Indexing Severity of Diabetic Foot Infection With 99mTc-WBC SPECT/CT Hybrid Imaging
- William A. Erdman, MD1⇓,
- Ji Buethe, MD2,
- Rafia Bhore, PHD3,
- Hans K. Ghayee, DO2,
- Chiarra Thompson, MD1,
- Param Maewal, MD1,
- Jon Anderson, PHD1,
- Steve Klemow, MD2 and
- Orhan K. Oz, MD, PHD1
- 1Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas
- 2Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- 3Department of Clinical Sciences–Biostatistics, University of Texas Southwestern Medical Center, Dallas, Texas
- Corresponding author: William A. Erdman, .
OBJECTIVE Management of diabetic foot infection (DFI) has been hampered by limited means of accurately classifying disease severity. New hybrid nuclear/computed tomography (CT) imaging techniques elucidate a combination of wound infection parameters not previously evaluated as outcome prognosticators. Our aim is to determine if a novel standardized hybrid image–based scoring system, Composite Severity Index (CSI), has prognostic value in DFI.
RESEARCH DESIGN AND METHODS Masked retrospective 99mTc-white blood cell (WBC) single photon emission CT (SPECT)/CT image interpretation and independent chart review of 77 patients (101 feet) suspected of DFI-associated osteomyelitis at a large municipal hospital between January 2007 and July 2009. CSI scores were correlated with probability of favorable outcome (no subsequent amputation/readmission after therapeutic intervention) during median 342-day follow-up.
RESULTS CSI ranged from 0–13. Receiver operating characteristic accuracy for predicting favorable outcome was 0.79 (optimal cutoff CSI, ≤2; odds ratio of therapeutic failure for CSI >2, 15.1 [95% CI 4.4–51.5]). CSI of 0 had a 92% chance of favorable outcome, which fell progressively to 25% as indices rose to ≥7. Image-based osteomyelitis versus no osteomyelitis assessment was less accurate than CSI at predicting outcome (P = 0.016). In patients with intermediate severity (CSI 3–6), treatment failure decreased from 68 to 36% when antibiotic duration was extended to ≥42 days (P = 0.026).
CONCLUSIONS 99mTc-WBC SPECT/CT hybrid image–derived wound infection parameters incorporated into a standardized scoring system, CSI, has prognostic value in DFI.
This article contains Supplementary Data online at http://care.diabetesjournals.org/lookup/suppl/doi:10.2337/dc11-2425/-/DC1.
- Received December 13, 2011.
- Accepted April 10, 2012.
- © 2012 by the American Diabetes Association.
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