Indexing severity of diabetic foot infection with 99mTc-WBC SPECT/CT hybrid imaging.
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.


METHODS
Masked retrospective (99m)Tc-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
(99m)Tc-WBC SPECT/CT hybrid image-derived wound infection parameters incorporated into a standardized scoring system, CSI, has prognostic value in DFI.
Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA. william.erdman@utsouthwestern.edu
William A
WA
Erdman
Ji
J
Buethe
Rafia
R
Bhore
Hans K
HK
Ghayee
Chiarra
C
Thompson
Param
P
Maewal
Jon
J
Anderson
Steve
S
Klemow
Orhan K
OK
Oz
D017719:Diabetic Foot / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D012189:Retrospective Studies; D013669:Technetium Tc 99m Medronate; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D013669:Technetium Tc 99m Medronate