The relationship between calcium (water) density and age distribution in adult women with spectral CT: initial result compared to bone mineral density by dual-energy X-ray absorptiometry

Background Calcium (water) density (DCa(Wa)) of gemstone spectral imaging by spectral computed tomography (CT) is a new method of evaluating bone structures. Purpose To investigate age-related change of DCa(Wa) of a chosen lumbar vertebra in adult women with spectral CT and the correlation between the DCa(Wa) and bone mineral density (BMD) of dual-energy X-ray absorptiometry (DXA). Material and Methods A total of 305 adult women underwent spectral CT, 127 of whom simultaneously underwent DXA. All the patients were divided into 11 subgroups based on age. DCa(Wa) and BMD were measured at the second lumbar vertebra on the calcium (water)-based material decomposition images of spectral CT and DXA, respectively. A one-way analysis of variance (ANOVA) was performed for the difference of the measurements among adjacent age subgroups. Pearson correlation was used to assess the association between age and DCa(Wa), age and BMD, as well as DCa(Wa) and BMD. Results There was a significant negative correlation between DCa(Wa) and age (r = −0.719) as well as BMD and age(r = −0.851). The mean DCa(Wa) of L2 vertebral body was significantly different between the 40–44- and 45–49-, 45–49- and 50–54-, 55–59- and 60–64-, 65–69- and 70–74-year-old age subgroups. BMD was significantly different between the 35–39- and 40–44-, 45–49- and 50–54-, and 65–69- and 70–74-year-old age subgroups. There was a significant positive correlation between DCa(Wa) and BMD. Conclusions The DCa(Wa) of lumbar vertebra by spectral CT demonstrated similar age distribution as BMD of DXA and could be used as a method of measuring the vertebral bone mineral density in adult women.