Title: Potential role of FDG PET in the setting of diabetic neuro-osteoarthropathy: can it differentiate uncomplicated Charcot’s neuroarthropathy from Osteomyelitis and soft-tissue infection?
Authors: Sandip Basu, Timothy Chryssikos, Mohamed Houseni, D. Scot Malay, Jagruti Shah, Hongming Zhuang and Abass Alavi
Source: Nuclear Medicine Communications. 2007; 28: 465-472
PODIATRIC RELEVANCE:
Differentiating osteomyelitis from Charcot deformity has proven to be both a clinical and radiographic challenge for foot and ankle surgeons. Among the various imaging modalities, the fluorodeoxyglucose positron emission tomography scan (FDG PET) is becoming more useful, and possibly superior, in diagnosing and differentiating between acute Charcot neuroarthropathy, osteomyelitis (OM), and soft tissue infections (STI) in complicated diabetic foot. FDG is most commonly used in the medical imaging modality positron emission tomography. After FDG is injected into a patient, a PET scanner can form images of the distribution of FDG around the body. The images can be assessed by a radiologist to provide diagnoses of various medical conditions. The objective of this prospective study is to show whether FDG PET demonstrates a specific uptake pattern in Charcot’s neuroarthropathy and, if so, whether that could be utilized to differentiate it from diabetic foot infections like OM and cellulitis. In addition, the authors sought to determine if this technique exhibits any superiority over MRI diagnosing these conditions.
METHODS:
A total of 63 patients were divided into 4 groups: the first group contained 17 diabetics with suspected Charcot neuroarthropathy; the second group contained 5 diabetics with proven OM; the third group contained 21 diabetics without any acuted disease processes; the fourth group consisted of 20 non-diabetics who had undergone FDG PET studies for other purposes but had no abnormal findings in their feet. Each group underwent FDG PET imaging of the lower extremities in addition to MRI and findings were compared to the final diagnostic outcome based on histopathology and clinical follow-up. The images were examined visually for focal abnormalities.
RESULTS:
In the first group, 16 out of 17 cases with suspected Charcot neuroarthropathy based on FDG PET scans were proven to suffer from the disorder, while one case was proven to have Charcot foot with superimposed osteomyelitis. In contrast, MRI only confirmed 10/17 cases of neuroarthropathy. In 3 cases of proven Charcot disease, neither MRI nor plain film examination suggested either Charcot or infection, whereas PET was most consistent indicator Charcot’s foot in all 3 cases. The overall sensitivity and accuracy of FDG PET in the diagnosis of Charcot’s foot was 100% and 93.8%, respectively, and only 76.9% and 75%, respectively for MRI. In the osteomyelitis group both MRI and FDG PET demonstrated a 100% ability to diagnose OM. Of the 7 diabetics that demonstrated a final diagnostic outcome of soft tissue infection, 2 of the 7 were accurately diagnosed with MRI while 5 of 7 demonstrated a positive FDG PET scan.
COMMENTS:
This prospective study establishes the potential role of FDG PET and shows its superiority to MRI in diagnosing and differentiating between Charcot neuroarthropathy, osteomyelitis and soft tissue infections. One of the shortcomings of the study was the relatively small number of diabetics with osteomyelitis. A large scale trial of FDG PET in the evaluation and management of these conditions is warranted.
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Disclaimer:
Scientific Abstract Monthly postings are submitted by podiatric surgical residents. The ideas presented are not the opinions of the American College of Foot and Ankle Surgeons (ACFAS), nor are they presented as facts. ACFAS presents this information without any warranty of any kind, expressed or implied, and is not liable for its accuracy nor for any loss or damage caused by the user's reliance on information obtained in these areas.