The Value of Apparent Diffusion Coefficient from Diffusion-Weighted Imaging in Differentiating Osteomyelitis and Reactive Bone Marrow Edema in Diabetic Patients.

Objectives: This study evaluated the diagnostic performance of the apparent diffusion coefficient (ADC) in distinguishing osteomyelitis from reactive bone marrow edema (RBME). Methods: This cross-sectional study included three groups of consecutive patients with diabetic foot ulcers (DFU) presenting with osteomyelitis, RBME, or healthy bone. All patients had DFU and were referred for magnetic resonance imaging (MRI). Patients with a history of foot surgery or biopsy before MRI, those who received antibiotic therapy for three or more days before imaging, and those with contraindications to MRI were excluded from the study. Osteomyelitis was confirmed by tissue biopsy, whereas RBME was diagnosed by exclusion. All participants underwent diffusion-weighted imaging (DWI), and ADC values were measured independently by two radiologists who were blinded to the clinical diagnosis. The diagnostic performance of ADC was then assessed. Results: A total of 45 patients with diabetic foot ulcers (DFU) were recruited, of whom 18 (40.0%) had osteomyelitis, 16 (35.6%) had reactive bone marrow edema (RBME), and 11 (24.4%) had healthy bone tissue. Osteomyelitis demonstrated significantly higher ADC values compared to normal bone (P < 0.001) and significantly lower ADC values compared to RBME (P < 0.001). Using a cut-off value of 1478.0 × 10⁻⁶ mm²/s, ADC differentiated osteomyelitis from RBME with an accuracy of 88.2%, sensitivity of 94.4%, specificity of 81.2%, and an area under the curve (AUC) of 0.958. Conclusion: These findings support the applicability of diffusion-weighted imaging (DWI) as a non-invasive and accurate diagnostic tool for differentiating osteomyelitis from reactive bone marrow edema.