What This Means
This research examined how well ultrasound compares to MRI for diagnosing infections in diabetic foot wounds, particularly bone infection (osteomyelitis), which is a major driver of amputations. The study enrolled 127 people with diabetes who had foot wounds serious enough to raise concern for infection, and each patient received both an ultrasound and an MRI. Researchers found that ultrasound was very good at detecting skin and soft tissue infections (cellulitis), agreeing with clinical diagnosis 99.2% of the time, and it caught every abscess that MRI also identified. However, for the more serious complication of bone infection, ultrasound only detected about 18 out of every 100 cases confirmed by MRI — meaning it missed roughly 82% of osteomyelitis cases.
This research suggests that a negative ultrasound result should not be used to rule out bone infection in people with diabetic foot wounds. Because ultrasound is widely available, affordable, and quick, it may still be useful as a first-step screening tool, particularly for identifying abscesses or soft tissue infections. However, when there is clinical concern that infection may have reached the bone, MRI remains the necessary next step, as ultrasound is simply not reliable enough to exclude that diagnosis.
The practical implication is that clinicians and health systems should not replace MRI with ultrasound when osteomyelitis is a possibility in diabetic foot care. Instead, the two tools are best used in a stepped approach: ultrasound first for accessible triage, followed by MRI when bone involvement is suspected. The authors also caution that since MRI itself is not a perfect diagnostic standard, their results describe how well the two imaging methods agree with each other rather than measuring absolute truth about infection presence.