Application Of Thoracic And Abdominal CT In Opportunistic Screening Of Osteoporosis In Patients With Rheumatoid Arthritis

Objective:To explore the attenuation of CT derived from abdominal CT and the evaluation of vertebral fracture grade in patients with rheumatoid arthritis(Rheumatoid arthritis,RA).On the premise of taking the results of dual energy X-ray absorptiometry(Dual-energy X-ray absorptiometry instruments,DXA)as the gold standard,the applied study on the screening of osteoporosis and the correlation of the attenuation of CT attenuation of L1 vertebral body were studied.Methods:A total of 95 patients who met the clinical ACR/EULAR diagnostic criteria of rheumatoid arthritis were collected.All patients underwent DXA and spiral CT scans within three months.Osteoporosis group and non-osteoporosis group were defined according to the results of DXA;osteoporotic vertebral fracture group and non-osteoporotic vertebral fracture group were defined according to the evaluation of vertebral fracture and previous fracture history;osteoporotic fracture(vertebral and/or non-vertebral body)and non-osteoporotic fracture group were defined.The(Region of interest,ROI of L1 vertebral body was delineated on the axis of thoracic and abdominal CT images.The CT value,that is,the CT attenuation value of L1vertebral body,was measured.On the reconstructed sagittal images,the most effective and widely used semi-quantitative Genant analysis method in vertebral fracture evaluation(Vertebral fracture assessment,VFA)method was used to evaluate the fracture grade of thoracolumbar vertebrae(T4-L4).In order to provide a comprehensive opportunistic screening method for improving the screening rate of osteoporosis.Results1.Compared with the non-osteoporotic group,the CT attenuation value of L1vertebral body in the RA osteoporosis group decreased significantly and the age increased,and the difference was statistically significant(P<0.05).Compared with the non-osteoporotic fracture group,the CT attenuation value of the L1 vertebral body in the RA osteoporotic fracture group was significantly lower and the age was higher than that in the non-osteoporotic fracture group.2.The course of disease in RA osteoporosis group was longer than that in non-osteoporosis group.Female,menopause and hormone therapy significantly affected the loss of BMD.3.The cut-off value of CT attenuation value of L1 vertebral body for predicting osteoporosis was 113.5HU,AUC=0.792,sensitivity=0.614,specificity=0.868,which could screen out osteoporosis patients with 82.09%(55/67)osteoporosis.The cut-off value of CT attenuation of L1 vertebral body for predicting osteoporotic fracture was 75.5 HU,AUC 0.740,sensitivity=0.973,specificity=0.448,and osteoporotic fracture could be screened out in 46.6%(27/58)RA patients.4.Compared with the detection rate of osteoporosis screened by DXA,the detection rate of osteoporosis diagnosed by Genant semi-quantitative analysis of vertebral fracture grade was significantly higher than that of osteoporosis(56.7%).The detection rate of severe osteoporosis was 43.3%(29/67).5.The CT attenuation of 5.L1 vertebrae was negatively correlated with age,BMI and the course of disease,respectively.Age(r=0.652,P<0.001),BMI(r=0.498,P<0.001),and course of disease(r=0.218,P<0.034),but had no significant correlation with RF+,CCP+,DSA28,ESR and so on.6.Multiple linear regression analysis showed that CT attenuation value of L1vertebral body=387.337-2.243*Age-6.106*BMI-14.579*N(N=1 or 0),R~2=0.577(P<0.05).Conclusion:1.The CT attenuation value of L1 vertebral body derived from thoracic and abdominal CT scan has a good diagnostic efficacy in the diagnosis of osteoporosis and osteoporotic fracture in patients with RA.Combined with Genant semi-quantitative analysis to evaluate the grade of vertebral fracture provides a comprehensive opportunistic screening for osteoporosis and severe osteoporosis,and significantly improves the detection rate of osteoporosis.2.The CT attenuation value of 2.L1 vertebral body was negatively correlated with the age,BMI and climacteric status of RA patients,the CT attenuation value of L1 vertebral body decreased 2.243HU and 6.106 Hu with the increase of age and BMI of RA patients,and the CT attenuation value of L1 vertebral body of climacteric RA patients decreased significantly(P<0.05).