Preliminary Study On The Diagnostic Value Of Dual-energy CT Of Urate Deposition In The Foot And Ankle In Subclinical Gout And Its Correlation With Disease Duration And Laboratory Tests

Objective:To explore the distribution characteristics of MSU crystals in the foot and ankle of subclinical gout,and the correlation between the total volume of crystals in the foot and ankle and biochemical indexes and the course of disease.The factors affecting the detection of MSU crystals by DECT were discussed,and the prediction model of MSU crystals detected by DECT in subclinical gout stage was established.Materials and methods:The DECT examination,biochemical indexes and course of disease of 171 patients with asymptomatic hyperuricemia were analyzed retrospectively.Record whether MSU crystals were detected in the foot-ankle,crystal distribution and total crystal volume.The differences of involvement between the same parts of both sides and the distribution of crystals between the dorsum of foot and tibiofibular side of the same joint and whole foot were compared;The correlation between the total volume of foot-ankle crystals,biochemical indexes and course of disease was calculated;Logistic analysis was used to analyze the factors affecting the detection of foot and ankle MSU crystals by DECT,and the best cut-off value was calculated to establish a model for predicting the detection of foot and ankle MSU crystals by DECT in patients with asymptomatic hyperuricemia,Hosmer-lemeshow test was used to evaluate the effectiveness of the model.Results:Among 171 patients with asymptomatic hyperuricemia,113 cases had MSU crystal deposition in the foot-ankle,and MSU crystals existed in the surrounding soft tissue.(1)There was no significant difference in the involvement of the same parts on both sides(P>0.05).The most easily deposited part was the tibial side of MTP-1(83,73.45%).There were differences in the distribution of crystals between the dorsal and plantar sides and between the tibial and fibular sides of the whole foot(P<0.05).(2)SUA value[535(478-596)μmol/L,H=-2.001,P=0.045],ESR value[9(6-19)mm/h,H=-5.289,P<0.001],duration of disease[60(35-120)months,H=-4.869,P<0.001]of positive group were greater than negative group,GFR value[90.813(76.265-104.807)ml/min·1.73m2,H=-2.721,P=0.007]was less than negative group.(3)The total volume of foot-ankle was positively correlated with SUA(r=0.215,P=0.022),ESR(r=0.292,P=0.002)and course of disease(r=0.200,P=0.034),and negatively correlated with GFR(r=-0.225,P=0.017).(4)The risk factors of MSU crystal deposition in feet and ankles of patients with asymptomatic hyperuricemia detected by DECT were SUA(OR=1.005,P=0.028),ESR(OR=1.049,P=0.010),course of disease(OR=1.017,P<0.001).The best cut-off values were 508.5μmol/L,5.5 mm/h,42 months.Hosmer lemeshow test of prediction model P=0.643>0.05,and the predicted value of the model can better reflect the actual observation value.Conclusion:The most easily detected MSU crystal deposition site in the foot and ankle of subclinical gout is the tibial soft tissue of MTP-1.The deposition is more likely in the dorsal side of the foot than the plantar side and the tibial side than the fibular side.The imaging examination should focus on the above parts to avoid missed diagnosis.SUA value,ESR value,GFR value and duration of disease in patients with subclinical gout were correlated with the total volume of foot and ankle crystals.The increase of course time,UA value and ESR value will increase the risk of detecting MSU crystal deposition in the foot and ankle by DECT.Patients with such characteristics should have early imaging screening and early diagnosis and treatment of subclinical gout.