Vertebral bone attenuation on low-dose chest CT: bone mineral density assessment and osteoporosis screening

Abstract

Abstract Summary Osteoporosis is prevalent worldwide, increasing the risk of fragility fracture and mortality in the elderly. This study showed that low-dose chest CT (LDCT) can be fully utilized to measure the HU of thoracic vertebrae to assess bone mineral density (BMD), allowing osteoporosis screening while diagnosing the original disease. Purpose This study aimed to determine whether the bone-attenuation value of the vertebral body measured by LDCT scan was correlated with BMD measured by dual-energy X-ray absorptiometry (DEXA), as well as to determine its value in BMD assessment and osteoporosis diagnosis. Methods Healthy people who underwent LDCT scan and DEXA from January 2019 to March 2020 at the physical examination center of the First Affiliated Hospital of Anhui Medical University were selected. A total of 140 patients were included and randomly selected according to age and gender. They were divided into seven groups by 10-year age intervals from 20 to 90 years old, with each age group having 10 men and 10 women. Five vertebral bodies (T4, T6, T8, T10, and T12) were selected from chest CT to measure the bone-attenuation value (Hounsfield unit, HU) of the maximum ROI of the three sections of each vertebral body to obtain the vertebral body, as well as to analyze the correlation between the HU and the BMD measured by DEXA. The HUs of T12 in the normal, low bone mass, and osteoporosis groups were calculated by referring to WHO classification criteria for bone mineral density. Cutoff values and respective sensitivity and specificity for the diagnosis of osteoporosis and bone-mass reduction were determined by plotting ROC curves. Results The mean HU of the thoracic spine measured by CT was 186.21±60.74 (58.45–318.44). T4, T6, T8, T10, and T12 had no statistically significant differences among the various segments, and all showed a linear downward trend with increased age. The mean HU of single or five thoracic vertebrae was significantly positively correlated with the bone mineral density and T-score of the lumbar spine, femoral neck, and total hip. According to the WHO classification criteria for bone mineral density, the mean HU of T12 in the normal, osteopenia and osteoporosis group were 216.45, 143.67 and 88.49 respectively. The HUs of the three groups were statistically different (p =0.000, t=53.000) When the mean HU of T12 was ≥158.08, it can distinguish between normal and low BMD, with a sensitivity of 87.2% and a specificity of 74.2%. When the mean HU of T12 was ≤123.30, it can distinguish between osteoporosis and non-osteoporosis, with a sensitivity of 83.7% and a specificity of 100%. Conclusions The HU of the vertebral body measured by LDCT is closely related to the BMD measured by DEXA. It can be used to assess BMD and diagnose osteoporosis. Therefore, it is a potential supplementary method for BMD measurement.