Our colleagues Larry Lavery and Andrew Crisologo, alongside lead author Orhan Öz, have published a significant prospective study in Diabetologia. Their work tackles one of the most difficult challenges in limb preservation: accurately diagnosing diabetic foot osteomyelitis (DFO) and, crucially, knowing when the infection is actually gone.
The Challenge of the “Gold Standard”
While bone biopsy is the gold standard for DFO, it is invasive and often avoided in clinical practice. Most clinicians rely on MRI, but the diabetic foot is “noisy”—prior surgeries, Charcot neuroarthropathy, and marrow edema can make an MRI look positive even when an active infection is absent.
This study is the first to use paired bone biopsies to validate imaging performance both before and after antibiotic treatment.
Superiority at Initial Diagnosis
The head-to-head comparison between WBC SPECT/CT (which uses radiolabeled white blood cells to pinpoint active inflammation) and conventional MRI yielded a clear winner for the initial assessment. WBC SPECT/CT was significantly more accurate across the board:
- Sensitivity: 85% for WBC SPECT/CT vs. 73% for MRI.
- Specificity: 79% for WBC SPECT/CT vs. 43% for MRI.
- Positive Predictive Value (PPV): 90% vs. 75%.
- Negative Predictive Value (NPV): 69% vs. 40%.
The specificity gap is the headline here. MRI’s low specificity (43%) means it is often “too sensitive,” picking up bone stress or healing that isn’t actually an infection. WBC SPECT/CT, by contrast, provides a much “cleaner” signal by looking for the actual accumulation of immune cells.
Monitoring the Treatment Response
Knowing when to stop antibiotics is often a guessing game. After a 6–8 week course of therapy, the researchers re-imaged and re-biopsied the participants. At this follow-up stage:
- Equivalent Performance: Both modalities performed identically in their formal metrics (75% sensitivity and specificity).
- Clinical Correlation: Despite the identical numbers, WBC SPECT/CT better predicted long-term outcomes. Patients who were “negative” on follow-up SPECT/CT healed completely, whereas “positive” cases were more likely to face recurrent DFO or eventual amputation.
Why This Matters for Antibiotic Stewardship
Some often treat DFO for six weeks or longer based on tradition rather than hard data. This research shows that advanced imaging—specifically WBC SPECT/CT—can provide an objective indicator of therapeutic response.
By using these tools to confirm that an infection has resolved, we can move away from “one-size-fits-all” antibiotic durations. This not only improves patient safety by reducing drug toxicity but also helps combat the rise of multi-drug-resistant organisms in our patient population.
Prospective comparison of WBC SPECT/CT and conventional MRI for diagnosing osteomyelitis and monitoring treatment response in diabetic foot infections Authors: Orhan K. Öz, Amber M. Sherwood, Peter A. Crisologo, Amanda L. Killeen, Kavita Bhavan, Javier La Fontaine, Katie L. Rubitschung, Helena Hwang, Robert W. Haley, Lawrence A. Lavery
Journal: Diabetologia
DOI: https://doi.org/10.1007/s00125-025-06652-8
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