Background Ultrasonography (US), magnetic resonance imaging (MRI), computed tomography (CT), and X-ray are the alternative diagnostic modalities used to identify affected joints and surrounding tissues (tophi, erosions and synovitis) in gout patients, but the potential of each method for sequential assessment of disease regression in pts receiving urate-lowering therapy is not sufficiently studied 
Objectives Comparison of US, CT, X-ray and MRI efficacy for sequential assessment of affected joints in pts treated with urate-lowering agents.
Methods The open prospective study was conducted in 2013–2015 yy at V.A. Nasonova Research Institute of Rheumatology. 22 pts with crystal-verified gout (4 (15%) f and 18 (85%) m), mean age – 54,5±12,7 years, were included. The dose of allopurinol administered in all pts was adjusted by titration starting from 100 mg/day. Instrumental diagnostic examination (US, MRI, CT and plain X-ray of knee joints) was performed at baseline and after one year of follow up. US of knee joints was performed using multi-frequency linear array transducer, at 7 to 17 MHz frequencies; for MRI examination “Esaote Artrosan 0.25TI” was used, GE “Light Speed” - for CT scans, and Stephanix – for plain X-ray examination. Applied descriptive statistics STATISTICA 10.0 (StatSoft/Inc., USA) package was used for statistical analysis.
Results Mean serum level of uric acid decreased from 568±115 μmol/l to 302±135 μmol/l. The target level (<360 μmol/l) was achieved in 20 pts (91%), (<300 μmol/l) was achieved in 11 pts (50%). Median allopurinol dose was 400 [300; 600] mg/day, 9 (45%) pts had to take 600 mg/day and more. At baseline US examination detected periarticular tophi in 13 (59%) pts, MRI - in 6 (28%) pts, CT in 3 (14%), X-ray - 1 (5%) pts, after one year - by US in 9 (41%) pts and MRI - 3 (14%) pts, CT in 2 (9%), X-ray - 1 (5%) pts. At baseline intraosseous tophi were detected only by CT and X-ray in 18 (81%) and 2 (9%) pts respectively, after one year 17 (77%) pts and 3 (14%) pts respectively. At baseline erosions were detected in 19 (86%) pts by MRI, in 11 (50%) pts – by US, in 14 (65%) pts – by CT, and in 9 pts (41%) – by X-ray, after one year in 14 (64%) pts by MRI, 10 (45%) pts by US, 12 (54%) pts by CT, 8 (36%) pts by X-ray. At baseline synovitis was reliably diagnosed by MRI and US: in 15 (68%) pts and 17 (77%) pts, after one year in 2 (9%) pts and 3 (14%) pts respectively
Conclusions MRI and US, as for synovitis, erosions and tophi dynamics, are comparable, at that for erosions MRI is more accurate. CT is the most informative approach to monitor intraosseous tohhi regression. X-ray is low- informative modality for sequential assessment of gout.
Grainger R, Dalbeth N, Keen H, et al. Imaging as an outcome measure in gout studies: report from the OMERACT gout working group. J Rheumatol 2015; 42(12):2460e4.
Disclosure of Interest None declared