Imaging modality | Abnormal findings |
Plain radiograph* | Deep soft tissue swelling (3 days after onset) |
Periosteal reaction or elevation (10 to 21 days after onset) |
Lytic sclerosis (≥1 month after onset) |
Magnetic resonance imaging | Bone marrow inflammation (decreased signal in T1-weighted images; increased signal in T2-weighted images) |
Edema in marrow and soft tissues |
Penumbra sign (high-intensity-signal transition zone between abscess and sclerotic bone marrow in T1-weighted images) |
With gadolinium enhancement: absent blood flow, suggestive of necrosis or abscess |
Three-phase bone scan | Focal uptake of tracer in the third phase (delayed phase) |
Computed tomography | Increased density of bone marrow |
Cortex destruction |
Periosteal reaction (new bone formation) formation |
Periosteal purulence |
Sequestra (devitalized, sclerotic bone) |
Ultrasonography | Fluid collection adjacent to bone without intervening soft tissue |
Thickening of periosteum |
Periosteal elevation |