Should I order a CT scan of the right leg in a diabetic patient with a warm skin wound and normal white blood cell (WBC) count?

Should You Order a CT Scan for This Diabetic Leg Wound?

No, do not order a CT scan of the leg—start with plain X-rays, and if advanced imaging is needed, MRI or nuclear medicine studies (WBC scintigraphy or FDG PET/CT) are the appropriate choices, not CT. 1

Initial Imaging Approach

Begin with plain radiographs (X-rays) as your first-line imaging study for any diabetic patient with a foot or leg wound, even with normal WBC count. 1, 2 This is the standard initial step in the diagnostic algorithm for diabetic wound complications.

Clinical Assessment First

Before ordering any imaging, perform these specific evaluations:

• Probe-to-bone (PTB) test: Use a sterile probe to determine if bone can be palpated through the wound 1
• Measure erythrocyte sedimentation rate (ESR): This is more useful than WBC count for diabetic foot infections 1
• Assess for local inflammatory signs: Warmth alone is not sufficient—look for erythema, purulent drainage, and wound depth 1

Important caveat: Normal WBC count does NOT rule out osteomyelitis or soft tissue infection in diabetic patients. 1 ESR is a more reliable inflammatory marker in this population.

When Advanced Imaging Is Needed

If plain X-rays are positive AND you have a positive PTB test AND elevated ESR, no further imaging is required—treat presumptively for osteomyelitis. 1

If plain X-rays are negative but clinical suspicion remains high, proceed to advanced imaging with: 1

1. MRI (first choice—widely available, radiation-free) 1
2. WBC scintigraphy with SPECT/CT (if MRI contraindicated or equivocal) 1
3. FDG PET/CT (alternative to WBC scan) 1

Why CT Scan Is Not Appropriate

CT is not mentioned in any evidence-based guidelines for diabetic wound evaluation. 1 The diagnostic algorithm specifically recommends:

• Plain radiography → MRI or nuclear medicine studies 1, 2
• CT provides inferior soft tissue characterization compared to MRI 1
• CT exposes patients to radiation without the diagnostic advantages of MRI or functional imaging 1

Specific Considerations for Your Patient

Given your patient has:

• Warm skin (suggests inflammation)
• Normal WBC (unreliable marker in diabetic foot infections)
• Diabetes (high-risk for complications)

Your diagnostic pathway should be:

1. Perform PTB test and order ESR (not just WBC) 1
2. Order plain X-rays of the right leg/foot 1, 2
3. If X-rays are negative but PTB positive or ESR elevated, order MRI or WBC scintigraphy 1
4. If MRI results are equivocal, proceed to WBC SPECT/CT or FDG PET/CT 1

Critical Pitfalls to Avoid

• Do not rely on normal WBC count to exclude infection—diabetic patients often have normal WBC despite significant infection 1
• Do not skip plain X-rays—they may show diagnostic changes and are required as the first step 1, 2
• Do not order CT scan—it is not part of the evidence-based diagnostic algorithm for diabetic wounds 1
• Plain X-rays can take weeks to show changes—if negative but clinical suspicion high, proceed directly to advanced imaging 1

When to Consider Advanced Imaging Urgently

Order MRI or nuclear medicine studies when you need to: 1

• Assess the extent and severity of infection for surgical planning
• Differentiate osteomyelitis from soft tissue infection alone
• Evaluate for abscess formation requiring drainage 1
• Rule out Charcot arthropathy with superimposed infection 1

The warm skin in your patient suggests active inflammation, making timely advanced imaging important if plain films are negative or equivocal. 1, 3, 4