Magnetic resonance imaging evaluation of osteoid osteoma: utility of the dark rim sign

Imaging Osteomyelitis: An Update

BACKGROUND

 Hematogenous osteomyelitis has increased over the past quarter century in frequency, virulence, and degree of soft-tissue involvement, bringing about changes in clinical manifestations and management of the disease especially in children that should be reflected in the current imaging approach. Likewise, the global disease burden of diabetes has increased greatly in the same period, compounding the problem of ascertaining osteomyelitis in diabetic foot.

METHOD

 This article provides an updated overview of imaging findings in hematogenous and contiguous osteomyelitis based on the literature and our institutional experience, along with salient features of recent recommendations from expert groups on the diagnostic algorithms and reporting terminology.

RESULTS AND CONCLUSION

 Findings on radiography and especially magnetic resonance imaging (MRI) closely reflect pathophysiology in osteomyelitis, whereby the characteristic involvement of the metaphysis or metaphyseal-equivalents, the formation and subperiosteal extension of intramedullary pus collection, and the development of cloaca, sequestrum, and involucrum are all diagnostic clues. Non-enhancing foci within the medullary bone, the penumbra sign, intra- or extramedullary fat globules, and surrounding soft tissue inflammation or abscesses are among key MRI findings. Diabetic foot is a special condition with characteristic pathophysiologic and imaging features that suggest the likelihood of osteomyelitis and the main differential diagnostic consideration of acute on chronic neuropathic osteoarthropathy with or without osteomyelitis.

KEY POINTS

  · Imaging closely reflects pathophysiology in hematogenous osteomyelitis.. · Acute hematogenous osteomyelitis predominantly involves metaphyses and metaphyseal equivalent sites.. · MRI clues for hematogenous osteomyelitis include central marrow non-enhancement, intra- or extramedullary fat globules, and the "penumbra" sign.. · An increased fluid-sensitive MRI bone signal abutting a soft tissue ulcer, abscess, or sinus tract suggests a high probability of contact osteomyelitis..

CITATION FORMAT

· Aydingoz U, Imaging Osteomyelitis: An Update. Fortschr Röntgenstr 2023; DOI: 10.1055/a-1949-7641.

Chronic Osteomyelitis of Long Bones: Imaging Pearls and Pitfalls in Pediatrics

Chronic bacterial osteomyelitis is characterized by progressive inflammatory bone destruction and apposition of new bone most often caused by pyogenic bacteria. Clinical findings are nonspecific, and serum inflammatory markers can be normal. Prompt diagnosis and treatment are essential. Left untreated, chronic infection can lead to high morbidity and mortality. Imaging's major role is to suggest the correct diagnosis, exclude other diagnoses that can mimic osteomyelitis, document extent of disease, and guide interventions such as image-guided biopsy or surgical debridement. Several conditions can mimic chronic osteomyelitis clinically and radiographically. The main differential diagnoses include an oncologic process, chronic nonbacterial or chronic recurrent multifocal osteomyelitis, bone infarct in sickle cell disease, osteoid osteoma, and stress reaction/fracture. The oncologic process to consider includes metastatic neuroblastoma and Langerhans cell histiocytosis in a child younger than five years or leukemia, Ewing sarcoma, and osteosarcoma in the older age group. However, these lesions can typically be excluded based on radiographs and magnetic resonance imaging findings. Therefore, radiologist familiarity with imaging findings and mimickers is essential. In this article, we briefly review the epidemiologic, clinical, and histopathologic features of chronic bacterial osteomyelitis and emphasize imaging pearls and pitfalls, with discussion of the most common differential diagnoses.

Pediatric Hip Disorders: Imaging Guidelines and Recommendations

Hip disorders are a wide range of conditions commonly affecting patients in the pediatric age group. Reaching an accurate diagnosis of these conditions in children may be challenging. The optimal use of image modalities in the approach of a child with possible hip pathology is essential, which allows radiologists and clinicians to narrow the differential diagnosis and reach a definitive diagnosis, which can consequently result in early and appropriate interventions leading to improved outcomes. Therefore, this article aims to provide practicing radiologists and clinicians with up-to-date and evidence-based imaging spectrum guidelines and recommendations for common pediatric hip disorders.