1. Imaging of Pedal Osteomyelitis
Timothy W. Deyer, MD
East River Medical Imaging

2. Osteomyelitis Clinical assessment limited
Only 32% (9/28) of pts with ulcers and osteomyelitis were clinically suspected of having osteomyelitis (Newman et al. JAMA 1991)
Poor inter-observer agreement based on clinical exam in pts with ulcers (Edelman et al. J Gen Intern Med 1997)
Probing to bone is only 66% sensitive (Grayson et al. JAMA 1995)
In patients with ulcer and osteomyelitis will only probe to bone in 66%

3. Osteomyelitis
Early identification of osteomyelitis important for patient management and prognosis

4. Ultrasound X-rays MRI CT Gadolinium Bone Scan WBC Scan Marrow Scan
Radiology
Ultrasound
X-rays
MRI CT
Gadolinium
Bone Scan
WBC Scan
Marrow Scan

5. ACR Recommendations for Pedal Osteomyelitis in Diabetics (2008)
X-ray, MRI, Nuclear Medicine, CT, Ultrasound
Evidence based recommendations
6 different clinical situations
(-) neuroarthropathy with increasing soft tissue involvement
(+) neuroarthropathy with increasing soft tissue involvement

6. ACR Recommendations (2008)
No neuroarthropathy
Soft tissue edema, no ulceration
Ulcer without exposed bone
Ulcer with exposed bone
Neuroarthropathy

7. Soft tissue edema without ulceration or neuroarthropathy

8. Ulcer without exposed bone or neuropathy

9. Ulcer with exposed bone without neuropathy

10. Neuroarthopathy without ulceration

11. Neuroarthropathy with ulcer without exposed bone

12. Neuroarthropathy with ulcer with exposed bone

13. Suspicion of Osteomyelitis
Conclusion
Ulcer with
Bone
X-Ray -
High
Suspicion +
MRI +/- Gad
Suspicion of Osteomyelitis
Osteomyelitis
Moderate +
Soft Tissue
Swelling
X-Ray
Bone scan
No/Low

14. Why? MRI has the highest sensitivity and specificity
Wrobel and Connolly J Am Pod Med Assoc 1998
Radiographs 54% sens, 80% spec
99mTC BS 91% sens, 46% spec
In 111 WBC 88% sens, 82% spec
MRI 92% sens, 84% spec
Meta-analysis of studies from 1960 to 2006 (Kapoor et al ARCH INTERN MED/VOL 167, JAN 22, 2007)
“Magnetic resonance imaging performance was markedly superior to that of technetium 99m bone scanning, plain radiography, and white blood cell studies”
Diagnostic odds ratio:
Tc 99m Bone Scanning: 7 studies—149.9 vs 3.6
Plain radiography: 9 studies—81.5 vs 3.3
White blood cell studies: 3 studies—120.3 vs 3.4

15. Do I need Gadolinium? Does not increase sensitivity for osteomyelitis
Improves
Soft tissue evaluation
Abscesses
Sinus tracts
Assessment of tissue viability
Contraindications
Poor renal function (CrCl<30)
NSF-nephrogenic systemic fibrosis
Tan et al, The British Journal of Radiology, 80 (2007), 939–948

16. MRI of Osteomyelitis Primary signs Secondary signs Bone marrow edema
Bone marrow enhancement
Secondary signs
Cortical destruction
Periosteal reaction
Intra-osseous abscess
Ulceration
Sinus tract formation
Abscess

17. Case 1
Bone marrow edema
Cortical destruction
Ulceration

18. Case 1
Cortical destruction
Ulceration

19. Case 1
Bone marrow enhancement

20. Case 2 Bone marrow edema Ulceration with exposed bone
Cortical destruction

21. Case 2
Bone marrow edema
Sequestrum
Cortical destruction

22. Case 3
Bone marrow edema
Cortical destruction
Sinus tract

23. Case 3
Cortical destruction
Sinus tract

24. Case 3
Enhancing bone marrow
Cortical destruction
Sinus tract

25. Osteomyelitis vs. Neuroarthropathy
Contiguous spread of infection from the skin
Neuroarthropathy
Primarily a joint process

26. Osteomyelitis vs. Neuroarthropathy
Bone marrow signal
High T2, Low T1, Enhancement
Acute: mimics osteo
Chronic: normal or low
Bone marrow pattern
Single bone
Periarticular
Distribution
Focal
Several joints
Typical location
Wt bearing, toes, metatarsal heads, calcaneus
Midfoot
Deformity
Usually none without underlying neuroarthropathy
Deformity common with bony debris
Soft tissue changes
Associated with ulcer, abscess or sinus tract
Skin intact but edematous
Tan et al, The British Journal of Radiology, 80 (2007), 939–948

27. Neuroarthropathy Midfoot - Centered at tarsometatarsal joints
Osseous destruction and proliferation
Tarsal disorganization

28. Neuroarthropathy Bone marrow edema
Midfoot - centered at tarsometatarsal joints
Soft tissues not involved

29. Neuroarthropathy with Superimposed Osteomyelitis
Challenging diagnosis
Secondary signs of osteomyelitis most helpful
Sinus tract
Fat infiltration
Abscess
Joint fluid enhancement
Follow up MRI can be helpul
Increasing erosions
Increasing marrow edema
Disappearing subchondral cysts
Ahmadi ME et al. Radiology 2006;238:622–31.

30. Neuroarthropathy with Superimposed Osteomyelitis
MR images show development of a sinus tract. (a) Sagittal T1-weighted fat-suppressed postcontrast fast multiplanar spoiled GRE image (230/2) obtained in a 60-year-old man with neuropathic arthropathy of the midfoot and hindfoot shows multiple joint subluxations with subcutaneous enhancement only (arrow). (b) Twelve months later the patient presented with a draining plantar ulcer; another sagittal T1-weighted fat-suppressed postcontrast fast multiplanar spoiled GRE image (280/2) shows a tram-track pattern of soft-tissue enhancement representing a sinus tract (arrowheads) leading to the cuboid (arrow), which demonstrates enhancement proved to represent osteomyelitis at surgery.
Ahmadi M E et al. Radiology 2006;238:
©2006 by Radiological Society of North America

31. Conclusion Current ACR recommendations
X-ray
MRI
MRI is most sensitive and specific test
Gadolinium
No improvement of osteomyelitis detection
Improved detection of concomitant soft tissue processes
Neuroarthropathy
Often can be differentiated from osteomyelitis by MRI

32. Questions?
Thank You