Diagnostic performance of diffusion-weighted MR imaging in differentiation of diabetic osteoarthropathy and osteomyelitis in diabetic foot.

PURPOSE

To study the diagnostic performance of diffusion weighted MR imaging in differentiation of diabetic osteoarthropathy and osteomyelitis in diabetic foot.

PATIENTS AND METHODS

This prospective study was carried out on 41 patients with diabetic foot, 22 males and 19 females with mean age of 51 years. They underwent diffusion-weighted MR imaging of the foot. The apparent diffusion coefficient (ADC) values of the bony lesions were calculated by two reviewers and correlated with the surgical findings or biopsy. The kappa statistic (k) was used to estimate the proportion of inter-observer agreement of two reviewers.

RESULTS

The mean ADC of acute diabetic osteoarthropathy was 1.27±0.19×10mm/s for reviewer 1 and 1.26±0.21×10mm/s for reviewer 2. The mean ADC value in diabetic osteomyelitis was 0.86±0.11×10mm/s for reviewer 1 and 0.85±0.12×10mm/s for reviewer 2. There was excellent inter-observer agreement of ADC value of bony lesions in diabetic foot by both reviewers (K=0.93). There was statistically significant difference in the ADC values of both groups (P=0.001). The cut-off point of ADC value of both reviewers used in differentiating acute diabetic osteoarthropathy and osteomyelitis were 0.98×10mm/s and 1.04×10mm/s with an accuracy of 94% and 93% and area under the curve of 0.94 and 0.93 respectively.

CONCLUSION

We conclude that the ADC value is a non-invasive imaging parameter that can help in differentiation of diabetic osteoarthropathy from osteomyelitis with excellent inter-observer agreement.