| Objective1. To investigate the high-frequency ultrasound and DECT findings of gouty arthritis (GA).2. To compare the clinical value of DECT with high-frequency ultrasound in diagnosing GA.Materials and Methods(1)Patients treated at the Department of Rheumatology, First Affiliated Hospital of Kunming Medical University between October 2013 and October 2014, who had complete clinical data and underwent joint ultrasound and/or DECT examination(s), were collected. These patients were divided into three groups according to the type of examination:1. ultrasound group:80 patients who underwent ultrasound examination were further divided into two groups according to clinical data and laboratory examination:(1) GA group:65 GA patients, with a total of 236 joints. (2) Control group:15 patients for whom GA was clinically excluded, with a total of 38 joints.2. DECT group:110 patients who underwent DECT examination were further divided into two groups according to clinical data and laboratory examination:(1) GA group:90 GA patients, with a total of 384 joints. (2) Control group:20 patients for whom GA was clinically excluded, with a total of 50 joints.3. DECT+ultrasound group:63 patients who underwent both types of examinations, with a total of 222 joints, were further divided into two groups:(1) GA group:51 GA patients, with a total 188 joints examined. (2) Control group:12 patients for whom GA was completely excluded, with a total 34 joints examined.1. ultrasound group:the following ten ultrasound indices were observed, and comparatively analyzed between GA and control groups:(1) synovial hyperplasia; (2) synovitis; (3) hyperechoic deposits in skin, muscle and tendon; (4) joint bone erosion; (5) double-contour sign (DCS); (6) joint effusion; (7) hyperechoic spots in the synovial fluid (HSSF); (8) hyperechoic cloudy areas (HCA); (9) hyperostosis; (10) tenosynovitis.2. DECT Group:the following five imaging manifestations were observed, and comparatively analyzed between GA and control groups:(1) bone destruction; (2) HCA; (3) joint space widening; (4) joint effusion; (5) urate deposits in periarticular soft tissues.3. DECT+ultrasound group:GA detection results of patients in two subgroups were compared with the clinical and laboratory gold standards, and the diagnostic sensitivity, specificity, false positive rate, false negative rate, positive predictive value and negative predictive value of the approach were calculated. Meanwhile, ROC curves were plotted, and the agreement between ultrasound and DECT for GA diagnosis was evaluated.Results1. ultrasound group:65 patients in the GA group, with a total of 236 joints; and 15 patients in the control group, with a total of 38 joints. Among the ten indices observed, the following four showed statistical significance (P<0.05):(1) spotty hyperechoic deposits in skin and muscles (75.0%); (2) bone erosion (21.6%); (3) DCS (78.8%); and (4) HCA (75.4%). The following six indices showed no significant difference compared with the control group (P>0.05):(1) synovial hyperplasia (27.5%); (2) synovitis (3.4%); (3) joint effusion (9.7%); (4) HSSF(5.9%); (5) hyperostosis (4.6%); (6) tenosynovitis (5.5%). Among the 80 GA patients,37 patients were diagnosed to be in the acute phase, and have synovitis and synovial hyperplasia (54%); whereas 43 patients were diagnosed to be in the chronic phase, and have bone erosion (65%). We found that the incidence of bone erosion was higher during the chronic phase, while the incidences of synovitis and synovial hyperplasia were higher during the acute phase.2. DECT group:GA group consisted of 90 GA patients, with a total of 384 joints, among the 110 patients who underwent DECT examination. Control group consisted of 20 patients, with a total of 50 joints. Indices of bone destruction, HCA and urate deposits in periarticular soft tissues in GA group were significantly different from the control group (P<0.05). No significant difference was found in the remaining observation indices, i.e. joint space widening and joint effusion, between the two groups (P>0.05). Among the 90 GA patients,20 were in the acute phase, and had joint effusion (76%); while 70 were in the chronic phase, and had joint effusion (15%). Patients in the acute phase were more susceptible to joint effusion than those in the chronic phase.3. Diagnostic accuracy of DECT for GA:Sensitivity (true positive rate)=74.5%, specificity (true negative rate)= 83.3%, false positive rate (misdiagnosis rate)=16.7%, false negative rate (missed diagnosis rate)=25.5%, positive predictive value=95.0%, and negative predictive value= 43.5%. Area under ROC curve was 0.713, with standard error of 0.074, P<0.014,95% CI 0.546-0.838, indicating moderate diagnostic value of CT, which is of some diagnostic value.4. Diagnostic accuracy of ultrasound for GA:Sensitivity (true positive rate)=96.1%, specificity (true negative rate)= 41.7%, false positive rate (misdiagnosis rate)= 58.3%, false negative rate (missed diagnosis rate)= 3.9%, positive predictive value= 87.5%, and negative predictive value= 71.4%. Area under ROC curve was 0.795, with standard error of 0.104, P<0.012,95%CI 0.590-0.999, indicating moderate diagnostic value of ultrasound, which is of some diagnostic value.5. Agreement between DECT and ultrasound for GA diagnosis:Kappa test, P<0.05, showing significant difference in agreement between the two diagnostic measures; K=0.196, indicating poor agreement between the two measures.Conclusion1. There are three characteristic signs for ultrasound findings of GA:(1) spotty hyperechoic bone erosion in skin and muscles; (2) DCS; and (3) HCA.2. DECT can not only show the GA-affected joints and urate crystal deposits, i.e. tophi, but can also clearly show the scope of urate deposition and status of bone destruction.3. Comparison of GA diagnostic accuracy between DECT and ultrasound demonstrate that specificity was higher for DECT, while sensitivity was higher for ultrasound. DECT has lower false positive rate, higher false negative rate, higher positive predictive value and lower negative predictive value than the ultrasound.4. Both DECT and ultrasound have some values in diagnosing GA, but ultrasound may have higher diagnostic value than DECT.5. Both DECT and ultrasound have their respective advantages in showing GA. DECT can better show the bone destruction and urate deposition, while ultrasound can provide more information on early stage GA. For some atypical cases, combined DECT and ultrasound examination can improve the diagnostic rate of GA. |
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