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 (D-Ca(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 D-Ca(Wa) of a chosen lumbar vertebra in adult women with spectral CT and the correlation between the D-Ca(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. D-Ca(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 D-Ca(Wa),D- age and BMD, as well as D-Ca(Wa) and BMD. Results There was a significant negative correlation between D-Ca(Wa) and age (r = -0.719) as well as BMD and age(r = -0.851). The mean D-Ca(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 D-Ca(Wa) and BMD. Conclusions The D-Ca(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.