Diabetes-Related Foot Pathology High morbidity Lifetime ulcer risk - PowerPoint PPT Presentation

Diabetes-Related Foot Pathology  High morbidity  Lifetime ulcer risk for diabetics 25%  Nearly all diabetes-related foot infection secondary from ulcer

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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 Osteomyelitis Neuropathic Charcot  Marrow signal change  Marrow signal change  Multiple bones  Single bone  Periarticular &  Diffuse infiltration subchondral  Minimal deformity  Deformity with bone debris  Ulcer, sinus tract, abscess  Edema but intact skin  Wgt. bearing: fore/hind  Non-wgt. bearing: foot midfoot

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?