An MRI assessment of chronic synovial-based inflammation in gout and its correlation with serum urate levels

It is unclear when the synovial-based inflammatory process of gout begins. The aim of this study was to determine the percentage of patients with inter-critical gout who have chronic synovial-based inflammation as evidenced by synovial pannus on a contrast-enhanced magnetic resonance imaging (MRI) of their most involved joint and determine if the presence and/or severity correlates with their serum urate levels. All patients received a 3 T MRI of their index joint, serum urate level, CRP, and creatinine. The primary endpoint was to determine the prevalence of synovial pannus and the correlation of serum urate levels with the presence and/or severity of the synovial pannus on that same joint. MRI erosions, tophi, swelling, effusion, and osteitis were also documented. Seventy-two of 74 subjects (90 % men) completed the protocol. Fifty-three of 72 (74 %) index joints were the first metatarsophalangeal joint. Thirty-nine (54.2 %) of the patients were on urate-lowering therapy; 15 (20.8 %) and 7 (9.7 %) were taking colchicine or a NSAID daily, respectively. Of the 72 subjects, 63 (87.5 %) had synovial pannus on their MRI with good inter-reader agreement between the two radiologists. The mean serum urate level was 7.93 mg/dL. There was no correlation with the presence (p = 0.33) or severity (p = 0.34) of synovial pannus and serum urate levels. There was also no correlation with the presence or severity of synovial pannus and the secondary endpoints. The majority of patients with inter-critical gout have evidence of chronic synovial-based inflammation. However, the presence and severity of this inflammation do not appear to correlate with serum urate levels.