINK to measure Haglund's deformity were measured for each patient. Statistical analysis was performed using t-test and inter-observer reliability was calculated using kappa coefficient. RESULTS: The mean angle of BRINK to measure Haglund's deformity in the normal cohort was 20.04° (SD 4.88), and in the Haglund's cohort was 25.1° (SD 3.3). This was statistically significant with a p-value of less than 0.0001. There was excellent intra- and inter-observer reliability with kappa value of 0.8. CONCLUSION: Our proposed radiological angle of BRINK to measure Haglund's deformity is simple and easy to calculate on standard weight-bearing radiographs. Contrary to the traditional measurements used to estimate the deformity, it has shown a good intra- and inter-observer reliability and can support surgical decision-making process for management of patients with symptomatic Haglund's deformity.

A comparison of ChatGPT-generated articles with human-written articles.

OBJECTIVE: ChatGPT (Generative Pre-trained Transformer) is an artificial intelligence language tool developed by OpenAI that utilises machine learning algorithms to generate text that closely mimics human language. It has recently taken the internet by storm. There have been several concerns regarding the accuracy of documents it generates. This study compares the accuracy and quality of several ChatGPT-generated academic articles with those written by human authors. MATERIAL AND METHODS: We performed a study to assess the accuracy of ChatGPT-generated radiology articles by comparing them with the published or written, and under review articles. These were independently analysed by two fellowship-trained musculoskeletal radiologists and graded from 1 to 5 (1 being bad and inaccurate to 5 being excellent and accurate). RESULTS: In total, 4 of the 5 articles written by ChatGPT were significantly inaccurate with fictitious references. One of the papers was well written, with a good introduction and discussion; however, all references were fictitious. CONCLUSION: ChatGPT is able to generate coherent research articles, which on initial review may closely resemble authentic articles published by academic researchers. However, all of the articles we assessed were factually inaccurate and had fictitious references. It is worth noting, however, that the articles generated may appear authentic to an untrained reader.

Assessing ChatGPT's ability to pass the FRCS orthopaedic part A exam: A critical analysis.

AI technology has made significant advancements in recent years, with the notable development of ChatGPT in November 2022. Users have observed evidence of deductive reasoning, logical thinking, and coherent thought in ChatGPT's responses. This study aimed to determine if ChatGPT has the capability to pass the Orthopaedic Fellow of the Royal College of Surgeons (FRCS Orth) Part A exam. METHODS: To assess ChatGPT4's ability to pass the Orthopaedic FRCS Orth Part A exam, a study was conducted using 240 mock FRCS Orth Part A questions. The study evaluated the accuracy of ChatGPT's answers and the response time for each question. Descriptive statistics were employed to analyse the chatbot's performance. RESULTS: The evaluation revealed that ChatGPT4 achieved an overall score of 67.5% on Part A of the exam. However, ChatGPT4 did not meet the overall pass mark required for the FRCS Orth Part A exam. CONCLUSION: This study demonstrates that ChatGPT was unable to pass the FRCS Orthopaedic examination. Several factors contributed to this outcome, including the lack of critical or high-order thinking abilities, limited clinical expertise, and the inability to meet the rigorous requirements of the exam.

Validation of the supinator fat pad sign in radial head and neck fractures.

OBJECTIVE: To assess the displacement of the supinator fat pad in radial head and neck fractures and to validate its significance. MATERIAL AND METHODS: One hundred two adult patients from the Royal Orthopaedic Hospital, Birmingham, United Kingdom and Sultan Qaboos University Hospital, Muscat, Oman with confirmed radial head and/or neck fractures were included. Fractures were classified using the Mason-Johnston classification. The displacement of the supinator fat pad from the radius was measured on anterior-posterior (AP) and lateral radiographs and correlated to fracture classification. RESULTS: The supinator fat pad was on average displaced by 10.6 mm and 13.8 mm from the radius on AP and lateral radiographs, respectively. The displacement of the fat pad progressively increased between non-displaced (Mason I) and severely comminuted (Mason III) fractures on both the AP (10.25 to 14.25 mm) and lateral (12.70 to 16.00 mm) projections. The progression of displacement on AP (p = 0.016) and on lateral (p = 0.007) projections was statistically significant. Fracture dislocation was not associated with increased fat pad displacement. CONCLUSION: The supinator fat pad sign is a useful adjunct in the assessment of radial head and neck fractures.

The role of Grey Scale Inversion Imaging (GSII) as a diagnostic tool of neck of femur fractures: is it more effective?

