The role of diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging for the diagnosis of diabetic foot osteomyelitis: a preliminary report

Purpose
To assess the role of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) in diagnosing diabetic foot osteomyelitis (DFO).

Material and methods
Twenty-five participants with suspected osteomyelitis were included, who underwent MRI including DCE-MRI and DWI sequences. It was subsequently followed by bone biopsy and microbiological analysis (gold standard). The participants were divided into 2 groups based on biopsy results: DFO-positive or DFO-negative. The semi-quantitative DCE-MRI parameters (SI₀, SI_max, SI_rel, wash-in rate [WIR], and type of curve) and apparent diffusion coefficient (ADC) values were subsequently compared between the 2 groups.

Results
Out of the 25 cases, 19 were DFO-positive and 6 were DFO-negative on bone biopsy. The SI₀, SI_max, and WIR were significantly higher in DFO-positive cases (p-value 0.050, 0.023, and 0.004, respectively). No difference was seen in SI_rel. 100% negative cases revealed type-I curve, and 94% of positive cases showed type-II curve. SI₀ > 143.4 revealed a sensitivity of 94.7% and specificity of 83.3%. SI_max had a sensitivity of 89.5% but lower specificity of 67.7% at a cut-off value of 408.35. The most significant difference was seen with WIR; p-value ~0.004. At the cut-off value of > 1.280, it had a specificity and sensitivity of 100% and 76%, respectively. Also, ADC values below 1.57 × 10^-3 had a sensitivity of 88.2% and specificity of 80% for diagnosing DFO.

Conclusions
DWI and DCE-MRI provide non-invasive sequences, which can help to increase the overall specificity and sensitivity of conventional MRI for the diagnosis of osteomyelitis, differentiating it from acute Charcot’s arthropathy.