The role of FDG-PET imaging in detecting early Charcot's arthropathy in diabetic patients

Abstract

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Objectives: Early identification and treatment of Charcot's arthropathy (CA) in diabetic patients is essential for preventing deformity and decreased function of the lower extremities, as well as possible subsequent amputation. Early diagnosis of CA is made based on clinical criteria. When structural abnormalities are noted on conventional imaging, the pathological changes are relatively advanced. We hypothesize that FDG-PET imaging can accurately determine the joint inflammatory activity and therefore serve as a marker for identifying patients with early CA. Methods: FDG-PET imaging of the lower extremities was performed in 11 diabetic patients with clinical suspicion of CA and no evidence of infection, and in 12 patients with neuropathy (8 mild, 4 severe. PET images were acquired approximately one hour after the intravenous administration of FDG. Degree of neuropathy was determined by using the Michigan Neuropathy Screening Instrument (MNSI). MR images of the feet were also acquired according to standard institutional protocols soon before or after the PET scan. Regions of interest (ROI) were drawn both around the tibiotalar joint and the sinus tarsi and maximum SUV was measured. Long term clinical follow up served as the gold standard. Results: MRI detected structural changes related to CA in 7 of 11 patients. The mean SUV of the tibiotalar joint in patients with clinical suspicion of CA was 1.34±0.34 which was higher than that measured in patients without CA with mild (0.45±0.12, P<0.001) or severe neuropathy (0.92±0.18, P<0.01). SUV of the sinus tarsi was 1.47±0.57 in CA patients which was significantly higher than that in the mild (0.48±0.57, P<0.01) and severely neuropathic states (1.03±0.22, P<0.01). Conclusions: FDG-PET imaging detects inflammatory changes in the joint spaces of patients with clinical suspicion of CA and can complement information provided by clinical examination and other laboratory tests to diagnose CA and differentiate it from other complications of the diabetic foot.