INTRODUCTION: Grey Scale Inversion Imaging (GSII), a radiology reading software, has been utilized to improve anatomical and pathological delineation and consequently increase the diagnostic accuracy in a variety of trauma and Orthopaedic conditions. OBJECTIVE/AIM: The objective of this study was to assess whether Grey Scale Inversion Imaging (GSII) has any impact on the diagnostic accuracy and inter-observer reliability in diagnosing neck of femur fractures. METHOD: We performed a retrospective, single-centre study, to identify 50 consecutive anteroposterior (AP) pelvis radiographs of patients who presented to our unit with suspected neck of femur fractures between 2020 and 2021. The images included a combination of normal pelvic radiographs and others with features suggestive either intracapsular or extracapsular neck of femur fractures, which had been confirmed on computed tomography (CT), magnetic resonance imaging (MRI) and/or subsequent surgery. Four independent observers (two Trauma and Orthopaedics (T&O) consultants, one T&O Trainee Registrar (ST3 level) and one Trainee Senior House Officer (SHO in T&O) reviewed the images and graded each radiograph image using the Likert scale in response to the statement "there is a fracture". Following this, the same radiographs were inverted to Grey Scale Inversion Imaging (GSII) grey scale images and reassessed. RAND correlation was used for statistical analysis. RESULTS: Overall, observers appeared to have similar accuracy with normal radiographic imaging and with GSI sequences. CONCLUSION: Grey Scale Inversion Imaging (GSII) of digital radiographs did not affect the diagnostic accuracy of detecting neck of femur fractures in our study.

Can Non-Contrast 3T MRI scans predict the type of labral procedure in hip arthroscopy?

PURPOSE: The study proposed a simple classification system that aimed at predicting the labral procedure during hip arthroscopy using images from unenhanced 3T MRI scans. PATENTS AND METHODS: Forty patients undergoing hip arthroscopy had their MRI scans reviewed pre-operatively by one of two senior radiologists and classified into: type 1: stable labrum with intra-substance degeneration (no labral repair required), type 2: unstable labrum, no intra-substance degeneration (labral repair required), or type 3: unstable labrum with intra-substance degeneration (Labral repair not feasible). Hip arthroscopy is carried out by one of two surgeons and classified accordingly while blinded to the radiologists' assessment. RESULTS: The pre-operative radiological classification managed to predict the labral procedure in 29 cases out of 40 (72.5%). The gamma value was 0.83, and the kappa value was 0.46 denoting moderate agreement. The inter-class correlation coefficient was 0.52 indicating moderate reliability. CONCLUSION: The proposed classification showed a moderate agreement between the radiological findings and arthroscopic findings. As we cannot accurately correlate the MRI findings with the type of surgical management, the surgeon should be prepared for all scenarios of labral procedures. LEVEL OF EVIDENCE: Level IV (case series).

A deep learning approach for automated diagnosis of pulmonary embolism on computed tomographic pulmonary angiography.

BACKGROUND: Computed tomographic pulmonary angiography (CTPA) is the diagnostic standard for confirming pulmonary embolism (PE). Since PE is a life-threatening condition, early diagnosis and treatment are critical to avoid PE-associated morbidity and mortality. However, PE remains subject to misdiagnosis. METHODS: We retrospectively identified 251 CTPAs performed at a tertiary care hospital between January 2018 to January 2021. The scans were classified as positive (n = 55) and negative (n = 196) for PE based on the annotations made by board-certified radiologists. A fully anonymized CT slice served as input for the detection of PE by the 2D segmentation model comprising U-Net architecture with Xception encoder. The diagnostic performance of the model was calculated at both the scan and the slice levels. RESULTS: The model correctly identified 44 out of 55 scans as positive for PE and 146 out of 196 scans as negative for PE with a sensitivity of 0.80 [95% CI 0.68, 0.89], a specificity of 0.74 [95% CI 0.68, 0.80], and an accuracy of 0.76 [95% CI 0.70, 0.81]. On slice level, 4817 out of 5183 slices were marked as positive for the presence of emboli with a specificity of 0.89 [95% CI 0.88, 0.89], a sensitivity of 0.93 [95% CI 0.92, 0.94], and an accuracy of 0.89 [95% CI 0.887, 0.890]. The model also achieved an AUROC of 0.85 [0.78, 0.90] and 0.94 [0.936, 0.941] at scan level and slice level, respectively for the detection of PE. CONCLUSION: The development of an AI model and its use for the identification of pulmonary embolism will support healthcare workers by reducing the rate of missed findings and minimizing the time required to screen the scans.

The influence of spinal position on imaging findings: an observational study of thoracolumbar spine upright MRI in elite gymnasts.

