Background: The goal of this study is to demonstrate the feasibility of [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) for non-invasive visualization of muscular, neurovascular, and skin changes secondary to complex regional pain syndrome (CRPS).
Methods: Seven adult patients with CRPS in the lower extremity and seven healthy adult controls participated in our [18F]FDG PET/MRI study. All participants received whole-body PET/MRI scans one hour after the injection of 10mCi [18F]FDG. Resulting PET/MRI images were reviewed by two radiologists. Metabolic and anatomic abnormalities identified, were grouped into muscular, neurovascular, and skin lesions. The [18F]FDG uptake of each lesion was compared with that of corresponding areas in controls using a Mann-Whitney U-test.
Results: On PET images, muscular, neurovascular, and skin abnormalities were found in 5, 4 and 2 patients, respectively. However, on MRI images, no muscular abnormalities were detected. Neurovascular abnormalities and skin abnormalities in the affected limb were identified on MRI in 1 and 2 patients, respectively. The difference in [18F]FDG uptake between the patients and the controls was significant in muscle (p = 0.018) and neurovascular bundle (p = 0.0005).
Conclusions: The increased uptake of [18F]FDG in the symptomatic areas likely reflects the increased metabolism due to the inflammatory response causing pain. Therefore, our approach combining metabolic ([18F]FDG PET) and anatomic (MRI) imaging may offer non-invasive monitoring of the distribution and progression of inflammatory changes associated with CRPS.
Trial registration: ClinicalTrials.gov, NCT03195270. Registered 19 June 2017 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03195270