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Diabetes-Related Foot Pathology
High morbidity Lifetime ulcer risk for diabetics 25% Nearly all diabetes-related foot infection
secondary from ulcer
Nothing To Disclosure
MRI Sensitivity & Specificity Osteomyelitis of Diabetic Feet
1995 (no Gd): 82% sensitivity, 80% specificity 1997 (with Gd): 90% sensitivity, 70% specificity
no effect of Gd (disputes earlier data)
2007 (no Gd): 90% senisitivity, 83% specificity
MRI Primary Findings
Marrow signal (HIGH STIR/T2 & LOW T1)* Gd Marrow enhancement
Ulcer or sinus tract leading to bone with abnormal
marrow signal Presence of abscess
MRI Secondary Signs
Cellulitis Foreign body Periosteal reacton
Osteomyelitis vs. Neuropathic Charcot
Marrow signal change
Single bone Diffuse infiltration Minimal deformity Ulcer, sinus tract, abscess Wgt. bearing: fore/hind
foot
Marrow signal change Multiple bones Periarticular &
subchondral Deformity with bone
debris Edema but intact skin Non-wgt. bearing:
midfoot
Osteomyelitis Neuropathic Charcot
Location, Location, Location
Neuroarthopathy (Charcot)--MIDFOOT: Tarsal-Tarsal Tarsometatarsal (TMT)
Osteomyelitis FORE & HINDFOOT: Distal to tarsometatarsal Calcaneus Malleoli
Distal phalangeal osteomyelitis
Low T1 signal
Distal phalangeal osteomyelitis
High T2 signal
Distal phalangeal osteomyelitis
Gd enhancement
Metatarsal head osteomyelitis with sinus tract
Forefoot osteomyelitis with contiguous abscess
Abscess and Osteomyelitis
20% of osteomyelitis are + for soft tissue abscess 100% correlation with osteomyelitis (same as sinus
tract) Abscess more common in post surgical foot 50% of all abscesses in fore foot and are directly
contiguous Mid/Hind foot abscess may be remote from site of
osteomyelitis
Calcaneus osteomyelitis with sinus tract and abscess
Osteomyelitis with intramedullary bone abscess of talus
Osteomyelitis: confluent, geographic medullary distribution
No osteomyelitis: Ulcer with minimal subcortical T1/T2 signal
Osteomyelitis: ulcer with confluent abnomal T1 signal
No osteomyelitis: T1 “hazy” pattern
No osteomyelitis: T1 reticulated pattern
Neuropathic arthropathy of midfoot
Neuropathic arthropathy of midfoot
Neuropathic arthropathy with superimposed osteomyelitis
Bone Biopsy
For histological proven osteomyelitis, positive rate of percutaneous biopsy: 50% 42% 34% (largest study)
Bone Biopsy
Aspiration of > 2cc’s purulent fluid—83% positive osteomyelitis rate.
Risk of seeding uninfected tissue. Utility of identifying an organism?
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