PURPOSE: To investigate whether upright magnetic resonance imaging (MRI) has a role in defining thoracolumbar spine pathology in elite gymnastics. METHODS: A prospective cross-sectional observational study of National Senior and Junior Artistic gymnasts in three MRI positions (standard supine, upright flexed and extended positions). Two specialist musculoskeletal radiologists independently analysed images with neutral as a baseline with the effects of flexion and extension reported in line with Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. RESULTS: Forty (18 males) gymnasts aged 13-24 years with a mean (SD) of 32 (5.3) training hours per week consented with 75% showing MRI abnormalities. Degenerative disc disease (DDD) was evident in 55% participants with vertebral end plate (VEP) changes in 42.5%. Spondylolysis was present in 40% with an additional 17% showing chronic bilateral complete L5 pars defects. 23% participants demonstrated different MRI findings in upright flexion compared to neutral. CONCLUSION: Findings suggest a high levels of MRI abnormalities in elite gymnastics including altered disc morphology and posterior element abnormalities. High prevalence of T11/12 DDD and VEP changes reflects the thoracolumbar junction being a transition zone. Upright MRI and varying spine position offer promise for enhanced visualisation of posterior element abnormalities.

Bone stress injuries in the presence of tarsal coalition as a cause of hindfoot pain in adolescents: case series of 6 patients with literature review.

OBJECTIVE: To highlight causal relationship between stress fracture in the presence of tarsal coalition and hindfoot pain in adolescents on magnetic resonance imaging (MRI). MATERIAL AND METHODS: A retrospective review was performed of the clinical and MRI imaging findings of 6 adolescents referred for MRI to evaluate symptoms of hindfoot pain with possible tarsal coalition. MRI studies were systematically assessed for cause of hindfoot pain, types of tarsal coalition, patterns of stress fractures, bone marrow oedema and any other associated features. RESULTS: All the 6 patients (4 male: 2 female) aged between 12 and 19 years developed insidious onset of hindfoot or midfoot pain over a period of weeks to months. On MRI, all 6 cases had features of fibrous tarsal coalition predominantly in the calcaneonavicular articulation (5 out of 6 patients). Associated stress fractures/response were in the posterior facet/body of the calcaneus (3), talar head (2), cuboid (1) and third metatarsal bone in one patient. CONCLUSION: Stress fractures/response adjacent to tarsal coalition could be because of altered biomechanics and can be an unusual cause of hindfoot pain in adolescents. A high index of suspicion and complementary MRI findings is crucial to interpret this condition to direct appropriate patient management.

MRI features of ERSA (exercise-related signal abnormality) lesions in professional soccer players.

OBJECTIVE: This study aims to describe the prevalence, anatomy and morphology of ERSA (exercise-related signal abnormality) lesions, a previously undescribed pattern of muscle signal changes on MRI in professional soccer players with suspected acute thigh muscle injury. METHODS: A multicenter retrospective review was performed of 287 MRIs of professional soccer players referred for suspected acute thigh injury from August 2017 to February 2020. MR images were reviewed for muscle signal abnormalities corresponding to a peritendinous ovoid region or a subfascial ring of faint increased signal on fluid-sensitive MR images. Imaging features including anatomical site, morphology, and craniocaudal length were recorded. Concomitant acute muscle injury was graded in accordance with the British Athletics Muscle Injury Classification (BAMIC). RESULTS: ERSA lesions comprising a peritendinous ovoid region, a subfascial ring, or both, were identified in 40 muscles across 31/287 studies (10.8%). These lesions had a mean length of 15.8 cm and were predominantly located in the proximal or mid-portions of muscles. Affected muscles were rectus femoris (n = 22), adductor longus (n = 11), semitendinosus (n = 6) and biceps femoris (n = 1). 21/31 studies (67.7%) had a BAMIC grade 1-4 injury in a separate muscle, which were largely (81%) in a separate anatomic compartment or contralateral. CONCLUSION: ERSA lesions were evident on MRI in 10.8% of our cohort of professional soccer players referred for suspected acute thigh muscle injury. Characteristic morphology and the longitudinal length (mean 15.8 cm) distinguish ERSA lesions from recognized patterns of acute muscle injury.

Imaging of Pediatric Bone Tumors and Tumor-like Lesions.

Bone lesions are commonly seen when reporting pediatric skeletal imaging. Distinguishing aggressive from nonaggressive lesions is essential in making the diagnosis. Not all aggressive lesions are neoplastic; indeed, osteomyelitis frequently presents with aggressive appearances and is far more commonly seen in the pediatric population than neoplastic lesions. In this article, we discuss an approach for the diagnosis of pediatric bone tumors and tumor-like conditions. The most common pediatric benign and malignant bone tumors are discussed in more detail.