CT Quantitative Evaluation Of Thoracic Vertebral Bone Mineral Density In COPD Patients

Objective:1.To investigate the correlation between CT value of thoracic vertebral body and bone mineral density in adult male.2.To evaluate the value of chest CT images in evaluating osteoporosis.3.To explore the quantitative evaluation of BMD status of patients with chronic obstructive pulmonary disease by vertebral CT values measured by chest CT,and analyze the correlation between BMD status and clinical variables of patients.Methods:Part I:We analysed 93 male patients who received spiral chest CT and dual energy X-ray absorption（DXA）bone mineral density examination in Bethune Hospital of Shanxi Province in 2020 retrospectively.DXA was used as a reference standard to evaluate the feasibility of thoracic vertebral CT value for BMD evaluation and determine the optimal measuring vertebral body for the diagnosis of osteopenia or osteoporosis by measuring thoracic 1-12 vertebral body CT value.The CT values of thoracic 1 to 12 vertebral bodies were measured using an image post-processing workstation.Using bone mineral density t-score measured by DXA as the standard,patients were divided into normal bone mineral density group,osteopenia group and osteoporosis group.The CT mean difference of each vertebral body from thoracic 1 to thoracic 12 among each group and the correlation between CT value of each vertebral body and lumbar BMD measured by DXA were analyzed and compared.Part II:We analysed 107 male patients with clinically confirmed COPD in Shanxi Bethune Hospital from 2015 to 2021 retrospectively.CT values of the best measured vertebral bodies determined by the results of part I were measured by image post-processing workstation,and the thoracic vertebral BMD was evaluated by CT values.The percentage of FEV₁in the lung function test results to the predicted value was divided into 4 groups.Analysis of whether there is a significant difference in BMD between the 4groups of patients,and the correlation between thoracic BMD and clinical variables(age,BMI,FEV₁,FEV₁/FVC,FEV₁%of predicted value,carbon monoxide dispersion(DL_CO),and emphysema index（EI）were analyzed.Results:The mean CT values of thoracic vertebrae from 1 to 12 in osteoporosis group were significantly lower than those in normal BMD group and reduced BMD group（P<0.05）.CT values of thoracic 1-12 vertebral body were positively correlated with T-Score measured by DXA（r>0,P<0.05）,and the correlation coefficient of thoracic 9 vertebral body was the largest（0.617）.Receiver operating characteristic（ROC）curve was used to analyze the diagnostic value of CT values of thoracic 1-thoracic 12 vertebrae for osteoporosis.It was found that the AUC value of thoracic 9 vertebrae was the highest,and the decrease of CT values of thoracic 9 vertebrae below 153HU was highly suggestive of osteopenia or osteoporosis by calculating the Yoden index.There were significant differences in thoracic BMD between different grades of the Global Initiative for Chronic Obstructive Pulmonary Disease（GOLD）;BMD of thoracic vertebrae was positively correlated with BMI,FEV₁/FVC,DLco and FEV₁,but negatively correlated with age and EI（P<0.05）.Conclusion:It is a simple and feasible method to evaluate bone mineral density of COPD patients by thoracic CT values measured on chest CT,which has certain clinical application value.There were significant differences in thoracic bone mineral density between different grades of GOLD,and thoracic bone mineral density was slightly correlated with clinical variables and quantitative CT variables of COPD.