ObjectiveTo investigate the feasibility of dual-energy CT(DECT) virtual non-contrast scan in the quantitative evaluation of bone mineral density(BMD) measured by QCT as the gold standard in the absence of a body mode.

MethodsA retrospective study was performed on 100 patients with abdominal true non-contrast scan(TNC) and GSI three-phases enhanced scan, and the patients were randomly divided into the training set and validation set(50 cases in each set). The BMD value of L₁ vertebral body in two sets was measured using QCT Pro software. In the training set, the difference of L₁ vertebral CT value between conventional non-contrast scan image and GSI enhanced virtual non-contrast scan image in portal vein phase was compared, and the correlation between virtual non-contrast scan vertebral CT value and BMD value was determined. The regression model of virtual non-contrast scan vertebral CT value to predict BMD value was established through multiple regression analysis. The validation set was used to evaluate the accuracy of this equation in the diagnosis of osteoporosis and effectiveness of virtual non-contrast scan vertebral CT value in the diagnosis of osteoporosis.

ResultsThe CT value of L₁ vertebral body of VNC was lower than that of TNC(P < 0.01). After subtracting the TNC, the total radiation dose of image was reduced by 21.94%, the multiple linear regression model of CT value of VNC to predict BMD of L₁ vertebra was as follows: BMD=102.375+1.349×CT value-0.321×age-0.433×height(R²=0.979). The ROC curve analysis showed that the cut-off value of virtual non-contrast scan vertebral body CT value based on portal vein phase in the diagnosis of osteoporosis and osteopenia were 54.35 HU and 64.51 HU, respectively.

ConclusionsIn the case of independent body model, the DECT virtual non-contrast scan vertebral CT value can reliably measure the BMD, and the established predictive BMD model can quantitatively diagnose the osteoporosis and osteopenia, which is a beneficial supplement to QCT technology.