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E1163. The Deep Evil: Osteomyelitis
Authors
  1. Lawrence Wang; Atlantic Health System - Morristown Medical Center
  2. Frank Chen; Atlantic Health System - Morristown Medical Center
  3. Paul Schulze; Atlantic Health System - Morristown Medical Center
Background
Osteomyelitis is a common problem that requires surgical intervention if not diagnosed early enough and left untreated. Diagnostic imaging thus plays a critical role in confirming clinical suspicion of osteomyelitis to avoid any delay in diagnosis. Plain radiographs are often first line imaging diagnostics performed, though are low in sensitivity with findings only seen in subacute to chronic osteomyelitis. Computer tomography can better illustrate osseous changes in the acute stage and is best for assessing for sequestrum in the chronic stage. Magnetic resonance imaging is the ideal study in detecting acute osteomyelitis early. Bone scintigraphy also has a high sensitivity for acute osteomyelitis, but has a low specificity. This exhibit aims to discuss and illustrate the various appearances of the different stages of osteomyelitis across multiple imaging modalities.

Educational Goals / Teaching Points
Pathogenesis of osteomyelitis and its various routes of spread Different stages of osteomyelitis and treatment Review of imaging findings with multiple modalities • Plain radiography • Computer tomography • Conventional MRI • Triple phase bone scintigraphy Sample cases

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The route of pathogen spread varies based on patient demographic. In the pediatric population, osteomyelitis is commonly the result of hematogenous spread to the metaphysis of long bones. This is the result of slow blood flow to the region and gaps in the endothelial lining of the vessel walls that allow pathogens to permeate into the bone. In the adult population, contiguous spread from adjacent soft tissue or joint infections more commonly causes osteomyelitis. This is the result of the high prevalence of diabetes and peripheral vascular disease in the adult population, which causes poor perfusion and subsequently diminished immune response. MR is the best modality for detecting early acute osteomyelitis by illustrating bone marrow edema. The presence of intramedullary fat globules on T1 weighted images is considered pathognomonic for acute osteomyelitis. Brodie’s abscess is an indicator of subacute osteomyelitis and appears as an oval lucent lesion on plain radiograph. The penumbra sign is indicative of Brodie's abscess and is seen as presence of high T1 signal on MR along the periphery of this lesion which represents lipid laden macrophages and granulation tissue along the abscess wall.

Conclusion
Osteomyelitis is a common pathology that affects all populations. Given that progression of untreated osteomyelitis often requires surgery, it is important for radiologists to be familiar with the clinical presentation and more importantly the imaging manifestations of the various stages in order to avoid delay in treatment.