Magnetic resonance imaging (MRI) has a higher sensitivity and specificity (90% and 79%) than plain radiography (54% and 68%) for diagnosing diabetic foot osteomyelitis. MRI performs somewhat better than any of several common tests--probe to bone (PTB), erythrocyte sedimentation rate (ESR)>70 mm/hr, C-reactive protein (CRP)>14 mg/L, procalcitonin>0.3 ng/mL, and ulcer size>2 cm²--although PTB has the highest specificity of any test and is commonly used together with MRI.