To Evaluate the Value of Vertebral Body Cortical Thickness in Predicting Osteoporosis by Opportunistic CT

In vertebrae, the amount of cortical bone has been estimated at 30-60%, but 45-75% of axial load on a vertebral body is borne by cortical bone (1).The purpose of this study is to investigate the accuracy, sensitivity, specificity, positive predictive value and negative predictive value of vertebral body cortical thickness in predicting osteoporosis (OP) by analyzing the relationship between vertebral body cortical thickness and bone mineral density (BMD) in different age and gender groups. The optimal diagnostic cut-off value of vertebral body cortical thickness in predicting OP was analyzed.The data of 150 patients (50-89 years old) who underwent chest or abdominal Quantitative computed tomography (QCT) scan (obtained in one scan) in our hospital from July 2021 to July 2022 were retrospectively analyzed. The average volume bone mineral density (vBMD) of L1-L2 vertebral bodies was obtained and grouped according to BMD, age, and gender. According to BMD, the patients were divided into three groups: osteoporosis, osteopenia and normal. According to age, the patients were divided into three groups: 50-59 years, 60-69 years and ≥70 years. The axial images of T11, T12 and L1 were reconstructed with 1.25 mm slice thickness by AW4.7 workstation provided by General Electric Co (GE) Company. The images were imported into the computed tomography (CT) Spine Bone Quantification System software for spine analysis, and the vertebral body cortical thickness values were obtained. CT Spine Bone Quantification System is a software for quantitative analysis and separation of cortical bone and cancellous bone.A total of 150 patients were enrolled in this study, including 49 patients in the osteoporosis group, 51 patients in the osteopenia group, and 50 patients in the normal group. The cortical thickness values of T11, T12 and L1 were positively correlated with BMD, and the correlation coefficient was 0.750 at T11. According to the receiver operating characteristic (ROC) curve analysis of T11, T12, L1 cortical thickness value and BMD, OP was diagnosed when T11 < 2.75 mm, T12 < 3.06 mm, and L1 < 2.67 mm. The sensitivity was 83.67%, 87.76%, 75.51%, respectively. The specificity was 79.21%, 71.29% and 90.10%, respectively, and the difference was statistically significant.Vertebral body cortical thickness is correlated with BMD and age. According to the cut-off value of different vertebral bodies, OP can be predicted when T11 < 2.75 mm or T12 < 3.06 mm or L1 < 2.67 mm.